need help with plans

[tugboat]

Anyone out there know about adapting plans for a steel tug to ferro cement?...I believe in ferro as a solid (and not obsolete) material...IF it is done right. My issue is that I have great plans for a 45 ft steel tug (designed for the us navy 1943-1950's). I cannot figure out some things:
1. what is the knuckle in the table of offsets? 2. why are there more frames than stations??? this one i have been trying to decipher for a month but to no avail(o.k. don't laugh). So anyone have any idea why there are more frames than stations? there are only offsets for the stations but the construction plans show a lot more frames than there appears to be offsets for...there is no info missing i am just not getting it. hope someone could help...

[Bito]

Stations usually run FP, 1, 2, 3, 4, 5, 6, 7, 8, 9, Midships, 11, 12, 13, 14, 15, 16, 17, 18, 19, AP. These are used to define the hull shape in the linesplan and when you loft the boat. Frames are where structural frames are located for the boat. They don't need to correlate to the stations. You could draw a boat with 10 stations that had 59 frames if you wanted to. I built a rowboat with 10 stations and 3 frames.

I don't follow the knuckle -- is it just a knuckle? Sometimes tugboats have knuckles. It's easier than bending the steel, and it doesn't cause a significant increase in resistance if the knuckle is aligned parallel with the flow over that part of the hull.

[tugboat]

Hi Bito, thanks for replying, i hear what you are saying about the stations, but that leaves me with the problem of building the frames. if there are more frames than stations how do i figure out how the frames are developed?
Would i need to loft the lines out to full size and then get the frames from that info? seems to me that would need a heck of a lot of space and money to build a loft floor? i would not even know how to begin to lift the frames from what is given...anyway i am a little confused. there are some frame details in the construction plans but only about half are shown...what i was wondering is if i build it in ferro, would i need the same amount of frames as in steel? then i could just use the stations as frames and build the counter stern from the construction drawings?

Regards

Doug

[Bito]

Regarding frame spacing -- You can't just take a construction plan for a steel boat and use cement -- you need to get a qualified naval architect to actually go through and determine how to build the hull. I agree that the lines and the arrangement may be great, but you can throw the construction plan in the trash.

Regarding the lofting -- lofting is the fun part!! You can get the offsets of the frames pretty easily. If you don't have a 45-foot floor to loft the boat on, you can do it to scale (1/4 scale should be accurate enough, and I could do that in my dining room) You can also use a computer program like Rhino. You essentially draw the boat in three views, using the offsets in the offsets booklet. Then you draw lines where your frames are supposed to be in the profile view and top view, and measure the offsets from those two views. It's not that tough of a process and there are many books that explain it fairly well.

May I ask -- are you actually planning on building this boat? Do you have a boatyard? Do you have the $$? Why do you want a tug boat? Even though the boat is cement, it's still going to cost a bit to make a 45 foot boat, and you're going to need someplace to build it.

[Guillermo]

Tugboat:
I think it's better to digitalize the forms, do the hull fairing (based in the available sections in the forms plan), by using a devoted computer program and then take the needed frames profiles from there. But you have to take into account that usually forms for steel boats are drawed "out members" or, in other words "inside the skin". Ferrocement forms are rather drawed "out skin", so there is a subtle diference and you have to provide for it.
To know where the frames, bulkheads, stringers, etc. have to be located, you need to perform structure calculations for ferrocement first. As Bito says you should contact an NA with experience in that material.

[Bito]

I know that Rochester Marine Design would be able to throw something together fairly easily if you were interested in going forward with the project. I'd contact them.

[Guillermo]

Tugboat:
You'll find intersting articles on ferro construction at:
http://boatdesign.net/directory/Designers/Design_Articles/
And more info:
http://www.ferroboats.com/

[vishnubaiju]

I saw this link only today.
Generally, in Naval Arch, Knuckle is the joining of the straight line bottom to the staright line portion of the side of the hull. In steel construction The CHINE form (That is knuckle) has two staright parts, the bottom of hull and the side hull are staright parts joint at the knuckle. This is free of curvatures. So cionstruction becomes easy.No bending of plates. In ferro cement you need not follow knuckle. Ofcourse you can. But need not.

Adapting steel to Ferro needs to have modifications in the plan.The weight and the center of garvity changes.

[Guillermo]

...In steel construction The CHINE form (That is knuckle) has two staright parts...
Well, it depends on design. There are steel boats with no chine. Most round steel forms can be adapted to ferrocement, just taking in account the skin issue previously mentioned.

[tugboat]

hey everyone-sorry its been so long since i posted on this thread but it took me this long to get a big enough place to build the boat. ok so- the design is a round bilge design 45 ft army /navy st tug- a 1943 US Army design, their size came about as being the maximum length that could be transported as a unit aboard a railroad flatcar of the period. Mass-produced for the war effort, they served both Army and Navy, designated as YTL by the latter. Several are still in service with the Navy.
dimensions- 45 loa, beam 12.5 ft, depth 6 ft.
the hull is beautiful one of the nicest workign platforms i have ever seen wioth low freeboard stern for working lines...do any pro-ferro-cement advocates think ferro-cement could be used as a viable alternative in working commercial operations if built strong?...and what about getting a commcercial inspection..would it pass?....the only other thing i could do since i cannot afford 1/4 inch plate , is to buy 3/16 plate and ballast it a little more...

what are steel advocates ideas on using 3/16 rather than 1/4 inch?...i personally dont think the stability or characteristic of the hull would be much f a problem using slightly lighter guage..

with ferro i could use thick hull forms which could make it very strong...

btw im starting a new thread using this post as my beginning since its been so long since i have replied...look for it if you think its worth reading the posts...

[tugboat]

can't believe ive put this off for 4 years- got sidetracked by my sub project. but want to just "do it" ... Ive since figured out everything about the build. I have decided to build in steel..ive costed the steel out at aprox 7000.00 plus some extras. I am going to loft out to 1/4 size. then have the drawings reproduced to actual size.
And i amn not going to use 1/4 inch plate as in the scantlings for the hull plating. yes- its going to be lighter...and yes its goingt to throw of some characteristics of the vessle but i doubt the effect will be great and i will compensate with extra ballast below.
but thats better than being heavier. using the legendary
cat d318 marine (NA) w/ mg 61 3:1 gear turning a 36 x 34 steel prop. this was running well in a 40 ft tug before i got it. i expect the build to take about 3 years.

and hopefully as stupid as this sounds, i hope were still around in 2012 long enough to enjoy it. my guess is fossil fuels will be gone soon, and we prolly dont have much time left to enjoy our current use of those fuels...

[JRMacGregor]

I suspect steel is a safer bet than ferro in this case.

Your tug probably had very low freeboard as designed, and cannot afford to be heavier in a new incarnation.

Many ferro cement hulls are heavier than their steel equivalent, and if this proved to be true in your case (and you built to the exact same lines), your ship would float deep, have insufficient freeboard and thus insufficient stability.

However, you should be careful about changing the plate scantlings from 1/4 (6.35mm) to 3/16 (4.7mm). This is not because of overall weight characteristics - you are correct that you could ballast to adjust for lighter steel weight. It is more to do with other things.

The thin plate does not give much impact resistance for workboat duty and is harder to weld without distortion. More importantly (especially since you seem to want to work commercially) you may struggle to get the "new design" approved by ABS or US/Canadian Coast Guard or whoever controls your commercial operation. The originally specified plate thickness went with an original design of frame spacing and frame size - change one element and other things will have to be looked at as well.

Also, having said all that, why not buy a second hand steel tug hull of the type you like ? In the present climate there should be a few around - sold out of the USN. No use for you, but over here in Europe there are one or two old Dutch tug steel hulls around - some in good condition.

[tugboat]

Thanks Jr MacGregor,

i appreciate the response. I know it sounds nuts, but im so picky about deisgns. I wanted a boat that has beautiful lines(in my opinion). and i love this tug.
The issue for me is- in order to buy a tug hull i have to get a loan. I really would rather just invest my "loan" payments each month and not pay interest and build the boat as i go. Yes a loan would mean using it sooner- but i have lots of time to get it right. also i looked at many hulls- and most would cost as much to recondition as to build. I saw one thta needed complete replating and it would have cost me the same to build from scratch and it wasnt really the nice design im looking ofr. i guess it comes down to what i really desire for the characteristics. also I really wont be doing much commercial work..i just want to have a tug- and be different than others. so there wont be the day in day out requirements of a commercial vessel. i may occasionally help unground a boat under the table for a small fee. but thats about it.

can you bend 1/4 inch plate the same as 3/16 using pad eyes and come alongs? to a radius bilge?

[apex1]

Not to become a killjoy, or to discourage you, but allow one question please, tugboat.

Are you aware of the cost you will have to stem all the way down to launching?

It seems you work on tight budget, which can be done. But too tight a budget, or underestimating cost, always ALWAYS, ends up in desaster.

All the best for you, your family, and your project.

Take care.
Richard

[tugboat]

thanks Richard, Yes , there is a great amount of money involved. the steel alone is about 8000.00 cdn.

sadly, It will take me three years to finish this project start to finish- just to launching stage, and there will still need work to be done on it. After studying so long and going back and forth on so many ideas--i just got tired and started the build since lifes too short to keep searching for the perfect boat, , this boat is probably too big for my needs. but it is the ONLY boat I like as much as i do..tomorrow I take my plans to a steel yard to help me cost out the steel.
they will see the construction details and hopefully give me a clear idea. It is winter here so i will have to erect a temporary shelter too.

Richard--maybe you can help: i am not sure if its better to build upside down or right side up?..any ideas on which would be better?
i was leaning towards right side up..but seems plating might be easier upside down?

[tugboat]

also i have the keel ready...

[pdwiley]

Richard--maybe you can help: i am not sure if its better to build upside down or right side up?..any ideas on which would be better?
i was leaning towards right side up..but seems plating might be easier upside down?

There isn't any 'better' IMO, there are only different sets of advantages & disadvantages. How, for example, are you going to turn over a 45' hull?

I'm building right side up and it works for me. I am not claiming that this is the correct way but, for the hull I'm building, it is the way that the designer recommends. What is the recommendation for the hull you want to build?

PDW

[sorenfdk]

Tugboat;

You can not just change the plating from 1/4 inch to 3/16! That's a 25% reduction!
And it's not because of the weight and stability - it's because of the strength of the boat! A thinner plating needs more frames, which leads to more welding which takes time and costs money.
At least get a NA to recalculate the scantlings with the reduced thickness before you go ahead with the building. If you don't, you might very well end up with something dangerous!

[apex1]

Søren,

to stay in metric, we have either 5mm or 6mm hull plating here. And 5x5x5 = 125, whereas 6x6x6 = 216, that is a lot more than 25% difference!

Tugboat,

there is no better way, as PDW pointed out. Yards prefer to build right side up in metal.
And the cost for 6mm vs 5mm is not worth to redesign a boat, so go for 6mm.

You bear in mind, that the steel probably counts for 5% of the total cost only? The entire hull/deck and superstructure will represent about 20% of your project. A tad more when the furnishing gets pretty basic.
Take care Mate, do not destroy your life!
Try to look at your project from a distance, and ask if you would encourage your best friend doing it?

Regards
Richard

[tugboat]

Thanks Richard and sorenfdk....I think your correct--i looked into the difference in price and its not worth going to 3/16th plate--actually i went to the steel dealer today. had the project priced out--you were exactly right about the costs. it appears i did underestimate the costs- i figured on about 12000.00 u.s. but it may be more like about 20000.00 thats more than I wanted to pay. which leaves two options- a smaller design- or doing it in something like ferro-cement and i dont like that material for a tugboat hull...
wood is just not the same... i dont really know where to go from here...i have a smaller tug design, and ill probably have to use that--i wanted the "perfect boat" but it looks like the perfect boat is way too costly...so ill just build a 30 ft'er. I have the keel material and the 30 ft'er is a chine hull and i wanted a radiused or round bilge design. I do have a engine and prop for it. do you like Mal Lows designs?..one is 25.5 ft...maybe thats a better place for me to start... Ill take your advice to build her righted...

[apex1]

Have you seen the Atkin Tug?

All wood! But not cheap at 50ft.
http://www.boat-links.com/Atkinco/Misc/images/HenryJohnsonJames-1.gif

Ferro Cement is more costly than steel, take care before you run into the next error!
(and in all honesty it is cr@p)

Never heard Mal Lows.

Regards
Richard

[pdwiley]

Thanks Richard and sorenfdk....I think your correct--i looked into the difference in price and its not worth going to 3/16th plate--actually i went to the steel dealer today. had the project priced out--you were exactly right about the costs. it appears i did underestimate the costs- i figured on about 12000.00 u.s. but it may be more like about 20000.00 thats more than I wanted to pay. which leaves two options- a smaller design- or doing it in something like ferro-cement and i dont like that material for a tugboat hull...
.

If you build in ferrocement, factor into your calcs that the resale price is going to approximate $0.00 assuming you get it done. I really cannot see FC as being cheaper but I can see it being very labour-intensive.

Have you factored in the cost of blasting your plate to white metal and priming? If not, DO IT NOW!!!!!! My cost locally is $22/m2 - add that up for the size hull you want to build and the cost may equal or exceed the plate itself. If you can get blasted & primed or pickled & oiled plate, do it.

Really if you can't afford the hull then you can't afford the boat. I spent years collecting stuff before even buying the steel for my 11.8m hull. The money still flows out.....

PDW

[tugboat]

wow thanks Richard!...thats a nice design too---check out also www.smalltugs.com, look for the pintle--i own a set of those plans..let me know if you think its worth doing--scantlings are 3/16th frames with 16 inch O.C. 1/4 inch longitudinals, and 3/16th plate? 25.5 ft x 10.3 ft x 4.5 depth??...its small but within my budget...i like the atkins design but im just not a wood guy. however--cna wooden boat be used for commercial applications-i.e. insured and surveyed etc etc for cokmmercial use?? not that I intend to use it for that but i did think of going with a crossover design??? im guessing mooring costs would be cheaper for a 25 - 30 ft tug?

[tugboat]

pdwiley-you make some good points. I have been looking into something called fer-a-lite. its a polyester synthetic morter. I saw a video of it and it looks unbelievably strong and less brittle than fc. In steel what you are saying is very true- but im time rich. I can grind the plate down with a wire brush and grinder wheel bit by bit. .then coat it instead of blasting it.
the steel costs for the 45 ft'er make it out of my range. barely...but nevertheless...

fc is cheaper--i costed out the 45 ft'er at about 6000.00 -7000.00 to do all inclusive (hull and deck). the armiture is about 2000.00. fer-a-lite is even better but a little more expensive but i save big since I dont need plasterers, and it can be done a little at a time.- my only issue is that you cannot easily join parts as in a steel boat - i.e. you cannot weld something to it..it must be epoxied. six of one?.....at this point i have few options-
1. build a self designed 30 ft'er. single chine based on mal lows deisgns and using his scantlings. or build a stock design which i dont like as much.
2. build the 45 ft'er out of a diff material. i.e. perhaps fer-a-lite or ferro or wood or a product called Mg Krete which is a self bonding epoxy based morter at about 45.00 a bag! but incredibly strong. at 11 000 psi compressive strength.
3. give up.
since I refuse to give up--that leaves options 1 and 2.

i better point this out to people so there are no misunderstanding. Im not rich but have enough money to build a good sized boat over a long period of time - three years for example.
what i have lots of is "time"

[tugboat]

this is my UNCORRECTED single chine hull in steel
particulars
30 ft loa,
beam 11 ft 3 inches (molded)
depth 6.5 ft
draft 4.5 ft
single screw
3/16th plate
36 inch prop.


This hull is uncorrected as viewed- I have the corrected plans.

yes i know the shear is not drawn perfectly nor is it parallel with the rub strake here...the plans I corrected are fine.

I haven't done stability calcs but i trust my design cuz its based on others of almost the same dimensions and scantlings. I have taken all the points from other tugs i liked and made it my own...
please dont point out that there is no stability calcs with it or that it wasnt a pro design...i dont care- since i have seen vessels that are more poorly designed that work quite well...its beamy enough to be pretty stable...

[apex1]

Your link does not work, but I tried tugs instead of tuge..............

The Atkin Tug was designed for Navy use during WWII, so I would guess there are no restrictions.

Of course when you have to pay mooring rates, every meter (yard) counts.

Yes I now remember these little Tug´s from that guy. Beatiful, sturdy little ships, in deed.

when you are fine with the size of that small craft, I would guess you get happier with it than with a too big and eventually unaffordable design. A halfway´s finished homebuild is zero value, you know?
Same is valid for a completed FC boat btw. There is hardly any buyer to find for a floating pavement...........which in the end is NOT cheaper. ANd forget about the "advanced" methods, they never made it on the mass market, for good reasons.
Do not make the mistake to compare just the material cost. Your time has a value, no matter how one looks at it. But more important, everything you want to attach to a FC hull/deck will cost you a fortune, and time, time, time.....

Cannot (and don´t want to) comment on the scantlings, I am not a NA! Go for what the designer planned it.

Regards
Richard

[tugboat]

yes they are good tugs...the thing i didnt like on the "Pintle" was the bow is very wide...almost a half moon shape. it didn't seem to be very hydrodynamic...may i aks -why would he design such a bow with a dull entry??? it pushes a lot of water.

...I absolutley agree with you on the size--makes more sense to have a lower slip fee.... mals tugs are already good designs. proven.

costs are fairly low too! it will accept my d318 cat too--sorry to everyone for the typo ill go correct it for the small tugs link...

Richard- my 30 ft'er is based on the Mal low design called the "porker" the only difference is i added a chine so the hull could take a bigger engine and have a straight shaft output...i used a similar wheelhouse design as the 45 ft'er navy and 'ville class tugs" from the war era. everything is 3/16th plate. do you think my design could work?

[tugboat]

Richard -Do you have any other pics of the Atkins or any of it being built?..have you seen one? -i would love to see how it was built...

[pdwiley]

pdwiley-you make some good points. I have been looking into something called fer-a-lite. its a polyester synthetic morter. I saw a video of it and it looks unbelievably strong and less brittle than fc. In steel what you are saying is very true- but im time rich. I can grind the plate down with a wire brush and grinder wheel bit by bit. .then coat it instead of blasting it.


I'm willing to bet money that you give up grinding off mill scale loooooong before you get even close to a 2.5 white blast. You have to do ALL the plate, both sides, and ALL the framing stock and ALL the longitudinals. If you haven't done it, sorry but you really don't know what you're talking about. Wire brushes on an angle grinder will NOT remove tightly adherent mill scale. It doesn't matter how time-rich you are, unless you want to leave your plate to weather until all the mill scale just rusts off, wire brushes will not remove it regardless of what you might think.

As for using grinder wheels, perhaps I should post a picture of the stack of wheel hubs I have used up to date - on blasted & primed steel. You'll go through more than 10X that many.

You're being unrealistic. You've quoted Gil Klingel's book a couple of times (I have a copy), go read what he says about it, then Tom Colvin, every other boat builder out there. I know where you are because I've been there myself. You cannot get away from the bottom line - if you want to do a decent job on a steel hull, all the mill scale has to go and unless you can buy plate with the scale removed, blasting is the only practical way to do it. Thinking otherwise defies everyone else's experience.

Basically you're in denial about the costs involved in what you want.

PDW

[tugboat]

PDW- ok assuming your correct and I am in denial(does that mean I gotta go to meetings?)- is there an inexpensive way to blast a hull?..for instance if i own a compressor- what else would i need and what kind of costs would i be looking at if I did it myself? how much sand for a 30 ft x 11 ft tug? your correct ive never sandblasted anything--but i do have lots of metal work experience. please advise on best -cheapest way to blast a hull--

if I need to look at doing blasting -i will find a way...

[pdwiley]

PDW- ok assuming your correct and I am in denial(does that mean I gotta go to meetings?)- is there an inexpensive way to blast a hull?..for instance if i own a compressor- what else would i need and what kind of costs would i be looking at if I did it myself? how much sand for a 30 ft x 11 ft tug? your correct ive never sandblasted anything--but i do have lots of metal work experience. please advise on best -cheapest way to blast a hull--

if I need to look at doing blasting -i will find a way...

Go and have a read of Murielle's Web site.

http://www.magma.ca/~ovenden/index.htm

She's got a lot of information on how they're blasting their boat.

I chose the option of sending my steel to a local industrial blaster and get it back blasted & primed. It costs me $22/m2 but I don't have to do it myself.

I do have an air compressor big enough to do blasting. It's output is 120 cfm, on the 'acceptable' side of adequate, not overkill. There's a 25HP 415V 3 phase motor driving it. This is not overkill for the work, believe me. I can't give you figures on sand etc consumption because I'm paying a place that's set up to do this. I bought the compressor so I could do small amounts of blasting and run other air-demanding tools.

My understanding is that in the USA both wheel abraded & primed and pickled & oiled plate is available but generally you need to ask your steel merchant for it. Try to see if this is available because if so, you can save yourself a lot of time, money & tears.

I'd happily pay AT LEAST 25% more for steel with the mill scale off straight from the merchant. I'd even compromise on my ideal plate sizes (but not thickness) to get it.

I think we all have gone through this disbelief-denial-cost terror-grudging acceptance cycle on steel work so don't think that I don't sympathise - I do. However you have to build from steel free of mill scale or blast to clean steel before painting when the hull is finished, both ways have pros & cons but the end result is the same.

PDW

[tugboat]

PDW-what type of boat did you build?..what's the stats on her?

[pdwiley]

PDW-what type of boat did you build?..what's the stats on her?

I'm still building her which is why I'm all to painfully familiar with the steel blasting issues. ATM I'm plating the hull.

I chose a Tom Colvin Saugeen Witch design stretched to just under 12m, displaces approx 7.5 tonnes. Tom did the stretch calculations and rigging plan for the lengthened hull plus the new stability calcs etc. Lot of work building but no dramas. The lines & offsets are excellent. I lofted her full scale and picked up all the frame dimensions etc off the loft floor.

PDW

[apex1]

yes they are good tugs...the thing i didnt like on the "Pintle" was the bow is very wide...almost a half moon shape. it didn't seem to be very hydrodynamic...may i aks -why would he design such a bow with a dull entry??? it pushes a lot of water.

Tugs are not raceboats! They need "inefficient" hull shapes to do their job.

...I absolutley agree with you on the size--makes more sense to have a lower slip fee.... mals tugs are already good designs. proven.

costs are fairly low too! it will accept my d318 cat too--sorry to everyone for the typo ill go correct it for the small tugs link...

Richard- my 30 ft'er is based on the Mal low design called the "porker" the only difference is i added a chine so the hull could take a bigger engine and have a straight shaft output...i used a similar wheelhouse design as the 45 ft'er navy and 'ville class tugs" from the war era. everything is 3/16th plate. do you think my design could work?

The ONLY difference is, that you changed the entire design! That is not the way to go Mate. It just does not work, you most probably produce a bitch.

Tugboats are amongst the most dangerous craft afloat! Each and every detail of the design is far more important than on a ocean going cruiser !!!

When you have a vessel at the hook, a screwed design easily kills you.

Stay with a proven design, or give that tug idea up!

Pdwiley gave you the right advice on blasting, he obviously knows what he´s talking!

Regards
Richard

[tugboat]

I'm still building her which is why I'm all to painfully familiar with the steel blasting issues. ATM I'm plating the hull.

I chose a Tom Colvin Saugeen Witch design stretched to just under 12m, displaces approx 7.5 tonnes. Tom did the stretch calculations and rigging plan for the lengthened hull plus the new stability calcs etc. Lot of work building but no dramas. The lines & offsets are excellent. I lofted her full scale and picked up all the frame dimensions etc off the loft floor.

PDW

Awesome stuff--I actually didnt know if Mr Colvin was still doing any design work?..when he had written the book i believe he mentions that he is not going to build any more boats except for his own pleasure. Ill have to go look that up. IS that sail design?..he does have some complicated ornementations ie. the spar on his pinky design and the style of stern look a bit tricky. He is definitely old school...i loved his tugboat reference for cant framing. if you have any pics--i would love to see them?
soryr my pic of the tug hull is so small...
btw i did some calcs for the hull and blasting--it appears that blasting
at $22 /m3 would cost me aprox 2600.00 which isnt bad...hope im on base with the cost figure? the boat would be about 600 square feet give or take...so i figured about 1200 sq ft inside and out roughly?

[tugboat]

PDWILEY- i just called a place here that does blasting- i got a quote based on the 30 ft vessel- he told me the hull would be about 500-1000 dollars to do and about 4 hours of work...thats much less than i thought. but ill have to see if its less work and expense to buy the treated plate...

[apex1]

PDWILEY- i just called a place here that does blasting- i got a quote based on the 30 ft vessel- he told me the hull would be about 500-1000 dollars to do and about 4 hours of work...thats much less than i thought. but ill have to see if its less work and expense to buy the treated plate...

That is not possible to achieve! He meant the outside only, take care! even a 30ft boat interior blasting is much more than a few hrs.

[tugboat]

Richard- asusming that im incorrect about the chine and how ive done the vessel--whats the worst thing that could happen?..im certain it will float..thats the first step--the second is that im sure it wont be too heavy and if too light, ballast will solve that problem...IF NECESSARY...

3rd--i know that the plate thickness is stiff enough. im using the same scnatlings as the 25 ft double chined pintle design...
I cant really see what if a any problems would be??..ive sene other deisgns with almost identical configurations below the waterline...whats the worst thing that can happen--realistically??? I just cant see any real probs with it. but im open to hearing what specific problems might be encountered??...and if necessary ill adjust it accordingly...
yes you are correct that was for outside blasting...

[apex1]

Richard- asusming that im incorrect about the chine and how ive done the vessel--whats the worst thing that could happen?..im certain it will float..thats the first step--the second is that im sure it wont be too heavy and if too light, ballast will solve that problem...IF NECESSARY...

3rd--i know that the plate thickness is stiff enough. im using the same scnatlings as the 25 ft double chined pintle design...
I cant really see what if a any problems would be??..ive sene other deisgns with almost identical configurations below the waterline...whats the worst thing that can happen--realistically??? I just cant see any real probs with it. but im open to hearing what specific problems might be encountered??...and if necessary ill adjust it accordingly...
yes you are correct that was for outside blasting...

First, I don´t know the changes you made, because I don´t know the original design! But changing from round bilge to hard chine is a severe operation, especially on a rather critical vessel, which a tug is generally.
Second, I cannot lead you to a solution, I just don´t have the knowledge to redesign that given boat (or any, if you like), I am not a NA, just a builder.
Third, the scantlings of one 25ft boat can be heavier than for another 30ft craft, for several reasons. So any comment on that issue is not serious without having all the info about the vessel in question. And even then, I am not going to comment on them.
After more than three decades in business and over 40 years at sea, I would NOT design my own yacht. Though I dare to comment on designs and even force NA´s to major changes before I produce a yacht.

That was not too helpful, but it was frank, I hope you can live with it.

Regards
Richard

[MatthewDS]

pdwhiley is correct, you cannot remove mill scale with a wire brush. Additionally, a wire brush will not leave a profile on the surface of the steel.

What this means in simple terms is that a brushed surface will be smooth and slightly polished, resulting in poor coating adhesion. By contrast, a blasted surface will have a rough profile, which is to say, a toothed surface, that your coating will adhere to better.

Hire yourself a professional blasting company, it may seem like a lot up front, but they will be done quickly, and your coating won't fall off afterwards.

I used to be a Nace Coating Inspector.....

Updated: here is a list of qualified coating contractors, most of them will blast as well:
http://www.sspc.org/links/contractor.html

[pdwiley]

Awesome stuff--I actually didnt know if Mr Colvin was still doing any design work?..when he had written the book i believe he mentions that he is not going to build any more boats except for his own pleasure. Ill have to go look that up. IS that sail design?..he does have some complicated ornementations ie. the spar on his pinky design and the style of stern look a bit tricky. He is definitely old school...i loved his tugboat reference for cant framing. if you have any pics--i would love to see them?
soryr my pic of the tug hull is so small...
btw i did some calcs for the hull and blasting--it appears that blasting
at $22 /m3 would cost me aprox 2600.00 which isnt bad...hope im on base with the cost figure? the boat would be about 600 square feet give or take...so i figured about 1200 sq ft inside and out roughly?

The Witch is a stock design and has been stretched before so I don't think it was a lot of work for Tom to change. Yes it is a sail design. As far as I know Tom isn't building boats but he still sells plans and consults. He is in his early 80's as far as I can figure.

The bow on the Witch is strip plated to give compound curvature and looks lovely (if one overlooks a few hollows in mine that I need to fix...). After the bow area it's all developable plates. First boat I've built and it's going well.

The $22/m2 is PER SIDE and you really need to do both sides. Also here we have this lovely thing called GST that adds 10%. 5 plates of 3000 x 1800 cost me $1320 inc GST. I figure I'll use 15 plates by the time I'm done. As near as I can figure it would cost me $5000 to buy sufficient equipment to do the job myself, plus consumables like garnet. Problem is finding the equipment used near where you need it and then you still need to spend the time blasting when you could be doing something else. It's a noisy dirty horrible job, some things are worth paying for. You also need to be on a site where you can get away with blasting, a suburban yard isn't going to be the place and possibly nor is a commercial yard if they also have paint work in progress. There isn't a right answer, circumstances alter cases. I've got 3.5 acres of land and only 2 neighbours who both have more so I can blast (and run angle grinders for hours etc).

BTW I also would not design my own boat nor would I screw with a stock design. You would be amazed (horrified) how seemingly small changes add up to really big ones when you translate a set of 2 dimensional lines to a 3-D object. Build it to the plans, pay the designer to make the mods or I guess pay a NA to do it for you. Professional plans & design advice is dirt cheap compared to the materials costs alone in a 30' plus boat of any type. I'm definitely a DIY type and have designed/built 3 houses including a 3 storey one, but the boat is getting built as closely as my skill permits to the plans provided. Even seemingly little things add up; Tom is adamant that one not use steel for the cabin tops for example because it was designed for ply & glass and the weight of steel raises the COG. OK, you can add ballast to counteract this but now you've reduced your ability to carry stores for the same DWL. OTOH I swapped the keel shoe from 200 x 25 flat bar to 200 x 40 because I got it cheap, but I asked the designer first and got his OK. Steel is cheaper than lead and it's all ballast there.

PDW

[tugboat]

First, I don´t know the changes you made, because I don´t know the original design! But changing from round bilge to hard chine is a severe operation, especially on a rather critical vessel, which a tug is generally.
Second, I cannot lead you to a solution, I just don´t have the knowledge to redesign that given boat (or any, if you like), I am not a NA, just a builder.
Third, the scantlings of one 25ft boat can be heavier than for another 30ft craft, for several reasons. So any comment on that issue is not serious without having all the info about the vessel in question. And even then, I am not going to comment on them.
After more than three decades in business and over 40 years at sea, I would NOT design my own yacht. Though I dare to comment on designs and even force NA´s to major changes before I produce a yacht.

That was not too helpful, but it was frank, I hope you can live with it.

Regards
Richard

Its all good Richard--i learn from everything that gets said, just one thing i maybe didnt mention was that i hadnt planned on changing from a round bilge to a hard chine or vice-versa. the pintle is actually a double chine design. but i just used a single chine for the tug hull as shown.
as you know any input is always welcome when it is in the spirit of helpfulness...I appreciate that you are frank--It gives me a good idea of the difficulties in this process- all i can say for sure now is that -In the next 20 days ill have the engine shipped up to the build site, change the transmission (an Mg 61 twin disc gear 3:1) and ill be starting the build. Ill post pics of it...humorously- At this point my wife/partner intervened and told me to stop ping ponging and build the 45 ft boat since thats the one i want...she supports me--so even though its not the boat i designed it will be sound.--ill build it from the N.A. plans as given. *but fair warning*--you may not like my choice of materials...but thats for another day and thread...

[tugboat]

pdwhiley is correct, you cannot remove mill scale with a wire brush. Additionally, a wire brush will not leave a profile on the surface of the steel.

What this means in simple terms is that a brushed surface will be smooth and slightly polished, resulting in poor coating adhesion. By contrast, a blasted surface will have a rough profile, which is to say, a toothed surface, that your coating will adhere to better.

Hire yourself a professional blasting company, it may seem like a lot up front, but they will be done quickly, and your coating won't fall off afterwards.

I used to be a Nace Coating Inspector.....

Updated: here is a list of qualified coating contractors, most of them will blast as well:
http://www.sspc.org/links/contractor.html

Hi MathewDS- yes it turns out i was in denial afterall...but i was quick to realize this fact. however --since i posted last My partner has stepped in and basically tired of my boating rants and when the women of the house decides soemthing -she usually knows better than me...anyway -ill be building the 45 ft tug- but -ill not be doing it in steel. I did check into the cost of blasting and it wasnt as bad as i first thought- about 2000.00..inside and out.

your post was appreciated!

[tugboat]

The Witch is a stock design and has been stretched before so I don't think it was a lot of work for Tom to change. Yes it is a sail design. As far as I know Tom isn't building boats but he still sells plans and consults. He is in his early 80's as far as I can figure.

The bow on the Witch is strip plated to give compound curvature and looks lovely (if one overlooks a few hollows in mine that I need to fix...). After the bow area it's all developable plates. First boat I've built and it's going well.

The $22/m2 is PER SIDE and you really need to do both sides. Also here we have this lovely thing called GST that adds 10%. 5 plates of 3000 x 1800 cost me $1320 inc GST. I figure I'll use 15 plates by the time I'm done. As near as I can figure it would cost me $5000 to buy sufficient equipment to do the job myself, plus consumables like garnet. Problem is finding the equipment used near where you need it and then you still need to spend the time blasting when you could be doing something else. It's a noisy dirty horrible job, some things are worth paying for. You also need to be on a site where you can get away with blasting, a suburban yard isn't going to be the place and possibly nor is a commercial yard if they also have paint work in progress. There isn't a right answer, circumstances alter cases. I've got 3.5 acres of land and only 2 neighbours who both have more so I can blast (and run angle grinders for hours etc).

BTW I also would not design my own boat nor would I screw with a stock design. You would be amazed (horrified) how seemingly small changes add up to really big ones when you translate a set of 2 dimensional lines to a 3-D object. Build it to the plans, pay the designer to make the mods or I guess pay a NA to do it for you. Professional plans & design advice is dirt cheap compared to the materials costs alone in a 30' plus boat of any type. I'm definitely a DIY type and have designed/built 3 houses including a 3 storey one, but the boat is getting built as closely as my skill permits to the plans provided. Even seemingly little things add up; Tom is adamant that one not use steel for the cabin tops for example because it was designed for ply & glass and the weight of steel raises the COG. OK, you can add ballast to counteract this but now you've reduced your ability to carry stores for the same DWL. OTOH I swapped the keel shoe from 200 x 25 flat bar to 200 x 40 because I got it cheap, but I asked the designer first and got his OK. Steel is cheaper than lead and it's all ballast there.

PDW

PDW-ohhh we have that nasty little thing called a harmonized sales tax too! used to be GST but they merged it with the provincial and federal tax to the tune of 13%!!

and your reasons in your post which paralleled mine-is exactly why today -i sat down-took out my models of both hulls, and locked myself into a room for an hour --still couldnt decide between either two- then consulted my oracle(my partner gf). since then i have firmly decided to just build what i wanted in the first place- a stock design at 45 ft tug hull- but im not going to use steel..

i can get a close approximation of the wieghts with the materials, but ill need ballast-however I understand in some cases this is actually an asset.
and Ill be calling the design office too- but its unlikely that the office still has the deisgner from 1952 still there- however I may take the plans to a engineer. or N.A for some advice and pay for it--it cant be all that expensive-and less than sandblasting- cnc'ing curved plate and frames for a 45 radiused or round bilge hull!!
I know of a product on the market thats as strong as steel and more resistant to puncture than steel. Ill be using that instead. There will people who will tell me not to do this-that the material will need to be heavy or that the material is junk--im sorry for them because they dont knwo what i know about it...
--but -i am just a rebel--so we will see, its been a pleasure PDW- i appreciated that last post since I am a Colvin fan and owe him a debt of gratitude to understanding how a steel boat is built. I really wish he would have designed some smaller tugs...say in the 35-40 ft range. but i am very very intent on having a radius chined or round bilge tug design for economical running. I dislike hard chine designs. There was a nice plan for a 40 ft'er in steel by the MacNaughton group--but just didnt quite meet my needs. i didnt like the upswept fantail stern. maybe I could see if Mr Colvin would design a small tug for me? what do you think he would charge?

[pdwiley]

I know of a product on the market thats as strong as steel and more resistant to puncture than steel. Ill be using that instead. There will people who will tell me not to do this-that the material will need to be heavy or that the material is junk--im sorry for them because they dont knwo what i know about it...e?

You're going to use Fer-a-lite I'd guess. Good luck with it. I have nothing further to contribute to the discussion, however, as not only do I know nothing about it except what I read 30+ years ago (it isn't new), I also have no interest in its use. The resale value of the boat is going to be a small fraction of a steel hull built to plan because nobody else believes in that material either.

Have fun whatever you choose because there's little other reason for building your own boat.

PDW

[apex1]

Its all good Richard------------------------------------------ *but fair warning*--you may not like my choice of materials...but thats for another day and thread...

Oh, you must not warn me, it is completely unimportant if I like a material or not.
Your choice anyway, but a terrible bad choice for a tugboat.
As mentioned by PDW, the final value of your boat will be close to zero, but the cost will be at least as high as for a steel boat. And it will never stand any tugboat service, no matter what the snakeoil sales drivel tells you.

I made my comments already here:http://www.boatdesign.net/forums/boat-design/can-you-decrease-plate-thickness-use-fc-tug-32369-4.html#post411933

I am out of here.

Good luck
Richard

[MikeJohns]

......... I may take the plans to a engineer. or N.A for some advice and pay for it--it cant be all that expensive-and less than sandblasting- cnc'ing curved plate and frames for a 45 radiused or round bilge hull!!

I know of a product on the market thats as strong as steel and more resistant to puncture than steel.

Ill be using that instead.
There will people who will tell me not to do this-that the material will need to be heavy or that the material is junk--im sorry for them because they dont knwo what i know about it...
--but -i am just a rebel--so we will see,.........


.................but i am very very intent on having a radius chined or round bilge tug design for economical running.........

Post your plans here and I'll comment. Or send them to me if you are shy.

But someone's put kangaroos in your top paddock:rolleyes:
You cannot beat steel for durability in adverse situations . If anyone's telling you a ferralight hull is stronger and robust they are so ignorant it's criminal. And I'd be happy to go over the facts with you.
Ask the salesman the shear strength of the material for a start! You'll also find they are comparing A36 yield with ferralight rupture which nicely ignores the reserve strength steel has before it finally ruptures.

As for chines and performance. A properly placed chine can actually reduce the hull resistance and there's a lot of current testing along those lines, even for racing sailboat hulls,
Even poorly placed chines aren't too bad providing they are more or less aligned to the flow underway in the forward part of the vessel. A radiused chine using a constant rolled section is easy to insert with care but time consuming and hard to do well yourself.

I'd suggest a softened chine aft above the waterline for aesthetics but it's not necessary for performance.
I have seen many attempts at a radiused chine that would have looked so much better if they had simply opted for a softened hard chine.

There have been very large salvage tugs build with entirely flat panels fwd with no curvature in any direction they look very 'cubic' but still perform surprisingly well, as a general rule provided your flow lines are not asked to follow angles less than 130 degrees they don't shed vortices ( no increased resistance).

For ease of building sheet boats (and ease of repair) you cannot beat fully developable plates. Steel is the most forgiving material by a country mile for amateur construction.

Don't get talked into wonder products by fast talking salesman. Post the material specs here at least for starters.

[MikeJohns]

.........

I am out of here.

Good luck
Richard


No no stay, if we gang up on him maybe we can talk some sense to his confused rebellious inner self. :)

[pdwiley]

But someone's put kangaroos in your top paddock:rolleyes:
You cannot beat steel for durability in adverse situations . If anyones telling you a ferralight hull is stronger and robust they are so ignorant it's criminal.

Don't get talked into wonder products by fast talking salesman. Or post the material specs here at least for starters.

Take 2 examples of really, really hard service vessels. Ice breakers and tug boats. I spent 11 years working with ice breakers.

Now show me one, built anywhere, ever, that has been built from FC or fer-a-lite. It hasn't happened and it isn't going to happen because it's a totally inappropriate material for the job.

The first time a big load comes onto a bitt or pintle or whatever attached to a FC or fer-a-lite deck is the time that a big chunk of that deck peels right out of the boat. Hell, I've sheared 8 24mm bolts holding a hydraulic winch down to a steel deck when it got heavily loaded up. An engineer did that design and I never did think it was any good (lucky it wasn't you, Mike....)

PDW

[rasorinc]

Wood, Wood, Wood,wood, Wood Followed By A Fiberglass Overlay Or Dynal
Or Even A Stronger Fiber Material. Wood Lasts Generations.

[apex1]

Take 2 examples of really, really hard service vessels. Ice breakers and tug boats. I spent 11 years working with ice breakers.PDW

Aha,
hello comrade!
Made my master on Icebreakers in the Baltic. 13 Ice campaigns spread over 18 years.

Mike,

I still hope we can convince him. Tad tried also on the related thread.

Lets hope our united force will manage to steer him away from disappointment or desaster.

Richard

[tugboat]

No no stay, if we gang up on him maybe we can talk some sense to his confused rebellious inner self. :)

hehe-- good luck on that!

[tugboat]

Post your plans here and I'll comment. Or send them to me if you are shy.

But someone's put kangaroos in your top paddock:rolleyes:
You cannot beat steel for durability in adverse situations . If anyones telling you a ferralight hull is stronger and robust they are so ignorant it's criminal. And I'd be happy to go over the facts with you.
Ask the salesman the shear strength of the material for a start! You'll also find they are comparing A36 yield with ferralight rupture which nicely ignores the reserve strength steel has before it finally ruptures.

As for chines and performance. A properly placed chine can actually reduce the hull resistance and there's a lot of current testing along those lines, even for racing sailboat hulls,
Even poorly placed chines aren't too bad providing they are more or less aligned to the flow underway in the foreward part of the vessel. A radiused chine using a constant rolled section is easy to insert with care but time consuming and hard to do well yourself.

I'd suggest a softened chine aft above the waterline for aesthetics but it's not necessary for performance.
I have seen many attempts at a radiused chine that would have looked so much better if they had simply opted for a softnened hard chine.

There have been very large salvage tugs build with entirely flat panels fwd with no curvature in any direction they look very 'cubic' but still perform surprisingly well, as a general rule provided your flow lines are not asked to follow angles less than 130 degrees they don't shed vortices ( no increased resistance).

For ease of building sheet boats (and ease of repair) you cannot beat fully developable plates. Stel is the most forgiving material by a country mile for amateur construction.

Don't get talked into wonder products by fast talking salesman. Or post the material specs here at least for starters.

Hi Mike- I actually actively pursued the product when i heard about it..The salesman didnt say much...have you ever seen this stuff??? until you see it in action --regardless of your opinion NOW- then comment..I know steel is strong--but this is comparable...I worked on Tugs also a 65 ft twin screw and three 90 ft'ers. pushing barges-- steel is easily bent punctured etc...its not the miracle material that you and others make it out to be--plus its three times the cost if done to the scantlings I have...the difference between cost and strength makes the extra cost not cost effective in comparison to cost/strength...

[tugboat]

Aha,
hello comrade!
Made my master on Icebreakers in the Baltic. 13 Ice campaigns spread over 18 years.

Mike,

I still hope we can convince him. Tad tried also on the related thread.

Lets hope our united force will manage to steer him away from disappointment or desaster.

Richard

Richard--the Distaster might end up being--that you guys could all be wrong???.ouch!.. lol all said in the spirit of fun!!...ill just have to prove to you guys--itll be "I" who cracks the ferro-police's denial before its over...(winking)!

cheers to all

[tugboat]

ill pit my 1 inch thick fer-a-lite hull against 1/3 inch steel any time in ice!!!

[tugboat]

Take 2 examples of really, really hard service vessels. Ice breakers and tug boats. I spent 11 years working with ice breakers.

Now show me one, built anywhere, ever, that has been built from FC or fer-a-lite. It hasn't happened and it isn't going to happen because it's a totally inappropriate material for the job.

The first time a big load comes onto a bitt or pintle or whatever attached to a FC or fer-a-lite deck is the time that a big chunk of that deck peels right out of the boat. Hell, I've sheared 8 24mm bolts holding a hydraulic winch down to a steel deck when it got heavily loaded up. An engineer did that design and I never did think it was any good (lucky it wasn't you, Mike....)

PDW

PDW- Just cuz it aint built dont mean it aint good! besides there were a few C-logger deisgns built--see above pdf...in ferro...

[tugboat]

Post your plans here and I'll comment. Or send them to me if you are shy.

But someone's put kangaroos in your top paddock:rolleyes:
You cannot beat steel for durability in adverse situations . If anyones telling you a ferralight hull is stronger and robust they are so ignorant it's criminal. And I'd be happy to go over the facts with you. Mike please tell me the cons of fer-a-lite on my thread...im not shy :)

For ease of building sheet boats (and ease of repair) you cannot beat fully developable plates. Stel is the most forgiving material by a country mile for amateur construction.***** agreed thats the advantage of steel...you can just weld to it anything---im in agreement there except try to fit round plate...and we all know that ideally a round bilge hull is the best hullform... only steel lovers say chine hulls are better...Don't get talked into wonder products by fast talking salesman. Or post the material specs here at least for starters.

see responses in bold

[apex1]

As I assumed, that seems to be senseless.

Tugboat,

you will be extremely surprised in the end, both costwise and about the vessel you built.

But make your own experience. Sure we are all wrong.

edit: in Ice I break your boat in one second! Even with 5in. hull thickness.

Richard

btw
Mike has forgotten more about FC boats than you probably will ever learn.

[tugboat]

As I assumed, that seems to be senseless.

Tugboat,

you will be extremely surprised in the end, both costwise and about the vessel you built.

But make your own experience. Sure we are all wrong.

edit: in Ice I break your boat in one second! Even with 5in. hull thickness.

Richard

btw
Mike has forgotten more about FC boats than you probably will ever learn.

cool-- name the place and time!!..im up for that bet...if i win i get your boat!
Im sure mike knows his stuff too...not syaing he doesnt but were tlaking something else not F.C. ill do a test slab and youtube the destruction of it...hows that?

[apex1]

Don´t make bets you cannot win.

[MikeJohns]

............have you ever seen this stuff??? until you see it in action --regardless of your opinion NOW- then comment........

..........I know steel is strong--but this is comparable...I worked on Tugs also a 65 ft twin screw and three 90 ft'ers. pushing barges-- steel is easily bent punctured etc...its not the miracle material that you and others make it out to be--...........

I've seen the material. I inspected a vessel around 8 years ago for a friend (polyester based ferralite) and it had problems. The boat ( A 50 foot sailboat) was just about given away. It had blistered and there were pockets of acidic fluid in contact with the steel core it was eventually sorted and fibreglassed over and is still around. The material I saw on that boat absorbed moisture and hydrolised. I can't get enthused about marine materials that do that.

Metals are only easily bent permanently if you exceed the yield strength. You can design accordingly. Steel boats (as opposed to ships) are not prone to being holed to the extent that it's almost completely unheard of.

Material properties are the absolutes here, nothing magic happens when you form a hull out of a certain material. We design structures around material properties, it's an applied science called engineering:).

So some really simple and hopefully eye opening questions for you to ask. What is the SHEAR strength of the material you are advocating? And what is it's STIFFNESS. These are very simple but important material properties.

I'd be interested to know. If the supplier can't tell you then run a mile.

[tugboat]

Hey Mike- here is a comparison of concrete and the fer-a-lite, notice the bending strength. and this is WITHOUT reinforcement--that point alone sells me not to mention the stuff can be trowelled on by one guy over a period of weeks if necessary.... a coat of epoxy should keep it from soaking up water...


FER-A-LITE DATA

PHYSICAL PROPERTIES COMPARISON

(without wire reinforcing)

Portland Cement------------------------------------------------- FER-A-LITE

bending strength (Modulus of Rupture) 700 psi ------------------ 3600 plus psi



Compression strength 5-10,000 psi ----------------------------------8000 psi



Weight lbs per cu. ft. 144 --------------------------------------------------60

[MikeJohns]

Hey Mike- here is a comparison of concrete and the fer-a-lite, notice the bending strength. ........


Standard plaster with no reinforcing vs ferralight with high tensile steel reinforcing ,mmmmm that's really useful and honest.
There's a lot more to materials than they have given you there:!:

Unfortunately that’s cherry picking numbers that have little real meaning on their own. Do they have a proper material properties data sheet?

You really need to know the stiffness of the material AKA Youngs Modulus(E). For both tension and compression. (You will also find being a plastic that the properties vary with temperature).

You should be provided with the shear strength as well. They are both important properties.

Also consider how it gets on with the mesh will depend on the bond strength to bare steel and the thermal expansion coefficient.

Material properties for elastic materials should also be given for a % change in dimensions and this is used as a practical yield figure.

Finally barrier coats don't stop moisture ingress they just slow it.

[tugboat]

Hi Mike - I dont think this material is absorbent...ill check, i have a sample coming but concrete is actually tried and proven too. I'm not saying your wrong--i just cant see epoxy allowing moisture or water to penetrate the hull? On a true FC hull- concrete absorbs so little..and then a barrier coat of epoxy literally seals it up...Ive seen quite a few FC boat hulls -ive seen them opened up too but never saw moisture probs unless the work was shoddy...but ill keep it in mind for sure...

[Knut Sand]

-------------- FER-A-LITE

bending strength (Modulus of Rupture)

Another interesting number is the tension properties, (I'm a little unsure of the right word here...) I mean the clean tension/ pull, the material can take in a clean pull, straight out..

That will determine the 0-axis, the cross section where the material will collapse about. Of course, you'll have a steel cage, reinforcement that will help, but salt sea is an unforgiving place, it may not always be there....:confused:

Epoxy and correct use of electricity may be enough to give the steel a long and lasting life, but then again... You may only need a neighbour in the boatyard that screws that up...:rolleyes:

[Landlubber]

tugboat,

Do a bit of homework on resale values of non "standard" boats......it may just open your eyes.....building a boat from a non standard material immediately limits the saleability (and sometimes sailability too) to certain individuals that have generally no idea of what they are buying....most purchasers listen to other boatbuilders or surveyors and realise that one day the vessel will be sold, limiting the amount of potential purchasers from the start of build is not real smart mate.

[tugboat]

tugboat,

Do a bit of homework on resale values of non "standard" boats......it may just open your eyes.....building a boat from a non standard material immediately limits the saleability (and sometimes sailability too) to certain individuals that have generally no idea of what they are buying....most purchasers listen to other boatbuilders or surveyors and realise that one day the vessel will be sold, limiting the amount of potential purchasers from the start of build is not real smart mate.

HI landlubber- appreciate the input--i suppose i should have stated this some time ago since your point has been metioned a few times about resale---

the bottom line for me about resale: I don't really give a crap...i build my boat to enjoy it. i am building it for me -not to turn a profit--if i get ten years out of it and get what i put into it--thats a-ok for me...

cheers

[Landlubber]

tugboat,

I understand, that is your choice, but it would be nice to at least get back what you put in. Unfortunately i am a boatbuilder, I do not see any reason at all why you should build a boat and then loose money on it (but i am very aware that this happens many times)... to each his own, at least you have listened to others opinions and decided to do what you consider best for you.

[MikeJohns]

Hi Mike - I dont think this material is absorbent...ill check, .....

It will absorb moisture it's the nature of the material. Barrier coats work with some materials becasue the water molecules pass through at a greater rate than they pass the barrier. Some materials such as polyester actually 'hold' the water molecules until they are saturated.
FC with pozolanic additive is very impervious to water, more so than polyester. Other materials like wood are quite happy with a certain moisture level. Some materials hydrolise ( water actually breaks the material down) and unfortuantely polyester is in this arena. The side product is acidic which is the opposite to the alkaline conditions that passivate steel.

[tugboat]

Mike--if this was such a bad product -i.e using polyester resin--no one would have fiberglass boats at all...

and fer-a-lite boats wouldnt have last 30 + years---for info-checkl out the fer-a-lite thread..theres some good info on there--and lots of naysayers..
however im not disregarding what your saying, ill look into it further...

cheers

[apex1]

Mike--if this was such a bad product -i.e using polyester resin--no one would have fiberglass boats at all...

No?
You are obviously not aware that you are not the only one completely ignorant on the globe!

Some in the industry are still selling poly crap to the boaters, well knowing that it is not what their customers expect. And on top of that, they would just need some pennies more to do better.

and fer-a-lite boats wouldnt have last 30 + years---for info-checkl out the fer-a-lite thread..theres some good info on there--and lots of naysayers..
however im not disregarding what your saying, ill look into it further...
cheers

In the port of Hamburg was a FC hulk afloat for more than half a century. Never finished, so, never sailed a mile, but afloat. Finally broke into pieces, just so.

What did that prove?

One can say, the material is very durable.
--yes of course, when not sailed or otherwise stressed, and in fresh water.

One can say it is very weak, when it breaks without any damage from impacts or thelike.
--yes of course, that should not happen, but, hey, it was never finished and never maintained.

And one can say, it proves nothing. There are far older steel boats / hulks around, and they did cross the seas, and did not rust away. But many younger steel boats are long gone.

You see?
Your preconception and stubbornness must just be strong enough, to see only what you want to see, and it is the truth, at least for you!

As I said, go for it, make your own experience, and be happy with it!
Who cares......................

[Landlubber]

"Who cares......................"

...you do you poor bugger, just try to let it go mate, you can lead a horse to water, you cannot make it drink......it is a worry eh. I feel sorry too for what some people do, but we have to respect them for their own decisions if that is what they wish to do, c'est la vie.

[MikeJohns]

Very quickly, looking at the test figures Fer a light has an almost identical modulus of rupture to standard ferro cement which is around 62MPa (9000 psi).

Wood is a similar ( some types are better) performer. Steel is around 5 times stronger to yield and 6 1/2 times stronger to rupture.

[pdwiley]

Very quickly, looking at the test figures Fer a light has an almost identical modulus of rupture to standard ferro cement which is around 62MPa (9000 psi).

Wood is a similar ( some types are better) performer. Steel is around 5 times stronger to yield and 6 1/2 times stronger to rupture.

You're missing the point. Engineering data has no relevance in the light of revealed truth. Ask any member of a religious sect.

BTW other than bloody heavy (1.2g/cm3 in my reference book) how does iron bark stack up? Grey iron bark if it matters. They built all the old Sydney wool stores from that stuff, beams 300 x 300 x 9m or longer.

I've been fighting the good fight with a sheet of steel on the bottom of the hull. Its recalcitrance is yielding to brute force and a good technique I picked up from Murielle's web site. The next one should be quicker as I know what to expect (suuuuuure.....)

PDW

[MikeJohns]

Peter
Strength to weight wood is hard to beat without going to carbon fibre. Even then wood can have an edge in some areas.

The Eucalypts like steel are great for heavy displacment craft and some like Ironbark are tremendously strong where stresses run in the main fibre direction. But tools blunt very quickly working with those woods so they are hard to laminate.

[M&M Ovenden]

Tugboat,
I'm just getting back on your posts about your sandblasting quotes. I realize you decided to walk away from steel but want to clarify something about sandblasting a boat as I don't believe those quotes were for proper blasting quality and should make things clear for other readers of the thread. As I'm lazy this morning I'll just copy and past part of my website:

"The sandblasting of a steel boat has two reasons to be. First we want to remove the mil scale to avoid it causing galvanic corrosion by reacting with the steel. We are then aiming for as white of a finish as possible. Sandblasting to white metal (SSPC-SP5 (SSI-Sa3), or NACE #1 surface preparation standard ) means what it means, the result is a white (pale grey) surface. A commercial blast (SSPC-SP6 (SSI-Sa2), or NACE #3) would leave some of the tougher scale on the metal and a brush blast ( Brush Off Blast SSPC-SP7 (SSI-Sa1), or NACE #4) would only blow the loose impurities. If you are hiring a contractor to sandblast your boat, make sure the finish you want is clear and verify that you are getting the finish you want before he gets to much done. The second purpose of sandblasting is to provide an anchor pattern to increase paint adherence. Epoxy paints work by mechanical adherence and will stick better to a gritted surface than a polished surface. The anchor pattern depends on the sands grit size. We use 35-70 (#40) sand. "

What I'm saying here is that there are different quality of blasting and if you don't precise exactly what you need done, you'll get a quote for a brush blast. If you ask for white metal blasting and are very clear about wanting all the mil scale gone, I doubt you get a clear quote. You will most likely get an hourly rate. Some contractors will actually shy away from the job.

If that quote was really for a proper white blast. Either it is for workers hourly rate only and the guy is not paying himself much, than you should expect a lot more "ching ching" for diesel and sand. Or that guy is making you an absurd favor, because he's not going to get into his money.

cheers,
Murielle

[tugboat]

Hi Murielle, yea--it was looking really expensive...it seems the blasting would be about half the cost of the steel needed...for this this is an issue since steel is reputed to be one of the more inexpensive. Steel will always be my fav way to build and i ahev one other boat i built in steel..but did not blast since it was small enough to grind down to white metal (pontoons).
sadly--the costs make this big cost prohibitive. not necessarily that over three years i cant build it but because i am stubborn and want to find econimical solutions to problems...
i appreciate your posts...love your boat too!!

[tugboat]

In the port of Hamburg was a FC hulk afloat for more than half a century. Never finished, so, never sailed a mile, but afloat. Finally broke into pieces, just so.

What did that prove?

One can say, the material is very durable.
--yes of course, when not sailed or otherwise stressed, and in fresh water.

One can say it is very weak, when it breaks without any damage from impacts or thelike.
--yes of course, that should not happen, but, hey, it was never finished and never maintained.

And one can say, it proves nothing. There are far older steel boats / hulks around, and they did cross the seas, and did not rust away. But many younger steel boats are long gone.

You see?
Your preconception and stubbornness must just be strong enough, to see only what you want to see, and it is the truth, at least for you!

As I said, go for it, make your own experience, and be happy with it!
Who cares......................

steels always been my first choice...but FC is undeniably strong and practical IF done right...

[tugboat]

Very quickly, looking at the test figures Fer a light has an almost identical modulus of rupture to standard ferro cement which is around 62MPa (9000 psi).

Wood is a similar ( some types are better) performer. Steel is around 5 times stronger to yield and 6 1/2 times stronger to rupture.

yes--thanks i appreciate the facts ...not accusations ...

Absolutley Mike-- steel is my first choice-im only saying that FC is a viable alternative and less money---if it is a commercial vessel--i would be goign steel..but for a crossover vessel like mine--id be comfortable with either..

[tugboat]

Another interesting number is the tension properties, (I'm a little unsure of the right word here...) I mean the clean tension/ pull, the material can take in a clean pull, straight out..

That will determine the 0-axis, the cross section where the material will collapse about. Of course, you'll have a steel cage, reinforcement that will help, but salt sea is an unforgiving place, it may not always be there....:confused:

Epoxy and correct use of electricity may be enough to give the steel a long and lasting life, but then again... You may only need a neighbour in the boatyard that screws that up...:rolleyes:

Knut--i hope im understanding you correctly--are you talking baout a hull fitting and the puling stress?? i.e. when towing for instance the bitts are welded to a steel deck making them a part of the whole structure??..in thats sense then a bitt might pull out of fer-a-lite?? hope that i understood...

[tugboat]

You're missing the point. Engineering data has no relevance in the light of revealed truth. Ask any member of a religious sect.

BTW other than bloody heavy (1.2g/cm3 in my reference book) how does iron bark stack up? Grey iron bark if it matters. They built all the old Sydney wool stores from that stuff, beams 300 x 300 x 9m or longer.

I've been fighting the good fight with a sheet of steel on the bottom of the hull. Its recalcitrance is yielding to brute force and a good technique I picked up from Murielle's web site. The next one should be quicker as I know what to expect (suuuuuure.....)

PDW

Pdw- please explain--i dont know what iron bark is??

off topic but --since i was asking earilier about sandblasting--do you plan on blasting her to white metal ??.or is there some happy medium in doing that? please post pics...Colvin has great designs...im guessing your either pulling a plate in with pad eyes and come alongs or some similar method? i have a bad back--do you find your in any back pain at the end of the day?--this was one reason for not doing the boat in steel for me...i can barely move when i work long periods..form back pain..hence for these reasons i had to rethink doing steel...i didnt want to post my reasons for obvious reasons...

[tugboat]

Peter
Strength to weight wood is hard to beat without going to carbon fibre. Even then wood can have an edge in some areas.

The Eucalypts like steel are great for heavy displacment craft and some like Ironbark are tremendously strong where stresses run in the main fibre direction. But tools blunt very quickly working with those woods so they are hard to laminate.

Ironbark then must be a tree species not found here in Canada--there is a tree here called iron wood..i wonder if it has similar properties -in fact my tugboat will be named "Ironwood"

[darr]

Now suddenly instead of just a separated matrix on the mystery boat, it now suffers from multiple and severe blistering?

There must be a laminate involved for blistering, I have never heard of blistering that did not require a laminate issue to start the process. Or perhaps you failed to continue the statement to the possible conclusion that they had applied Gelcoat and was seeing Gelcoat blistering between the Gelcoat and skinning material on the Fer-A-Lite hull.

That is not a failing of the Fer-A-Lite material or process, in fact Gelcoat blistering is the biggest issue on any boat that suffers from blistering.

Fer-A-Lite does not contain any fibers of sufficient length or orientation that would allow blistering.

If in fact there is an issue around the interface of the steel and the Fer-A-Lite material, it is because they applied the material to an armature that was not at a sufficient temperature to allow the full curing of the material.

This is clearly spelled out in several places that you must not attempt to use the material below x degrees and that the armature must be at or above that ambient temp.

A similar issue occurs on any any fiberglass hull if they do follow the temp guidelines.

Give me a break!

[darr]

Mike,

If in fact they did apply the material below the recommended temp. the following happens, you end up material that never fully sets in direct contact with the armature, the armature is nothing but a big heat sink during plastering, if the armature is too cold, the material never fully kicks.

And it is very easy to detect. Fully cured Fer-A-Lite will ring with a high pitched note, if there is unkicked material, it will respond with a hollow thud.

This would definately impact the strength of the entire matrix, and cause a reaction between the various components in the uncured mass and the steel armature.

Platt had several warnings about temp of application in his directions that shippped with the material as well as in the book he sent along.

That is not blistering as a failure of the material, that would be a failure due to improper building process, not following the clearly defined application temp. guidelines.

That would allow the matrix to separate with repeated vibrations.

I sure would like to know what part of the world, what time of year it was built.

Possibilities why the mystery boat has a problem

Did not follow proper and documented instructions in regard to:
1. Temp guidelines for application
2. Failed to skin the vessel at construction
3. Improperly applied GelCoat

So pretty much except for #2, the same issues could and do occur with production fiberglass hulls (in some instances)

[tugboat]

now heres a practical question on the plans-- im going to start to cut my frames...
ive never lofted "Diagonals" before can someone-without throwing insults- explain to me if the diagonal is measured from the CL downwards on the diagonal , or is it measured outwards from the CL??..when i check it against the offsets it seems the diagonal is measured outwards to a point past a buttock. but the book says its measured downwards at an angle(or at leats thats what i got from it-ill recheck in case i misunderstood)???

[Landlubber]

Diagonals are generally placed so as to be perpendicular to the planks. You can put a diagonal anywhere if you so desire, it is the best measurement to the true planking at any particular piont.

Be aware of the moulded depth however (the "thickness" of the hull, as measured from the centre of the boat to the outside of the hull), some plans have inside measurements, some have outside measurements.

[tugboat]

Diagonals are generally placed so as to be perpendicular to the planks. You can put a diagonal anywhere if you so desire, it is the best measurement to the true planking at any particular piont.

Be aware of the moulded depth however (the "thickness" of the hull, as measured from the centre of the boat to the outside of the hull), some plans have inside measurements, some have outside measurements.

Landlubber--thank you ever so much!!!!
may i ask you to clarify for me- with regards to the offsets; in the offsets table- do the measurements given refer to the distance from the centerline to the points measuring diagonally?.or are they measured outwards longitudinally using the diagonals as a simpe reference? god its hard to explain when i don't have the plans on here to show you what i am trying to ask...sorry...

i have no trouble getting the other points...just the diagonals - want to be absolutely sure i get it right...and understand...

[Landlubber]

...diagonals are measured from the centreline along the diagonal, to the refference point on the lines plan, it is quite OK for you to throw in as many "diagonals" as you feel necessary to define a particular point of the hull build (as such)...they can be anywhere that pleases you, they do not have to meet the buttocks or any waterline, but of course, these points are already defined, so they often do all meet a such points. Where there are complicated shapes, 3 or 4 diagonals drawn and interpolated at those difficult areas would be quite Kosha......

[Landlubber]

try getting a copy of my old text book, Boatbuilding Manual by Robert Stwward, he explains well how to read the lines and offsets tables (my copy is ed3 P.81).

[tugboat]

try getting a copy of my old text book, Boatbuilding Manual by Robert Stwward, he explains well how to read the lines and offsets tables (my copy is ed3 P.81).

great ill look for it...yes I understand now--ill just take loft the diagonals, and measure down to the given lengths on the diagonals...there are four per view...should be enough ...i appreciate your patience landlubber...

have you seen that book anywhere??. also, im going to strat a new thread--im going to see if anyone on here would input my plans int autocad and I will pay them for renderings. I was thinking of going to full size patterns for this for ease and to speed up the build...and for accuracy...

do you know anyone that could do this?

[Landlubber]

http://www.bruceroberts.com.au/books/bm.htm

[liki]

http://www.bruceroberts.com.au/books/bm.htm

Just a hint; This is where I buy around 90% of my books, it is usually the cheapest inside Europe and has a fast delivery:
http://www.bookdepository.co.uk/book/9780070613768/Boatbuilding-Manual

Amazon.com has the book also available at quite more affordable price, and might be easier to use for you in North America. I have no idea how annoying it is to deal with your local customs.
http://www.amazon.com/Boatbuilding-Manual-Robert-Steward/dp/0070613761/ref=sr_1_1?ie=UTF8&qid=1288594482&sr=8-1

[tugboat]

Tugboat:
I think it's better to digitalize the forms, do the hull fairing (based in the available sections in the forms plan), by using a devoted computer program and then take the needed frames profiles from there. But you have to take into account that usually forms for steel boats are drawed "out members" or, in other words "inside the skin". Ferrocement forms are rather drawed "out skin", so there is a subtle diference and you have to provide for it.
To know where the frames, bulkheads, stringers, etc. have to be located, you need to perform structure calculations for ferrocement first. As Bito says you should contact an NA with experience in that material.

hi guillermo-yes I have seen the light on that issue and it didn't cost me much at all..and in fact ill have the frames nested and cut too. regardless of the material..i should have looked into that earlier-they are going on a dxf file for cnc cutting.-- costs and time savings are substantial.

kudo's