need help with plans

also i have the keel ready...

 

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

 

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!

 

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

 

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...

 

Have you seen the Atkin Tug?

All wood! But not cheap at 50ft.


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

 

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

 

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?

 

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"

 

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...

 

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

 

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?

 

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...

 

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

 

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...