opening up the fer-a-lite debate again...

Actually it might be a good idea to hire a surveyor to document your build at several stages up until its plastered,it might be money well spent.
Steve..

 

Yes, I agree. Shouldn't cost that much really and if done to the surveyor's satisfaction it's going to make insurance easier/cheaper to get.

I hired a civil engineer to do inspections when I was building a 3 storey steel framed post & beam house. I wanted to make sure it was done *right*. Saved me more than his entire fee on the first inspection as the steel fixers had screwed up the reinforcing steel going into the basement slab. After they wanted to argue about it ('we ALWAYS do it this way') I fired them & did it myself.

PDW

 

I've retired these days but I started off as a fisheries biologist. Moved into software development & pretty much stayed there for the rest of my career, mostly scientific or engineering systems though. Financial systems are too simple & boring. These days I just dabble in open source code development for neonatal screening laboratories.

And build stuff. This photo is months old.

PDW

 

Thats impressive--the boat is coming along nice even at that stage..wont be long and you'll be sipping pina collada's off the deck, to the sounds of the breakers on shore. i am sorry if i asked this before but whats your expected launch date?

do you have an engine for her yet??

I have a shot of my present boat--its just a quick shot in the video i have up- but you can see it behind a clothesline. I just got two beautiful sliding windows for free.., they will go in the wheelhouse...ill have to make a video of the boat and post it for you guys..its the first stage of a number of stages for my grand scheme...i have a small 30 hp thorneycraft diesel 90 marine with a 2.6:1 reduction for it. will install it in the spring.

Its small at 24 ft x 9ft but cost me under 2000.00 to build and was a two month build--of course--id do it in steel if i was doing it over--hence i might sheath it in the fer-a-lite...

but its a BIG 24 ft--has accomodations of much larger boats ...
ill show you the vids..or pics--btw --If i have my n.a. diploma, doesnt that qualify me to do my own surveys? or is there more you need for that?--i belong to the N.A.M.E organization --as a student at least..when im done i will be my own surveyor...for abs or whatever...
but yea, I will document it--i dont know if ill go for the offical guy throughout the build to oversee it but its a good suggestion ..thanks...
.

 

Launch date will be before Christmas. I'm not specifying which one though.

Engine - I have a few. Probably the 30HP Yanmar coupled to a 3.5:1 reduction box. Need to rebuild the Yanmar and I need to get on with it as in the near future I have to make a decision on engine beds etc.

As for documenting yours IMO the really critical bit will be the shell. Document the wire layup and then the plastering. Mould in brackets etc for where you want the interior and anything else that attaches to the hull. You're going to fit a pretty big engine, yeah? Think carefully about the torque of that engine feeding into its bearers. Ditto prop thrust. You're really not dealing with a strong material and here its flexibility may be a bad thing. Think heavy angle iron well tied into the armature. I'm not an engineer, here I'd get advice from someone who knew structures and make everything to design.

PDW

 

Thats a good sized reduction gear...whats the rpms on the 30 hp?..im guessing three cyl- 3gm? or something like that??..yanmars the best...as for flexibility-- it doesnt seem so flexible to me...at 3/4 inch especially.

- perhaps the shear yield of 10 gauge maybe more with 8 layers of mesh and steel rods...who knows- but i can say its "preety" solid...

but i'd make them(the bearers) integral...i think a 6-71 would be a good engine for it...but right now talks are in the works for another project. I have a business partner that might meet me dollar for dollar on an earlier idea, ill be able to know within the next few days if ill be doing a 180 since this could be my opportunity of a lifetime..
ill let you guys know--it would involve fer-a-lite or possibly steel as the hull..but i dont want to say anything until i know for sure...
i really dig your 40 ft'er, she will be a ice sailing vessel, and since you did it "legit" the whole way it takes the guesswork and the worry out of how she will sail...what have you used for ballast??
did it need any? for you guys summer is coming but for us here--build season is coming to a close sadly...

 

It's a 3QM30H, 2600 rpm tops. I picked it up cheap but no g/box and the exhaust manifold is totalled. $1600 for a new manifold, think I'll make one. I bought a new Chinese h/duty box off of Ebay. I'll use a Fenner flex coupling to mate the box to the engine and a couple of CV joints to get the power to the shaft. It's got its own thrust bearing setup so no worries there. The things you do when you have a machine shop....

I've got a couple of 3 blade props but if the budget stretches I'll get an Autostream or similar. Nobody makes small CP props any more or I'd have gotten one somehow. Need to find a good Sabb 20HP engine but I've never seen one for sale in Aus.

Lead for ballast, cast into bricks and placed in the hollow keel. I've got about 1200kg which should be enough. My 200x40 keel shoe adds nearly 500kg of ballast in itself.

As for building, yeah, the weather is improving so I'd better hike over to the shed & get on with it.

PDW

 

It would seem to me that ferro could be modernised by using composite reinforcement and fiber mesh in the mix. Epoxy coated in and out, the exposed fiber mesh becomming a fiberglass skin and the ferro the core. Rick

 

The problem with ferro isn't it's strength or durability, but the ability to confidently inspect it (within reasonable cost limits) before and after repairs or during a sale assessment and secondly, repair it with confidence. I suspect it can now be repaired well, using modern materials and techniques, but then how do you know without dragging out an x-ray machine.

It can be the greatest build method in the world, but once it's plastered up, you really don't have any idea how well the wire armature has survived 10 years later, how much "egg shell" damage was accrued, in the last hard smack or if all the damage was addressed during a repair. This is the *** kicker with ferro, regardless of fiber introduction, aggregate changes, different plastering formulations, etc.

 

yes-this is exaclty the idea i had--if we can use cores for lightweight boats such as mjulithulls--then for powerboats it seems a core from fer-a-lite or even cement should work..epoxy sticks to anything...the core acts like an I-beam.it takes incredible stresses. thanks for the reply...

 

Yea- when i did my test slab i saw that there may have been areas -or voids possibly that could have allowed water in--but it was hard to tell if any occurred--the nice thing about the fal is that i can do it in many applications--this means i could do one side so i can see where the morter has penetrated and then do the other side which should get it all..it really does go nicely into the mesh. if epoxy was affordable--id do it all in epoxy...

i might even opt for a couple layers of small mesh to hold the product in the mesh better. I think if all the armiture gets covered-and even the ferro-advocates say that the biggest danger is voids- then if all gets convered, hopefully no water can get in to ruin the armiture-


but i have read many books relating to how easy it is to fix it this type of construction if it does--yes its hard to break apart with a hammer or air hammer the plaster away and remesh it-then cover over the voids... but it would likely be just as strong as it was--in fact--you could--for small areas or holes use epoxy.

after i tried to destroy the test slab-(actually i did when i put it right against a concrete slab and pounded it 100 times as hard as i could until it broke right up-even though i still never went through even three layers of mesh)-i should have posted the video of replastering it and how effective it was to have the spalls i created look good as new--of course the mesh wasnt in great shape where i pounded the crap out of it. that would have had to be replaced, in a real boat situation...

but if both sides were covered with a skin and epoxy--it should not let water in--

in fact i can point out that cores such as balsa will also become absorbed with water and has high fryability factor. other cores such as core-cell are also fryable and there is no way unless you do core samples throughout every sq ft of the boat to tell if the hull has any sections that broke apart some layer of corejust as much of a nightmare to try to find voids in a cored hull of standard expensive cores. -(in my opinion)

...nevertheless...these issues are inherent in all type of builds with a core. but the original idea of a core was that if done right and glassed- no water would enter into the core at all...for light cores--i think honeycomb is the best because water cannot eat away the core or migrate through the cells if it does manage to niggle its way in...but in heavy displacement boats- a nice 1/2inch layer of fal and two sides glassed would be a nice hull indeed...also if one wanted a cruiser for voyaging even something like a tri- it could be done with a light core say 1/4 inch of FAL and two layers of light cloth. it would still be heavier than expensive cores but you gain in strength. plus the armiture would be so light there would be a much less likely occurance of voids.

 

here is the steel quote for the 45 ft tug---its was the LOWEST costs of any distributer i tried...keep in mind -sadly-this wasnt even the full B.O.M.

ill post the fer-a-lite quote next...

 

here is the fer-a-lite rough quote...
sold based on weight

45 ft x12.5 by 7ft boat needs
resin- 220 kg's per 55 gals.
@3.40 kg
3.40 x 220 x 7.5 drums = 5610.00
steel mesh- 1500.00
fer-a-lite 385(discounted for large order) x 7.5 units of FAL =
3000.00 w/shipping
steel rod 1000.00(using hard drawn wire i.e. fencing wire 9 guage.)
ties aprox 300.00
total- 11 000.00-12000.00

aprox costs.

 

I don't think your material comparison is realistic....What about the construction method?

Look at the FAO booklet on ferro construction costs/time/materials. You need a form of some sort to drape your mesh bag over, and there's lots of steel involved. So far you don't have a structural plan for the ferro version so the construction cannot be compared. It's one thing to take a hammer and pound on a little square of skin, quite another to punch say a 4' square panel with a 2 ton log at 8 knots.....something has to support those panels...in the FAO boat (fishboat and not a tug) there's considerable (2000 pounds?) 1/2" and 5/8" rod welded into web frames and deep floors. Add that cost to the mold cost and they're becoming comparable.....

 

Yes tad correct! i plan on using 5/8ths rebar. then again wrap the coils of hard drawn wire. but steel costs are definitely more than this type of construction. yes its accurate that i wont know what an impact will do to this material in the way you suggest--but i know from working with it., that it'll take a hell of a lot to dent it...as for the build--the mold IS the rebar! like the hartley truss system. the only diff is--i would use a steel post to anchor the frames to--check out the hartley method. he uses steel trusses and plasters them--this adds the strength of flatbar frames to it. I wish i could do a test like that--take a 4' panel and run it into a log at 8 knots--i personally would love to know..fail or not fail..it would be interesting...but like the tugboat master designer Mal low (paraphrasing) says- "if your overstress fiberglass, you reglass it later- over stress steel and you bend it back or reweld it..six of one...?