Help layperson choose materials for small pilothouse build

[shizlenut]

Hoping to get some help choosing materials and advice on a small pilothouse I would like to construct on my 74 Boston Whaler. I am a amateur and have limited experience with fiberglass and no experience with composite construction. I am a heavy equipment mechanic/metal fabricator and have good "instincts" when it comes to various types of construction.

So my questions are these.

In general, if you were a competent layperson, what process/materials would you use to insure a sound construction without breaking the bank.

What materials are most forgiving for a new builder? wood or foam? something else?

can a layperson confidentaly hand lay fiberglass over foam/wood without vaccum bagging or other infusion process?

Are there any specific forum threads anyone can point me towards?

[tunnels]

Originally Posted by shizlenut

Hoping to get some help choosing materials and advice on a small pilothouse I would like to construct on my 74 Boston Whaler. I am a amateur and have limited experience with fiberglass and no experience with composite construction. I am a heavy equipment mechanic/metal fabricator and have good "instincts" when it comes to various types of construction.

So my questions are these.

In general, if you were a competent layperson, what process/materials would you use to insure a sound construction without breaking the bank.

What materials are most forgiving for a new builder? wood or foam? something else?

can a layperson confidentaly hand lay fiberglass over foam/wood without vaccum bagging or other infusion process?

Are there any specific forum threads anyone can point me towards?

WOOD IS THE EASYEST TO WORK WITH AND GET THE BEST RESULTS !!Forget about vac bagging and infussion it not even worth a second thought !!

[tinhorn]

Originally Posted by tunnels

Forget about vac bagging and infussion it not even worth a second thought !!

I agree. On the other hand, I never like to see wood mixed up with fiberglass.

There are two relatively simple ways to go about your project. One would be to build a mold from plywood covered with Abitibi (that shiny white hardboard you see at Home Depot and in cheap apartment bathrooms). Then you can gelcoat the mold and lay up the part. It should look pretty classy.

The other way would be to lay up flat fiberglass panels on a slab (like the Abitibi), then cut them to size and join them together. Depending upon your joints, this might look good, too.

Either way, the product I would use instead of foam or wood is CoreMat. If you can't find it locally, some dude sells it on eBay.

[tunnels]

Have done complete deck rebuilds using 5 mm core matt with a 450csm on each side ! Cut to shape and glassed the joins and then when its all done glassed and peel plyed inside and out then faired and sanded to a final shape and undercoated etc etc . Works a treat!!!
Just used 3 mm ply shapes hot glued in place as a frame to hold the glass panels in place till they were lightly glassed !!

[shizlenut]

So, I have been looking into this project for literally 5 hours total now and am still pretty vague on many processes but let me see if I have the right idea. first build the pilothouse (Mold) to spec, maybe even on the boat itself, out of thin plywood (is this considered a male mold?). remove the mold from the boat and cover with abitibi (as a release material? is it flexible to allow radius corners?). Gelcoat the mold first(I thought gel-coat was used to finish fiberglass, but then again I don't know much, obviously), then layup the part (saturate 450csm, layer on saturated 5mm coremat and recover with saturated 450csm layer?). pop out the mold, glass into boat inside and out (what kind of joint configuration should I use? CSM?) Then continue on to build console etc... on interior.
Not sure if im anywhere close, but thanks for your time guys, if you could go into details of the process, I would greatly appriciate it.
Needy Noob Out.

Oh and just to give an idea of what im going for, i live in seattle and want to build an alaskan bulkhead style pilothouse, possibly forward swept windshields. Mini Trawler style I guess.

[shizlenut]

I do have a fair amount of experience with woodworking, since that is the case will it be considerably easier for me to construct completely out of ply and then glass over outside, then flip, glass inside, flip again and glass onto boat. I am assuming the biggest downfall would be weight and possible rot down the line somewhere. Anyway im totally lost and basically asking you guys to school me on all this stuff.
Thanks again for any help.

[tinhorn]

When I built Abitibi molds I often glued the Abitibi to 3/4" plywood before joining the panels together. Abitibi is 1/8" hardboard, so there's not a lot of flex. For an outside radius you can use a 3/4" router bit, then use Bondo to fill the roughness of the underlying plywood. Sand the Bondo smooth, paint a bit of resin or gelcoat onto it if necessary, and make sure you wax it well before gelcoating.

For an inside radius, pack some Bondo into the joint, then use a machine screw with a flat washer bolted against the head to scrape the Bondo into a fillet. You'll want to wax the Bondo well, and make sure there's a healthy layer of gelcoat over it (when you get to that stage) so that you can sand the radius smooth on the finished part.

I guess you could consider gelcoat to be a type of paint. Check out this thread and look at the pics of barnaclebill's boat mold: Redoing mold . It's like a reverse boat. When barnaclebill makes his first boat, he'll spray white gelcoat onto the orange mold, followed by fiberglass. When he pops the boat from the mold, you're gonna see a white boat.

That's what you want to do if you build a quick-and-dirty Abitibi mold.: pop completed parts out of a mold. So the OUTSIDE dimension of your part is gonna be the INSIDE dimension of your mold. The advantage to doing it this way is that your part will be smooth and shiny on the outside. I'm not sure you want to do the complete pilothouse this way (as a one-piece part, I mean), but you certainly could.

You could also use your EZ-build process, but instead of plywood (rot is why I don't like it) use a CoreMat panel you've prebuilt instead. I picked up a free granite countertop for a kitchen island that I use as a layout table for creating flat panels. Then you only have to join the seams--you'll have a pretty smooth outside surface, and no need to 'glass both sides as you'd do if you used plywood.

Or someone may convince you to use the 'glass-covered plywood.

[tunnels]

Originally Posted by shizlenut

I do have a fair amount of experience with woodworking, since that is the case will it be considerably easier for me to construct completely out of ply and then glass over outside, then flip, glass inside, flip again and glass onto boat. I am assuming the biggest downfall would be weight and possible rot down the line somewhere. Anyway im totally lost and basically asking you guys to school me on all this stuff.
Thanks again for any help.

Like i said if you are comfortable with wood then thats a good way to go . And yes Epoxy and glass the outside after you have it to the shape you want . Fair and paint then do the inside and screw , bolt or glass it to the boat what ever turns you wheels . Keep it simple !! Simple things always work best. Making moulds and the like is one hell of a lot of hard work that gets duplicated ,once making the mould and then second making the artical which then still has to be finished off !!.

The rot thing id look at getting the best wood to combat rot and also a wood preservitive , Here in nz we have metalex its a green color and mix it with kerosene or turps and paint it on and let it dry then a coat of thinned epoxy resin ,allow to harden and then another epoxy and glass , paint or what ever you want to put on as a finishing coat !!
I dont mind work but i dont like doing unnessasary things that cost a lot .

[shizlenut]

Thanks again guys, one last question for now. If a guy buys 5lb foam instead of wood can he build the pilothouse the same way? is it much less forgiving for layup and delamination problems down the road? Structurally will it suffice for a pilothouse. I just can't help but like the idea for its weight savings, insulating factors etc... more than I want to deal with?what are the pitfalls in your minds.
Great forum fellas

[ondarvr]

You can also buy FRP cored panels already made, I'm using 1/4 and 3/8 plywood cored panels to build it.

Since you're in Seattle this may be handy, this company is located in Spokane. They also have these panels at little lower in cost if want to use blems, the blems may have a small cosmetic flaw.

http://www.fiber-tech.net/Products.htm

[tunnels]

Originally Posted by shizlenut

Thanks again guys, one last question for now. If a guy buys 5lb foam instead of wood can he build the pilothouse the same way? is it much less forgiving for layup and delamination problems down the road? Structurally will it suffice for a pilothouse. I just can't help but like the idea for its weight savings, insulating factors etc... more than I want to deal with?what are the pitfalls in your minds.
Great forum fellas

If you really want to work with glass on this project theres a cople of ways ! Make flat panels from glass using glass /corematt/ glass or alternitively glass /foam /glass !!
To make either of these methods you need a sheet of mdf board with a smooth shiny waxed suface to make your panels on .
You can make each panel very close to the actual size and shape you need so to cut down on the waste of materials , then release the panel and simply trim to is final shape ,same method as if you were using plywood ! by making the panels to shape theres very little waste involved , if you just buy a sheet of something there will be a much higher % of waste and it all costs money !!
Its possible to make radiused corners and edges as well in long strips and fit and use them everywhere .
But I will let you think about this for the moment !!

[tinhorn]

I've seen fiberglass delaminate from both wood and foam--wood as it deteriorates, and foam because, well, the bond to the foam is only as strong as the foam itself. If it gets smacked, the foam will let go. If you have enough fiberglass "studs" (to use a carpenter term) joining the inner and outer layers, maybe you'll be fine even in a worst-case scenario. (I've even seen these studs made out of wood.)

[missinginaction]

You need to be in the wooden boat forum. I like fiberglass, but for what you are doing a wood pilothouse sheathed in epoxy and painted will serve you well and won't break the bank. Take a look at a couple of photos of a cabin I've been working on. This is on an old 73 Silverton. The exterior walls are mahogany beamed and marine ply (okume) sealed with three coats of epoxy, sheathed with 4 oz fiberglass cloth and painted with Interlux Perfection. The cabinets & interior walls are just good exterior grade ply coated with epoxy and covered with HPDL (think Formica). Even the door is fabricated from ply and coated with epoxy/fiberglass and painted.

IMO for what you are contemplating, believe it or not, wood and a little epoxy, fiberglass and paint is best, and least expensive.

Regards,

MIA

PS...I didn't know jack about boat building a few years ago when I started this project so it's well within the reach of a dedicated amateur.

[thaikarl]

not a pilot house, but a raised cabin for my 24' Lapworth Gladiator. the gladiator already has a cabin 'lid' that kind of pops-up and is propped up with posts. but it blocks the view to the bow and offers no protection from the sides. mostly for 'in port' use i think. but i want out of the rain and wind when i go out in the winter.

my thinking is to build the thing out of thin (1/2", maybe 3/8") plywood first - mostly to prove the concept. i need to have something on the boat to see if it's a good fit, good shape, functions the way i want it to, first. if it lasts one season that's fine by me. don't want to spend the time and money on fiberglass, epoxy, foam core, etc etc and find out that it does work like i hoped. building an inexpensive prototype will enable me to work out the bugs, modifications, sizing etc. THEN i'll do it right with better materials.

i won't know if it's "too tall" or "too short" until i have something in place and sail around with it for a while.

(@shizlenut. i'm in seattle also and would love to compare notes with ya on this kind of project. message me from this board)