DIY-1972 thunderbird shawnee tri-hull boat restoration-(after shop repair gone wrong)

[Woodonglass]

Re: DIY-1972 thunderbird shawnee tri-hull boat restoration-(after shop repair gone wr

Looks right cept I think you meant 10 gals of resin.

 

[jarrpal001]

Re: DIY-1972 thunderbird shawnee tri-hull boat restoration-(after shop repair gone wr

how much would i need to do the transom only first?

 

[jarrpal001]

Re: DIY-1972 thunderbird shawnee tri-hull boat restoration-(after shop repair gone wr

question on my stringers. if you notice the center stringer, its kind of low on the hull. isnt it supposed to be as high as the other two?
or do i leave it the same height when i replace it? if so then what does the floor rest on in the center?

 

[zopperman]

Re: DIY-1972 thunderbird shawnee tri-hull boat restoration-(after shop repair gone wr

question on my stringers. if you notice the center stringer, its kind of low on the hull. isnt it supposed to be as high as the other two?
or do i leave it the same height when i replace it? if so then what does the floor rest on in the center?

How much lower is it? Are you sure it isn't just teh keel? My boat has bulkheads and a gas tank in the center....

 

[jarrpal001]

Re: DIY-1972 thunderbird shawnee tri-hull boat restoration-(after shop repair gone wr

View attachment 120061

How much lower is it? Are you sure it isn't just teh keel? My boat has bulkheads and a gas tank in the center....

 

[JDA1975]

Re: DIY-1972 thunderbird shawnee tri-hull boat restoration-(after shop repair gone wr

Looks like the keel, how wide is that center gap? If you feel uncomfortable with the support your floor gave originally, you can add a few cross supports...some 1x2 or 2x2 and glass them in prior to redecking

 

[zopperman]

Re: DIY-1972 thunderbird shawnee tri-hull boat restoration-(after shop repair gone wr

Looks to me like a regular keel stringer...

You could add a crossmember if you're concerned... glass a 2x4 put between stringers and there you go...

 

[jarrpal001]

Re: DIY-1972 thunderbird shawnee tri-hull boat restoration-(after shop repair gone wr

Looks like the keel, how wide is that center gap? If you feel uncomfortable with the support your floor gave originally, you can add a few cross supports...some 1x2 or 2x2 and glass them in prior to redecking

do you mean between lt and rt stringers?

 

[jarrpal001]

Re: DIY-1972 thunderbird shawnee tri-hull boat restoration-(after shop repair gone wr

so the keel stringer is ok?
reason why i ask is because i passed by another boat repair shop and the owner told me that the keel stringer needs to be same level as the lt & rt. that way the keel is supported by the floor when i put it on.

 

[Woodonglass]

Re: DIY-1972 thunderbird shawnee tri-hull boat restoration-(after shop repair gone wr

the keel stringer needs to be same level as the lt & rt. that way the keel is supported by the floor when i put it on.

Not always true! My boat is just like yours. And so are many others on here. The Glass tabbing to the hull is what offers the strength to the hull/keel. Like others have state you can if you want, eithe rais the stinger to the height of the deck or install bulkheads between the stringers. Not necessary, IMHO. The Designers of the hull felt that their design offered a safe hull and I see no reason to argue with their engineering logic. I'd put it back exactly the way I found her and go boating.

 

[JDA1975]

Re: DIY-1972 thunderbird shawnee tri-hull boat restoration-(after shop repair gone wr

do you mean between lt and rt stringers?

yeah between stringers, plywood will span and support weight a certain distance, add in the fiberglass reinforcing and sealing it. if the width isn't that much, and it probably isn't since factory did not install cross members, I wouldn't worry... If on the other hand you felt like the original floor, even after repairs was not strong enough, it wont hurt anything to add a few cross members. Cute a small (size of cross member) notch in your stringer on both sides and lay it across them then glass them in.

 

[jarrpal001]

Re: DIY-1972 thunderbird shawnee tri-hull boat restoration-(after shop repair gone wr

thanks guys thats good to know.

now a few questions:

i need to figure out what wood i am going to use. i went to home depot the other day and looked at some plywood.
they had bc sanded pine and there was one that cabinet grade. the cabinet grade looked better than the bc sanded pine. i noticed that the bc sanded pine had little pieces of wood missing in the middle of it while the cabinet grade didnt.

can i use cabinet grade for my transom and floor? i dont want to spend the extra money for marine ply.

what do i use for my stringers? my stingers are .75 w x 6.5 h x 11.25 L

 

[zopperman]

Re: DIY-1972 thunderbird shawnee tri-hull boat restoration-(after shop repair gone wr

I'd use acx arauco ply. You don't need cabinet grade. Any exterior grade fir would work too.

 

[JDA1975]

Re: DIY-1972 thunderbird shawnee tri-hull boat restoration-(after shop repair gone wr

on stringers use 3/4 ply and join 2 pieces to get your length since its over 8 foot. joint method is up to you, I dont know what others recommend. but i would cut both pieces 6" longer than needed, use a circular saw, set depth to 3/8" to cut the 6 inches. then using a chisel remove half of the plys. join these 2 together, glue, and clamp. thats just what I would do, there may be better easier ways, so maybe someone else can point you a different route

 

[jarrpal001]

Re: DIY-1972 thunderbird shawnee tri-hull boat restoration-(after shop repair gone wr

Not always true! My boat is just like yours. And so are many others on here. The Glass tabbing to the hull is what offers the strength to the hull/keel. Like others have state you can if you want, eithe rais the stinger to the height of the deck or install bulkheads between the stringers. Not necessary, IMHO. The Designers of the hull felt that their design offered a safe hull and I see no reason to argue with their engineering logic. I'd put it back exactly the way I found her and go boating.

what are the chances that someone replaced the stringers before and didnt follow the The Designers design? it is a 1972.

 

[Woodonglass]

Re: DIY-1972 thunderbird shawnee tri-hull boat restoration-(after shop repair gone wr

Looking at your pics, those are the factory stringers. That's is how your boat was designed. Again no need to raise the Keel stringer but you can if you want, I just don't see the need. I'd use the Arauco Plywood for Everything. Deck, Transom and Stringers. Very good stuff to work with. No need to lap joint it. Just but em together and use some Titebond III wood glue and some 3/8" x 18" "Sister" pieces on either side to bring em together.

Here's some Drawings that might help you visualize how to fabricate everything...

Click the Pics to Enlarge

 

[jarrpal001]

Re: DIY-1972 thunderbird shawnee tri-hull boat restoration-(after shop repair gone wr

Looking at your pics, those are the factory stringers. That's is how your boat was designed. Again no need to raise the Keel stringer but you can if you want, I just don't see the need. I'd use the Arauco Plywood for Everything. Deck, Transom and Stringers. Very good stuff to work with. No need to lap joint it. Just but em together and use some Titebond III wood glue and some 3/8" x 18" "Sister" pieces on either side to bring em together.

Here's some Drawings that might help you visualize how to fabricate everything...

Click the Pics to Enlarge

View attachment 120215View attachment 120216

WOW!!!!!!!!!!!
Thats awesome!
thanks

 

[jarrpal001]

Re: DIY-1972 thunderbird shawnee tri-hull boat restoration-(after shop repair gone wr

Looks right cept I think you meant 10 gals of resin.

yes my mistake 10 gallons

 

[jarrpal001]

Re: DIY-1972 thunderbird shawnee tri-hull boat restoration-(after shop repair gone wr

CAP REMOVAL

 

[oops!]

Re: DIY-1972 thunderbird shawnee tri-hull boat restoration-(after shop repair gone wr

have you got your wood yet?......the cabinet grade WILL NOT DO.

at the minimum you need exterior grade plywood. the reason is because the glue used in the wood is waterproof. interior grade does not use this glue and the wood will de laminate with moisture. even though you are going to encapsulate the wood with fibreglass.....moisture will remain in the wood.

i would suggest you buy your wood and get drying as soon as you can.....throw a heat fan on it for about a week and keep turning the wood to get all the moisture out of it.
even though you think the wood id dry it isn't.
the less moisture in the wood will mean easier penetration by the resin and far better wet outs with the resin at glassing stage.

the reason the people suggested to replace one stringer at a time is because they are worried that the hull might warp if not supported correctly.

that sounds like a good way to make sure the job lasts weeks if not months to me ! arrgh !
make sure the hull is supported fully stable and flat before you rip the stringers out.....supported under the keel, the outer chines, and the plaining surface. then you can rip em out all at once.

it also looks to me like the reason for the low centre stringer is because the boat was also designed to have a belly tank and a ski locker. not not all models had these features.
so for ease of production, the builders cut all stringers the same way....and just added cross braces (or frames) under the deck of the units without the under floor gas tank.

that means you can make some modifications if you wish....like a belly tank and a ski locker.

if you wish to add a ski locker....(i would...we need all the stowage we can get in boats). just keep the stringer at the same height and in the locker area....add a bulkhead a the front and back of the locker.....then make a plywood floor for the locker with space under the floor for natural bilge water to drain. the ski locker could also be carpeted.

btw....now you see as you buy the materials.....that the guy you took your deck to in the first place did as little as he could......the materials just to do the deck are around 600 bux. and for a grand......it is tough to make any money on a job that takes 20 -30 hours to do.