Material choice for new seats/hatches?

[Sabre66]

I'm planning on replacing the wooden seats on my Sabre with fiberglass. I've done enough glass work to know that it's hard to get the true 90 deg bends I need (without a vacuum bag) by laminating over marine plywood.
Does anyone know of a suitable material that comes in 1/4" thick sheets that can be epoxied, machined and painted? I originally looked at using G10, since I've worked with it before, but it's way to expensive.
Any thoughts?

[PBzeer]

Did you think about using epoxied plywood?

[Sabre66]

I was considering it but I was hoping to get away with 1/4 thick material to save a little weight and I doubt that's strong enough for a seat/hatch that's 30" long and 13" deep?

[Faster]

Are the old seats in good enough shape to take a mold off, and laminate new ones out of glass? You could then use a foam core for weight and stiffness issues.

[Sabre66]

Originally Posted by Faster

Are the old seats in good enough shape to take a mold off, and laminate new ones out of glass? You could then use a foam core for weight and stiffness issues.

The old seats are junk. They lacked a proper edge that drops down into the "female" grooves, thereby letting water pour in during heavy weather. I could laminate but I need to make tight 90 deg bends, and without a vacuum pump that's almost impossible, With the G10 you just epoxy it all together (1/4" thick ) round over the edges with a router, fair it in, paint it and your done.
The problem is the cost G10 in 1/4" thickness is roughly $450 for a 20 X 42" sheet.

[sailingdog]

Faster-

You could make fairly light seats using foam and fiberglass. I wouldn't use foam core though... the paper coating on it will interfere with the proper bond you need for a core material in a laminate. I'd use one of the PVC foams designed for use as fiberglass core material.

BTW, you really can't do a sharp 90˚ bend with any kind of laminate, be it fiberglass, kevlar or carbon fiber... it has to be a radiused curve to keep its strength.

[Faster]

Originally Posted by sailingdog

Faster-

You could make fairly light seats using foam and fiberglass. I wouldn't use foam core though... the paper coating on it will interfere with the proper bond you need for a core material in a laminate. I'd use one of the PVC foams designed for use as fiberglass core material.

That's true - I guess I was mainly referring to a cored construction in general as he was concerned about weight and stiffness.

Even so, a mold could be built out of plywood and glass, the edges properly radiused and then you'd have good glass seats and no worries for some time. Even vacuum bagging something that size is not too difficult.

[sailingdog]

I get the feeling he doesn't have the vacuum pump or other equipment needed to vacuum bag it...

[Sabre66]

Originally Posted by sailingdog

I get the feeling he doesn't have the vacuum pump or other equipment needed to vacuum bag it...

I've re-cored the entire deck, fitted out my own carbon fiber boom, plus done extensive repairs on the hulls of several boats, so I have plenty of equipment. This is the first time I've taken on something square with square edges.(I know they have to have a slight radius)
I might have to invest in a vac pump I don't think it would take a whole lot to do what I need. Any recommendations?

[sailingdog]

You could always make them out of Starboard, which can be worked fairly easily with regular wood working tools. You might have to add some reinforcement to the bottom, depending on how much weight you're going to be putting on the seats. It is weather-proof for the most part..and accepts regular hardware fittings, like wood would...but might be a bit heavier than a fiberglass piece. However, it would probably be simpler to manufacture.

I don't think 1/4" starboard is strong enough for what you want though... You'd probably need to go heavier.