Engine Bed Construction

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John, CD28
Master Varnisher
Posts: 109
Joined: Sat Mar 29, 2008 10:44 am
Boat Name: Tiara
Boat Type: Cape Dory 36
Location: MA (our taxes are lower than Sweden's)
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Engine Bed Construction

Post by John, CD28 »

I bought a Cape Dory 36 that needs a little work. On the short list of things to fix is the engine bed/bearer that's rusted to the point it's about to drop the old Perkins down onto the hull. The original bed is a tubular steel structure glassed to the hull, and is now failing badly. I'd like to cut the glass tabbing that holds the rusted old structure to the hull, and build an entirely new structure that won't rust into dust over time. And, I'd like to take advantage of modern materials.

Would it be horribly wrong to build a new engine bed from structural fiberglass (FRP)? I've never seen anything stick fiberglass together like 5200, so maybe that could play a part here. Essentially I'd be using the old steel frame as a model to fabricate a new FRP engine bed, then glue it down to the hull with 5200.

I like the square tube FRP, but the temperature range for FRP looks low (140°) - maybe Garolite instead?

Any thoughts? Advice?

John
McMaster-Carr's FRP & similar: http://www.mcmaster.com/#plastic-rectan ... ng/=jg7e5r
McMaster-Carr's data sheet on FRP and similar materials: http://www.mcmaster.com/#8549kac/=jg78vk
McMaster-Carr's stuff on Garolite: http://www.mcmaster.com/#grade-ce-garol ... ng/=jg7w69
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Engine-Bed-fwd-webfile.jpg
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Sailing involves the courage to treasure adventure, and the wisdom to fear danger. Knowing where one ends, and the other begins, makes all the difference.
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earlylight
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Boat Name: Early Light
Boat Type: 1982 Sabre 34 MK I
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Re: Engine Bed Construction

Post by earlylight »

There's nothing wrong with using FRP for the new bed logs, I would grind the hull clean and then add tabbing to attach the bed logs to the hull using several layers of bi-axial glass cloth and epoxy resin. Do not use polyester resin as you will only get a secondary bond. This should be a fairly easy project once the diesel is out of the way.
Good luck
Dick Coerse
Early Light
Sabre 34 MK1
Solomons MD

http://earlylight160.net76.net
LazyGuy
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Boat Name: Paper Moon
Boat Type: Luders 33 (Allied Boat Co.)
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Re: Engine Bed Construction

Post by LazyGuy »

I agree with Early Light. Skip the 5200 and go with epoxy. Set it in thickened epoxy then tab it in with biaxial and epoxy.
Cheers

Dennis
Luders 33 "Paper Moon" Hull No 16

Life is too short to own an ugly boat.
Tallystick
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Joined: Fri Sep 09, 2011 10:54 am
Boat Name: Nostalgia
Boat Type: Pearson Triton Yawl

Re: Engine Bed Construction

Post by Tallystick »

I used white oak bedded with thickened epoxy, then glassed it in with epoxy. My boat has metal brackets the motor rests on, kinda like the L shaped plate your motor mount is sitting on except on mine they are T shaped, and I used a bed of 5200 with lag screws to attach those to the glassed in supports. Glassing in your supports helps to spread the load and has much higher shear strength compared to just bedding the supports with adhesive. They have to be strong enough to handle the load cycling as the boat pitches and rolls.
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