Your engine box lid has a difficult job to do. It has to keep lots of heat in, noise too, plus it has to be self supporting when it's 100 outside and 250 inside, tolerate people standing and walking on it, all while retaining it's shape, not sagging under the savage life it leads.
This is a pretty tall order for a simple engine box lid.
Plywood was used for several reasons, but the two biggest are; pound for pound it's stronger then steel (amazingly enough) and it's relatively cheap, plus it's easy to work with. A regular wonder material, though like my in-laws, it too can have issues, which you've discovered.
I'm not sure what hatch configuration you have on you boat, but if it's as I suspect, you'll have a great deal of trouble spanning the distance and depth of your compartment with a light weight, yet strong substitute that can provide the same attributes.
Since your only support is around the edge, you should consider an angle or box tubing frame work (maybe aluminum), with some athwartship ribs to stiffen things up, yet remain light. Then skin this will a marine grade of 1/4" plywood (the good 5 ply stuff, not the Lowe's/Depot 3 ply junk). You can screw it to the ribs and the perimeter frame work, which will make both much stiffer. Closely space ribs can replace the much thicker plywood of the previous hatch.
Cover this with a 1/8" or 1/4" foam pad, then vinyl over that, stapling to the plywood underneath. Of course you'll want to install sound proofing and heat insulation, both available at marine stores like West Marine (bring you first born, they may ask). You can't have too much insulation, but you sure can have too little (okay, maybe you should bring along a second child).
If you could post a picture or two, it would be helpful. The boat year, make and model will also be useful.
04-29-2008, 04:52 PM
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