Engine cover design

[MarkGT]

I just got a great deal on a 14'jet boat to use on the small inland lakes when the 21GT is to big. Problem, engine cover (hatch) was lost on the expressway by P.O. I was planning on replacing it with a padded sun deck. It is 5 FT wide X 3.5 FT with about 2" total curve across the short side. I was considering using 3/8 marine plywood with a couple of 3/4 x 1 1/2 ribs to form the curve. Maybe sealing the underside with a layer of glass & resin since it will be exposed to alot of moisture from the engine compartment. The cover will be supported on all 4 sides. It seems that 1/2" maybe to heavy & hard to bend without a lot of saw kerfs. However someone weighing 200+ lbs could be standing in the middle!!
Does anyone know what the current boating industry is using for there covers? Is a higher density foam normally used on top?

Any thoughts, or input would be greatly appreciated. :)

[BigGrizzly]

Make a jig and use 2-1/4 sheets they will bend easily epocie or glue between the sheets- this works every time, use only marine ply- I prefer birch- but its hard to find in marine.

Randy

[oldLenny]

If you are going to go the "bending wood" way, try "Rubber Ply" This is not a brand name but a concept. It is 3/16 mahogany and poplar, 5 ply lay-up, and all skins have the grain aligned in one direction, not cross layered as per the norm. Any large wholesale
cabinet wood supply shop will have access to this product and they come in 4' x 7' sheets for about $25 Can, so look for about $15 US a sheet. We use it to do curved cash counter and office desk work. It will bend effortlessly into about a 6" radius all day.

[MarkGT]

Thanks Randy

I had consider doing that, its the easy way to follow the sharpest part of the curve. The glue process is a concern with the large surface. Maybe a roller (100% coverage), couple dozen clamps around the perimeter, alot of small screws in th middle!! (I don't want any voids) Any perfered brand of glue?

Len that plywood sounds great!!
Does it have an exterior rated glue?? That stuff soundS great for making curved back bucket seats, with a couple layers of glass for strength.

MARK

[BigGrizzly]

The voide problem isn't really a problem because you are laying a arc. . just start in the middlewith a screw basr then work to the edges.

Randy

[oldLenny]

UF-109 is still a preferred exterior glue outside of the ultimate,...(epoxy)
The rubber-ply is void free and is used for lay-up and contouring. We laminate a phenolic surface onto it. Eg: Formica, Wilsonart etc. to create nice contours, positive and negative, across a linear surface. I am pointing to this product for use as a substrate in making a mould for a fibreglass product, something wonderful, not for use as a build-up of wood and glass to create a heavy wood based/glass cover. Use it for the plug.

[BigGrizzly]

I have used it before and had it split along the grain. Which is it weak point. Every thing has its weak points. I think mark was going to use as a structural member.

Randy