Racking the brain: advice needed on hard top for Albin 25

[DesertAlbin736]

Necessity being the mother of invention, I'm about to embark on a project to make a new hard top to cover the opening over the pilot house on our Albin 25 "La Dolce Vita".

The situation is thus: our boat came with a previous-owner installed hard top made of 1/4 inch white translucent plastic material like Lexan or something. It was hinged on the aft edge allowing it to be raised like a pop-top for ventilation, held open by spring hatch supports and held closed by Sea Dog hatch latches on the corners. For those not familiar with Albin 25's, the opening is 5 ft 8 inches wide side to side by 3 ft long fore and aft.

There was only one problem with this setup, that is when trailering at highway speeds it would tend to catch air and flip open, the latches not being strong enough to withstand 65 MPH slipstream. The solution was to jerry-rig tie downs. Well actually there was also other minor problem, that being that opening the top for ventilation interferes with the raked stub mast that mounts just above the windshield.

Long story short, the issue was forced last week when returning from the lake. I neglected to do the tie down routine since we were not going to be driving on freeways and our speed on the road during our 15 mile route home would not be over 50 MPH. That turned out to be a mistake, because it was windy that day, and on the way a headwind blew the top open, only this time it shattered into 3 pieces and is toast.

So now I'm thinking of making a solid replacement by glassing over a panel of 1/2 inch marine grade plywood. I'd prefer 3/8th inch, but there's only one local source of marine grade ply in the Phoenix area and they only carry 1/2 inch and 3/4 inch.

What I'd like to do is make this new hard top only cover the opening, make it fixed in place, and build/install a pair of opening vent hatches.

The main problem with this plan is that the roof of the pilot house is curved athwartships. If one were to lay a strait edge across the opening, the apex of the curve would be about an inch above the straight edge.

So the question is, can that 1/2 inch ply be bent that much without steaming or kerfing, and if so, what's the best method to accomplish it? Or should I return the plywood for refund and do a foam core? I plan to encapsulate the wood with epoxy and either glass cloth or chopped strand mat. Since the width of the opening is more than 48 inches, the surface grain of the plywood piece would go side to side, that is cut from the long dimension of the 4 X 8 sheet.

The photo below shows two Albin 25s at the recent Pacific NW Rendezvous. Our boat "La Dolce Vita" is at right with the top popped open, and the Canadian boat "Transitions" is at left with their version of a hard top. I like their setup, except I'd prefer making our hard top as close to being flush with the existing surface as possible with no overhang extending out past the windshield since we have a mast step for the sailing rig that is right up close to the windshield. Any advice and suggestions would be appreciated. Thanks!

[jleonard]

You can "score" the plywood and it should bend.
What I would do is make 2 bows out of wood to the contour you want and screw the plywood to that first then do your glass work.

[DesertAlbin736]

That's kind of the direction I'm thinking. Just wondering how much bend 1/2 inch plywood can take? This plywood is 5 layer, that is three 1/8" plies plus thin outer veneer layers on each side. Have read that scoring/kerfing should only be done on 3/4" or greater ply? Would much rather laminate 2 layers of 1/4 inch ply, but marine grade in that thickness is just not available locally. Otherwise would have to go with a commercial grade exterior construction ply.

Two schools of thought on installing the panel: The opening has a raised & radiused ridge around it, since the stock factory setup was to have a canvas/Sunbrella cover snap in place with f/g battens across the opening to maintain shape. Option 1 would be to overlap the edge with the panel sitting on top of the ridge. Option 2 would be to the have the panel fit snug inside the opening, caulked or f/g'd in place and faired over flush and level with the top of the ridge, being able to screw those bows horizontally into the surrounding structure, which is about 1" thick. The roof is only curved athwartships. Fore and aft it's a flat surface, so the curve is a simple convex one. Option 1 could include screwing those bows in place an inch or so inside the edges, framed on all 4 sides to have the panel sit on top of the ridge and the bows drop into the opening and attach that way besides using caulk or adhesive to seal the opening, and of course rounding the edges in order to be able to wrap the cloth or mat around.

I'm on my way to Lowes to buy a sheet of masonite to use as a pattern/mock up and trace the curvature. Won't be able to start this project until sometime next week as the boat and trailer are in the shop now getting the hubs repacked and won't be done until Tuesday or later. The good thing is we have lots of fair weather in store, as fall in AZ means sunshine and temps in the 80s with low humidity well into November, and 60s and 70s in December.

[Jay Knoll]

You might talk to these people about their products

http://www.qualityplywoodspec.com/bendi ... d2011.html

If you're going to epoxy the whole thing anyway I really wouldn't worry about marine ply vs regular plywood

http://www.woodweb.com/knowledge_base/M ... ywood.html

Going to be a fun project to watch!

[jleonard]

Ditto regarding marine grade. Just use exterior grade.

[DesertAlbin736]

Already purchased a sheet of 1/2" marine grade ply. Glue used in marine grade is probably not much different than regular exterior, but the finish of the outer veneers is good & smooth. Plus if we ever go to sell the boat I can honestly say that marine grade ply was used & did not skimp on materials. Went down to Lowes yesterday, and the plywood they sell is Roseburg brand, and I've read reviews online that the quality of that brand is not all that great. Lowes has some good pieces of 1x2 and other sizes of fir door trim lumber that looks like it would do well to make bows out of. They also have similar trim lumber of poplar, but I'm guessing fir would be the better choice.

[Phoenix27]

I went to a boat wrecking yard and got a pc of fiberglass from the sidee of a wrecked houseboat screwed it down and put car moldind and covered the rough edges .and painted it .