Using epoxy to build out a plywood edge w/ pic

[drewpster]

Ok so I have got the first coat of finish paint on the hull. It has been sanded and is ready to take the next one. Before I move ahead I need to do some work on the plywood edge of the deck where the rubrail attaches. When the boat was originally built it had a rigid aluminum rubrail. I guess knowing the rubrail would cover and finish the edge, the factory did a lousy job finishing the cut at the edge of the plywood. It is not a good square flush cut to the hull. There are areas where the deck edge extends out slightly. And other areas where is was cut slightly too far in not coming flush with the side of the hull. I need to jigsaw cut the overhanging areas and build out the parts that are recessed making a clean flush edge for the new rubrail. The new rubrail is a flexible vinyl one from Taco. Cutting the edge off flush is simple enough, but how do I build out the edge where it is recessed? There are only two small areas where the deck does not come out all the way flush and they are less than 1/4" in depth.
Can I use epoxy and fiberglass cloth to build out the edge? Or should I use a piece of wood sliver as a 'core' with epoxy to build it out?

 

[KnottyBuoyz]

Re: Using epoxy to build out a plywood edge w/ pic

Hey Drewp

Are the screws for the rub rail going into the plywood? Kinda looks like that's how they hold the deck on!!! That's a tough one. Epoxy & Glass might work, you'll have to build a dam to hold it back and from running all over the place. You could try just thickening some epoxy with woodflour and filling it that way. I'd be careful trying to epoxy glue the plywood to the hull. That looks like it'll get some movement as the boat is used.

If you can get the ply to hull area close together a more flexible sealant might be better as the hull flexes. I'd be afraid of leaks. Hard to tell from the pics exactly what's going on.

Rick

 

[drewpster]

Re: Using epoxy to build out a plywood edge w/ pic

I think the gap you can see between the deck and the hull is making things unclear. The deck of the boat is attached from below and through the top to the structure of the frame inside the hull. The gap you can see in the pictures is frankly just poor fitting by the boat manufacturer.
The rubrail (the original and the replacement) do not attach the deck to the hull. Its easy to see why you would think so because of the gap. I thought so too until I looked at it closer.
The rubrail simply screws to the edge of the plywood and is not part of the structure itself.
When the boat was built the deck shape was cut badly in a couple of places. This was ok originally because the ridged aluminum rubrail covered the bad spots. I am going back with flexible rubber rubrail.

Can you see the overhang of the plywood? I will have to cut this off to flush.

here you can see where the plywood was cut too much and is not flush with the hull.

If I install the rubrail without having a flush edge the rubber will look twisted and the line will not be straight. The gap you see is about a quarter of an inch deep and I will be filling it with 4200 or silicone just to keep water from collecting. Its the plywood edge where it cannot be cut back to flush, that needs to be built out. Now its really confusing huh.

 

[sport15]

Re: Using epoxy to build out a plywood edge w/ pic

An epoxy mix ?build out? would work as long as you have a good bonding agent in the epoxy. Some folks call it tiger hair others cut up chopped mat that has been pulled apart, even more a royal pain in the stern.. The mix can thickened up with cabosil or wood flour. The idea is to make the goop tough enough so it will not shatter when it gets bumped, the glass strands should help with that, the cabosil will keep it from running everywhere.

If you go to all that trouble, you can scarph pieces of epoxy coated ply into the shy areas and use a router with a flush bit on the proud areas. This is a lot more work but the end result will be a better job in the end..

 

[Boomyal]

Re: Using epoxy to build out a plywood edge w/ pic

I would rip some suitable depth material to the approximate thickness, saturate it with thinned epoxy, epoxy glue and brad nail it to the edge of the deck. I'd tend not to use plywood because I would not trust the lamination strength in 1/4ish inch strips, although with epoxy glue behind it it might be ok. Then I would take a belt sander and contour it to the lower hull rubrail surface and sand as nec to flush with the deck. I would epoxy fill any voids between the strip and the deck, recoat any exposed surfaces with thinned epoxy, and finish off as required.

 

[luckyinkentucky]

Re: Using epoxy to build out a plywood edge w/ pic

Why couldn't you just get some aluminum strips and edge it out with that after filling in with 5200? They make the "L" shaped edging. A good thing about aluminum strips is that they can be 'rubbed down' to meet the curvature of the boat. It would also provide a rigid edge to smooth out some of the imperfections of the cuts. If you have a bend in a corner you could just heat it and bend it slowly. You could use the 5200 to adhere to aluminum to the wood. If you decide to ... be sure to buy the large caulking gun size though. The little tubes can get pricey.

I assume you will be painting it anyway. Right?

 

[drewpster]

Re: Using epoxy to build out a plywood edge w/ pic

I like all those ideas and I think I will use them all. My Father has a router and some fancy roller tip bits, maybe he has a flush cut bit. (he is a wood worker type) In the deeper recessed edge epoxying in a wood strip then cutting back is the ticket. In the shallow recess the wood four+ silica+ chop strand is the way to go I think. And I really like the idea of putting a narrow aluminum strip around the perimeter to give a clean straight line all the way around. That will also help if I get a screw in that stupid gap.
I cut a piece of the rubrail off the roll (about 2 inches...cost me $6) to see how it would lay on the rough edges and it will look wrong if I don't do something. (man I wish someone would compete with Taco, this rubrail is ridiculously expensive)

 

[ondarvr]

Re: Using epoxy to build out a plywood edge w/ pic

I like Boomyal's method.

The pics from the other thread look good.

 

[drewpster]

Re: Using epoxy to build out a plywood edge w/ pic

I just got off the phone with Dad and he suggested, since the finish coats of paint are not on the deck yet, use his fancy router to cut back the recessed areas slightly. (just 1/4" or so) Then, again using the router, cut a shallow slot into the edge of the ply. Then glue in a hardwood strip with a corresponding daydoe to slip into the slot using epoxy. He seems to think this would help bond the strip to the edge. And make it less likely to get damaged in case of a hard hit. Sound good? Or are we over thinking?
BTW if I hit anything that hard I'm gonna be a little miffed.

 

[drewpster]

Re: Using epoxy to build out a plywood edge w/ pic

Thanks ondarvr, can ya tell i'm a little excited?