Doghouse/bilge cover replacement

[mattsmall1972]

Hey guys,
My boat used to be an I/O diesel that was replaced with an Armstrong bracket and a Suzuki outboard when the diesel blew due to manufacturer defect. The previous owner had the doghouse replaced with a bilge cover thing that is perfect to hold a cooler. The problem with it is that it's ugly and made with some weird wood that looks like wet cardboard.

I am terrible with woodworking, but I have an expert carpenter working for me right now who can build it stronger/faster/better like the six million dollar man. I am planning on fiberglassing it after it's built using marine ply. What I am asking for is opinion on the thickness of the wood needed for this project. I was originally thinking 3/4 ply, but I think about how heavy that would be to raise up if I need to. Now I am thinking 1/2 inch would be good enough with a fiberglass shell. What's your opinion?

I also am entertaining thoughts of just fixing this since the main part of this appears to be fiberglass, but that wet cardboard stuff just makes me uneasy. I have pictures of what I am talking about:

The whole thing from the front (notice the chipped area on the right side):

The bilge that it covers (so much cleaner and neater than it used it be... believe me):

The bottom of the beast:

The wet cardboard area that freaks me out:

What the hell is this stuff?

Another view of this material:

 

[mattsmall1972]

Well, I got all inspired to go out and chip away at it some more. It appears that this is MDF covered by a thin layer of fiberglass resin and painted over. The thing is, the construction of this thing is solid as far as fiberglass goes. I was thinking maybe take out the MDF and replace it with plywood, then refiberglass over it and repaint using a rough texture such as Kiwigrip or durabak.

That's 1/4 inch thick fiberglass construction - great everywhere except the sides maybe?

 

[Woodonglass]

If you use 1/4" ext. grade plywood and coat it with 3-4 coats of epoxy and 1-2 layers of 3oz fabric it'll be a Tank!!! Paint with 3-4 coats of Rusoleum Pro Oil based Paint with Hardener and it'll look GREAT!!!eace:

 

[mattsmall1972]

OK... perfect. I am going to follow your advice for this. Do I need to be careful about the kind of plywood I use, aside from using untreated exterior 1/4 ply?

 

[mattsmall1972]

Also, what would your recommended procedure be? 3 coat of epoxy first, then 2 layers of fabric? I just want to be sure I get this right.

 

[Woodonglass]

Coat the wood with a layer of epoxy. As it tacks up lay down a layer of 3 oz fabric and coat it with another coat of epoxy and then when it tacks up lay down the next layer of 3 oz fabric followed up with 1 or two more coats of epoxy. Just enuf to fill the weave of the fabric and smooth everything out like glass. Using a hair dryer or heat gun to LIGHTLY blow over the surface on the final coat will help level it out and remove any tiny air bubbles in the mix and give you a Glass Like surface. This should be done on both sides of the plywood. If done this way it will last for decades!!! Might be a bit over kill but it's how I'd do it. OR you could use the less expensive Polyester resin and CSM but...it has a tendency to not be as good as an adhesive and when it flexes (which it probably would with this application) it might crack or checker the paint. It might work however and would be a bit less expensive and you could prolly get all your material locally.

 

[mattsmall1972]

Any plywood recommendations?

 

[TruckDrivingFool]

If it was me I would make the base from 3/4" to give some meat to attach your hinges/pivots and some extra strength as it looks like it might get stood on. The rest certainly 1/4" would be fine.

Whatever plywood make sure it has X (exterior) in the grade stamp. I'd say ACX as it will have one face that good, you could go BCX but the savings are usually lost in time filling the defects in the "good" B face.

 

[Woodonglass]

As TDF states the base should PROLLY be reinforced with 3/4" material...either Douglas Fir our plywood. I agree that most any AC Ext. Grade Sanded on one side plywood will be fine. Once it's sealed in glass it'll be fine. Remember that if and when you put any hardware into the mix you should always Pre-drill and then coat the screws and holes with resin in order to prevent any water from entering those holes. Also pay close attention to the edges of the plywood and ensure they get plenty of resin soaked into them especially on the first coat.:thumb:

 

[mattsmall1972]

I'm a little confused now. You're recommending that I put 3/4 along the "base" (where the hinges are), and the "floor" (where the cooler will sit), and maybe the top where the handle will be? The rest can be 1/4, right? I am going to order the wood today and want to get this right.

As for construction - pl construction adhesive and simple brads to hold it together until dry will be good enough? Or should I plan on having stainless screws as well?

Sorry for all of the questions, just want to make sure to get this right. After I get this put together properly I'll order the epoxy for super strength.

 

[Woodonglass]

Yup, you got it!!! Are you going to use the 3 oz glass fabric as well??

 

[mattsmall1972]

Yes, if that's what you said to do. Would a gallon of epoxy be enough for this job? Too much? Too little? Do I need to fillet inside corners to wrap glass around them? I've been reading this forum since 2006 but have yet to do any fiberglassing myself.

 

[Woodonglass]

Filleting will make it easier but...the 3 oz glass will conform pretty easy to anything. Use the cheap chip brushes and cut 1/3 of the bristles off and then "Dab" the resin into the corners and crevices! Don't try to brush it. You'll end up moving the fabric and causing bubbles.

 

[mattsmall1972]

I am finally having a cabinet maker create the new doghouse for me. The guy I had didn't work out. I expect to have it back next week, so I want to go ahead and order the fiberglass and resin. Do you think a single gallon would be enough? I know it's hard to tell from pictures. If it's not quite clear that a gallon would be enough, then I'll order two.

 

[Woodonglass]

You have to pre-coat and soak the wood first and then apply the glass. It soaks up more than you think. I'd get two gallons. You may have some left over but better to have more than run out mid-project!!!

 

[mattsmall1972]

I've placed my order for 2 gallons of epoxy and a roller. Can't wait for it all to get here so I can get it done.

 

[mattsmall1972]

My cabinet maker called me today with the results of the new bilge hatch. To say I'm stoked would be an understatement. Now it's time for fiberglass and paint! And he did it all with a single piece of 3/4inch marine-grade ply. I am going to take my cooler to him (I forgot it the other day) and he's going to custom fit it to the hatch.

 

[Woodonglass]

Uhmmm... YEAH!!! Nice fitment!!! So mix up some thickened resin first and fillet all the inside corners. Use a plastic spoon to form nice coved filets so the glass will conform to the corners really well and not leave air bubbles. Also use the thickened resin to fill all the recessed screw holes and any other deformities. Once all is cured give it a good final sanding. Apply the glass an dab it into the corners using a cheap chip brush with 1/2 the bristles cut off. Dabbing will help avoid air bubbles. Go slow and take your time. You can even use your finger to get it to lay down in the corners just right. Use a 4" short nap nylon roller to roll out the flats. And then if you want to get real crazy buy some 3M fairing material...
and use it to fill in any small imperfections once the glass cures. TIP: Thin it a bit with acetone to make it really creamy and it'll spread like a dream!!!! It's now ready for Primer and Paint. You're using epoxy right??

 

[redneck joe]

whatever you paid for that you got your moneys worth.

 

[mattsmall1972]

WOG - You said I didn't need to fillet if I'm using 3oz cloth:

"Filleting will make it easier but...the 3 oz glass will conform pretty easy to anything. Use the cheap chip brushes and cut 1/3 of the bristles off and then "Dab" the resin into the corners and crevices! Don't try to brush it. You'll end up moving the fabric and causing bubbles. "

I went ahead and ordered the cabosil to do this, but if you can clarify, that would be helpful.