making a compartment "waterproof"

Wakeboarder3780 · Posted: Feb 08, 2009 2:51 pm Post subject: making a compartment "waterproof"

Well long story short, I plan on turning the insides of my back seat into a ballast system. I plan on building a completely new back seat system. I'm no stranger to fiberglassing but I know this wont be enough to keep it from rotting out and I think after glassing I will need to gel-coat it.

Let's just talk basics. If I fiberglass over the top of some plywood lets say about 3 layers over the wood. Then would i use something like the following?

http://www.boatbandit.com/3m-marine-high-gloss-gelcoat-compound-gallon-5336.aspx

If this is the stuff I use, can i get away just brushing it on instead of investing in an air compressor and a paint gun? I want to do something that may look crude but will work great. Let me know what you guys think.

scgolfer88 · Newbie Joined: 16 Dec 2007 Posts: 16 City: Lexington

Dont know about the gelcoat product, but I would recommend an airless sprayer at the least to apply it. A simple wagner wideshot will run you 60 bucks and does wonders with that kind of stuff.

Wakeboarder3780 · Posted: Feb 08, 2009 7:05 pm Post subject:

Well I know most people deal with bags, but I have a dream of just tossing a hose from a pump right in the "bucket" under my seat and filling the sucker right up. I also plan on putting one or two bilges at the bottom so pumping it out will be a breeze. Just want to make sure I know what I'm doing to make everything waterproof so it doesn't rot out after a season or two.

Wakebrad · Ladies Man Joined: 11 Dec 2003 Posts: 12257 City: Dallas

Most people will just build an enclosure for a bag. That way it doesn't slop out when you turn - if you leave it open ended. Or if you close it and just leave a hole you can't use it for other storage.

Wakeboarder3780 · Posted: Feb 09, 2009 5:49 pm Post subject:

Right and I know most people do that, but I really don't want to deal with bags. I don't want to deal with burping the bags and trying to get water out of the bags. It's a big pain IMO. I plan on having the entire back seat filled with water. I would hinge the sweat and put a gasket on it with compression latches so it would be water tight.

All I need to know is the basics of gelcoat. I believe there are spray kinds and brush kinds and i believe you need to mix in a hardener just like fiberglassing. Can anyone validate this is correct and perhaps provide links to some products for brush on gelcoat with hardener if it's needed?

jclorfeine · Newbie Joined: 17 Jun 2003 Posts: 5

Why don't you think the fiberglass and resin by itself will work.
I'm planning on doing the same thing myself, so I'm wondering what you think the issue will be?
I've heard of least one person doing it that way...
I thought the gelcoat over fiberglass was pretty much just for looks.
Don't typicall small wooden boat constructions use glass over wood (no gelcoat)?

Wakeboarder3780 · Posted: Feb 13, 2009 9:57 pm Post subject:

I was under the impression fiberglass alone would rot over time, without gelcoat. Perhaps I was wrong. I was hoping to get someone who had answers.

Brit Rider · Posted: Feb 14, 2009 7:01 am Post subject:

Fibreglass will degrade under UV light. but assuming it is dark pretty much all the time, water ingress shouldn't be an issue assuming its plenty thick enough as to not allow water through small gaps and holes.