Fiberglassing question

[salmonmandan]

I'm building a flat bottom hull for my 8'x28' trailerable houseboat. 2 layers of 1/2" plywood for the sides and bottom with fiberglass over the plywood. The plans call for at least 2 layers of 6oz mat over bottom, up to the rub rail. My question is can I do one layer of 1.5oz chopped strand mat then one layer of 24oz mat? I plan on coating the bottom with one of the roll on truck bed materials like Iron Armor from Harbor Freight for the bottom paint. Not concerned about hull speed so I'm guessing I could apply the Iron Armor over the 24oz mat once it's all cured out? Please advise.

 

[Scott Danforth]

welcome aboard.

I would be looking at 1 layer of CSM, and about 4-5 layers of 1708. then fairing and gel coat.

No way I would trust bed liner, especially from harbor freight

 

[salmonmandan]

welcome aboard.

I would be looking at 1 layer of CSM, and about 4-5 layers of 1708. then fairing and gel coat.

No way I would trust bed liner, especially from harbor freight

The bedliner idea came from the outfit i got my plans from. He says several people went that route and had success. I plan to be beaching the boat a lot so it makes sense to me. Not hung up on a particular brand, just used Iron Armor as an example. I already have the 1.5oz csm and enough 24oz mat to cover the bottom is why I asked about it. 1708 is what a lot of people in sales suggest and I'm sure it's great. I'm trying to keep the cost down on the build so would rather use what I already have.

 

[Scott Danforth]

You are building a boat. The cost of the correct materials vs the wrong materials is about $300

If you plan on beaching, you need significantly more high strength cloth. I suggest 7-8 layers of 1708 and vacuum bag it to remove excess resin

If you want to use the 24 oz cloth, suggest minimum of 3-4 layers (5 on the keel and bow area you will be smacking into the beach) with a layer of CSM in between. And bag it

The woven roving adds a lot of bulk and not as much strength as the 1708 does in layers

The Harbor Freight bed liner comes loose from paint above water. I wouldn't trust it below water, specifically since it's not a polyurea product

 

[JASinIL2006]

The worst part about the bedliner stuff is that when it fails - either by getting cut/abraded while beaching or by losing its adherence to the substrate - you will have a huge mess on your hands trying to remove and replace it with something intended for marine use.

 

[salmonmandan]

The worst part about the bedliner stuff is that when it fails - either by getting cut/abraded while beaching or by losing its adherence to the substrate - you will have a huge mess on your hands trying to remove and replace it with something intended for marine use.

Yes, I was thinking it may not be a good idea after all. Looks like I'm just going to have to put out a few dollars more and go with fairing it out and then paint with a good bottom product. It's more of a shanty boat than a traditional boat so there's that. May as well do the hull in the traditional way and cut corners on the cabin maybe.