Gap-filling before fiberglass

[zachduckworth]

Hi all, looking for advice/opinions on the next step in a fiberglass project.

I'm working on a project to stiffen and extend the fiberglass deck hatch on my Islander 30 Bahama. This boat was from an era when custom made flush-to-the-deck windows were popular. The interior hull was mostly left unfinished and the unfinished work hidden with headliner. The headliner in the head was beginning to fail so I pulled it out along with 350 or so staples yesterday, with the intention of re-doing the overhead.

A critical part of this project is to reinforce the deck hatch. The gel coast around the hatch has some cracks in it already that have been patched by a PO, but I want to make permanent fixes as water has previously damaged this fairly critical feature. To begin, I cut out the damaged wood, and then epoxied a mohogany frame to the bottom of the existing fiberglass frame. The epoxy is bonded either to wood on the horizontal axis, or to the fiberglass on the vertical axis.



The new wooden frame below the existing gel coat you see in the pictures is set back about 1/8 of an inch from the line of the existing gel coat. The idea is that I can fill the gap with some polyester vinyl gap filler that I can then fair and put a radius on, then lay the fiberglass over that and marry it up with the fiberglass of the deck on the far side of the new wood.

What I was wondering is what is the best product for filling the gap that the fiberglass will go over? I was looking at Total Boat structural putty. Would this be a good application for kitty hair (which is cheaper)? And what would be the best product for creating a radius on the bottom of the new wood?

For that matter, how about some tips on fiberglassing upside down?
thanks in advance!

[Turtle Blues]

Two West System suggestions. they sell empty cartridges so that you can mix filler to your needs and apply or the one I am currently using for filling horizontal seams is the Six10 thickened epoxy adhesive. Two chambers in single tube with mixing spout. it stands up fairly well. on wide gaps I fold painters tape in half, set folded edge to bottom of seam and then cover as I'm filling. Still end up grinding some bulges. other option is a backing batten wrapped with wax paper put against seam but usually by the time I have that in place it's a mess. Good luck

[Chotu]

Fiberglass and upside down sucks. There is no way about that. Not unless you flip the boat over. Ha ha ha.

Don’t mix the resins. If you are using epoxy for the project, continue with epoxy for the filler and everything.

Just thicken your epoxy up with colloidal silica. Thicken it up until it has the consistency of like something between mayonnaise and peanut butter that won’t be dripping off the edge that you are trying to level.

https://www.acehardware.com/departme...E&gclsrc=aw.ds

You do not have to buy West system products. Those are the most expensive. It’s all the same stuff. Not necessary to spend extra on that. However, it is available readily at West Marine and maybe at Ace like it says on the link that I put above. But you can order colloidal silica right off Amazon as well. It’s all the same stuff.

If you want to round off the bottom of the new wood, take a router to it. Use this type of bit. A round over bit. Somehow ace keeps coming up in the Google searches. They are doing really well today.

https://www.acehardware.com/departme...E&gclsrc=aw.ds

Glassing upside down is definitely going to suck. But one way to deal with that is too wet out the glass on a piece of plastic sheeting. Then lift the glass up into place and press it. Roll it. Get the air bubbles out. They will be less drips that way. But there will still be drips. So just protect whatever is below.

[Turtle Blues]

Professionally I completely disagree with the comment on West Systems. It is unfair to blame a top quality manufacturer for some retailers pricing policy.
Let me try that approach with you as the customer: We used a product specifically formulated for the marine environment, an adhesive with a proven quality and durability. or alternately; We got some cheap epoxy off the internet and think it will work.
OP apologies for hijacking your question with a rant. Signing Off

[Chotu]

Originally Posted by Turtle Blues

Professionally I completely disagree with the comment on West Systems. It is unfair to blame a top quality manufacturer for some retailers pricing policy.
Let me try that approach with you as the customer: We used a product specifically formulated for the marine environment, an adhesive with a proven quality and durability. or alternately; We got some cheap epoxy off the internet and think it will work.
OP apologies for hijacking your question with a rant. Signing Off

I’m always one to take the bait. Ha ha.

If you can prove to me that the colloidal silica sold in the can from West Marine is different than any other colloidal silica sold by other distributors and resellers, I will gladly take back my statement.

[zachduckworth]

Originally Posted by Chotu

Fiberglass and upside down sucks. There is no way about that. Not unless you flip the boat over. Ha ha ha.

Don’t mix the resins. If you are using epoxy for the project, continue with epoxy for the filler and everything.

Just thicken your epoxy up with colloidal silica. Thicken it up until it has the consistency of like something between mayonnaise and peanut butter that won’t be dripping off the edge that you are trying to level.

https://www.acehardware.com/departme...E&gclsrc=aw.ds

You do not have to buy West system products. Those are the most expensive. It’s all the same stuff. Not necessary to spend extra on that. However, it is available readily at West Marine and maybe at Ace like it says on the link that I put above. But you can order colloidal silica right off Amazon as well. It’s all the same stuff.

If you want to round off the bottom of the new wood, take a router to it. Use this type of bit. A round over bit. Somehow ace keeps coming up in the Google searches. They are doing really well today.

https://www.acehardware.com/departme...E&gclsrc=aw.ds

Glassing upside down is definitely going to suck. But one way to deal with that is too wet out the glass on a piece of plastic sheeting. Then lift the glass up into place and press it. Roll it. Get the air bubbles out. They will be less drips that way. But there will still be drips. So just protect whatever is below.

Regarding sticking with epoxy for the whole project, I have read that you can prep it with water/soap/sandpaper to get it to take gelcoat, but that won’t add the strength that fiberglass has, right?

Thanks for the advice on the router. I’m going to do that. Seems much easier than my prior idea, and will add a bit more headroom.

[Chotu]

Originally Posted by zachduckworth

Regarding sticking with epoxy for the whole project, I have read that you can prep it with water/soap/sandpaper to get it to take gelcoat, but that won’t add the strength that fiberglass has, right?

Thanks for the advice on the router. I’m going to do that. Seems much easier than my prior idea, and will add a bit more headroom.

You probably could get it to take gel coat. If you rough up the epoxy and clean well as you suggest, but it’s not that easy. And it’s not necessarily going to come out looking very good. Gelcoat is not easy to apply as an afterthought. It’s typically sprayed into a mold. A female mold. Then you put your laminations on top of that. That’s why it looks so good usually. Because it was the first thing into a mold. Then it is popped out and it’s beautiful. It mimics the smooth surface of the inside of the female mold.

In your case, you are creating a sculpture rather than filling a mold.

The easiest way to do the sculpture is to use epoxy all the way up to the end. Sand that very smooth just how you want everything to look. And then use paint on top of the epoxy. A nice quality hard paint that’s not going to ding and scratch. Typically they talk about linear two-part polyurethane paints for that. However, that might be overkill for the trim ring of a hatch. Any paint that will stand up to you bumping things into it passing stuff through the hatch would work just fine.

[Chotu]

Oh yeah. And to answer your question about strength and gelcoat and what not.

The only strength comes from the Fiberglass. When you combine that with epoxy, it becomes a different sort of hybrid material. There is some strength in epoxy alone. But it goes up dramatically when you combine it with Fiberglass. Just like when they put rebar into concrete. The composite material has better properties than either material alone.

When you put gel coat on, which is just polyester resin colored like paint would be, It’s best to just think of that as not adding strength. It doesn’t really do anything. Nothing on the order of magnitude that your Fiberglass job does.

[boatpoker]

Originally Posted by Turtle Blues

Professionally I completely disagree with the comment on West Systems. It is unfair to blame a top quality manufacturer for some retailers pricing policy.
Let me try that approach with you as the customer: We used a product specifically formulated for the marine environment, an adhesive with a proven quality and durability. or alternately; We got some cheap epoxy off the internet and think it will work.
OP apologies for hijacking your question with a rant. Signing Off

I built a 24 sailboat from scratch, totally rebuilt three 37-47' powerboats (including my avatar), built three fiberglass boats and three fiberglass cars ... all with the cheapest expoxy I could find.

I put around 24,000 hours on those three rebuilds and have never had a problem with "cheap" epoxy.

[Lake-Effect]

How about fabricating fiberglass strips on the bench, (including the gelcoating) that could then be trimmed and epoxied up into where you need them, then the only extra work is fairing and gelcoating the corners.

[coopec43]

Originally Posted by Turtle Blues

Professionally I completely disagree with the comment on West Systems. It is unfair to blame a top quality manufacturer for some retailers pricing policy.
Let me try that approach with you as the customer: We used a product specifically formulated for the marine environment, an adhesive with a proven quality and durability. or alternately; We got some cheap epoxy off the internet and think it will work.
OP apologies for hijacking your question with a rant. Signing Off

I strongly disagree with your statement regarding West System being a better epoxy!! (Just more expensive that's all)

"Most Carolina boat builders do not use west system. Other brands are much cheaper and work well. I just can't remember what brands they use now. I don't think there is any significant difference between the brands."


IT SEEMS YOU HAVE TO COPY-N-PASTE THIS LINK

https://www.thehulltruth.com/boating-forum/651604-west-system-epoxy-vs-other-marine-epoxy.html