Poly removal/repair advice

BamaBill

BamaBill

Active member
I'd mentioned this in a thread some time back, but I'm now getting ready to start my sanding of the hull in prep for re-coating, etc., so here goes: I have a commercially made, riverhawk hull with some glass (and some burlap towards the stern), added by a previous owner using polyester resin (auto-type, I'm pretty sure). I know that I first need to sand all of this off, if possible. After that, I had planned on merely adding a coat of resin, or possibly a light coat of glass or even kevlar to strengthen/smooth things out. However, I'm thinking I may have trouble with any epoxy over the factory resin and any remnants of the poly applied later. If anyone has any advice, ideas, suggestions, etc. in dealing with this and finding/using something that fixes this/adheres correctly, it's much appreciated. BTW, I had planned on using a belt sander for most of the work, but would a disk be better? Also, my cheapest option might be to sand the hull as smooth as possible, w/o getting into the original finish, and then coat with something like steel flex or other airboat-type hull protectant? I do worry about that stuff chipping and peeling over time and just having to do it again, though. Keep in Mind this hull is for backwater use, where it will see the bottom quite a bit.
Thanks.
 
Last edited:
I'd mentioned this in a thread some time back, but I'm now getting ready to start my sanding of the hull in prep for re-coating, etc., so here goes: I have a commercially made, riverhawk hull with some glass (and some burlap towards the stern), added by a previous owner using polyester resin (auto-type, I'm pretty sure). I know that I first need to sand all of this off, if possible. After that, I had planned on merely adding a coat of resin, or possibly a light coat of glass or even kevlar to strengthen/smooth things out. However, I'm thinking I may have trouble with any epoxy over the factory resin and any remnants of the poly applied later. If anyone has any advice, ideas, suggestions, etc. in dealing with this and finding/using something that fixes this/adheres correctly, it's much appreciated. BTW, I had planned on using a belt sander for most of the work, but would a disk be better?
Thanks.
Click to expand...


Bill, are the repairs that you are doing cosmetic or structural? Epoxy sticks to everything that you have described in a cosmetic application - it will stick to gelcoat, poly, burlap, etc... If you need to do a structural repair type work, you need to get down to the origional resin and glass - that is remove the new poly and burlap and the origional gelcoat to get a good bond. I remember what you described and it sounded pretty nasty with the burlap, but as you describe it it sounds like to are trying to get back to origional not add something new. Either way, if you are going to put a piece of glass over top to smooth things out (it would also lock things in), you are going to want what you are glassing to be in the final shape and smoothness - what I'm trying to say is that a layer of glass over top at the end is a good idea. It isn't, however, going to smooth much out other than spider cracks and if the surface isn't as you want it as a final product.

I belt sander is a pretty sucky tool for that sort of work in what I've used. You would for sure want a palm sized random orbit sander and a sander polisher type sander. For the radial sander (the sander polisher) you can buy a drill mounted rubber disk (6"?) with adhesive disks that will work okay. The random orbit with 60 grit wodl work better than a belt sander in that you can control it better and it woudl remove material (if not more slowly than you woudl want).
 
It is the hull bottom. The inside had some, as well, but it was fairly easy to deal with compared to the bottom. I'm not looking at any structural damage, that I know of. I just want to ensure I remove all of the burlap and uneven glass, and seal things well. Ithought I might add a layer of Kevlar or something, as a long term hull protectant/stiffener, once the other work was undone. For some reason, I had it in my head that epoxy would not stick over poly? Thanks for the help.
 
Epoxy will stick very well to polyester resin, but less well to gel coat.

Is the boat gelcoated? What is directly under the layer you are trying to get off?

Have you tried using a chisel or thin sharp putty knife to seperate the poly from the boat underneath? You could even try a little careful heat applied and it may peel off, especially if there is a clean coating underneath.
 
It should be a factory (Riverhawk) gel coat underneath...should be...but I'm not certain what all has been done for prep, etc. by the previous owners. I just planned on going down to the first smooth, clean surface with sanding, and applying a coat of epoxy or kevlar and epoxy over the bottom. I will try a chisel, but I think it's likely to be hard to get it between the two resin materials. A sharp chisel did work on the inside, but the material there was bonded to a porous surface from the sprayed interior glass, with no gelcoat. I'm thinking the kevlar might be a nice addition, due to all the gravel, shells, hard clay and such, in the shallows it will see.

BTW, any advice on kevlar fabric type/weight appreciated. I'm assuming I'll need some special shears, but other than that, I have never worked with Kevlar before, only glass.
 
Last edited:
It should be a factory (Riverhawk) gel coat underneath...should be...but I'm not certain what all has been done for prep, etc. by the previous owners. I just planned on going down to the first smooth, clean surface with sanding, and applying a coat of epoxy or kevlar and epoxy over the bottom. I will try a chisel, but I think it's likely to be hard to get it between the two resin materials. A sharp chisel did work on the inside, but the material there was bonded to a porous surface from the sprayed interior glass, with no gelcoat. I'm thinking the kevlar might be a nice addition, due to all the gravel, shells, hard clay and such, in the shallows it will see.

BTW, any advice on kevlar fabric type/weight appreciated. I'm assuming I'll need some special shears, but other than that, I have never worked with Kevlar before, only glass.
Click to expand...


If it is gelcoat and not too scratched up or they really scuffed it up, I'd try really hard to get the poly off with a putty knife and soem heat from a heatgun. You may be able to come up with a system that will work and not hurt the hull.

If the hull is gelcoat, the epoxy may not stick to it as well as you woudl like in an abusive sort of situation, so you woudl have to sand the gelcoat off to get to the resin and glass. Epoxy does stick to gelcoat, but gelcoat isn't a strong base layer and the epoxy/gelcoat/fiberglass(kevlar) bond can only be as strong as the gelcoat, which is cosmetically strong, but not structurally strong, if that makes sense.

If you are going to go kevlar, there are a few things to consider. You need a barrier over it, so you can sand the finished surface to clean it up in teh final sanding like you woudl have to do with any resin/cloth combo. Typically the practice in a case of topcoating something with kevalr is to put a layer of glass like 6 ounce over it, so you have something on the surfact that you can sand. I put 5 ounce kevlar with 6 ounce glass over it on my snowgoose. I like it, but the kevlar is a bitch to deal with in terms of sanding. If the sandpaper ever touches the kevlar, it fuzzes awful and just can't be dealt with well. If the epoxy is very well cured adn hard you can kinda deal with it with a razor blade or scraper to eliminate the fuzz. I had 2 spots at a kevlar joint where I cut through the glass and hit the kevlar and it was pretty miserable to get under control. Maybe someone who deals with kevlar has better ideas, but I think the general idea is to never touch it with a sander.

Kevlar wets out harder than glass and it does not take bends as well (at least the stuff I used) - so if your boat has strakes or runners to deal with or a hard chine, I'd be very nervous. Those are points where it is also going to be easy to cut throught the glass and start a mess too.

Yes, good scissors are needed, I bought them with my fabric, but there are just good fiskars fabric shears.
 
Last edited:
Thanks Ted. If I'll have to put a layer of glass over the kevlar, it'll sort of defeat my purpose of keeping the weight down and providing a first defense against the rocks and such....might have to forego that idea, then. If there is a solid gelcoat under all that, and I can use chisels/heat to get to it, then I could just leave it alone (as original), in the end, I guess? I'll work on finishing up the inside TLC once this is done, but that will likely include some glass/epoxy encased pywood flooring in the center of the boat.....if I decide I can tolerate the additional weight.
 
Sand and grind away down to the substrate (where you want to stop)....Poly can be softened with chemical paint removers also....just make sure you have no residue and glass over it...
 
Well, I started out sanding, but decided I'd try to chisel/pry it loose....it worked, mostly. My trim mason's flatbar has worked very good...there were multiple pieces (another layer) of glass, under the piece I could see at first. The burlap/bondo area has been the worst. I still have a little glass to remove and the rest of the burlapped area, and then I'll have the original gellcoat showing over the entire bottom...albeit scattered with patches of resin and glass remnants I'll need to remove. This is when I'll probably have to sand, but I don't want to harm the gelcoat. ANy experience with this appreciated. I may not need to go back over it with glass, as it's in pretty good shape, save for some chips or scratches here and there. I have worked with applying glass, etc. on boats before, but never removing it or messing with gelcoat, so any continued advice is appreciated. I do have some pictures from when I started, and will try to take more tomorrow, before I get all of the burlap and glass off, so anyone interested can see exactly what I'm dealing with here. Thanks again.
 
Bill,

You have a couple of options,
1. You can repair the gel coat using a bit of epoxy or gel coat.. sand and then paint.
2. Sand and remove the gel coat trying to not go into the structural part of the composite, then add more cloth and epoxy. Do not add to much weight if you can prevent it..

Check for cracks or damage as you go and repair...

Remember gel coat is not structural....

Do yo have any pics of this boat you can post?
 
Last edited:
I can email pics...there are quite a few and they'll be large. PM me your email, and I can email you some of them. I actually think they gelcoat will be fine, if I can keep from damaging it when sanding the rest of these gobs of resing and glass remnants off...it actually looks good under it all.
 
Paste type paint removers will soften gel coat, so for sure they will remove auto body filler.

I had layer on layer of bottom paint that I wanted to remove from a dory years ago. That is when I learned to be careful with paint remover. Still, attacking a fiberglas hull with a belt sander doesn't sound like a great idea.

Before doing any grinding, first thing I'd try is laquer thinner. It might remove the burlap & whatever was used to glue it on. Then paste paint remover being careful not to get down to gel coat. Whatever the paint remover won't take off is stable enough to epoxy over (to me).
 
I actually decided against the belt sander and am using a reciprocating sander and different disks...since it has a vac attachment for my shop vac to reduce the glass dust. I should be able to chisel/solvent to the point where my sanding needs are light and can be accomplished with fine/very fine grit paper, which should merely prep the gelcoat for any follow on painting or other layer of gel...at least that's my plan? Keep the thoughts coming. Thanks.
 
When ya get to the last sanding before the epoxy coats, I'd use 60 or 80 grit sand paper, gives the poxy some tooth to grab & stick to. IMO
Dennis
 
I went to Riverhawk's website:
​
"RIVER HAWK boats are constructed from hand layed fiberglass hulls, marine composite materials and marine-grade foam for light weight, durability, stability, stealth and a high degree of unsinkability. Metal or vinyl side rails and metal transom motor brackets ensure years of trouble-free service.​
No wood is used in RIVER HAWK boats. NO WOOD = NO ROT. "​
​
Considering all of the above, as long as the foam core is adequately covered/protected, not much else matters a lot. The governing rule should be "do no harm".​
 
I'm pretty sure what was/is supposed to be underneath all of it, and (so far), most of the factory gelcoat, etc. looks good. I'm thinking that my decision is whether to fill any nicks/chips in the gelcoat, etc. by re-gel coating, or should I just add a layer of tinted epoxy, or epoxy AND glass? From the looks thus far, I could merely fill any voids and paint, should I want to do the easiest/quickest route to 'done'. Rain is slowing me down right now, since sanding/removal is being done outside. Thanks for the help.
 
I would fill the places that are "voids" as you call them and then sand and paint..just check for anything structural such as a bad crack.. You can get some gel coat maybe to match the old to help fill the voids but it is a pain...

Matt
 
I'm pretty sure I don't have anything structural to deal with....just some nicks, chips, and scratches through the gelcoat, and a slightly worn area by the drain hole at the transom...epoxy would surely take care of all of that. I'm just wondering the best approach for paint adhesion over gelcoat?...same as always, sand, wash, degrease, and paint?
 
Last edited:
yup sand...I would go no less than 120, prime, sand with 220-320, and then the final coats if you do not need a second coat of primer..
 
You must log in or register to reply here.
Back
Top