15' Trophy boat hull repair

[tonk62]

Hello, I am in the process of repairing some bottom side hull damage on the boat I just purchased.

my questions are, how far from the damage should i sand down to the original fiberglass, to place a patch over damaged area? Are all fiberglass boats, coated in bondo, over fiberglass and under paint / gel coat? This boat has about a 1/16 th to 1/8 inch coating of bondo type material covering the entire hull, on the bottom side.

 

[Cadwelder]

Re: 15" Trophy boat hull repair

Re: 15" Trophy boat hull repair

Hello, I am in the process of repairing some bottom side hull damage on the boat I just purchased.

my questions are, how far from the damage should i sand down to the original fiberglass, to place a patch over damaged area? Are all fiberglass boats, coated in bondo, over fiberglass and under paint / gel coat? This boat has about a 1/16 th to 1/8 inch coating of bondo type material
covering the entire hull, on the bottom side.

Well, there should not be any bondo on your hull at all....

The places you have prepped in the pictures look really thin to me...is that interior wood showing in a couple of them?

Can you get to both sides of the repair areas?

It looks to me like you you need some built up for sure in what I see.

 

[tonk62]

Re: 15" Trophy boat hull repair

Re: 15" Trophy boat hull repair

if you look close, you can see a pink color, that is some sort of filler, (bondo) and it is covering the whole bottom of boat, I guess they used it to smooth out the fiberglass before painting. It is pretty thick, fiberglass, except where the damage is, most of the damage appears to be made from beaching the boat, and the trailer. that spot at the stern, was caused by sitting on the rear roller of the trailer, bunk boards are not adjusted right. the keel will need built up, as it is worn down from beaching all these years.

No wood showing, just several layers of worn fiberglass. Cant get to the inside, without tearing out the floor, and it is solid, but I am sure they didnt do it right either.

 

[Cadwelder]

Re: 15" Trophy boat hull repair

Re: 15" Trophy boat hull repair

if you look close, you can see a pink color, that is some sort of filler, (bondo) and it is covering the whole bottom of boat, I guess they used it to smooth out the fiberglass before painting. It is pretty thick, fiberglass, except where the damage is, most of the damage appears to be made from beaching the boat, and the trailer. that spot at the stern, was caused by sitting on the rear roller of the trailer, bunk boards are not adjusted right. the keel will need built up, as it is worn down from beaching all these years.

No wood showing, just several layers of worn fiberglass. Cant get to the inside, without tearing
out the floor, and it is solid, but I am sure they didnt do it right either.

Ok, you can do the repairs from the outside, but I'd really like to see the bond gone, you'll need to sand and prep the entire hull anyway before the new paint. As far as the repair areas, grind them to taper from the damaged area out to a good 8" or so, and build it back up with altering layers of mat and cloth (1708 is the main choice here). Start with mat ( CSM ) about the size of the main damage, then get progressively larger with each layer until the original thickest is met. Finish with a layer of CSM and then grind to match.

 

[tonk62]

Re: 15" Trophy boat hull repair

Re: 15" Trophy boat hull repair

thanks for the info Cadwelder, that bondo I am talking about covers the entire area of the hull.

What is the best thing to sand with? I was using a 4.5 inch grinder with a flap sanding disk, but it doesn't follow the curves well and leaves gouges, would a 6 or 8 inch grinder, with a rubber backing plate be better? and what grit works best?

 

[Cadwelder]

Re: 15" Trophy boat hull repair

Re: 15" Trophy boat hull repair

a DA works well for this too. Experiiment with the grits. I'm use to grinding fiberglass which is a 24 grit, but that's way to course for your hull. I'd start with a 220 grit and see how it goes.

 

[tonk62]

Re: 15" Trophy boat hull repair

Re: 15" Trophy boat hull repair

thanks for the info cad, I was using 40 grit with the 4.5 grinder, the problem is, cant get the grinder flat enough to boat, so it doesnt try to dig in. would poly resin be good to use for the repairs, and what is the difference in the resin from say, home depot compared to the risen from an automotive plant supply store?

 

[tonk62]

Re: 15" Trophy boat hull repair

Re: 15" Trophy boat hull repair

got some grinding done today, will be picking up the resin and fiberglass saturday, to start the patching process

 

[Cadwelder]

Re: 15" Trophy boat hull repair

Re: 15" Trophy boat hull repair

The angle grinder isn't the best choice for the operation you're doing hence the mention of the DA. The resin from the box stores is mostly all waxed (which you don't want) and there is also a freshness issue...polyester resins have a short shelf life. About the same with automotive store.

US Composites is the supplier of choice here, but there are many out there. I see you're from Norman....we have a memeber in Okalahoma that goes by Woodonglass...he may be able to turn you on to a local supplier in the area.

 

[Woodonglass]

Re: 15" Trophy boat hull repair

Re: 15" Trophy boat hull repair

Call these guys and see if they sell to the Public.
I'm not sure if they do or not.


Superior Fiberglass
104 N Falcon Dr,
Oklahoma City, OK 73127
(405) 495-8585

Ok, Does the pic accurately reflect what you are talking about?

(Click the Pic to Enlarge)

 

[tonk62]

Re: 15" Trophy boat hull repair

Re: 15" Trophy boat hull repair

thanks for the input, I just bought a DA sander today, going to see how it works in the AM when it is cool.

Yes Wood, that pic is what I was talking about, looks like a thin layer of bondo covering the entire hull, under the gel coat?

 

[Woodonglass]

Re: 15" Trophy boat hull repair

Re: 15" Trophy boat hull repair

R U sure your boat is Gelcoated and NOT Painted. That PINK stuff could be PRIMER for the Paint. Not being there its hard to tell. I have NEVER heard of any kind of undercoating being use prior to gelcoat and for sure NOT BONDO.

 

[ondarvr]

Re: 15" Trophy boat hull repair

Re: 15" Trophy boat hull repair

There are some barrier coats that are applied between the gel coat and laminate and some are about the same color as Bondo. I can't tell from the pics if that's what it is for sure, but that would most likely be what it is if that's the original finish.

 

[tonk62]

Re: 15" Trophy boat hull repair

Re: 15" Trophy boat hull repair

it could possibly be painted, I have never seen a pink primer before. it appears to be thicker than primer, 1/32 to 1/16 inch thick. I have seen where body shops will put a thin layer of bondo on older vehicles to smooth out the metal, on say a hood or fender, because the metal was not always perfectly formed as it is the the presses used today.

 

[ondarvr]

Re: 15" Trophy boat hull repair

Re: 15" Trophy boat hull repair

The barrier coat I'm talking about is used in the original production of the boat and is sprayed on between the gel coat and laminate.

 

[Woodonglass]

Re: 15" Trophy boat hull repair

Re: 15" Trophy boat hull repair

OK, ondarvr is the expert and that is probably what it is. SOOOOOOO tonk are you regelcoating or painting the hull.

 

[Cadwelder]

Re: 15" Trophy boat hull repair

Re: 15" Trophy boat hull repair

Barrier coat....da*** I knew that, just never thought of it. Only seen it once, but it does sound like that's what you have there.

Just sand it down smooth to prep for paint...

 

[tonk62]

Re: 15" Trophy boat hull repair

Re: 15" Trophy boat hull repair

I will be painting, I got the areas patched this morning, and am in the process of sanding them down. The DA sander I bought from harbor frieght works great, but ......... they listed the cfm as 4 at 90 psi, my compressor is rated 5.5 cfm at 90 psi, and it cant keep up with the sander? I think the sander was miss rated.

 

[Woodonglass]

Re: 15" Trophy boat hull repair

Re: 15" Trophy boat hull repair

Do you have a R/O Electric Sander. It'll do the same job. What Paint R U planning on using??

 

[tonk62]

Re: 15" Trophy boat hull repair

Re: 15" Trophy boat hull repair

I am considering using Rustolium after reading your restore thread and seeing the results. I think I read in one of your later posts, that you changed your recipe to include an automotive reducer, is that correct?

Did you order the rustolium or buy it locally? My problem is, ordering it on the internet, you can't see the true color, I am wanting a bright blue, to match my truck and Harley, as close as possible and I cant tell how bright the bikini blue is that is on the internet.