warped hull repair

[Woodonglass]

Ok since you've done the best you can from the inside Here's my recommendation. Using either the blue or pink slab foam you can get at Lowe's or Home depot, I'd epoxy a piece to the hull and then use a grinder to shape it as best as possible to conform to the shape needed. then I'd use 3 oz glass and do mutltiple lams to tie it into the hull using epoxy resin. Each lam being 2" larger than the previous one. If you do this you should be able to blend the patch to the hull with a pretty much an un-noticeable seam. I hope this makes sense.

 

[apolite1016]

Reason I was thinking about the high density foam was I figured I could pour it and it would conform better to the high and low spots in the hull not only that but the compression strength I think would better suit the location being that it is located where the bunks are going to be on the trailer.

 

[Woodonglass]

Your glass laminations and the epoxy will give you the strength. The foam is just the "Form". The beauty of bunk trailers is that the bunks distribute the load across a broader range than do roller trailers. You can use the HD foam but IMHO it's not needed. 1/4" of Mulitiple lams of Epoxied glass will be "Armor Like" and with only a 36" span of varing depth will provide all the support needed. You can do as you see best, I'm just describing how this Old Dumb Okie would "Git er Dun" That Don't mean it's the only Way!!!!:noidea:

 

[Rickmerrill]

Please keep us posted. This is an interesting one.

 

[apolite1016]

Ok so having browsed around on line and doing a little bit of research, weighing cost vs benefit I think im going to go ahead and use a polyester isophalic layup resin Epoxy just Isnt in the budget considering I'd need over 5 gallons of the stuff plus cloth filler and all the other goodies, I already could have bought a new aluminum boat this size for what ive spent on it so far besides this boats not going to be in the water every day and will be parked inside most of the time any ways.
I figure its just going to be my " I need a day on the local pond type thing once in a while" here in Delaware its all shallow ponds and streams any ways so i figure it should be fine.

Any ways im going to grind a bit more gell coat off using a 26 grit disk That should give a real good rough surface to bond to since I'm going to be relying on primarily a mechanical bond with polyester.

Ive decided to not use the foam as a core.
I did talk to some one who did that and the fix didnt last more than two years so im not taking a chance with that
I do have a few questions and maybe some one can confirm im on the right track with my plan.
since the areas I need to fill vary in depth I was planing on mixing my own filler material using chopped strand and a fumed silica or what ever is best, fill the low spots no more than 1/8" at a time then cover each fill with a layer of mat or cloth.

I guess my questions now are
what ratio of fillers to resin
what type of cloth or mat between layers.
and should i use a fairing compound over the final layer with micro baloons or just go with fiberglass flock or milled fiber and then epoxy prime over that?

 

[Woodonglass]

What would you guess-ti-mate the square footage of the area you're going to fill is?? You want to remove ALL the gelcoat and get to good fresh glass in order to get the best bond. I'd also recommend you look into using Vinylester resin. A bit more expensive than Poly but less than Epoxy, and it has much better adhesive characteristics. Kinda the best of both worlds.

 

[Rickmerrill]

Just thinking out loud (crazy talk) but I'm wondering if PB will be able to flex without cracking? I don't know maybe the thing will be like a piece of iron. I'm just wondering if layers of mat and heavy roving would build up bulk quick and be a little more like conventional hull construction.

 

[sphelps]

^^^^^ I was thinking the same thing ^^^
And WOG is right, good clean glass . the first lay up will be the most critical ..

 

[apolite1016]

I figured the total area is about 30 sqft with an average of 1/4 " depth i took measurements in several locations to get a average.

 

[Woodonglass]

Ok, My best recommendation would be to grind the area using 24 grit resin coated discs down to fresh glass and then wipe clean with Acetone. Mix up some Hairy PB using 1" strands shredded CSM. This will make it very structural. Then I'd drill some 1/2" holes into the hull at various locations so the PB will ooze thru and create a kind of Fiberglass Rivet structure. This may sound controversial but it won't hurt a thing and the pb will seal them just fine. I would apply this with the widest plastic putty knife I could find. I would leave it a bit low and then finish it off with a layer of CSM, 1708 an 2 more CSM. Then Fair and Sand. Thats how I would do it and I think you'll be ok. The ONLY problem may be the exothermic heat. You may have to do several thin layers and that's ok as long as you do them on right after the other while it's still tacky the bond will be good. You want the PB to be pretty thick and gooey and hairy!!

Hope all this makes sense.

 

[apolite1016]

So what ratio of glass to resin? Should I add any thing to it aside from chopped strand? And if so how much of what. I've seen a few threads on mixing pub but I think most mixtures I came across we're for bedding stringers, transom cores etc, this situation is a bit different so I guess I'm just looking for the best recommended mixtur for this application.

 

[Woodonglass]

1000 ml resin, 1,500 ml cabosil, 750 ml of shredded 1" CSM (use your hands to pull and tear the fibers apart from some scrap CSM then use scissors to cut it into 1" lengths). 100 ml of MEKP. Mix the MEKP and Resin first for about 45 seconds, then add the Cabosil and CSM Fibers. It's gunna get real Gooey and Gunky and you only have about 15 - 20 mins before it will start to Kick so make sure you have everything prepped and ready before you mix and spread. I recommend you mix in a 1/2 gallon plastic container. It'll make things a LOT easier. You might wanna mix a 1/2 batch first and spread a real thin layer first just to see how it goes.

 

[apolite1016]

would AR " alkali resistance chopped strand work it seems to be readily available in 1.5" and i can get it local from the concrete company. i just cant find any info as to weather or not its sutable to use in a polyester resin.

 

[apolite1016]

also basalt seems to be available in long strand lengths as well.

 

[Woodonglass]

Never used either but after some research I believe the Basalt should be fine. I'd experiment with a small batch first to ensure it was compatible. It should be noted that you can get CSM At Lowes and Home Depot!!!

 

[apolite1016]

Yea i have some CSM but thats alot of time spent pulling it apart to make that much filler, i already did that when i did my transom i also used some to bed the stringers and tab In the benches, I just figured it would be more cost effective by weight to just buy it already chopped if i could find it local.

 

[apolite1016]

if i do it that way its almost $16 a pound to pull apart and chop up CSM from home depot or lowes

 

[apolite1016]

Should i add the strand by weight? it seems it can be rather inconsistent by just adding it in by using a bucket with ml markings cause it could be packed or fluffed to that measure.

 

[Rickmerrill]

I haven't seen 1" CSF.

 

[apolite1016]

I found some here.

http://www.pnta.com/props/make-your-own/aqua-resin/aqua-resin-aqua-glass-1-chopped-1-lb/