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Shark bite in bow...help!

mixmkr

Well-Known Member
I wouldn't mix poly and epoxy. Use one or the other. As far as a mold for repair...if the front foot or more of the bow was missing, a mold might be helpful. With the size repair you have, I don't see a problem guestimating the original, as you have enough there to still give you a good idea. As mentioned previously, making the strength on the inside, now the boat is open and then extra glass layers on the outside and fair it out smooth.

On the topic of strength, although epoxy resin has better bonding than polyester, the resin itself is not the "strength" but instead the fiberglass cloth and how it is laid and applied. As I mentioned previously as well, bonding can be more than sufficient with polyester, if the surfaces are correctly repaired.... sanded well and clean. A good mechanical bond will be basically impossible to rip apart.

I only suggested poly previously, mainly on the basis of seeing too many failures of gelcoat applied over "unprepared" West System finishes. West System creates a "blush" that CANNOT be sanded off completely (unless you remove a lot of product!), but must be scrubbed of sufficiently with soap and water. If you're painting, a good primer and paint, ..the decision is less important which you use.
 

L&VW

Well-Known Member
So, where to find a sunfish to make a bow mold?
A nearby city should have a yacht club who should be able to find a cooperative Sunfish owner or three. A half-day rental? A neighbor? A free Sunfish from Craigslist? Advertise for one—"Wanted". Craigslist ads are free, and there's always somebody around who's storing one and would like to have the space. Familiarize yourself with "clones", some of which have identical hulls. (Viking, AMFlite, List).

Especially as I have two spare Sunfish handy, I would attempt a bow mold. But it sounds like West Systems epoxy + micro balloons would require less effort. (And no mold needed).

Should I be using poly resin or a combination of poly and epoxy in different locations?
1) Epoxy should be able to do the whole job. The main disadvantage with epoxy is that unless you do many minutes of layering all at once, each layer has to be sanded after curing.

2) Did the gelcoat of the top of the deck turn out OK? IIRC, Webfoot1 says new gelcoat doesn't work well on epoxy.
 

Webfoot1

Active Member
Well that's interesting, can you post a link or location of the article. Molding a bow would in effect be working
on the same curved surface. If I remember correctly epoxy has a bond strength 20% greater than polyester. I can
attest that West epoxy does work very well from using it over the years. There is a endless argument that always
pops up over which is better, poly or epoxy. Personally, I think it comes down to personal preference with one argument
being that that is what was used to make the boat and another that epoxy has greater bond strength. By "play well" I'm not
sure they mean bonding to a curved surface or getting the cloth/mat to work its self around the surface. For the inside
of the bow I know the cloth will deform enough to cover the compound surface without problem. If you can't work it
flat the use of slow cure hardener gives you more than enough time remove the mat/cloth and go with plan B. The weight
of the cloth you use is also going to make a difference in how well it forms. I've never heard of anyone using a combination
of poly and epoxy.

There is nothing wrong with molding a new bow but I think going this route for the amount of damage you have increases
the complexity and difficulty of the repair. I have Sunfish I could try and make a fiberglass mold from it you go this route. Basically
I would be doing on the outside what you would be doing on the inside. I can see where the complex shape might force
me to go with multiple pieces of fiberglass and then use filler to smooth the inside of the mold. The advantage of working
inside the bow is it does not have to look pretty, just be a solid repair. You're not laying up into the keel section which would
greatly complicate the compound curve. What I'm trying to aim for is to give you the simplest method of repair that pretty much
gives a goof-proof result.

Hum, I'm thinking you need something for a confidence builder before you tackle this. Do you have anything you could use to
practice laying up fiberglass that you don't care about, say like a Styrofoam ice chest like the cheep kind they sell at stores. This
would give you flat surfaces and curves to do some layout on. Sort of get a feel for how well you can bend the mat/cloth before
it will not lay flat. Craft stores sell Styrofoam shapes like cones, spheres, torus/donut etc.

I'm going to get hit for this but I really have good luck with West-Epoxy and 206 Hardener. I have a can of poly I've
never used so maybe I'll have to break it out and give it a try. Get a bag of cloth and a bag of mat and it will last for
years over many projects. To totally digress, I plugged a hole in a air-tank by coating cloth with J.B. weld to make
a patch, pretty dumb huh?

Generally, fiberglass filler covers the epoxy before the gel coat is applied doing repairs. I
really don't have enough experience to say what happens to gel-coat directly over
epoxy. My attempt with brushing on gel-coat was not a happy one but then I learned
that gel-coat has a shelf life of only one year and purchasing it at West-Marine might
not have been such a good decision.
 
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Sailflow

Active Member
That was a minor repair, a couple layers of glass, dry time. Some marine tex after the glass. Some sanding with a block and you would have the bow shaped back to original. Splitting just adds another variable.

No need to mold.
 

Webfoot1

Active Member
Sailflow said it in the fewest words. Keep it simple! This repair is level 3. Trying to mold and get all the edges of the new bow line up with edges of the hull is like level 9 difficulty. You're working with really thin stuff and there's no guarantee the cuts will line up exactly. This dog ain't going to bite you if you don't try to make him jump through a flaming hoop!
 

L&VW

Well-Known Member
That was a minor repair, a couple layers of glass, dry time. Some marine tex after the glass. Some sanding with a block and you would have the bow shaped back to original. Splitting just adds another variable. No need to mold.
Yes, a quick fix, if dougd plans to practice fiberglass repair skills, and then to sell this Sunfish. While this repair could be dismissed as "minor", the bow takes a beating on most sailboats. (Even those with reverse!) :confused: Ask me how I know! :oops:

If dougd plans to keep this Sunfish, starting to patch from the inside with narrow strips, and lay-up several layers with epoxy—then add micro-balloons to the outside epoxied layers—would make this bow indestructible. :cool: A similar "hit" to the bow would damage the hull somewhere else!

On another epoxy topic, now that I have a fresh half-pint left over from my keel repair (and "spring"), I'm wondering about the half-gallon of leftover West Systems epoxy that's been sitting elsewhere for several years. (And since then, the price has more than doubled :(). A friend says it'll still be good, just heat it to evaporate any water that has collected through condensation. What say you?
 

Sailflow

Active Member
This was a minor repair.

Also, my repair work is not a "quick fix" it would take a similar hit and when paint or gelcoated, you could not tell the difference.
 

Webfoot1

Active Member
What I was trying do was give dougd a easy fix by going on the inside and not having to try to level/hide a three layer patch that sits above the surface on the outside of the damaged area. Repairs are generally make on the inside if possible and dougd went the extra mile by popping the deck so now he can take advantage and add extra reinforcement the factory did not due to cost. What Sailflow is also correct, you can make a repair from the outside and with beveling back of the fiberglass and using filler make a strong invisible repair. Given the location and nature of this repair I believe it's easier for a beginner to lay-up on the inside, encapsulate the damage with a layer on the outside and use filler to reshape. Sunfish are non mission critical so we can make repairs in a lot of different ways.

I'd contact West Systems and see what they say about shelf life. Since its a two part system I'd think it could sit years with no problem. I'd worry more about heat causing a deterioration in the compound rather than anything else.
 

mixmkr

Well-Known Member
West System will last a looong time. You'll know immediately if it is not usable. It might thicken a bit and change color, but some heat will thin it out.
 

L&VW

Well-Known Member
If it has thickened, is there a solvent that could be added to make it useable? Would a big dose of fresh epoxy work?

What I was trying do was give dougd a easy fix by going on the inside and not having to try to level/hide a three layer patch that sits above the surface on the outside of the
damaged area.
Now that dougd has "popped the hood", what grade of sandpaper is recommended for roughing-up the coarse roving cloth within? Sandblasting would be my choice on such a coarse weave—especially, as I have the equipment—but sandblasting is messy. :(

I photographed a side shot of my spare Sunfish bow for finishing-up a good profile. As soon as I find it :confused: I'll post it here.
 

mixmkr

Well-Known Member
No solvent, heat like I mentioned

60 or 80 grit well sanded and clean iz fine. Just scuff it up good. Less worries if using west since it bonds well. Clean and dry iz the goal....wipe with acetone
 
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L&VW

Well-Known Member
Two thoughts:

1) I happen to have a large roll of "rescued" 4-inch wide fiberglass cloth tape. I'd layer it up heavily at the top, and fan it out about 20" back into the hull. Add two layers to the keel. 'Be easier than cutting cloth.

2) There's going to be a lot of expensive "filler" needed at the very tip of this bow restoration. What do you think of using some relatively non-compressible "formable" substance like wood or Bondo?
 
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Webfoot1

Active Member
Just use wax paper and shirt stock cardboard to form a curved backer on the
outside of the bow. Should come out close to the original shape.
 

Webfoot1

Active Member
Short strand filler like Dyna-Glass would be good for areas
subject to impact. Should double your filler strength.
 

L&VW

Well-Known Member
A body shop video contrasted Dyna-Glass to Bondo—Dyna-Glass being better—more flexible, less tendency to crack at seams. :)

Dougd should be advised to start collecting clamps to close up the deck. (Last) Was it a pic at the site at my2fish that showed 40 or 50 hand-clamps attached during a radical deck reattachment? :eek: Screw-type clamps can be used with 1x2s to clamp the longer stretches. Closing up the deck should be done with equal pressures simultaneously on each side. Amiright?
 

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Webfoot1

Active Member
Used small spring clamps found at hardware store. Sell for about $1.25 each. I now have a tool box full of 3 dozen clamps for what ever
project comes my way.

Strips of cloth mat wetted with epoxy are laid along the joint before clamping everything together. Everything clamped and glued in one
session. Clamps need to be spaced together as close together as economically possible.
 

mixmkr

Well-Known Member
A body shop video contrasted Dyna-Glass to Bondo—Dyna-Glass being better—more flexible, less tendency to crack at seams. :)
Before I finish whipping you for your Bondo remarks, here on a boating forum.... although Bondo "tries" to advertise itself as being waterproof... Good luck. It'll absorb water and do things, making you wished you'd never ever heard of the stuff.
The "kitty hair" or other "NAPA" fillers are ok... but marine stuff is more expensive for a reason!!! (because it is!)
 

L&VW

Well-Known Member
Go out to the woodshed and be prepared to be whipped!! :-D
Bondo
has such a bad reputation, even among body shops, I've been using it as a joke here. ;)

I have had good luck with the red "glazing/spot putty"—used prior to spray-painting automobiles—on my (two) Sunfish that ARE painted.

Without a garage or other enclosure, my Sunfish painting is only by brush (and True-Value's equivalent of Rustoleum). While that Rustoleum finish is not very durable—even suffering when dragged across wet grass—I do have a lot of brushes. ;)
 

L&VW

Well-Known Member
With such a strong repair, is it really necessary to add mat to re-seal the deck?

With added mat, will the trim still fit OK? :confused:

Say, it's been a while since we heard from dougd. :(

Would you change "our" advice to peeling the deck, and repairing from inside? That mold idea came from a years-back thread, and I'm thinking it's laborious, and too difficult to match-up. :oops:

Peeling the deck, then cutting off the nose is a lot of work as well, but the job can then be moved off the trailer, and moved indoors. :cool:
 

dougd

New Member
Sorry - didn't mean to go dark! Work and family calls. I plan on hitting up Ace hardware this weekend and getting started.
 

dougd

New Member
So, I made it down to Ace hardware and picked up some glass (Evercoat Sea Glass Fiberglass Cloth and Evercoat Sea-Glass Fiberglass Mat ). I also bought some West System epoxy 105 resin and 206 hardener. I did my best to interpret the advice given here (many thanks) and the bow is more or less repaired from both the inside and the outside. I still have to fair it and paint it. Before those steps I plan to re-attach the deck to the hull and do a leak test. I have the guide on "Replacing Foam Flotation Blocks" [Yahoo | Mail, Weather, Search, Politics, News, Finance, Sports & Videos] which has a nice section on how to complete this repair. I have 40 clamps, paint sticks, wax paper, epoxy and glass mentioned above and a helper. It does mention to use "mat". Will the type I bought above work here? Is there a reason not to use the cloth? Thanks!
 

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shorefun

Well-Known Member
Key take aways from fixing poorly repair sunfish.

Sand to clean and roughen up the surface for best adhesion. I have been using poly resin.

Feather back the gel coat and glass. The longer contact area is more bonding area.

Gel coat is usually white. If you have a glass place near by you can get a match. If color matters, the factory white is an offwhite. You can get some resin tint online economically and play with adding some yellow and black. I suck at it, but it tones down the white.

These older boats tend to have thick gel coat on the bow. You also will likely not quite get the shape right. It will still work pretty good.

Dont over wet the glass. Just enough to get it to lay down.

I think that handles the beginner glass tips.

Relax and dont worry. These fixes usually work even if they are not quite right. If not then you grind it out and do it again. Ya, I ground some out.
 

signal charlie

Well-Known Member
Staff member
Welcome back!
1) Did you replace the bow handle blocker and bond it well with marine grade adhesive?
2) We've used cloth strips cut about an inch wide and 3 feet long. Any longer and they get hard to manage. Whatever you decide to use put a dry piece in a dry seam first, clamp the seam closed lightly and make sure your trim piece will fit back over the deck/hull flange. IOW don't put something too thick in the seam. We believe that the main purpose of the cloth is to hold the resin/hardener in place while it dries. We also like to use thickened resin to get the best gap filling consistency, and reduce resin escaping the seam.
3) We prop the seam open with a few paint sticks turned on their side, then remove them as we lay cloth into the seam.

Hoops seam.jpg

4) A syringe comes in handy to force resin into the small space at the end of the seam split.
5) Use just enough clamp pressure to see resin starting to squeeze out. Too much clamping can squeeze all of your adhesive out of the seam. If you see an area with no adhesive squeezing out, use a syringe or a paint stick to force adhesive into that area.

WAVE Clamps copy.jpeg

6) Lightly wipe off excess adhesive after giving it a few minutes. Don't wipe aggressively or you can dredge adhesive right back out of the seam edge.

Post pics!
 

dougd

New Member
@shorefun thanks, I think I settled on painting the surface white(ish) after reading that gelcoat is both difficult for novices and not recommended over epoxy repairs. I was first going to sand it back down to slightly below the gelcoat line level and then use low density 407 to fair it.

@signal charlie I re-attached the metal bow handle blocker with a ~3 inch strip of fiberglass cloth and some leftover epoxy resin, while the boat was upside down after doing the outside portion of the bow repair. I didn't think it needed much more, given it will be through bolted back on. Easy enough to add more while it's open, or start over with marine adhesive underneath if that's preferred. I definitely don't want it to fall off on the next guy or gal who needs to replace the handle! I do have some adhesive that I planned on using in the actual fastener holes.

IMG_0808 (2).JPG

Any tips on the type of filler to add for the deck/hull joint? Could I (should I) also use the 407 here? Product sheets indicate that other fillers are more suited for bonding strength, but if the idea is to just thicken it enough so that it doesn't run too much maybe it doesn't matter?
 

signal charlie

Well-Known Member
Staff member
The way the manufacturer did the backer block/plates was a belts and suspenders approach, the block was bonded to the underside of the deck with adhesive and the block was also held in place with a strip of fiberglass. Over time the adhesive dried and failed, and the strip of fiberglass would crack.

Hoops bow backer installed.jpeg

Around 1988ish the manufacturer switched to an aluminum backer and from the few we've seen the entire plate was fiberglassed over. Self tapping stainless metal screws were used to attach deck hardware.

I like your metal plate. I'd consider using self tapping metal screws vs machine screws and nylocks.

We used 406 Colloidal Silica for seams in the past, nowadays we used thickened flexible epoxy, such as GFlex, THIXO Flex or Pettit Flexpoxy. Given the location of that repair area, and you've seen the abuse a bow can take, you should consider a structural filler or thickened flexible epoxy vs a fairing filler.

https://www.marinechandlery.com/blog/introduction-to-additives-for-epoxy-fillers/
 

dougd

New Member
The two leaks are interesting cases.

The first was in the spot where I originally had difficulty splitting the deck. Upon closer inspection, the new seam was holding - but there was a secondary split about an inch long above it, very near the surface. The repair also has a change in elevation in that spot and maybe I created a small air pocket?

port split 2.jpg

The second was on the port side of the bow curve where the seam was split from the impact damage. I don't think I clamped this area well enough during the repair - maybe it just doesn't fit back together very well.

port split.jpg

I ground out both spots with a thin grinding wheel and filled with thickened epoxy. Going out of town for a few days so will check the results on Thursday.
 

signal charlie

Well-Known Member
Staff member
The fit looks good, we'd guess that epoxy never made it to those spot. We'd inject thickened epoxy from a plastic syringe, preferably flexible epoxy like GFlex, Thixo Flex or Flexpoxy.
 
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