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Old 11-05-2014, 06:19 PM   #1
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A nose job for Kokanee

Last month my anchor winch gave up on me. I wasn't overly disappointed, as I was looking for a reason to replace it. The old winch was a vertical capstan only and I had to haul the chain by hand.
I shopped around and found a nice vertical Muir with both combination gypsy and capstan which would fit the limited space available.

A simple changeout....? Not a chance! As I removed the old winch and other deck hardware, it became obvious than the plywood core was badly rotted. It appears their has been water ingress via the bolt holes for the forestay bracket & chainplate.

The area around the winch had slight dry rot, but as I removed the bad core wood towards the bow it became softer & wetter. Around the forestay bracket I was spooning out porridge.

I ended up removing the entire 3/4" core in the bowsprit area (about 12" x 30") between the bow and the anchor locker using a variety of home built tools. I managed to hollow out the void back to good dry plywood. This required removing a non structural panel under the bowsprit, and cutting a notch at the nose of the bow to gain additional access. This also allowed me to custom fit the new bow roller so kindly donated to me by Hendo. Thanks mate!

The fibreglass layers on top & bottom are both 1/2" FG so there is very little flex even without the core. Right now, she's just open to dry out any last bit of moisture that might be lurking. In the next few days I plan on relining the bowsprit with 3/4" x 2" strips of grey box, a local hardwood.

Once relined, I will fill the voids and impregnate the wood. I'm undecided whether to go polyester or epoxy. I don't expect there will be much void space, but there may be a few gaps.
I am also wondering whether to cut the 3/4 x 2" strips to fit tight, or slightly loose to allow the filler to migrate around each strip.

I'm open to suggestions...
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Old 11-05-2014, 09:05 PM   #2
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Polyester has no place in boat repair. I dont agree with the way you are doing the repair (I completely remove everything and recore the area, then replace the plug) but however you are doing it at least use a good 2 part epoxy. I wouldnt use hard wood either, it expands and contracts to much. A good straight grain cedar would be a much better core. My biggest concern would be how the rest of the deck fittings were bedded and hom much rot do they have. Like capn Ron said "they all got some"
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Old 11-05-2014, 09:06 PM   #3
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G'day My vote is for epoxy every time. I think it does a better job of gap filling and of penetrating the wood than polyester does. I would coat each piece as you put it in rather than pouring it on once everything is together. I know in the past I have had glass come off of plywood and the resin has failed. The surface of the plywood was unharmed. Every time I have tried to take something apart that was put on with epoxy I have to tear the wood to get it apart. My 2 cents worth.
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Old 11-05-2014, 10:29 PM   #4
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Kulas, I've been slowly rebedding all the deck fittings on the boat, and until now, have been surprised how little rot damage I had come across (until I came across this job).
You're right- even with the short strips; the less expansion the better. I have some cedar in the shed I can use.

One of the more popular epoxies used here is West Systems. Marine Epoxy - WEST SYSTEM Epoxy - WEST SYSTEM by ATL Composites
It sounds like it may do the job.

Bryan - Your idea of coating the strips prior to insertion sounds like good advice.
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Old 11-06-2014, 02:21 AM   #5
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How about using CPES to ensure the fringe areas are sound before filling the void?
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Old 11-06-2014, 03:07 AM   #6
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Your whole boat is manufactured poylester resin. Would you weld a steel boat with aluminum rod. Epoxy is a better wood glue no doubt, but your not gluing up wood your using it as filler. Epoxy is much more difficult to work with, sands harden and shrinks more. You won't find many professionals making this kind of repair with epoxy. Epoxy is stronger and it's used with exotic materials like carbon fiber and Kevlar, but why make your job harder than you need to. I watch boat owners struggle with epoxy trying to repair blisters, they turn a easy job into a wavy mess. Plus they have to apply multiple coats to fair them out. Polyester's is much more flexible to work with as you can very your working time to adjust for temperature.
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Old 11-06-2014, 06:38 AM   #7
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> As I removed the old winch and other deck hardware, it became obvious than the plywood core was badly rotted. It appears their has been water ingress via the bolt holes for the forestay bracket & chainplate.<

Thats why ALL bedding needs to be replaced , every few years with any wooden core construction..

>While a plastic boat is constructed of polly laminating resin , polly is a very poor choice for any repair.<

It has far less sticking ability and is easy to tear off by hand.
Polly resin only sticks to other green polly resin for a day or two , with out problems in boat construction.

Even on a well done secondary bond , ground down so 85+% of fresh glass shows.polly is far weaker than epoxy.This is is why boat parts like hulls are done in one day , at worst 2.

If its cosmetic , who cares , Bondo is choice of many ,

but for a structural repair epoxy is the ONLY choice.(if you are keeping the boat).
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Old 11-06-2014, 09:13 AM   #8
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Scary, you are wrong on almost every assumption you have made about epoxy. Every professional I know in the fiberglass industry uses epoxy exclusively for repairs. If you're going to sand it just use the correct fillers (Cabosil, micro balloons, etc.), Use the correct product for the ambient temperature and mixing is less difficult and more accurate than poly/mek. Polyester shrinks WAY more than epoxy and would probably crack in this application. A poly tooling gell would work ok, but most folks wont have that on hand. NidaBond (a poly type product) would also work well, even without the coring, but the minimum order of 5 gallons and limited shelf life preclude its use for smaller projects like this. And, I have never heard of anyone, pro or otherwise, using anything but epoxy for blister repair. After all it was a poly problem to begin with.
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Old 11-06-2014, 09:44 AM   #9
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Quote:
Originally Posted by kulas44 View Post
Scary, you are wrong on almost every assumption you have made about epoxy. Every professional I know in the fiberglass industry uses epoxy exclusively for repairs. If you're going to sand it just use the correct fillers (Cabosil, micro balloons, etc.), Use the correct product for the ambient temperature and mixing is less difficult and more accurate than poly/mek. Polyester shrinks WAY more than epoxy and would probably crack in this application. A poly tooling gell would work ok, but most folks wont have that on hand. NidaBond (a poly type product) would also work well, even without the coring, but the minimum order of 5 gallons and limited shelf life preclude its use for smaller projects like this. And, I have never heard of anyone, pro or otherwise, using anything but epoxy for blister repair. After all it was a poly problem to begin with.
I agree with everything and add..... Poly has good cohesion when used as a new system but has terrible adhesion when used for repair. Poly is not very good for repairs.

Alternately epoxy has much much much better adhesion for repairs. Use alcohol to absorb the water, and thin the epoxy with acetone to fill the voids.
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Old 11-06-2014, 11:46 AM   #10
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There was a through hull in the aft stbd quarter of Willy's bottom and I had the local FG guy the yard uses to take it out and turn the hole back into hull. This guy used vinylester resin.

To do most of our other repair we use epoxy filler, a 3M product w microballons. It's mixed like JB Weld. I like it a lot.

But I'm w Scary very significantly here. Everybody seems to jump on "newer" "better" products and forget the stuff we've been using since we were boys. Just because there's epoxy it dosn't mean that a good quality oil based paint applied carefully won/t last for years and years. You can buy and use a Rocna but 99% of the time an old Danforth will hold the boat just the same or possibly even better.

A lot of guys are think'in w their butt to an extent and buying new high tech products that are actually best for only certain applications. Typical is the guy that buys "premium" fuel because he thinks it's the best but unless you need it it serves no purpose whatsoever.

Getting back to polyester resin I think most boats today are mostly made w the stuff and vinylester, epoxy, Kevlar and other "better" high tech products are used for special applications where their cost/performance ratio is fully cost/effective.

Knowing the better products makes you smart and also makes you look smart in the company of others but knowing when to use an older tried and proven product that is better suited to the application is even smarter still. And consider the fact that most all products, old or newer are better in some ways and not good in others. There are no miracles.
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Old 11-06-2014, 01:44 PM   #11
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Well, a bunch of old Warram trimarans (and countless other glass on ply boats) are sitting all over the country with the polyester resin applied fiberglass falling off in sheets. Mostly because the builder didnt have a clue what he was doing but also because polyester resin just will not remain stuck to plywood, or any wood for that matter. It has to do with the fact that polyester is fairly hard, more so than most epoxies, and isnt able to stretch and contract with the substrate. After enough temp cycles the poly just delaminates. The correct epoxy doesnt have this problem, its modulus of elasticity is tremendously better and its adhesion properties are better. As an aside, poly adheres good to unwaxed poly, BUT, your boat was built with WAXED polyester. I quit using cast iron fillet knifes as soon as carbon steel became available, but you use whatever you like
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Old 11-06-2014, 02:33 PM   #12
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Flywright - I looked into using CPES. From what I've read and heard, it relies on using a high proportion of solvents to lower the viscosity. While that allows for good penetration into the wood, it has negative effects as well.
The other problem is - I can't find it locally. So that makes the decision easy.

Right now, I am sealing off all the cutouts and bolt holes on the bottom panel using poly. This will keep the traditionalists happy.

Then I'll use the West Systems 105 epoxy resin to coat the new cedar core, and to fill any voids.
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Old 11-06-2014, 02:40 PM   #13
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AusCan,
I used WS105 in Alaska dealing w my small blisters (think quarter .. most smaller) and being in AK I thought I needed the catalyst for cool temps. In 4 minutes it started smok'in and getting real hot. Had to throw the cup on the ground. Beware which catylist you choose.
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Old 11-08-2014, 12:10 AM   #14
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Eric,
Yes I've made up a few batches to get a feel for how how quick it sets. I'm using WS105 epoxy with the 206 Slow Hardener. Like with polyester, it can get hot if over-encouraged.

There are 3 things affecting the heat buildup and set time; the hardener, the ambient temperature, and the mass of the epoxy mix. It heats up in your container much more than after being applied, unless you fill a large void.

I've relined the core with epoxy-encapsulated cedar strips about 2" wide. I sized them to fit with about 1/8" gap all round. My next batch of resin will be diluted 5% with epoxy thinner to minimize the viscosity. WS doesn't advise diluting any more than this.
I'll funnel it into numerous holes in the foredeck and expect to get full coverage throughout the void.
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