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Old 09-10-2010, 14:27   #1
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Rotten Deck Core Around Windlass

Because our electric windlass once tried to come up through the deck, water penetrated the area around the windlass over time and there is now an area where the deck core is rotten (about 8" or 10" in diameter) around the hole in the deck that windlass shaft goes through to meet up with its motor under the deck in the anchor locker.

This hole is about 4" in diameter, so I should have enough room to attack the rot that surrounds it with an electric drill or whatever tool seems appropriate at the time. The fiberglass is basically OK except for some radial cracks around the hole which can be sealed up with silicone to prevent further water intrusion.

My plan is to chisel and drill out as much of the rotten deck as possible -- hopefully without destroying the fiberglass above or below the core -- and to fill the void with either Git Rot or System Three's Rot Fix. I also plan to install a 1/4 thick aluminum backing plate under the deck to prevent future problems and I may also place a piece of Starboard between the windlass and the deck to serve as a platform for it to rest on, adding more strength and helping to keep the water out. There was no backing plate below the deck or gasket above the deck previously.

Any thoughts or suggestions from anyone who has dealt with this problem will be most appreciated. Also, would you suggest Git Rot, Rot Fix or some other product to replace the core that I plan to remove?

Many thanks.

Phil McGovern
s/v Sunshine
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Old 09-10-2010, 14:43   #2
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what you want to do, as gitrottd wood hasnt any stuctural strength, is to cut out the core and replace it with new core-- then redo the deck and innards and have a good fix. you wwill have to feather the work for strength--- might want to use ply as your core under windlass---i would use cpes to prevent rot/seal the wood. then finish and add windlass. a poor or inadequate patch could cause you more problems in the long run. might want to make a large deck sized backing plate for the deck. mine is laminated of doorskin and epoxy. my deck is plywood core in fiberglass made in taiwan..
anywhere there needs to b a hole in an outer surface of a boat, one should always protect the part thru which was cut with epoxy.

the windlass places a lot of torque on the deck and plate-- you will want a solid and reliable base for it, as well s protection for the deck.
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Old 09-10-2010, 15:47   #3
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Rot is like cancer. If you leave any it will continue to rot your wood. I would sound till I found good wood ,cut out the top glass deck and remove. Remove the bad wood cut a new piece to replace it with. Lay it in, mark the bolt holes on the wood thru the bottom glass, drill the wood out 3/4" to 1" where the bolts go thru, tape the holes thru the bottom glass epoxy the new wood in filling the holes. Fair then epoxy the top glass back on. Make your backing plate larger than the cut area if possible.
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Old 09-10-2010, 16:22   #4
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Use sillycone if you don't like yourself. Sillycone belongs in boobs, not boats.

You could try and fill the void with epoxy mixed with a non compressible filler. If the rotten area is only a few inches back from the puka, it might work. Clean out the rotten core, tape the dege of the puka to keep the epoxy in place, drill a bunch of holes and inject thickened epoxy into the void. If you can get the void mostly filled, it will be good as new.

GitRot is to stabilize rotted wood. The epoxy replaces organic material that's rotted away fixing what cellulose that's left. It's basically good for wood in compression. Might work in this case but not for filling a void by itself. It's really a chancy fix, however.

Best would be to take Zeehag's advice and cut out the deck skin, replace the core with something like plywod that isn't compressible and reglass with expoxy and FabMat.
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Old 09-10-2010, 16:53   #5
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I helped do this on my father's (33 foot) motorboat a couple of months back. Replacement of a electric windlass (many years non-working - don't put the motor in the anchor locker - also electrolysis had eaten away a chunk of the aluminium on the windlass ) with a manual windlass. mostly for show / to cover the hole in the deck

Was an interesting learning curve / PITA.

Found that deck had distorted under the windlass (as core rotten away deck then compressed)........and drilled out the bolt holes well oversize and dug out all the rot / soft balsa (pretty much everything under the winch was gone or fell out - but only dug out a couple of inches away from the winch footprint - was expecting more). same for the electric motor hole (which we filled with wood and epoxy). and the chain hole (which we didn't fill )

Used plywood as an underdeck backing plate. probably half inch - well oversized and as big as the space allowed (working in the chain locker). good news was that finish not important. epoxied (thick) the pad under the deck (held up with props / wedges) as not smooth / flat under deck but wanted the pad to spread the load evenly.

mounted the winch on a wooden block (hardwood - an old outboard pulpit bracket - varnished before fitting) to both spread the load a bit and also cosmetically to cover the sins left (apart from the filled holes epoxy also used to flatten out the deck distortion).

Drilled the hard wood deck mount using the windlass paper pattern (and checked the windlass did fit ), then used this block as the guide to drill the deck. useful to check that all 4 bolts do fit at the same time - after you drill each hole, drop a bolt in to lock the block in place.

Probably find will also need threaded bar instead of a bolt due to the thickness (winch / deck mount / deck / backing plate) - on deck we used dome nuts.

Used plenty of sealant (black ****) around the bolts / threads through the deck and also under the hard wood deck mount. ummed and arred about fixing with epoxy, but decided might want to remove one day.

Underdeck got a coat of paint - and looks very tidy, even if I say so myself and if that winch ever pulls off the deck it will mean we've hooked Moby Dick and lost the first 4 foot of boat / deck

I would say a job that is fairly easy - just a bit of a PITA due to access. and having to think / learn through the job.
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Old 09-10-2010, 18:12   #6
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Second roverhi's recommendation on no silicone. The stuff will penetrate the fiberglass and forever after nothing will stick to that spot, not even more silicone. Use your favorite flavor of epoxy for the fix.
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Old 11-10-2010, 22:08   #7
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Aluminum backing plates are not such a good idea in a windlass locker - see my picture of one in this thread. Backing Plates Also, Starboard is not such a good idea - sealant does not stick to it, and apparently it is compressible. Plywood, fiberglass and epoxy are the way to go.
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Old 11-10-2010, 22:56   #8
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I use to use SS backing plates but now I use G10 FG. It's EZ to cut/drill and it can be epoxied in place making the underside even stronger.

Composite G10/FR-4 Epoxy
G10 FR4 Electrical Insulation Material

If the gap between the inner and outer is a fractional size you could dig out the core and insert pieces of G10 in between with epoxy/filler. It would be stronger then any cored hull out there!
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Old 12-10-2010, 17:13   #9
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Thanks for all the great suggestions! The consensus seems to be:

1. Don't use silicone. (What was I thinking???)
2. Do cut out the bad core and replace with plywood.
2. Epoxy is my friend.
3. Forget GitRot and Rot Fix.

I'm left with two questions :
1. Can I get away with just carefully cutting through the glass skin under the deck along with the rotted area and leaving the upper layer intact? It seems that would eliminate the need to do any fairing since no one except me is going to see the fiberglass in the anchor locker.

2. What, besides expoxy, is going to hold the new plywood "plug" in place? It seems that the area below the windlass would be pretty weak right where it needs to be very strong. The windlass mounting bolts will be inside the area of new plywood, so it will be getting a lot of force. I guess I can try to expoxy the backing plate to the original, i.e. rot free, part of the deck and gain some strength that way.

Again, I appreciate everyone's help and look forward to any other suggestions you might have.

Phil
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Old 12-10-2010, 19:11   #10
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Yes, you can do the job from the underside. There are two problems: 1. What kind of working room will you have in the chain locker?? You are going to have to work with epoxy in a very confined area so will almost guaranteed to need a helper to mix the resin, wet out the FabMat, and hand everything to you. 2. Then there's this stuff Ole Issac quantified called gravity. Everything will be done working against it. BTDT and it ain't fun.

Just did extensive glass work on my transom from the inside and outside. Lying curled up in the lazarette working with epoxy and cloth on a mostly vertical but some overhead surface was not fun. I ended up with epoxy on almost everything including my hair. Fun part was peeling off my fleece shirt that was epoxied to my arm. Epoxy is nasty stuff, ended up shedding the skin on my arm and hands where epoxy got to it though my shirt and torn gloves. Washing your hair in acetone is not reccomended, either. Doing the layup on the exterior was a piece of cake compared to the same job inside the lazarette.

Fairing in the repair is really no big deal. Feather in the deck around the repaired area, set the new core into the bottom laminate using thickened epoxy and then lay up successive layers of mat and cloth/roving or Fab/Mat over the top. When you are level or just slightly higher with the rest of the deck, grind the layup smooth. Once it's painted or gel coated, no one will be able to tell what you did. Get a 9" buffer polisher that runs less than 3,000 and preferably less than 2,000 rpm with a foam pad on it to grind the layup smooth. http://www.tooldepot247.com/proddetail.asp?prod=MIL5460-6 or http://www.tylertool.com/makpv7verpol.html

No matter how you end up doing the job, put on 3 or 4 layers of latex gloves before you start and some plastic arm gaitors. That way you can rip off the messed up outer layer glove and still have glove protection and protection for your arms. If you are super neat, you can probably get by without the arm gaitors. Personally, I get 'into' my work and need all the protection I can get.

You can use polyester resin instead of epoxy but I don't reccoment it. Polyester just doesn't stick to old laminates all that well.
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Old 12-10-2010, 19:35   #11
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Personally, I would do it from the top. Any boat repair place probably would too. Like roverhi said gravity is your worst enemy.

If I absolutely have to do overhead work I lay pieces of glass out on a thin plastic sheet (one can get them at the fiberglass stores) and wet out the glass, then push it all up and spread it around with my hands and then pull off the plastic sheet. It'll drip down the sides a bit but won't all come down on you.

You project is a complicated job that even the experienced would not admire. The only problem of doing it from the top is it would be doing the gelcoat which is the hardest part labor wise and getting it right.

You might want to get an estimate from a local boat repair shop before diving into this. I'm thinking it would be anywhere from $1-2k depending on how bad it is. You can save some money by removing and installing the windlass yourself.
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Old 13-10-2010, 16:20   #12
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G'day, Philip, I just replaced my old Nilsson 3000 with a Maxwell VWC 3500. I was fortunate and did not have any deck rot, due to the high quality construction methods used by P.A.E. when building the Mason line of sailboats. Notice my deck pad above deck (I also have one below). Almost 6 inches total thickness. You might be able to do the pad above deck as well if your angle to your bow roller will allow it. All the best with the new installation. Cheers.
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Old 13-10-2010, 20:45   #13
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Phillip, at the risk of sounding like a broken record ... Everything you need to know for this project is in West System's "Fiberglass Boat Repair and Maintenance" publication #002-550. You can get a hard copy, www.westsystem.com, and GordMay has posted a link to an electronic version here: Backing Plates, which would also be a helpful thread for you to read.

It sounds like you have never undertaken anything like this before so this may be a slow project for you, but after this you will realize you CAN fix anything on your boat - it really changes your perspective of repairs and what is possible.

Matauwhi - lovely I can see you taking the picture!
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Old 14-10-2010, 02:57   #14
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G'day, again Phil. In addition to marine grade plywood, you should also give balsa consideration for to recore your deck in this area. Here is the a shot of the deck core that I removed to enlarge the area for the new windlass. A well-constructed and cared for balsa cored deck will stand the test of time and elements. Cheers. P.S. Good eye ShipShape
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Old 14-10-2010, 05:16   #15
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We are set up pretty much like you matauwhi but our lower support is probably 6 times the foot print of the winch itself. I would assume it is plywood, glassed below the deck and maybe 6 inches thick. Gives you and idea of the load on the windlass.

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Originally Posted by matauwhi View Post
G'day, Philip, I just replaced my old Nilsson 3000 with a Maxwell VWC 3500. I was fortunate and did not have any deck rot, due to the high quality construction methods used by P.A.E. when building the Mason line of sailboats. Notice my deck pad above deck (I also have one below). Almost 6 inches total thickness. You might be able to do the pad above deck as well if your angle to your bow roller will allow it. All the best with the new installation. Cheers.
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