Coring under pulpit

[dave1985]

Suggestions, please.

I'm in the middle of the repair the rotted core under the bow pulpit on my 85 series II 36c. I'm doing it from the anchor locker. The leakage appears to all be from the two rear pulpit bolts as I get to damp/dry coring at a point in a straight line across between the two forward cleats. I'm making an assumption that the cleats do not rely on the coring or the very thin roving that makes up the locker "ceiling" for strength. Am I correct to assume it is exclusively the metal plate embedded in the deck that provides the strength for the cleat?

Also, the coring is 3/4 balsa. I plan to use the same for the repair material. The boat does not have a windlass which I'm going to add at this point. It doesn't seem logical to go to all the repair work then go putting holes in the pulpit for the windlass, foot switches, chain stopper and the two pulpit bolts hoping that I do each of those correctly so the water intrusion doesn't reoccur. My though is to do the balsa repair but leave the area directly under the pulpit empty. Then, I thought of drilling a good sized hole where the windlass will be placed and then, from above, filling the void I left with a more fluid mixture of West System and some chopped fiberglass. Good Idea...dumb idea...any thoughts would be great.

Dave

 

[Boatsb]

The inner skin is part of the core system. It is important to replace it.

 

[Vincentc]

I removed the original windlass on my 43DC 1983, and discovered fairly extensive core deterioration. My expereince is recounted in a thread on this forum. entitled bow pulpit removal. Do a title search if the following shortcut does not work. http://www.samsmarine.com/forums/showthread.php?t=13460.

I drilled 3/4" holes from the anchor locker, identified and removed the bad core then filled the void with filled epoxy. You do not want to remove any more fiberglass skin than necessary but do want to remove core material in the area of any penetrations and replace the core with filled epoxy.

Suggest you read through what has already been posted then ask. I have quite a few photos of my project which may be helpful. Let me know.

Regards,
Vincent
Lilly Marie 43DC

 

[REBrueckner]

After your repairs are made and holes are drilled, before assembly coat each hole with epoxy resin...even two coats if you like...that way even if a bolt or other hole leaks, it will not get in the coring. And of course always use a quality flexible caulk.

When I replaced the windlass on my 1972 Hatt YF around 1989 I found the chain/rope hole for the original windlass had NOT been sealed and that seemed to be the source of my core moisture. Apparently there was enough salt water that I did not have actual rot, just moisture....I posted about that, but without pictures.

If you want to reinforce any holes you drill, you can removing the coring around the hole and fill the void with a thickened epoxy paste...then seal the hole opening with liquid epoxy...the paste will enable you to snug down bolts without crushing the coring. However, using backing plates is always adviseable when strength is an issue...like windlass and cleats...you don't want to worry about those in a storm or hurricane. backing plates distribute any strain over a much wider area and reduce unit area pressure.

 

[Boatsb]

You can also replace the balsa with a more structurally sound material.

I did 3 layers of alternating 1/4" plywood and 2 layers of mat and resin on an old egg I repaired and it was much stronger than new. Of course it weighed a bit more but structurally was stronger and because each layer was glassed all around I expect the rot problem was eliminated. I could have lag bolted the cleats to the deck but still through bolted them.

 

[George]

Look Familiar? http://www.samsmarine.com/photopost/showphoto.php?photo=1353&ppuser=765

It's never as easy as you think. you'll need to keep probing back to see where the core is in decent shape. I had to remove about 6' of my bow core. they replaced it with the synthetic core material.

 

[boatwright]

you can use a synthetic high density core under through bolt areas . the type i have used is coosa board. high crush resistant, wont rot, fiberglass or epoxy compatable, different thickness.... with other cores i would drill the outer skin only and core,undercut the core has you can (l use a cut off allen wrench in a drill ) than fill the hole with unthickened epoxy, let it saturate the core ,drill the hole again when cured. this gives you a solid epoxy plug to bolt through without the loss of strength of over cutting the top skin... when doing core work remember a cored surface works because one side is in compression and the other is in tension one side wont work right with the other

 

[Vincentc]

I've done only one repair to a bad deck core at the bow pulpit. Rather than go to the trouble of fitting a replacement core, I simply filled the void with thickened epoxy. It has worked fine and I believe it is stronger than a cored deck. The 3 square foot area could not have added 5 poundes to our lightweight 43.

What is the point of replacing the core vs filling with thickened epoxy?

Regards,
Vincent
Lilly Marie 43DC

 

[spindrift]

Dave:

I think boatwright makes an excellent suggestion on replacing the coring with a crush resistant synthetic material. Alternatively you could use plywood as others have done. Even with a backing plate under the new windlass instilation, you could risk crushing balsa coring. That is why builders are careful to put solid material in the laminate structure in areas that are going to be receiving any hardware mounting.

Spin

 

[Vincentc]

Dave,
My post on pulpit removal did not, as I thought, go into how I repaired the coring. Let me correct that.

Using a 3/4" hole saw I drilled a number of holes from inside the anchor locker throught the under skin of the deck without penetrating the top. I located and removed the bad coring with an allen wrench in the drill and shop vac.

I also drilled a number of holes throught the deck from the top but limited to the area that would be covered by the pulpit.

(to be continued)

photos below,
Vincent
Lilly Marie 43 DC

 

[Vincentc]

Coring repair continued

I used a grinder to level and rough up the anchor locker overhead to be sealed and learned that a plexiglas shield and fresh air source would be helpful.

I made a mold with 1/4 luan and covered it with vis-queen.

 

[Vincentc]

Core repair continued

I covered the 2 pieces of the "mold" with a piece of fiberglass cloth and a thick coating of epoxy thickened with cabo-sil/colloidal silica and wood flour, then screwed the two piece "mold" to the underside of the deck. I then poured thickened epoxy through the holes in the topside deck until the entire area was filled.

Once it had cured I removed the 2 piece mold.

This was not the most fun I've had on a boat but I do think it was easier than removing a large piece of deck, cutting and fitting a core replacement, replacing the deck, then patching and repainting.

Good Luck with your repairs

Vincent
Lilly Marie 43 DC

 

[Maynard Rupp]

When I added a chain gypsy to my winch, I added a chainpipe. Where the hole went through the pulpit and the deck, I lined the hole with 11/2" PVC. I roughed up the OD of the PVC and coated the entire hole with epoxy. Next I slid the PVC in the hole with epoxy on it also. This has worked well and it keeps water out of the core.