Unlaunching day

Scout · Post by **Scout** » Sat Jun 16, 2007 7:31 am

Was yesterday. Our centerboard repair was n.g. We've pulled her again yesterday and removed the previous repair by one of the p.o.'s

This is before, looking aft, on either side of the centerboard trunk is wedged wood that appears original. Underneath the backing plate and extending out and over the wood down to the hull is additional fiberglass that has started to peel back from the hull:

This is after, (there is still some fiberglass that was beneath the backing plate that needs to be grinded, the rest of the fiberglass pretty much came up with our bare hands:

This is an examle of what came off

The sheave box and it's backing plate are one solid piece, sheave in good condition.

So today, we grind down the remainder of the glass and add new glass. Using layers of woven roving and mat.

Perhaps this last repair failed because it was polyester to polyester. Perhaps it is because the wood got wet, swelled, cracked the glass, perhaps both. Now trying to figure out best way to go forward. Avoid covering all the wood again? Add another stainless plate? The thickness of the hull around the hole for the cable is about 1/4 inch.

Thoughts? (sorry about the poor quality of the pictures, bad light and not much patience, I guess.

Post by **Tim** » Sat Jun 16, 2007 8:03 am

Ouch...that's never a good subject line! Too bad you had to come back out of the water.

I'm not quite clear on what has failed, or what the situation is, so I don't have any specific advice on how you should proceed.

However, take your time to ensure that this repair is done strongly and well this time, so as to avoid ever needing to do this again. It's surely an annoying and frustrating situation, but you'll be well served to make a careful repair, rather than try to rush through it so as to get the boat back in as soon as possible.

Good luck!

Scout · Post by **Scout** » Sat Jun 16, 2007 8:14 am

What seems to have failed is the previous repair.

It looks like the original set up was the wedged wood, a build up of fiberglass, the size of the backing plate to raise and level the surface to accomodate the sheave. That must have at one point leaked and then it was refiberglassed but this time took it all the way over the wood and down to the hull...

Whatever we do will be permanent so we've got to get it right.

Post by **Tim** » Sun Jun 17, 2007 6:35 am

I think I roughly understand what you have there now. Your sheave assembly for the centerboard cable is (was) attached to a glassed-in wooden block; the block, and the tabbing, has failed.

Can you make a new backing plate (to replace the wood) out of prefab fiberglass sheets of appropriate thickness (such as these from McMaster-Carr (Link)), glued to the hull with epoxy adhesive and tabbed with epoxy and strong fiberglass material?

Clean the area thoroughly and grind it to further clean and prepare for new material. Secure the backing plate in a heavy, thick bed of epoxy and use the excess to form nice fillets around the edges. Then, glass over the entire arrangement with a few layers of your fabric of choice set in epoxy. You can install the fiberglass while the thickened adhesive is still green, or partially cured; this is stronger and quicker if you can wait a couple hours for the first step to set up to a tack-free (dentable) stage.

Be sure there are no sharp ridges or edges before laying fabric in place; you can shave down the partially-cured thick epoxy with a knife, chisel, or sandpaper to smooth any irregularities before laying in the fiberglass.

You can also install the tabbing in a separate step, as time and skill dictate. The repair will still be very strong. If you wait till the first step is completely cured, you'll need to remove any amine blush formation with water and then grind the area smooth to accept the fiberglass overlay/tabbing.

Quetzalsailor · Post by **Quetzalsailor** » Mon Jun 18, 2007 8:32 am

We might discuss which resin would be better for this. I used epoxy on my engine beds on a hull which had been out of water all winter and I appear to have gotten away with it. I heard later that vinylester is more tolerant of bonding to a wet-ish substrate.

I made the wood parts of the engine beds out of (very) dry pressure treated lumber. I covered/encapsulated the pieces in epoxy/glass before bonding 'em into the hull so no issues with wet and swelling. I prepared all the mounting holes by coating them out as well. I rounded all corners to allow the glass to go around w/o that annoying linear bubble.

Ceasar Choppy · Post by **Ceasar Choppy** » Mon Jun 18, 2007 10:38 am

Just for reference, this is the first centerboard sheave in my Pearson 39. That's a big blob of polyester!

Scout · Post by **Scout** » Tue Jun 19, 2007 12:18 pm

Yikes Cesear! Looks like a beached baby whale!

As for resin, we used expoxy. Our understanding is that polyester resin does bonded to polyester resin is not a good bond, many instances of it failing down the road. Epoxy is ...more better. Don't know if vinyl is different than poly.

We will probably go back in tomorrow. That will tell us how we did. Thanks all for the PM's and pictures.

Ceasar Choppy · Post by **Ceasar Choppy** » Tue Jun 19, 2007 1:29 pm

Agree the epoxy will be the better mechanical bond.
Also agree that that thing in my bilge resembles a beached whale. Not fond of it asthetically... but it appears to serve two purposes:

1. encases the sheave box to keep the water out;
2. aligns the sheave box with the height of the second sheave box in the engine room where the pennant makes its turn to the winch near the companionway.

As far as I know it is standard on P-39 and P-35s c. 1968 - onward

Scout · Post by **Scout** » Wed Jun 20, 2007 1:04 pm

Ceasar, our second sheave housing is much lower than the first as the conduit travels aft. Ours, too, goes up to the winch in the cockpit on the bulkhead underneath the bridgedeck.

Hmm, I wonder if that puts less or more stress on the first sheave housing. My guess, is less. My thinking is the 'pull' is down, as opposed to lateral or up...

Ceasar Choppy · Post by **Ceasar Choppy** » Wed Jun 20, 2007 2:06 pm

Interesting thought... although your angle on the first sheave is then less than 90 degrees, no?

Moot on the P-39 anyway since the second sheave can't go any lower... unless of course I pile more resin on that beached whale! :)

So how is your repair holding?

Jfwtc · Post by **Jfwtc** » Wed Jun 20, 2007 2:56 pm

I think the angel of the cable run on the Invicta is somewhat more than a 90 passing the first sheave to the second sheave. The second sheave is lower in the Invicta because of the depth of the engine and the need for the cable and conduit to travel under the engine to reach a point where it turns up to the bridge deck.

Jfwtc · Post by **Jfwtc** » Wed Jun 20, 2007 11:05 pm

I stand corrected in my statement above, the angle on cable around the sheave is less than 90 degrees. I was trying to say that because the cable angles down as it goes aft, there is more wap around the sheave.