Chainplate Replacement Question

[bhartley]

One of our boats is a 1973 Sea Sprite 23 Weekender (another Alberg design). She has suffered from chronically leaky decks and a crummy chainplate design. The chainplates are S shaped and glassed directly to the hull so there is a pocket to collect water and no way to inspect or change. I purchased new standing rigging for Ariel this spring which seemed a little pointless without replacing the problem chainplates. This is a relatively common failure point on the aging fleet. The picture below is someone else's broken chainplate and a good one.



I'll spare you the saga of grinding out the existing chainplates and the issues with the chainplate fabrication (yes, I know there is an unused hole)... Even though she had been covered and on the hard for 12 months, the chainplate pockets were still full of muddy water when I ground them out. I had excellent plans provided by another Sea Spriter to install straight chainplates and feel pretty pleased with the results so far.


My question is how to handle the slots in the deck. The deck is not cored in this area and there are chainplate covers due to be reinstalled. To install the new chainplates, I had to file the openings slightly to install the new straight ones.

The slots were originally hand cut and a little random. They are about 1/16th of an inch wider now and 2 are 1/8" longer due to issues with placement of the new chainplates.

So... how do I seal up the slots before reinstalling the covers. They were sealed with polysulfide but they never were 100% water tight. We were never able to determine the exact location of the leaks however. This is a before photo with the gaps exposed once the vinyl rubrail was removed.



The vinyl rubrail and teak toe rail have been removed and all holes sealed with epoxy and then Captain Tolley's. As long as the chainplate slots are covered the deck is now dry. Even one drop of water down below will break me after all of this effort.

So... how to seal the slots? Just polysulfide? How would I epoxy the slots with the chainplates in place? My instructions end with "Just reinstall the chainplate covers and you're done." The boat didn't originally even have chainplate covers. We installed them in an attempt to stop the leaks. Any advice would be appreciated.

By the way, the Sea Sprite 23 is one of the sweetest sailing boats ever built.

Bly

[Zach]

Haven't done it but thought it was cool...

Saw where someone made a mound of thickened epoxy around the chain plate opening so the slot was above the deck height. Used modeling clay to make the mold, and sanded it to shape... then bolted the cover on top. Hard to get a huge leak when it never has standing water!

Zach

[LazyGuy]

Bly,

As Zack eluded, use a piece of FRP slightly larger than the stainless cover 3/16 - 1/4" thick and bond it to the deck. You do not revise the geometry of the rig and you remove all but 2 square inches for water to pool. Radius the edges and paint. Most Sea Sprites are a bit bow down because there is no inboard so deck drainage can be an issue for those last few drops.

Oh, you do not have a toe rail only the rubber rub rail. Anyway, you can have fun with the shape of the deck risers if you like but I think the best bet is slightly larger than the cover then after the rig is tensioned, use a little poly sulfide.

[bhartley]

Dennis & Zack,

We definitely have a teak toe rail. I had to actually cut down the chain plate covers (none were installed originally) to get around the teak. If I make FRP "risers", they will be very narrow on the outboard edge, but it might work.

I guess I was thinking about a solution with the chainplates in situ to reduce the slot. The risers could be installed after the chainplates however and eliminate the problem. Now to find a very small piece of 3/16" FRP.


Bly

[The Froon]

Bly,

I also have a Sea Sprite (hull 217, see blog), and am currently restoring it. I have noticed that my chain plates are glassed in, but notice no real issue with water intrusion. I do plan to seal the chain plates gaps...polysulfide or a slightly raised epoxy base around the chain plate. My thought was to shape a base mold with modeling clay, then fill with thickened epoxy, remove clay and sand to shape. Finally, I would apply some polysulfide then attach the chain plate cover.

Can you send me the instructions you mention in your post, I would be curious to see them.

Thanks,

Brian

[Case]

Bly, I envy you for having an earlier Sea Sprite 23... with no cabin liner.

I have one with a cabin liner so getting to the chainplates will be a nightmare for me. I have some leaks but they are coming from the toerail so not worrying about the chainplates for now.

If you asked earlier, I would have suggested going the Cape Dory way. Buy those bronze chainplates then fill in the holes, bolt them thru. NO LEAKS with these types of chainplates. I plan to go this route when I need to do my chainplates in the future. The smallest sizes Spartan offers will fit in the spot and still hold the rigging angles properly.

I don't have advice on how to seal the chainplates - I used polysulfide and they are still going strong now. Its not a permanent solution, it has to be renewed constantly, though.

- Case

[Rachel]

I think the mounds are a good idea, but I see your clearance problem to the toe rail.

I saw another way done once - not sure if it will be more useful, and it seems quite a bit fussier than the mounds, but I'll describe it here because it might be a bit slimmer. (Wait - your chainplates are already installed? This might not work then...)

Basically, the person made a tube that extended up through the deck along with the chain plate. I can't remember the details of how it was finished off on deck but I'll still post it for the idea. What they did was make the chainplate non-stick by either waxing or taping it, then they wrapped it in fiberglass cloth like an Ace bandage. Once that cured they took it off the chainplate (erm... I can't remember this detail either, but maybe they cut it off and then put it back together and made some more fiberglass wraps.) Finally they installed the chainplate with the "tube" slightly above deck level and sealed everything.

I know it's probably too late for your installation, but I think outside (the hull) chainplates could look pretty good on a Sea Sprite and would basically eliminate the leakage problem. It doesn't look like you'd lose too much sheeting angle since they're so close to the outside of the hull.

I have to say "Congrats!" for digging in and getting the old chainplates and mounting blocks (there must have been some for the "Z" in the old plates?) out of there. That can't have been fun in the confines of a small boat.

Rachel

[bhartley]

Thanks for all of the suggestions. I think I'm going to press <Pause> on what to do until I get the toe and rub rails back on and the mast stepped to see how the angle changes.

Brian,
If you send me a PM with your email, I will send you the file and pictures from John. The system has worked quite well. I would be truly surprised if you haven't got some water in your chain plate pockets. The source of most of the water is from along the hull/deck joint. The joint is covered with a layer of glass that hides the ends of the screws (doesn't go into the quarter berth however). This makes a very slight hollow behind which funnels the water quite nicely along which is why is was soooo hard to find the origin of the leaks. The chainplates, however, formed the low spot where the water could accumulate along with 35 years worth of crud! With the vinyl rubrail and teak toe rails off, I filled every screw hole and rivet head with epoxy and there was still a drip. Finally I ran Captain Tolleys over the entire exterior joint twice. Voila! No more leaks. I don't know that the leaks (or metal fatigue) are what are causing people's chainplate to sheer off, but I feel better with new chainplates that I can remove and inspect if needed.

Case,

I have to admit I would probably have just waited for one to break if I had a liner! Getting the one out between the mast beam was torture enough.

As for the CD style chainplates, I don't think the deck is substantial enough. It isn't much thicker than 1/4" where the chainplates go through. The area is also very outboard. There is 1" from the hull to the slot. The new blocks are shaped to conform to the exterior of the hull and provide a direct vertical shot out the deck. We had to cut the chainplate covers down to even get them in along the toerail.

Rachel,

A friend has a SS23 which was a "finish it yourself" model. It has exterior chainplates. Not too snazzy though. The SS23 has so little freeboard that they look out of place. Now on the Pacific Seacraft 25 just down the dock from us, they look perfect!

My old body is definitely looking forward to this little project getting done. If I hit my head on the mast beam one more time, I may not live. I have the locker lids out which give me some place to put my legs while I'm lying on my back trying to work. There is no sitting room in the v-berth.

Sadly once the job is complete, no one will notice it at all! I painted everything today and you already can't tell that they weren't built that way. I will, of course, point them out to everyone who comes on board.

I hope someone is out there sailing! I am ready to get out of the yard.

Bly

[Case]

Bly - I now see why you did not consider the Cape Dory method for your SS23. The construction looks different than that of my SS23. It looks like your SS23 is of the "shoebox" design, meaning the hull-deck joint is external, covered by the vinyl rubrail which yours has. My SS23 has an inward flange from the hull, the deck is on top of this flange and its screwed together - screws go thru the toerails then the deck and hull flanges. The toerails hide the hull-deck seams on the top of the deck. The hull and deck skins are visible from the interior and the chainplates go thru both skins. Where the chainplates go thru, its maybe 7/16" thick.

The chainplates on my SS23 is the "T" type. I believe C.E. Ryder SS23s have this layout. Earlier ones had the chainplates attached to the hull itself.

Not looking forward to the inevitable replacement, I probably will have to destroy some of the liner. I often think about removing all of the liner in my SS23 - its just sitting there. Does almost zero work structurally...

- Case