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  • Writer's pictureSailing Koinonia

Replacing chainplates on a Passport 47 sailboat

Updated: May 21, 2020

The Nature of Boat Projects

First, let me begin by acknowledging what any experienced sailor knows and any aspiring sailor will eventually learn: every boat project has a surprise waiting for you. I've come to realize that's part of boat life. Whatever time I estimate a boat task will take — I triple it. Murphy loves boats, so whatever can go wrong, will. If your spidey senses are telling you something isn't right, don't ignore it. Don't look at it and say, "'ll be fine." No - it won't. Just ask my wife, Amber, how many times I've said, "Hey Hun, I'm going to knock out [insert random boat task]. I'll be done in an hour." Ha! Famous last words. And on the rare occasion a boat task goes as planned, it feels so strange it makes me afraid, so I end up double-checking everything to make sure I didn't miss a step.

Before I get into the nitty gritty of replacing the chainplates on Koinonia, bear in mind, I've done major refits, all kinds of glass work, deck re-coring jobs, etc. But this project had some serious wrinkles up it's sleeve; the kind that will test your grit. I had to stay focused on the big picture. This project was necessary to keep my family safe, keep boats and crew around us safe, insure our boat, and thankfully the job wouldn't need to be repeated for 25+ years. And when that day comes, doubtless that fortunate soul won't have this same mess to deal with and will never know of the ordeal they’ve been spared.

Surprise, Surprise

So this was the situation: I knew the chainplates had to be replaced when we bought the boat. No compliant there. Under normal circumstances, the job is time consuming but not especially difficult. But two surprises took this job from a week or two of labor to a hot mess that took up most of my summer weekends for a season:

1) I discovered the side stay and shroud chainplates were glassed into the hull where they passed through the side decks, instead of the usual method of caulking. This is highly unusual as it renders periodic inspection and rebedding impossible.

2) The backstay chainplate, which was glassed into the transom had two horizontal plates welded to the main vertical plate, which meant there was no chance of simply removing the bolts and extracting the plate from above deck.

Replacing the Backstay

Below, you can get a taste of the effort that went into extracting the backstay chainplate, which was by far the most difficult part of this entire project. The only access was from the very cramped space under the starboard aft lazarette. An excellent respirator and good eye protection was mandatory!


The GRP layup on this boat is thick. The side decks, including the Coosa foam coring was over an inch thick. The transom is solid fiberglass and over an inch thick. The Taiwanese build a stout boat! I have to tell you, cutting into the transom with an angle grinder and down through the side decks is pretty nerve racking. And talk about making a mess!



Tools List

- 4000 Series Dremel Tool with diamond edge cutting wheels to get into the really tight spaces.

- Fine tooth saw and chisel to notch the teak cap rail so the new chainplate could be mounted outoard.

- 1/2' thick G10 plate 16 x 24 as a backing block to help distribute the load.

- Kitty Hair long stranded body filler to fill the inboard void after removing the chainplate.

- Teak 1x4 shaped using a router with 1/2" round-over bit to cover the hole in the cap rail from the old chainplate.

- 5 Gallon Wet/Dry Vac to clean up the mess, which was considerable.

Replacing the Side Stay & Shroud Chainplates

Compared with the backstay, the side stays and shrouds were easy. The biggest challenge was getting the fit right, since I was replacing one plate at a time with the rig still standing. Since the mast is stepped on the keel and well supported, this was no big deal; I simply brought a halyard down to the deck near the shroud or stay I was replacing, merely as a precaution.


The first step was to remove the stainless cover plate and cut each plate free from the deck. I was deceived by the presence of caulk, at first, but quickly realized the deck was solid underneath.


Cutting each chainplate free was done using a trusty Dremel tool with a standard multipurpose cutting bit. They are capable of cutting through the material with surgical precision, which is perfect, since the idea is to minimize the amount of material you cut away. I burned through one cutting bit per plate. I hugged as close to the plate as possible while angling out slightly. I wanted to remove the old plate but also have about 1/2 inch of space to pack the caulking once the new plates were installed. Of course, more surprises were waiting. Several of the bolts that attached the chainplates to the fiberglass knees along the hull sheered off, which fortunately could be removed easily by tapping another unbroken bolt to push it out. This was a sobering reminder this job was long overdue!

Even though the core of the deck is Coosa (fiberglass reinforced foam board, similar to Airex), I decided to grind the core back about 1/4" to create a void that I could fill with epoxy thickened with microballoons. This was done as a precaution against water intrusion. I decided to make new cover plates out of a sheet of G10. I made these a bit larger than the originals and painted them a gloss white to match the topsides. This was preferable to stainless steel since the G10 will never corrode.


I ordered our new 1/2" thick 316 stainless steel electropolished chainplates from Chainplates Express in Texas. The service and turn-around time was outstanding. I highly recommend sending the old plates as a template from which to pattern the new plates. Instead of using caulk, I decided to use Bed-It butyle tape to fill the void around each chainplate and to seal the cover plate. It remains flexible, never dries out, and forms a water tight bond that lasts virtually forever. This also makes inspecting the plates in the future much easier.

Tools & Materials List (in addition to those listed above for backstay)

- Thin G10 board (mechanically compressed fiberglass board) cut, sanded, and painted.

- West Systems Epoxy with 206 slow hardener thickened with phenolic microballoons

- Pettit EZ Cabin Coat in white - this is a fabulous water-based paint that is very mildew and moisture resistant, and also low odor.

To my knowledge, we're the only Passport 47 owners who have tackled this particular project. There were only 14 hulls built, so that's not surprising, but I certainly didn't have the benefit of the insights found in this post to inform my approach. I hope by sharing this information, it might help another mid-eighties Passport sailboat owner or anyone else trying to tackle the project of replacing chainplates on an older fiberglass boat. It's no walk in the park, but it's essential to the safety and soundness of your boat and crew.

Fair Winds & Blessings,

Ben Ward

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