How We Replaced a Chainplate on a Floating Boat in Tahiti

Disclaimer: All boat terms explained at the end of the text ⛵

🚨 The Problem

While renovating the aft cabin of Tauha, we found something that made our stomachs drop: a deep crack straight through the chainplate - right at the first bolt.

That’s not just cosmetic damage. The chainplate is what holds the backstay, the thick stainless-steel cable which adds tension to the mast from behind to keep it upright. If that fails mid-ocean, best-case scenario: the rig loses tension. Worst case? The entire mast comes down. We weren’t about to take that risk.

But time was tight, and we didn’t have a spare part. Chainplates are often custom-made and vary in design from boat to boat. Additionally we wanted one made out of stainless steel to avoid rusting through again. Finding a part like that in French Polynesia within a few days? Sounded nearly impossible.

🔍 The Hunt for a New Chainplate

We’d been to what felt like every boat shop on the north side of the island, growing more discouraged with each stop. Most vendors just shrugged. A few didn’t even know what a chainplate was. At our final stop, more out of desperation than hope, we asked the guy behind the counter if he happened to know a metalworker who could custom-make a part like this. To our surprise, he didn’t hesitate: “Actually, yeah. There’s a guy on the south side of the island. I’ve heard only good things. I’ll send you his WhatsApp.”

Welcome to island networking, where WhatsApp is king.

We sent the metalworker a quick sketch of the part along with a desperate plea. Within an hour, a response came back. He mentioned that he already had a stainless-steel piece that was almost the right shape. With a bit of extra work overnight, shaping and drilling, it could be ready by the next day, for a small additional fee for the night shift.

We couldn’t believe it. And sure enough, the next day we picked up a beautifully finished, custom-made chainplate from his little workshop on the south side of the island. It was heavier, thicker, and stronger than the original. Perfect.

🛠️ The Install

Now came the next challenge: installing it.

This is the kind of job you'd normally do with the boat on land and the mast unstepped. But Tauha was moored behind a reef, gently bobbing on turquoise water, and we had no time (or budget) for a haul-out.

Fortunately, the next morning brought perfectly calm weather. Time to get it done.

Step 1: Secure the Mast

We couldn’t risk the mast shifting while the backstay was disconnected.

• Tighten the boom topping lift and the main sheet to help pull the mast backward

• Crank the main halyard tight and secured it aft

• Tie a safety line between the backstay and the chainplate to catch it if something slips

Step 2: Remove the Old Bolts

• Five bolts held it in

• I hung off the stern like a bat, gripping bolt heads halfway down the back wall of the boat with a wrench

• Below deck, Alex was sweating in the aft cabin with a tiny wrench and, eventually, a hacksaw for the two bolts that refused to budge

Step 3: Remove the old Chainplate

• Loosen the turnbuckle to disconnect the backstay from the chainplate.

• With all bolts out and the cable detached, the chainplate could finally be pulled free. There it was, corroded, cracked, and clearly not something you'd want to sail with.

Step 4: Install the New Chainplate

• The new one was slightly wider, so we filed the hull opening to fit

• Once widened, it slid into place beautifully

• The new bolts? Perfect match. Jackpot.

Step 5: Seal and Secure

• We sealed all bolt holes and the chainplate with marine-grade Sikaflex, which turned out to be black (whoops). But it sealed beautifully.

• The backstay was reconnected, the safety lines removed, and… Voilà, new chainplate installed.

💭 Final Thoughts

Changing a chainplate on a floating boat in tropical heat, with salt in your hair and sweat in your eyes? Not our favorite. But with a little luck, some island ingenuity, and a healthy dose of teamwork, it’s doable.

The good news! All the other chainplates still look solid. Let’s hope they stay that way. 🤞

⛵ Boat Terms Explained

Chainplate - A thick stainless-steel plate bolted through the hull used to anchor rigging cables (like the backstay). It helps keep the mast upright and under proper tension.

Backstay - A tensioned cable running from the mast’s top to the stern. It prevents the mast from falling forward and stabilizes the entire rig.

Main Halyard - The line used to raise and tension the mainsail. Here, we used it to support the mast during the repair.

Boom Topping Lift - A line holding the boom up when the mainsail is down. In our case, it helped brace the mast rearward.

Boom Sheet - The line controlling the angle of the boom. Tightening it helped us keep mast tension while the backstay was off.

Turnbuckle - An adjustable metal fitting that connects the backstay to the chainplate and allows us to fine-tune tension

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