DIY Square-Top Mainsail: 3D-Printed Batten Receptacles
Paikea’s mainsail started life on a 72-foot superyacht.
It was a delivery main — big, heavy cloth built for a boat three times our size — picked up during lockdown when boat parts weren’t exactly easy to come by and budgets were tighter than usual. Anna took it on: cutting it down from scratch, reshaping the head into a modern square-top, and rebuilding it into something that would actually work on a 42-foot cruising catamaran. It’s the kind of project that sounds simple in a sentence and isn’t. A full sail recut, done solo, during a lockdown, with none of the usual sailmaking resources on hand.
The batten receptacles were the part that nearly stalled the whole project.
We’d committed to carbon fibre battens for the new square-top — stiffer, lighter, and the right call for the load a square-head shape puts through the top of the sail. The batten track fittings we managed to source and fit without too much trouble. But the receptacles — the end fittings that actually hold the batten in place at the leech — were another story. Bought new, they were expensive enough to blow the budget on their own, and between the cost and the timeline we couldn’t make them work.
The fix came from someone in our network offering to 3D print a set of insert receptacles instead. Shayne built fibreglass surrounds to house them properly in the sail, and between the two solutions — printed inserts, glassed-in housings — we had a way to mount carbon battens without paying superyacht prices for superyacht hardware. We bolted the receptacles to the sail, cut the battens to length, and finished the whole thing at anchor in La Grande Motte.
Telltales came next, and this part was pure trial and error. We didn’t have proper telltale material on hand — the only spinnaker cloth left on the boat became the source — so we cut strips, held them up into the wind to check they weren’t too wiggly or unstable, and sewed the better-behaved ones onto the main. Simple problem, low-tech solution, exactly the kind of thing that happens when you’re building a sail at anchor rather than in a loft.
The first sail with the new main was the payoff for all of it — square-top up, carbon battens locked into their 3D-printed receptacles, and a mainsail that started its life on a boat nearly twice Paikea’s length now doing exactly what a cruising cat needs it to do.
In the Members Library
Members can discuss sail builds and repairs like this one directly in the forum — a good place to ask questions if you’re planning something similar. The 3D print file for the batten receptacle insert used in this build will be added to the members downloads soon.
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