Recycling Massive Carbon Fiber Battens
There’s a rule on this boat that makes life simpler for anyone who ever has to work on her after us: if it’s black, it’s carbon and epoxy. Everything else is glass and polyester. It sounds like a small thing, but it means Shayne — or whoever owns this boat next — never has to guess what a component is made from or what it’ll bond to. Consistency now saves confusion later.
That rule was put to the test this week fitting a curved carbon-Nomex panel into the cabin top — a piece with a genuine compound problem, following both the curve of the cabin roof and a twist through the panel itself. Getting it to sit properly took real patience, and the result is bonded and laminated permanently in place with epoxy and carbon, exactly matching the front beam, longeron, and chainplates elsewhere on the boat. One more piece speaking the same structural language as the rest of the refit.
What actually makes a race batten different
While the panel was curing, the real subject of the week came out: a set of enormous carbon fibre sail battens from C-Tech, sized CT40. The number isn’t arbitrary — C-Tech battens are classified by the internal mandrel width, the one dimension that stays constant while everything else about the batten is custom. A CT40 measures 40mm across the batten pocket dimension; a CT22 measures 22mm. Beyond that width, every batten tapers differently depending on the draft and bend profile a specific sail needs, and the laminate itself is tailored on top of that shape. In race boat sailmaking, a batten isn’t just a batten — it’s engineered for one specific pocket in one specific sail, and swapping it into a different pocket, let alone a different sail, generally doesn’t work.
That level of customization is exactly why these particular battens ended up available to us at all. On a superyacht or grand prix programme, once a sail’s shape changes even slightly, the old battens rarely fit the new one — too tailored to reuse, not valuable enough to keep, and too good to throw away. They pile up in containers instead. Which is exactly where these came from.
The construction itself is worth understanding if you’re ever evaluating a used batten for a project like this. Battens are built almost entirely from unidirectional carbon fibre running along the batten’s length, with just enough off-axis “hoop” fibre — typically at 45 or 60 degrees — to hold the structure together sideways. Cut a batten’s cross-section and you can actually see this in a prepreg laminate: a dark black zero-degree layer dominating, with only thin, lighter-coloured bands showing where the fibre direction changes. Reading that cross-section tells you a lot about what a given batten can and can’t be used for — whether it’s suited to pure compression loading, or whether it has enough off-axis reinforcement to work as a structural beam in bending.
Why you can’t just cut one in half
The obvious temptation with a batten this size is to split it lengthwise for smaller jobs. It doesn’t work, for two separate reasons. First, the off-axis fibre layup inside these battens is often deliberately unbalanced — some sections biased toward plus angles, others minus — which stays perfectly stable as a closed section but twists the moment it’s split open, since the balancing forces that kept it straight no longer cancel out. Second, cutting the bottom flange off a rectangular hollow section to make a C-channel destroys the very thing that made it stiff in the first place — it’s the separation between the top and bottom flange that gives a closed section its resistance to bending, and removing one flange can cut that stiffness by more than half while concentrating stress at the newly exposed edges. A batten built to be strong as a closed tube is a much weaker thing once opened up.
Where these are actually going
Rather than cut them down, the plan is to use full sections where their built-in strength does real work. One is destined as a compression post reinforcement behind the mast base bulkhead — not because anything’s currently wrong, but because older Catanas, like plenty of other cruising cats, sometimes carry timber in the mast compression post. Timber that gets drilled into or takes on moisture over years can rot from the inside, and mast base compression failures from exactly this cause aren’t rare across multiple boat brands. Bonding carbon to the back of an already-exposed bulkhead, tied directly into the mast base, is cheap insurance against a failure mode that’s well documented elsewhere.
Another length is earmarked for a carbon pushpit, following a rethink after sourcing this batten stock changed the plan from stainless steel to carbon — the kind of plan change that happens constantly on a project like this, chasing whatever material actually becomes available. A further piece is destined to extend upward as a mounting post for Starlink, integrated into that same pushpit structure.
The transom beam is another candidate — specifically as reinforcement for a future traveler track. Since fitting the new carbon front beam, the difference in stiffness compared to the aft beam has become obvious underfoot, and asking the back beam to carry mainsheet loads from a traveler track it was never originally engineered for means it needs the same treatment the front end already received. The straight, largely unidirectional core of these battens is exactly the right material for building up a lower flange in that structure.
The unresolved challenge: the cabin top
The trickiest application is still being worked out — using a batten to stiffen the cabin top itself, partly for structural rigidity and partly to hide wiring runs for future electrical work. The problem is straightforward physics: the batten is straight, and the cabin top roof is not, especially over a boat this age. Laminating a rigid straight member directly onto a curved surface without addressing that mismatch risks a component that looks fine but never properly transfers load into the surrounding structure. Routing a groove into the existing inner skin, bonding the batten into that recess, and then reinstating a lightweight skin over the top is the more structurally sound approach — more work, but a proper load path rather than a cosmetic fix.
This isn’t a sponsored plug for C-Tech, but it’s genuinely worth understanding what they build and why sailors around the world end up hunting down their offcuts. If you ever come across a program running C-Tech battens — race boats, superyachts — it’s worth asking what happens to the old ones when a sail gets recut. More often than not, they’re heading for a bin rather than another sail. A far better outcome is a batten holding up someone’s bimini, stiffening a mullion, or reinforcing a dinghy davit on a cruising boat instead.