Rebuilding a Forward Bunk: Beam Boxes, Panel Span, and Water Catchment

Rebuilding Harry’s forward bunk space meant moving his bed further back and lowering it slightly for more comfort and width — straightforward on its own, but it sits right beside two bulkheads doing real structural work, which meant thinking carefully about what could change here and what couldn’t.

The Front Beam’s Beam Box

These two bulkheads sit unusually close together, and together they form a genuine box structure supporting the front beam — one of them carries the mast base directly, and the other, just forward of it, sits close enough that the pair effectively brace each other. Looking closely at the existing lamination — not the tidiest factory work, but functional — the pattern is a textbook beam: a band of unidirectional fibre running across as the top flange, more unidirectional fibre lower down forming the bottom flange, and the bulkhead itself acting as the shear web connecting the two, carrying load in double bias rather than uni since its job is shear, not tension or compression.

Given that structural role, neither of these openings gets the same headroom or width treatment applied elsewhere in the boat. One doesn’t get walked through at all — the bunk runs all the way to it — so there’s no comfort case for opening it further. The other stays closed too, partly because of clearance challenges around the hole itself, but mainly because this pair of bulkheads is doing too much structural work, right where the front beam loads concentrate, to treat casually.

Restoring a Flange After Cutting

One opening elsewhere in this area had already been cut wider in an earlier stage of the refit, which left its lower flange smaller than it needs to be — effectively a beam with a top flange and no matching bottom one anymore. The fix is straightforward given the underlying beam logic already established elsewhere on this refit: run unidirectional fibre through that lower section to properly reform the bottom flange, then edge cap it the same way the chainplate channels were finished, with the same care already covered around penetration spacing near a structural joint.

Reusing an Ex-America’s Cup Floor

The floor in the very forward part of this space isn’t being replaced at all — it’s carbon fibre with an X-core, salvaged originally from America’s Cup boat material and installed during an earlier stage of this refit. There’s no reason to redo good work; the only outstanding job here is edge capping the exposed border, since the floor itself doesn’t need a hatch cut into it — it lifts as a single forward panel.

Why a Bunk Counts as Structure

The bunk being rebuilt here isn’t just furniture — it’s doing real structural work. Between the forward bulkhead and the one this bunk sits against, there’s a genuinely large unsupported panel span, and a big, unbraced panel like that will flex in and out under load without something breaking that span up. Building a substantial bunk across that space effectively cuts the panel in half vertically, which alone meaningfully reduces how much it can flex. A smaller bulkhead further down, in the section that takes the brunt of wave impact lower in the hull, splits that lower panel even further. Get a panel’s aspect ratio small enough and a bulkhead technically isn’t required at all for flex control — but this particular bulkhead earns its place for a second reason entirely: it’s also defining a water catchment compartment.

Water Catchment, Not Full Watertightness

Neither of these two forward compartments is a genuinely watertight compartment in the strict sense — practical realities like non-watertight PEX plumbing running through rule that out. What they are is a substantial water catchment boundary, sitting roughly 800mm above the waterline. If either compartment ever did fill, it would take a great deal of water before that height became a real problem — and if it ever did reach that level, there are considerably bigger problems to deal with than the compartment itself.

The meaningful improvement here isn’t perfection, it’s containment. In the original layout, water entering this area simply ran straight under the bulkhead and into the middle of the boat unchecked. Now, it has to fill a genuinely substantial compartment first — a real amount of reserve buoyancy and time bought before anything becomes critical, even without full watertight integrity.

Why This Isn’t Becoming a Toy Locker

A garage-style toy locker up forward is a genuinely popular feature on modern cruising catamarans, and it was considered here. The math doesn’t work in this boat’s favour, though: that much weight, that far forward, works directly against everything else this refit is trying to achieve. An empty space with a mattress in it, with someone sleeping there, is about as light as that volume can possibly be used — and with five people already aboard and gear needs spread across the rest of the boat, there wasn’t a strong enough case to trade that weight-forward penalty for storage that could likely be found somewhere better positioned instead.

A Practical Note on the Build

The new bulkhead here went in as two separate infused pieces rather than one — not a design choice, but a practical one: the laminating table simply isn’t large enough to infuse a piece this size in one go on a 42-foot boat with limited workshop space. Splitting it in two, infusing each piece separately, and joining them in place was the only realistic option — a good reminder that build sequencing often comes down to workshop constraints as much as the engineering itself.

In This Series

Rebuilding a Forward Bunk is one part of Paikea’s bulkhead reinforcement. Follow the rest of the build here:

Follow the rest of Paikea’s interior transformation on the Paikea’s Refit page.