Fitting the Engine Room Door — and Why Flow Coat Isn’t Just Paint

With obligations on the Balthasar refit wrapped up for now, it’s back to Paikea’s own engine room door — along with a hard look at a hydraulic steering system that’s genuinely on its way out.

Fitting the Door Frame

Getting this door frame in meant cutting the opening slightly larger than originally planned to get a proper fit, gluing one side on with epoxy — the material on hand at the time, since polyester wasn’t available — and fibreglassing the other side, which had no flange to bond against otherwise. Only the unflanged side needed that extra lamination; the flanged side didn’t require it.

The door itself is foam and fibreglass, with a carbon plate built into the section where the hinges bolt through — solid backing exactly where the hardware needs to grip, rather than relying on foam alone to hold fasteners under load. Dry-fitting it confirmed the geometry works before anything gets permanently sealed.

Getting the seal right here matters more than on most doors in the boat: this one sits between the engine room and the main bedroom, so it’s doing real work as a sound barrier, a fume barrier, and a fire barrier all at once — not just keeping the space visually separated.

A Hydraulic Steering System on Borrowed Time

While working through the door, the state of the current hydraulic steering came up — and it’s not a small problem. The hydraulic pump is cast aluminium, and where the two hydraulic hoses connect into it, corrosion has compromised the sealing surface, making a reliable seal genuinely difficult to hold. The bigger issue is what happens once the oil level drops: air gets into the system, and a hydraulic system with air in it isn’t really a hydraulic system anymore in any functional sense, since air compresses and the whole point of hydraulics is that the fluid doesn’t. On top of that, the rams themselves have worn past the point new seals can fix — the internal surfaces they run against are no longer smooth enough for a proper seal, regardless of how good the seal itself is.

The option under consideration is converting to cable steering instead — a carbon tube running from the rudder stock up to deck level, with a tiller arm or quadrant fitted near the top. The appeal isn’t just avoiding the leak problem: a cable system gives genuine feel and feedback through the helm, something a hydraulic system simply doesn’t provide — turn the wheel against a real load and a hydraulic system just locks up rather than telling you anything useful about what’s happening at the rudder. The trade-off is real too: hydraulic systems make wiring up an autopilot considerably simpler, and a full conversion isn’t cheap. This one’s genuinely undecided — a good idea on paper, not yet committed to in practice.

Closing Up the Old Wiring Holes

Elsewhere, the last of the old holes from previous generations of the boat’s wiring are finally getting filled — foam packed in first, then laminated over once cured. With that ground back and prepped, the surface is ready for a coat of flow coat before insulation goes on, closing the loop on holes that were first addressed back in an earlier filling-in session. Polyester resin being back in stock made continuing this work possible again.

Why Flow Coat, Not Just Paint

Putting flow coat over bare glass before adding insulation is a deliberate choice, not a cosmetic one. A sanded composite surface is covered in countless tiny exposed fibres that glue adheres to extremely well — which sounds useful until you ever need to remove that insulation later, at which point stripping adhesive off a fibrous surface is genuinely difficult. A smooth flow-coated surface gives adhesive somewhere to grip for now, while staying easy to clean off completely if the insulation ever needs to come off down the track.

Flow coat specifically, rather than ordinary paint, comes down to what the job actually needs: it’s thick and reasonably forgiving to apply in an awkward bilge space, it’s not going to be seen, so appearance doesn’t matter, and — while genuinely heavy, being essentially pure resin with pigment and light filler rather than a thinner paint system — that weight penalty is an acceptable trade for durability somewhere unseen and hard to access.

Flow Coat vs. Gel Coat: One Ingredient, Two Different Jobs

Flow coat and gel coat are the same underlying material with exactly one difference: wax. During cure, that wax migrates to the surface and isolates the resin from moisture in the air, allowing it to fully cure right through to the outer surface. Without that wax, airborne moisture inhibits polyester’s cure at the surface — which sounds like a downside, but it’s actually the mechanism that lets styrenated resin systems like polyester and vinyl ester form a genuine chemical secondary bond later, something an epoxy laminate can’t do in the same way.

Paikea was originally a gel-coated boat — gel coat being nothing more than polyester resin with pigment and light fillers added for workable thickness. It’s also the reason polyester has no business being used below the waterline: polyester resin isn’t waterproof, and that’s precisely where osmotic blistering — the “pox” familiar to most boat owners — comes from.

Worth knowing for anyone doing similar work: if a final laminate layer needs a fully cured, non-tacky surface without a separate flow coat or gel coat step, wax and styrene can be mixed directly into the resin for that last layer instead, achieving a complete cure much like an epoxy would. The catch is that a waxed surface like this needs treating exactly like an epoxy afterward if anything ever needs to bond to it again — full cleaning and sanding, since wax will block adhesion completely regardless of what’s applied over it. Precision matters with the catalyst too: too much, and it kicks off before the job’s finished; too little, and it won’t cure properly at all.

In This Series

Fitting the Engine Room Door is one part of Paikea’s door replacement. Follow the rest of the build here: