Boat Squab Foam: Reticulated Dry-Fast vs Standard Foam Compared

Nothing ruins a boat faster than squabs that turn into sponges. The foam you choose decides whether a soaked cushion is dry by lunchtime or growing mould by the weekend. Here’s how reticulated dry-fast foam compares with standard polyurethane, and where each belongs on a boat.

What makes a boat squab different

A lounge cushion gets a spilled drink once a year. A boat squab gets spray, rain, wet swimmers and a hose-down every trip, then sits under a cover in 90% humidity. Standard furniture foam is a closed-and-open cell mix that soaks up water like a sponge and holds it. The result is a heavy, cold cushion that never dries and a green bloom on the underside of the vinyl within a season.

Reticulated (dry-fast) foam explained

Reticulated foam is polyurethane foam that has had the cell membranes removed – usually by a controlled explosion in a chamber – leaving only the skeleton of the cell structure. The result looks like a very coarse sponge and is completely open. Water poured on top runs straight out the bottom. Air passes through it freely, so any moisture left evaporates in hours rather than days.

Typical grades are described by pores per inch (PPI). For seating, 30–45 PPI gives enough support; lower PPI numbers are coarser and drain faster but feel harsher.

Dry-fast vs standard foam side by side

Property	Reticulated dry-fast	Standard PU / HR foam
Water drainage	Drains through in seconds	Absorbs and holds
Drying time when soaked	2–6 hours in sun	Days, often never fully
Mould resistance	Very high – no trapped water	Low once wet
Feel	Slightly firmer, springy	Softer, more ‘lounge’
Density range	Typically 25–35 kg/m³	22–50+ kg/m³
Durability outdoors	Excellent	Poor if regularly wet
Cost (indicative)	Roughly 1.5–2× standard foam	Lower
Best use	Open cockpits, swim platforms, bow cushions	Cabins, saloon berths, enclosed helm seats

Where to use each on the boat

Reticulated foam: anything that gets wet

• Cockpit and bow squabs on open boats
• Swim platform and transom cushions
• Deck and sunpad cushions on launches
• Helm seats on centre consoles and RIBs
• Any squab that lives under a canvas cover rather than inside a cabin

Standard HR foam: the dry interior

Inside a cabin, saloon settees and berths are better in a good high-resilience foam. It’s more comfortable to sleep on, cheaper, and – provided the cabin is ventilated – it stays dry. Our HR35 seat foam is a solid choice for berths and saloon seating; use a breathable underside on the cover so the foam can vent.

Hybrid squabs

A common trade solution for semi-exposed seats is 25 mm of reticulated foam laminated on top of 75 mm of HR35, or the reverse with dry-fast at the bottom as a drainage layer. The combination gives lounge comfort with much faster drying. Bond them with a light coat of foam-safe spray adhesive; don’t use contact adhesive on reticulated foam or you’ll clog the cells.

The cover matters as much as the foam

Dry-fast foam only works if water can leave. A fully sealed vinyl cover with a vinyl bottom just turns it into a waterbed. Use one of these approaches:

• Marine vinyl top, mesh bottom: the standard for cockpit squabs. Water drains through the mesh; the seat stays wipe-clean.
• Solution-dyed acrylic all round: breathable, drains everywhere, ideal for sunpads. See our outdoor & marine fabrics.
• Vinyl with brass or stainless drain grommets: for squabs that must be vinyl on all faces.

Sew with UV-rated bonded polyester thread and stainless fittings. Salt air corrodes plated staples within a season – use stainless 71-series staples on any timber-based squab.

What about closed-cell foam?

Closed-cell foam – the stiff, rubbery material in life jackets and float cushions – comes up often in boat conversations. It doesn’t absorb water at all, but it is firm, doesn’t breathe and compresses permanently under a seated load. It suits a flotation cushion, a kneeling pad or a thin comfort layer on a hard bench, not a seat you sit on for a day’s fishing. For seating, reticulated foam gives you the dry result with real comfort.

Thickness and sizing

Most boat squabs are 50–75 mm; helm and bench seats you sit on for hours are better at 75–100 mm. Reticulated foam is slightly firmer, so if you are replacing 75 mm standard foam, 75 mm dry-fast will feel a touch firmer, not softer. Measure the empty cover, add 10 mm to length and width and match the boxing height. For curved bow squabs, trace the old foam or the locker lid onto cardboard and send us the template through the contact page – we cut to shape.

Foam and fabric fire ratings on boats

Survey and charter vessels in NZ may need upholstery that meets AS/NZS 1530.3 or the relevant Maritime NZ requirements, and even on a private launch a fire-rated foam in the cabin is cheap insurance. Reticulated foam is available in fire-retardant grades; ask for the test data when you order and keep it with the boat’s papers. Our guide to NZ fire ratings and marine fabrics explains what the numbers mean.

Care over the season

• Stand squabs on edge after a wet trip so they drain and air.
• Rinse fresh water over salt-soaked squabs; salt holds moisture.
• Store over winter dry, indoors if you can, off the floor.
• Wipe vinyl with a mild detergent; avoid bleach on stitching.

If the foam is already black inside, replace it – mould spores don’t wash out of foam. Recovering over mouldy foam is false economy.

Doing it yourself vs the trade

Straight bench squabs with a zip are a good DIY job. Curved bow cushions, hinged helm seats and anything with contoured foam are harder, and on a boat you’re usually working around fittings and templates. If you are in Auckland and would rather have the whole set done, our sister workshop Upholstery World does marine upholstery on-site at the marina or hardstand, including foam replacement and new covers.