Why hollow wooden surfboards need a vent
A hollow wooden surfboard is a sealed shell with air inside. That air doesn't stay the same. It expands when the board warms up and shrinks when it cools down, and the board has to cope with that every time you take it from a hot car park into cold water. A vent gives that air somewhere to go. Here's why it matters, how a vent works, and how to choose one for your build.
What happens inside a sealed board
Leave a board in the sun, on a roof rack, or in a hot car, and the air inside heats up. Warm air takes up more space, so the pressure inside the board rises and pushes outward on the skins and glue lines. When you paddle out, the water cools the board quickly, and the pressure drops below the air outside. Now the board is trying to draw air in, and if there's a pinhole or a small ding anywhere, it can draw water in with it.
Flying does something similar. Cargo holds are pressurised to a lower pressure than at sea level, so a sealed board will try to swell on the way up and pull back in on the way down.
One trip through that cycle is rarely a problem. Hundreds of them, over a few summers, put real and repeated load on a hollow board. A vent takes most of that load away.
How a vent works
A surfboard vent is a small opening covered by a breathable membrane. Our vented leash plugs use a Gore-Tex/Teflon type membrane, the same family of material used in waterproof jackets. Air and water vapour can pass through it, but liquid water can't. When the air inside the board warms and expands, it moves out through the membrane. When it cools, air can move back in, so the pressure inside stays close to the pressure outside.
The membrane needs enough open area to breathe quickly. Our leash plugs have a 10mm hole behind the membrane for that reason.
Your options
We make three ways to vent a board. All three replace a standard 32mm plastic plug, so they suit the hole size most builders already use.
Vented leash plug, glass-in type
The glass-in vented leash plug is glued in and laminated over, like a conventional plug. It has a Spotted Gum body, a 316 stainless steel pin, and a 1.5mm resin lip, and it's 16mm thick. Because the leash plug doubles as the vent, you only need one fitting in the tail. Tape the top of the lip before you laminate, then sand it flush afterwards.
Vented leash plug, no-glass type
The no-glass vented leash plug is made for boards such as foam cores, where the plug is set in with resin after lamination. It's 15mm thick, with ridges around the body for the resin to key into. A 1.5mm laser-cut plywood spacer comes attached to protect the membrane from resin, so you don't need to add one.
Screw-in surfboard vent
The surfboard vent has a CNC-machined Spotted Gum base that you glue into the board, and a nickel-plated copper M12 vent that screws in after lamination. The base is sealed underneath, so you drill a 4 to 5mm hole through it once the board is glassed. Unscrewing the vent leaves a straight hole into the board. That's handy for boards that fly often, and it lets you drain water out if the board ever takes some on.
Tips for builders
- Plan how air moves inside your frame. If the chambers in your design are sealed off from each other, each one needs its own way to breathe, or holes through the ribs so air can reach the vent.
- Keep resin off the membrane. A membrane full of resin can't breathe. Tape the glass-in plug before laminating, and leave the spacer on the no-glass plug in place.
- Set every fitting in solid timber. Leash plugs, vents, and fin boxes all need a solid block around them, not a thin skin.
- A vent helps, but care still counts. Store your board out of direct sun, keep it out of hot cars where you can, and fix dings promptly.
Not sure which one suits your build? Get in touch and tell us how you're building your board.