Foil maintenance: how to look after your hydrofoil

The full strip and rebuild, seven steps, from taking the front wing off to mounting the foil on the board.

Salt is what kills foil hardware, not riding. Strip the foil down between trips, put grease on the threads, and most of what people call wear never happens at all.

We are in an unusual position to say that. FoilHive is a membership, so the gear comes back to us. Every returned kit is inspected in our Tarifa workshop against a checklist, which means we see what fails across a whole fleet instead of one person's setup. This page is what that inspection keeps telling us.

What is in the box

Every set ships with two Torx screwdrivers and a set of INOX stainless screws. The two drivers are not interchangeable, and using the wrong one is the fastest way to round a screw head.

• T30 drives the two M6 screws on the tail wing. Nothing else.
• T40 drives everything else: front wing to fuselage, mast to fuselage, and mast to the board plates.

Four screws and four T-nuts for mounting the foil to your board are included as well. They also take the T40, so there is nothing further to buy.

Take the front wing off first

The order matters, and not for tidiness. With the board still attached, you can stand on the mast plates while you work, so the wind cannot pick the foil up and drop it. A lot of the broken gear we see started with a foil left balanced on a board in a gusty car park.

Then the mast, then the tail wing. Hold the part before the last screw comes out, every time.

Why foil screws seize, and what to do about it

Stainless screws sitting in an aluminium fuselage, soaked in salt water and then left assembled for weeks, will bond. The salt does not need to be visible to be doing it.

Prevention is the whole answer here. Grease or WD-40 on the threads before they go in, and take the parts apart between trips so salt cannot sit in the joints. A foil stored in pieces does not seize.

If one is already stuck, stop before you force it. A rounded head turns a five minute job into a workshop job. Members should send us a photo first, because we would rather free it properly than have you drill it.

Why screws keep coming loose

Usually because they were never properly seated. Screw everything down gently by hand first, and go slowly, since a driver that slips damages the foil for no reason at all.

When it starts to get harder, move the screwdriver into the lever position and give each screw one quarter turn. That is enough. Past that point you are not tightening anything, you are damaging the foil.

Does an aluminium mast corrode in salt water?

It will, if you leave it assembled and wet. There is a part designed to take that hit for you.

Look at the fuselage and you will count four holes. The front wing uses the first three. The fourth holds a sacrificial zinc anode, a small zinc bar that corrodes in place of the fuselage. ONIX Foils, our sister brand, fits one to every fuselage, and we fit a fresh one before a kit ships out. Leave it where it is, and expect it to look worse over time. That is the anode working.

Beyond that: rinse with fresh water, dry the joints, grease the threads, and store the foil in pieces.

Do foil parts wear out?

The carbon does not, in normal use. The hardware does. Screws, the anode and the shim between mast and fuselage are consumables, and treating them as permanent is where most problems start.

On a membership that is our problem rather than yours. Gear comes back to the workshop, gets inspected and repaired, and goes out again to someone else.

Putting it back together

Three things are easy to get backwards, and all three are easy to check.

• The fuselage will slide onto the mast the wrong way round. It fits, but the screw holes will not line up. That is deliberate, not a fault. If the holes do not meet, turn it around.
• The mast is rounded at the front and sharp at the back. Clip the shim onto the mast first and the correct direction becomes obvious.
• The tail wing's first screw goes in the first hole. Check it from the side. The tail wing should follow the shape of the fuselage with no gap behind it.

What this means on a FoilHive membership

FoilCare covers normal surface scratches and cosmetic wear from regular use. It does not cover damage beyond normal wear, or lost and stolen equipment.

Salt damage from a foil stored wet and assembled for a season is not normal wear. We would rather say that here than put it on an invoice later. The full detail sits in the House Rules, which is the page that governs it.