True ride height: forget the number on the mast

True foil height

Bottom of the board to the bottom of the fuselage. Where the foil actually sits relative to the board.

True rider height

The deck under your feet to the bottom of the fuselage. How far you are actually standing above the foil.

Why mast length is not enough

It starts at the bottom of the board, and you stand on top of the board. The thickness under your feet never appears in the number.

Typical board thickness

Most production foil boards are around 13 cm through the standing area — six centimetres more than a thin one, all of it between your feet and the foil.

The hydrofoil industry has always described ride height by mast length. 85 cm. 95 cm. 105 cm.

The problem is that there is no universal standard for exactly where that measurement starts and stops. One manufacturer's 85 cm mast does not necessarily put the foil at the same depth as another's. We have measured an 85 cm mast from another brand on our own bench, from the bottom of the board to the bottom of the fuselage, and read closer to 90 cm.

So what are you actually riding?

Two measurements that matter

True foil height runs from the bottom of the board to the bottom of the fuselage. It tells you where the foil actually sits in relation to the board, and it is the number that decides how high you can fly before the wing approaches the surface.

True rider height runs from the deck under your feet to the bottom of the fuselage. It tells you how far you are actually positioned above the foil.

That second measurement is the one mast length ignores completely. The mast number starts at the bottom of the board. You stand on top of it.

Board thickness is part of ride height

Most production foil boards are around 13 cm thick through the standing area. That is the number nobody quotes, and it is doing more to your ride height than any mast decision you are agonising over.

Take a setup with 85 cm of true foil height and put it under that 13 cm board.

85 + 13 = 98 cm true rider height.

Now put exactly the same foil under a 10 cm board.

85 + 10 = 95 cm true rider height.

And under a 7 cm board.

85 + 7 = 92 cm true rider height.

Nothing changed below the board. The foil sits at the same 85 cm in all three, with the same usable height. What moved is you — six centimetres closer to the foil, purely by standing on less board. That shortens the leverage between your feet and the foil and can create a noticeably more direct, more connected feeling.

The math

Or spend those centimetres somewhere else

Getting closer to the foil is one thing to do with the thickness you save. It is not the only one.

The centimetres you take out of the board are centimetres you can put back into true foil height and still stand exactly where you stand today. Drop from a 13 cm board to a 7 cm one and you have six of them to spend. Spend them all downward and your feet stay at 98 cm while the foil gains six centimetres of usable height below the board — more clearance before the wing comes near the surface, no change in how high you are standing.

So a thinner board is not one benefit. It is a budget, and you decide where it goes:

• Keep the foil height and bring your feet closer, for a more direct connection.
• Put it back into foil height and gain usable clearance below the board at the same rider height.
• Split it — some of each.

Why this matters

A mast's advertised length does not necessarily tell you how deep the foil sits. It definitely does not tell you how high your feet are above it.

That is why we think the industry has been looking at this from the wrong direction. Instead of starting with the component and asking "what length mast am I riding?", start with the complete system and ask "where is my foil, and where are my feet?"

That is your true ride height.

Measure your own board at the front foot — that is where your weight is, and it is rarely the thickest point. If it comes in near 13 cm you are on a normal board, and that is the point: normal is thick. Add it to the foil height underneath, then hold that sum steady when you change either part.

Mast lengths and profiles are on the masts page, and the mast selection guide covers where each length lands by discipline and skill. The horizontal lever works the same way — see the fuselage selection guide. And if you are choosing a frontwing by the number on the box, don't judge a foil wing by area alone makes the same argument about a different spec.

The build wizard keeps the connection right across whatever combination you land on.