Bigger wing or longer mast?


I would like to have my board lifted a little bit more while hydrofoiling so that my board in not skimming the water waves when runnning 50% throttle. Running at full throttle increase speed but don’t give more lift. Today I have a Gong mast with the length of 45cm and a wing from gong L size - 85cm. Should i buy longer mast or bigger wing? (I’m about 80kg + battery pack - 7kg and board 10kg)


Longer mast, 45cm is very short. Somewhere between 75-90cm is a good length.

With your weight the gong L wing will easily lift you. A longer mast will be the right thing to get, 45 is really too short.

but: there is something not right if you don’t get more lift at full throttle, it naturally depends on the wing angle also, i can almost foil standing still with my gong fuid LT wing - at 120kg total weight.

I double checked the wing length and it is a 70cm - M size that would explain why I don’t get the proper lift. I planning to buy the X-OVER wing, but which size: L or XL?

which wing and what area is your wing now?

(As long as you have lifted from the water it’s not really an issue with enough lift, lowest lift force is with lowest speed.)

do you just want to go slower?

My current wing is 70cm measured between wing tips which is a M size (Gong X-Over). I’m was mistaken that it was 85cm between wing tips.
What occurs today is that when I’m foiling the board barely touches the water surface thus slowing down. I have short moments of “pure” foiling. I guess a bigger wing L size and longer mast would solve the problem?

Thing is, i don’t think you need a larger wing to get the lift - it is not just related to wing width and your wing is 1250cm2. What i mean is that you might want to get a longer mast first, then decide if you need the larger wing.

(With a total weight of 120kg board + rider i have used from 800 to 2200 cm2 on efoil. The only wing that i could wish was slower on lift/start is the gong ypra m at 800 cm2.)


I have changed the mast to 65cm so when foiling the bottom of the board have enough distance from water surface. Now instead It’s difficult to keep the board “flying” - I hit the water surface after ~30m. I guess I’m to slow to re balance. Would a bigger stab or extend the fuselage help? Today I have 250cm^2 stab.

Your problem is probably riding technique and not the gear, as long as you can lift then you can foil (at least if your drive system is OK for more than a short burst)

The foot straps look way too far back. If you can ride like that then i wonder if your stab could be upside down? (stab should be tilted with the front end lower than the rear.)

Looks like you’re running the flipsky 7”x7.5” alu prop? then you would be better off with another prop, or you could cut it down to reduce the area and torque needed to drive it. 145mm diameter is better to keep current and heating reasonable.

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I am currently using “converted” windsurf board and started out with large Flipsky prop. Cutting prop down and then replacing it made a world of difference in being able to achieve sustained level flight.

I still touchdown more often then I want but I don’t worry about it, just pop back up and keep going. Part of that I think is caused by the long overhang of the front of the board makes it somewhat more challenging to not dip down or rise up when you compensate.

Two remedy’s

  1. More time on water
  2. Build or buy a more purpose built board

My recommendations to improve your setup - in the order of precedence - would be as follows:

  1. Get/print an adapter which goes between your motor and prop: As it is, this gap is creating a huge resistance; so this alone will increase your ride times by 30-50% I would guess
  2. Get a decent prop: The Flipsky prop is absolute rubish. There are very good 3D printable designs (Including adapter for the 65161 motor) available online. Even a home printed prop made from PLA on an Ender 3 is significantly better than the Flipsky prop.
    Search for user “blendezwonull” on here or directly on TinkerCAD and send a big thank you to Volker who is also on this forum… :wink:
  3. Your Mast is still to short: 65cm is the length for an absolute beginner; 80/85cm is a good length for everybody else.
  4. Your board is WAY to big: 125-150cm is a good size for almost everybody. Also you do not need any board length behind the mast attachment; place the mast as far back as possible.

Good luck & enjoy!

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You won’t find an improvement of 30-50% by streamlining in front of the prop. I’ve had to ride like this when i didn’t have the correct spacer for the prop with me and it works, off course not optimally and it’s worth fixing it.

I wouldn’t say that the board size makes a difference that is important just to foil, not the mast position either. A big board is nice for paddling, nice to learn on since it’s easier to drive it on the water, nice in rough waves and nice if you ride in the winter. I’ve started at 180cm, now after two cuts i’m at 150 on my longer board.

A mast more to the front makes the balance point for weight and the float of the board better centralized, and it gets the prop a bit further in from your feet, not that these are critical but there are some benefits to having the mast a bit to the front when you have a board that can fit it.

(I have tried from 30cm to zero offset from the rear, on my 115cm board it’s all the way to the rear, on my 150cm board approx 20cm from rear)


Short update: as you suggested I have shorted the board, got a bigger stab, installed an adapter between the motor and the propeller and used blendezwonull propeller. Now I can fly several hundreds of meter. Range has increased from 7km to 8.5km (my batter pack is 14s7p ~1kWh).
The blendezwonull propeller printed in PLA worked well but broke after 15km so I’m looking for a propeller in aluminum. I’m looking at “ULTRA Propeller FR” or “ULTRA Two Blade Propeller FLIPSKY” but which pitch? Both 6" and 7" pitch seems to be sold out for a quite some time now.

The fr propeller is for the fr motor so you can’t get this one. I’d get the 6”propeller since this generally will be more efficient for you (don’t think you will use the extra speed of the 7” much)