What benefits would I get from moving to a 90cm mast to a 75cm mast for a 100kg rider? I suppose I would get a better feel for the foil and more control. I also suppose the foil would be closer to the wave energy at the height to where I'm comfortable. But would it be easier to balance? Would it be easier to get up on foil?
Easier to get onto foil (less drag)
quicker roll response
potentially stiffer
not sure it's any easier to balance
I'm also 100kgs and I recently went from my usual 85 and 95cm long masts to a 75cm HM mast and I am loving it.. It shows that I rarely used the full length of my longer mast because I am not breaching all the time although I am also very conscious that I'm on a shorter mast now.. It feels easier to get on foil and also feels stiffer.. I think I'm running the foil closer to the surface now and it feels noticeably less draggy.. Also when you do breach it's easier to recover the landing because you're not dropping from so hight.. I haven't noticed it any harder to balance..
Definitely easier to balance. For the same lateral seperation between lift and weight, the roll angle is less for the longer mast, so your flight envelope is tighter on a longer mast, all other things being kept equal. Whether you notice it or not depends on how close to the edge of the envelope you were - agility, reflex time, how turbulent or mixed up the water you are foiling in, how twitchy or stable your foil is, etc.
I have both a 75 and 95 and prefer the 95. The 75 is great and it is easier but very slightly. Where I wing there is allot of boat traffic, current and wind swell and makes clearing everything a breeze.
End of the day you want to keep your foil as close to the surface as possible without breaching for maximum efficiency, longer mast doesn't help with that. The longer the mast the more room for error going up and over swell and waves, That is the only benefit. As others have stated shorter masts are better in every other way. Especially if wave riding aggressively you'll notice a significant difference in performance. I think the sweet spot is between 70-80cm.
I primarily ride a 76, 66 when it's flatter/extra small, used an 86cm as a crutch for a few sessions here and there when I was developing, and am testing a super high mod 80cm right now.
Shorter is easier for lightwind takeoffs.
Faster rail to rail. (less distance to travel on the circumference of the circle)
Makes big foils feel like more fun.
Can make little foils too twitchy if you're not ready for it!
If you don't like riding high on your mast (I don't) then yes, the shorter mast keeps you tighter to the wave energy very naturally.
Balance: This is a little odd to explain but in my experience longer masts are easier to balance when doing your water start. They act like a giant fin and if you progress towards narrow boards you can definitely feel the difference in mast length. However, in the air, the longer mast feels harder to balance in the air for my style of riding (fast rail to rail movement). The longer mast very obviously gets rail to rail slower and I have to alter my body motion to stay on the board.
Reinforcing what foilthegreats said, 90% of riders I talk to say they ride longer masts to help them with breaching. I'd argue that changing the fuse and stab is a better first stop to prevent breaching (learn how to go up and down the waves). The other 10% that ride long masts are racers and freestylers who are pushing high speeds and can't spare the time/energy to go up and down the waves. They don't do much turning other than their gybes/tacks.
I usually ride a 85cm mast (naish c35). Just recently I purchased a 105cm (naish c100) to use in choppy conditions. I just tried this longer mast out one time now in flat water. It was incredibly difficult, I barely made Jibes. I'm already thinking of getting rid of it again. Maybe I'll give it one more try, but it was not fun riding this thing at all for me.
