do any of you use different mast lengths for different conditions?
I have the hover glide foil and wonder if there are any reasons to keep the 60 cm mast as well as the 90?
The only reason I could see you wanting a short mast is if you wanted to foil in shallow surf. Long mast all the way, even when beginning I suggest go straight to a long mast as it gives you much more room for error when learning.
Yes, that's my thoughts to.
I have learned with an rrd foil with a full length mast but my slingshot one has both long and short. I was just trying to work out any benefits other than learning of the shorter one.
Shallow water. If you ever foil where the water depth is less than a meter, the shorter mast is great. I'm currently learning to foil on Cape Hatteras in the US, where we have to walk out a couple of hundred meters even with 60 cm masts. 90 cm mast would be unusable (unless you can fly 100% of the time) since there are plenty of shallow spots.
Shorter masts are also nice for timid beginners, since the drop when breaching is less dramatic. For some beginners, that is more important than fewer breaches with the longer mast.
I learned on my 85cm mast and still love it. Seems to be a good length. However I did buy a 110cm mast for wavier conditions. We have long lakes here in the Midwest US which can generate larger waves without the corresponding wind, and foiling between the swells were causing the foils to breach or at least slip with limited mast in the water. So the longer mast will help with keeping straight and handling in the swells/larger waves.
I use a little shorter mast when at sea (75 or 85) and the waves are big (2-3m or higher is quite big for NL), because otherwise it takes too much energy (and over 15minutes) fighting against the shorebreak to get deep enough to launch
for racing I get a 105 in a bit, for flat water freestyle im on a 95.