Interesting idea Holger!
Your Expedition Sprayskirt size does block where the bow-wave rises to hit the aka, which is the major cause of getting wet, especially in the TI. The AI has so many more ways to get us wet!
But I can see the shorter Sprayskirt cutting the majority of direct, buckets full of water in the face & chest, "spray".
I like how my Sprayskirts have help me to learn to control the boat better, especially in busy waves, adjusting the boats angle to the waves as to not sail off one wave so fast as to plow into the the next. Even if only by a few degrees. Less stress on the boat and it's captain and crew, and much more comfortable ride.
But, I can see many times, during longer distance trips or while fishing, where getting to a specific spot as fast as the boat can manage, or keeping on a set tack, and/or just keeping a constant speed on a set course (trolling) as being the primary goal. Even if that means cutting the waves at less than optimum angles and speeds, and getting a little bit beat up.
And since our AI's love to cut through the waves, instead of riding over them, some diving in rougher conditions can be expected. The full size SpraySkirt will stop the nose from submerging, to a point. But nothing will stop it from plowing into larger waves if that is where the boat is headed.
I like that with my Sprayskirt on, that if the boat does dive into a larger wave that it will slow quickly and then slice out to a side, out of the wave, instead of continuing to dive. Many times sailing without a Sprayskirt I've had water up to my armpits! Only the mast and sail visible!
But with the Sprayskirt on, diving the bow does slow headway quickly! And if you need to make good time or miles, or keep a steady speed, it's contrary to that goal.
I'll keep watch, to see responses to the short Sprayshirt idea. For most people, I still think the current full size would be best overall. But for really pushing the boat and in marginal conditions, your shorter Sprayskirt idea probably has a place!
I hope to hear more from you and others as you test it further.
- - - - - Hobie Island Sailing since 2006 - - - - - 2011 & 2012 Hobie AIs and a 2012 TI