I’ve been using their larger rig to help with downwind runs in canoes on large lakes. I probably don’t get anywhere near the speed you get with your kayaks but I often paddle or row while sailing to bump up the travel speeds (because it’s so much easier with wind aid). I’ve been thinking of mounting the base on a swivel seat bearing for turning it incrementally for best wind capture. If I use the leeboards and rudder from my lateen rig, I could see it being able to slowly make headway “upwind” … but since it has less than 20 sq. ft. of sail (and spills gusts over the top), it’s never going to be as effective that way as the 44 foot lateen. How are you managing to use your Spirit sail “upwind” ? Is your kayak low enough in the water that sideslip (sorry, don’t know sailing terminology) is negligible ? I think the best features of the Spirit sail are it’s unstayed simplicity and safety (battens flexing forward to relieve stresses). When I want to take it along, there’s not as much hassle and gear to stow as with the lateen (which needs leeboards and rudder, etc.). being able to tap wind aid as an “adjunct” rather than “primary” source of power is what interests me for wilderness travel. Now, if I can rig it for directional tuning and instant decommissioning, it will perform even better in more varied conditions. Keep up the sailing in small paddle/row vessels … it’s pure fun on a budget !!!