Thanks again, as always your responses are quite elaborate and provide lot information, which me make actually think a bit more.
Currently I have a 7.0 sail for my 104 l board (JP Freeride Carve
), which can carry up to 7.5 m2. I would hope that I can it get to plane latest at 15 knots if not a bit less with 7.5 m2 or is this too optimistic (I have never measured the wind speed)? If too optimistic, what wind speed will get me going then? This wind speed is then the decision point in that respect that the larger board should cover the range below this speed while having the capability to still perform acceptable if it is a bit more. My "problem" is that I have limited time (as many people) and prefer to sail at low wind speeds rather than sitting at the beach and watching the water if the conditions are not good enough for smaller boards. Maximising the time on the water would be a objective.
Lets assume (optimistically) to illustrate my thinking I get the 104 to plane at 12 kn and the wind speed is "steady" at 12-15 kn when I start then I will go straight for the 104 board. If it is less or not steady I want to use the larger board with being perfect in the range up to 12 kn. Then in ~12-17 kn range it should be still good since I wouldn't want to rig up a smaller (7.5 m2) sail immediately. If the wind would continue to get stronger I probably would change sail and board for the higher fun factor. If the planing threshold is not 12kn but more than the other speeds change accordingly.
In short the criteria would be a board that is excellent
in wind speeds that are lower than those that get me comfortably to plane on my 104 l board with a 7.5 m2 sail and has early planing capabilities. The board should have some "margin" at higher wind speeds to allow some overlap with the 104 l board while it has not
to excellent anymore - just ?ok'ish?. Which is the magic board that offers all that? When will I get plane with that board and what would the best sail size - it should be obviously a Freerace sail. It doesn?t have to be an iSonic while in the low wind speed range good top speed (2nd most important) on top of early planing is important to me. Good jibing capabilities would be great but are only number 3 criteria and carving is less relevant (priority 4).
I hope my long story makes sense and gives you some more insight in want I want. It is of course me who has to make the decision ? I just like to get good input from someone with loads of experience and good practical knowledge with different boards.