RE: mast position on iS145 and a few more Q's
I agree with nifty here, but on the demo Isonic 145 Wood that I have I usually start out in the middle because the mast slot is so short.
To get the best speed, on the Isonics, I've had the track from the middle to the back, but for the best marginal planing, pretty far forward seems to work.
We weigh about the same, so as Nifty suggests, start at the back and move it forward in increments, (esp. if it seems to tailwalk) and you will find a sweet spot for you with your stance and rigs.
The jybing technique is not quite so formula oriented as the F-155.
You still need to step well across, and try to keep the pitch (fore and aft trim of the bottom of the board) trim the same through your jibe as when you planed in to initiate your jibe. So, Maybe a little more of a forward and across step than the F-155 but watch the nose. If it drops and you fall off plane, try applying your rail pressure a little further behind the off side front footstrap.
You should ultimately be able to "tighten up" your jibes a little more on the IS 145 than on your 155.
You can wash the board with fresh water if you like, but it's not necessary.
The yellowing of the wood surface(which is fully sealed and saturated/installed similar to a fiberglass) is caused by UV exposure.
Try to keep your new board out of the sun as much as possible when you aren't actually sailing in.
If you leave it on the beach, turn it over so the wood isn't exposed to the sun.
Hope this helps,