I haven't been changing the spreader rake and/or diamond wire tension very often but only because Chris has been sailing with me steadily - our crew weight has remained consistent. With regards to the spreader rake, my feeling is that once it is setup to match the shape and reaction of the sail, it shouldn't be changed. I expect that the spreader rake specifications should come from the sailmaker. Diamond wire tension, however, helps to control the initial power setting (and keep the mast from inverting with the chute up!). So I would expect to make minor changes to this somewhat with changes in crew weight and wind/water conditions.

Having sailed in a pretty tight and reasonably populated F18 class for the last year, I have had opportunity to witness how important mast rake is. I've ended up without enough mast rake in some of the windier regattas and suffered pretty dramatically. Pointing ability suffered as did our speed because we were pretty overpowered (in some cases we probably we did not have enough downhaul cranked). Because we are a heavier team, my thought was to stand our rig up a little more than everyone else - but that has not proven successful.