In Detroit we went with a masthead spinnaker the same width as the
class spinnaker so that we wouldn't have to carry a longer pole as
well as the class pole and so that it would be possible to make a
masthead spinnaker by simply cutting a class spinnaker in half and
adding a panel in the middle. The masthead spinnaker does perk the
boat up noticeably in light air.
Another way to go would be to go to a spinnaker both wider and taller
than the class spinnaker. Actually, that was what was suggested by
one of our local sailmakers who had owned an E27 for a couple of
years when we started our fleet. He wanted us to have a spinnaker
that was a lot bigger than the class kite--taller and wider. We
wanted to keep it simple so the fleet didn't go that way. It might be
worth talking to a local sailmaker or your PHRF committee to see what
effect a wider fractional spinnaker (with a longer pole) or a wider
and taller masthead spinnaker (with a longer than class pole) would
have on your rating. However, the outcome of rating changes is often
hard to predict. I don't know enough about PHRF ratings to say
whether you could further lengthen the class pole without incurring
another 3 or 6 second penalty. It would seem to me worthwhile to try
to find out what the maximum length of the pole could be without
incurring an additional penalty and then make sure your pole and
spinnaker are at whatever that maximum is.
Another factor to consider is whether you are sailing mostly on
windward- leeward courses or on triangles. If you are sailing a lot
of reaches compared to runs, it may not be worthwhile to go to a
larger spinnaker. But if you are doing windward-leeward courses the
masthead spinnaker will allow you to sail deeper and faster.