Steve wrote:
... I need a whisker pole for my head sail (on roller furling). My boat
is cutter rigged, plus I have the ability to release the staysail
stay and move it back out of the way when necessary.

I'm about to build a whisker pole and the extrusion I have is 15 ft
long. I have enough room on the mast for 15-18 ft of track without
moving any hardware.

You will never need this length. Storing a 15 foot pole on the mast should
only require 10 feet or so of track, etc., when the height of the pole in
use is taken into account.

The mast is ~16 ft from the stem plus the bow sprit is 4'9" beyond
that. The staysail stay is about 18" behind the stem. I have enough
room to dip the pole under/behind the staysail stay if I restrict
the length to around 16-18 ft.

This gives "J" in the neighborhood of 20 feet.

I plan to store the pole vert. on the mast.

Even though I have roller furling for the head sail, I have several
sizes and often change, depending on the wind predictions and
size/experience of the crew.

See comments on collapsible poles below.

What would be the determining factor for a light weight whisker
pole??

Here is what Forespar has to say:

http://www.forespar.com/catalog/whis...sizerecomd.htm

The table is pretty comprehensive and should give you a good start.

However you have an approximate "J" measurement of 20 or so feet, and for a
single-hander that means a handful of pole, not matter how you look at it.
As you know it's usually not too difficult setting up the pole in light air,
but once the breeze comes up these monsters can be a handful to stow.

All in all I would consider a rig with some sort of collapsible pole, even
though this might mean buying a purpose-built item. You
could then use it for the staysail and various headsails. Also, I would
give strong consideration to some sort of topping lift (similar to spinnaker
poles) with a pole of this size. The last thing you need is this thing
dragging in the water at 5 or 6 knots.

--
Good luck and good sailing.
s/v Kerry Deare of Barnegat
http://kerrydeare.home.comcast.net/