For jiffy reefing you'll need a cheekblock on one side of the boom, located
aft of the leach reef cringle (grommet) so the reef line exerts a rearward
pull at a 45 degree angle when reefed. (The reef cringle becomes the clew
when you're reefed.) You'll need
some kind of eye or strap opposite the cheek block on the other side of the
boom. The jiffy reefing line is tied to the eye, routed up through the reef
cringle, then back down to the cheekblock, then forward to a cleat on the
boom. If you use two reefing levels, you'll need two such installations,
each with a cheekblock and opposite eye positioned appropriately aft of the
associated reef cringle.
For the forward (luff) reef cringle, the simplest installation, and the one I
use on my gunter rig, is a reefing hook mounted on the gooseneck. To reef, you
lower the main sufficiently to hook the forward reef cringle onto the
gooseneck reefing hook, then pull the halyard taut and cleat the halyard.
You then pull in the reefing line at the leach and cleat that, and you're
ready to sail away.
There is a diagram of a more elaborate two-line system on the Ronstan web
page at <http://paw.com/sail/ronstan/diagrams/reef1.html>. It's apparently
intended for larger boats (or to sell more Ronstan hardware). For a Potter
you can just cleat the aft reefing line on the boom instead of running it
forward, down the mast, etc.
There are also single-line reefing systems, where pulling one line reefs
both the luff and leach. Some have had success with that; many have not.
Your sail probably has some patches with grommets in the middle of the sail
at the reefing level and they may have lines hanging from them. These are
not necessary on a P15 but can be used to bundle up the reefed portion of
the sail for a neater appearance. If conditions are hectic, don't worry
about it. The lines should be tied under the foot of the sail, not around
the boom.
Hope that helps. You can find other diagrams illustrating jiffy reefing in
sailing books in a library or bookstore and in catalogs like West Marine's.
(Not sure if the current WM catalog has one.) You may find some useful
information on the Pineapple Sails page at
<http://www.sailmaker.com/articles/reefing.htm>.
Harry Gordon
P14 #234, Manatee
Mountain View, CA