I got to try out a patch kit called Tear Aid -- works great on hulls and makes a good temporary patch for fins.  Very tough, stretchable, with excellent bonding on non-flexing surfaces, it warrants consideration for all kinds of repairs.  This is how it comes:
I've had a patch on my Adventure for a for a couple of weeks -- no problems.  On a test strip, I gave it a torture test.  These next pics show its strength and flexibility.  Here's a Phillips head screwdriver:
Old Xacto knife (didn't pierce it):
When done, it recovered well:
On fins, it started lifting at the edges after about 10 hours pedaling, but was still working.  It is shown here patching a little fin tear (high speed strike on a submerged stump):
There are two versions -- I used the Type "A" for poly (and most other things).  There is also a type "B" just for vinyl.  Hobie sells it for about $9.25.  The kit includes a couple of alcohol cleaning pads and 3 or 4 different size patches (you can cut it easily with scissors).  It comes on backing paper and peels off.  Pretty handy stuff!   
