What does the leech string thing do ?

If its cleats near the clew, I think you are refering to the leach line. If it is the leach line, then it controls the flutter of the leach, typical on a big jib. For our jib, which is in the 90 s.f. range in light to medium air we don't need to tension it. In medium to heavy air we do need to tension it. If you over tension it it will curl the leach inboard, hooking it. If there is another use for it, hopefully, someone else can fill us in.

Hi,

Here is the Leech Line topic from the Hobie 17 Tuning Guide on our Hobie Fleet 929 page.

"LEECH LINE
The leech line is the small line that runs inside the back edge of the sail and cleats near the boom.
When pulled tight, this control will add camber to the top two or three battens of the sail.
Set it fairly tight if you need a lot of power in big chop.
In all other conditions, tie it off on the cleat without tension, unless your sail is too flat up top.
It will distort the leech if overtightened in light air.
The leech line can be set easily while on the beach and with some difficulty on the water between races.
Do not attempt to adjust it while racing."

If you would like to read the rest of the Hobie 17 Tuning Guide then go to...

http://www.hobiefleet929.org/hobie17.html

go towards the bottom of the page and click on "Hobie 17 Tuning Guide".

Nige