quote:
Originally posted by nebbian
Got to have a ride with Pete on his tandem.
Looking at you from the side was pretty funny though, you were both holding your respective sails at very different angles... maybe it was to do with airflow or something.
How did you go at turning it around?
Have a look at Sailquik's profile...he's a tandem eggspurt
www.seabreeze.com.au/Members/Profile/Details.aspx?member=sailquik& you'll see on his tandem board photos, the masts are also at different angles.
Which makes me curious...about the interaction of fwd sail(a jib in skiff terms) & rear sail (mainsail)
In windsurfing, "the slot" is the space between the board & bottom edge of the sail....
whereas with skiffs & yachts, "the Slot" is the space between the overlapping jib or foresail, & the mainsail. It is the control & use of the slot, plus interaction of both airflows that generates extra lift.

An explanation of this was written...
In the 1950's, C.A.Marchaj wrote a definitive book "Sailing Theory & Practice" (published by Alard Coles, London).
It is a mathematical & vector analysis of all the forces involved in sailing. Very heavy going




, but I was being a yachtie at the time & needed an explanation for some of the sail-trim calls.
With windsurfing, we get a lot more feel of pressures & forces to trim & respond, but have to stop to tune the rig.
So....like Mr. Nebbian, I'm curious as to why the 2 sails on a tandem board are not treated like a combinatiopn of sailboard & skiff, ie. the fwd sail should trim as if the rear mast was a mast on skiff & therefore increase air-flow & lift (sail pressure).
Whaddayareckon, Sailquik & any expert

