IOMICA Forum

Hi everyone,

When I turn the mainboom to the port- or starbord side, the tension off the mainsail bottom (foot) changes (Less).
This is because the chorde (length) changed (less).
I hope I can expain what my problem is, can you help?
http://foto.modelbouwforum.nl/displayim ... ?pos=-3537

tiepje wrote:When I turn the mainboom to the port- or starbord side, the tension off the mainsail bottom (foot) changes (Less).
This is because the chorde (length) changed (less).
I hope I can expain what my problem is, can you help?

Hi Tiepje

I'm not sure that this is a "problem" (smile), I think it is a "feature"... The gooseneck is designed to increase the camber or draft of the mainsail in exactly this way, because of the gooseneck axis offset. Of course, if your boat is not an IOM but, say, a Marblehead or an A, then you could have a gooseneck whose axis was the same as the axis of your mainsail luff, and then there would be no change in camber or draft. In the IOM class, the gooseneck axis must lie aft of the mast, as your diagram shows.

Also, the tilt of the gooseneck axis will cause the clew of the mainsail to rise (increase twist in mainsail) or fall (tighten the mainsail leech), and again this is something that you would do deliberately, depending on how you wish to tune your rig.

There are some technical details on one of my pages at

http://www.onemetre.net/Download/Goosegeo/GooseGeo.htm

Thanks
I have a lot of reading about the gooseneck to do.

The tension is now 1,5 cm open, but on SB or Port it is 2,5 cm open. lite air

http://foto.modelbouwforum.nl/displayim ... ?pos=-3538