Sardinian Islander wrote:
interesting. i have 2 questions:
- why did you use the backstay line to protect the mast from rear forces if the jib is used only or mainly for upwind sailing? what do u think about a solution with forestays and no backstay also avoiding the mast furling problem?
- why it is completely useless downwind? though it is covered by the mainsail i thought it could give u some little more power
another note. if, as everybody say 8and i agree the secondary sail (jib or spi) shoudnt be used with winds at more that 10/12 knots isnt'it better to use a cheaper material as lankotek? in a normal boat jibs must be very strong and hold 30-40 knots upwind but this is not our case...
The AI/TI mast is bendy. This is actually a good thing in a cat rigged boat since the mainsail automatically depowers in puffs (the mast bend takes camber out of the mainsail). BUT, for a jib to work to weather, there must be a taut luff--if the luff is not taut, the sail gets pushed inward which gives MORE camber and moves the center of effort aft so you can't point with it. SO, these enterprising people have given the mast a backstay so the jib luff stays firm. IF you repowered the boat with a stiff mast, then you wouldn't need the backstay and could just use a forestay and mainsheet tension to keep the jib luff taut.
The jib is probably not completely useless downwind, it is just that it won't provide a lot of difference on a broad reach since it is very small compared to the mainsail.
Lankotex is stretchy. Jibs must be made out of a fabric that is dimensionally stable to the extent possible-this is so that the center of effort of the jib is positioned 35% aft of the luff--if it moves aft of that spot, you can't point. Even in 10 kt breeze your boat may be going 8 kts so the jib is seeing 18 kts of wind. You can make a jib out of Lankotex but you would have to make it often since once it stretches, it stays stretched. I posted a video a while back making a jib out of a tarp for those folks who just wanted to try a cheap jib to see what it would do. Here's the link
https://www.youtube.com/watch?v=buyi5mu ... 0r&index=2 Granted, you can make a bunch of jibs out of tarp before you will get to $400-but most folks would rather sail than make sails.