How close to mast front

[kermwood]

I seem to remember reading somewhere that the jib leech should not be closer than 2" to the front of the mast,is this right or do the skippers out there set it closer ?
The reason l ask is that in the other class that l sail for my sins it has now become common practice to have it as close to the front of the mast as poss without it touching so why is it not the same for the 12 as there is not much difference between the sail area of the two classes?
Woody

[PaulP]

Woody,
Carl Olbrich put together a beginner's guide to tuning an EC12. http://www.trianglemyc.org/ec12tuning.htm

In it, he says:
<font color="blue"><font size="1"><i>Line the jib boom up with the mast and measure so that the clew of the jib is more than 2-2.25 inches away from the mast. The larger this dimension, the larger the slot will be. Experience will show that a larger slot in light air will work better. Too large a slot and the boat will not point.</i></font id="size1"></font id="blue">

I am hopeful others will join in on this discussion. I think we really underplay the ability of jib trim and location on how fast and how well our boats sail. Maybe an extensive discussion on this will unlock some of the secrets.

Paul P

[yachtie]

Interesting point Woody.

At our North vs South regatta over the weekend we discussed the slot issue - what's right and what's wrong? As a comparison I have put on the NZ forum a couple of photo's showing distinctively different setups of this but the result on the water was that the boats were very much evenly paced.

The only difference in the result was the old "operator error" which seemed to be the deciding factor. [:D]



Chris
NZL1 Longtack
NZL110 Swept Away NZL128 Ketch me if U Can

[kahle67]

Just thinking out loud but the only problem in the theory above is that the slot should be measured in the direction of the air flow, not across the deck. Therefore, your slot adjusments are of course your jib sheet and topping lift.

In the real world, an overlap of the main and jib is desirable to help the air flow over the top of the jib connect with the air coming around the leeward side of the main. Obviously, with a self tacking jib on a boom, an overlap is not possible and in light air, you really don't want the leech of the jib dragging across the front of the mast anyway.

I think the main reason some might have more space between the jib and the mast is the topping lift. The jib booms are sometimes longer than needed (for proper sail set) to accomodate the topping lift. Remember, the leach of the jib is not a straight line, there is some roach, so the sail needs to clear the TL when tacking. Also, the closer the topping lift runs to the mast, the more likely you are to have it get caught on the spreaders due to improper rig tension or elastic failure.

After measuring one of my rigs, the clew of the jib is around 2" from the mast (as Carl suggests in his tunning guide)which leaves the upper portion of the leach at max roach right around 1/2". I can live with that, but once again the positioning had nothing to do with the slot, it is because of my topping lift configuration.



Reichard Kahle
Charleston, SC


Oops! Where is spell check when you need it?