Would some of you guys talk a little about reading the jib slot?

Earlier this summer I took off the 4-way jib system from my P18-2. We never seemed to use the adjustment it provides and the cable was a pain (literally) for my crew. By removing this, I effectively moved the jib car out a couple of inches and as a result seem to have lost some power in heavier air.

In lighter air (less than 12 mph or so) I'm generally able to make the tales flow well. I was out yesterday in some nice steady 15-18mph air and almost every time the boat got moving nicely the upper lee tales would turn toward the front of the boat! It just feels like I just don't quite have the power for the wind speed!

So, assuming the slot is open too wide, when I close it back up, how do I know when it's closed too much? Same measure... power feel?

As always, thanks for the insight.

If your upper and lower tails (inside or outside - doesn't matter) are breaking at different times, then it's not necessarily the amount of out your sheeting is providing. This is more a function of how far forward or aft your sheeting point is. Envision that if you moved your sheeting point aft, it pulls more on the bottom of the jib leaving it flatter. It also would pull less on the top of the jib leaving it fuller. The opposite is true if you move your leads forward - the top gets flatter and the bottom fuller.

If your top inside tails are breaking before the leeward, you need to flatten the top and belly up the bottom a bit by moving the jib sheeting point forward.


Other things can affect this to such as the amount of tension applied to the jib. If you are not sheeting much and are leaving twist in the jib, you can also affect when the tails break.

With regard to inhaul, you are are trying to match the curve of the mainsail so the jib slot is the even from top to bottom. In/outhaul and tension will affect this. You need enough tension to be able to point well and the in/outhaul position to shape to the main properly.

There are basically two things to try and achieve here; getting the jib slot to be even from top to bottom with the main sail and to get the tails to break evenly. Three things will affect this; sheeting tension, jib in/outhaul, and fore and aft position.

I agree with the previous post. As a general rule, the jib should be made to break evenly, and this is usually done by moving the jib car forward (to get the bottom telltale to luff first) or aft (to get the top to luff first).

In addition, if your boat is set up with inboard/outboard jib cars, these should be set proportionally to the main traveler. I.e., if you travel out the main 6" from center, you should travel out the jib car a few inches from it's inboard position.

The jib should also be made to match the mainsail. So if the top of the main is twisted (top telltales luffing) then the jib should be twisted (with the top telltales luffing).

I usually depower by travelling out, twisting (by moving the car back), or easing the jib before the main, that way I don't run the risk of closing off the slot. My general system for depowering from initially having both sails set for max power is: 1st both sailors trapped out, then downhaul until maxed, then travel out the jib slightly (or ease sheet if no jib traveler). Ease main traveler.

One last note, if the boat feels sluggish, it's usually a good idea to ease the jib slightly. An oversheeted or stalled jib is very slow.

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Ah, the light bulb just turned on!! I was typing a response but just deleted the whole thing. Starting over now. In regards to moving the sheet point fore and aft, we're talking about jib twist. I need that twist to match the amount in the main. So if my main has little twist, and the jib is sheeted back further (causing more twist) that would make my upper tales break early and blow forward.

Two questions more then.
So by having the jib sheet point too far out compared to where my main is, I loosing air flow over the main sail and effectively loosing power? Correct?

Would this setup cause me to have more weather helm?

Thanks SRM. You answered one of my questions before I even asked it. So I probably need to get the cable system back on the boat or figure out a way to bring the jib sheet point in the couple inches that I lost.

You mentioned closing off the slot. That's back to my original question. How do you read the slot being closed (or too open)? Do the tales on the main tell me that?

If you replace the jib blocks inhaul system, then using a line made of spectra (very strong yet soft) or something similar will help much to reduce the discomfort that the SS cable caused before. It should have enough slack in it to lay flat on the tramp when the jib is not sheeted so that there is no cable to skin your shins on. You can end the lines into shackes that are easy to put on and take off. My crews thanked me when I changed my Mystere 6.0 to this kind of system years ago.

You can pull the jib blocks inboard and sheet the jib in until you backwind the main. It will be hard to notice this early on because of the stiff mylar material and the full length battens so you will have to focus on this to observe it starting. Too small a slot is as slow as too large a gap. Remember to tighten your main outhaul when you are traveled in on the jib. This is best done when the water is smooth, the load is light, and the wind is mild. Rick White refers to this as the 3 Ws and you should buy and read his books for this kind of instruction since he is hosting this forum.

Unfortunately, the main tell tails really don't tell you if the slot is too open or closed (at least in my experience). This is because there is generally going to be flow over the main even if the jib is too loose or tight. The only indicator of too tight a slot is usually backwinding of the main and counter-rotating of the mast. But by that point, you're way off.

Your best bet (as usual) is to find people who are fast and set your boat up like theirs. Otherwise, get the jib breaking even and try to get it to match the main. If the jib starts luffing way before the main, probably try bringing in the jib car.

A good starting point for upwind would probably be between 12 and 16 inches in from the inside of the hull.

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