If you read a bunch of sail trim ideas, they all tell you about the same thing but in a different way of looking at it. Power up or power down for what ever reason they try to get across to you. Me being a technician, I took it one more step and figured out the basic reason of what it really does to the sailboat and why. Being of simple mind, I look at sail trim a simple way.
A car and my Sailboat.
I'll use three jib fairlead positions that are similar to a three speed
vehicle transmission; 1st gear in a car being similar to the forward track
setting for a fairlead, 2nd similar to the middle position, and 3rd similar to
the rear-most position .
For this example, 1st gear (blue), 2nd gear (yellow), and 3rd gear (green), are formed when an imaginary line is drawn from the fairlead block through the clew and then through the luft. *(In your mind's eye, draw a straight line outwards using the jib sheet.)
Although sometimes modified by the designer for better sailboat performance, the middle block position (yellow) divides the luft directly in half. The foreward block position divides the luft towards the upper portion of the luft. The rear-most block position divides the luft towards the lower portion. This will always change if you modify or rake your mast differently.
As your boat accelerates, the power from the sails tip your boat forward. The bow essentially dives in the water. This "dive" allows more water to be pushed aside which adds up to more resistance. Eventually your boat speeds up and the plowing effect lessens. *(The difference from sail power to boat speed gets less and many boats either plane-up or lift as the speed increases.) Sure this is generally a small thing but if every second counts…
First gear, (Blue in picture).
To lessen the "dive" effect on your boat, move the jib's block forward. This puts more tension towards the head of the sail and in doing so, is allowing the foot to become loose. That lets a larger portion of the wind to be directed towards the bottom. The force from the downward blast of wind starts to lift the bow which in turn is lowering the resistance and lets the sailboat accelerate quicker. (Think of it as a sailboat wheely!)
Second Gear, (Yellow in picture).
Now that your boat has started out quickly, you'll need slightly more rearward wind to increase speed and not letting the bow down. By sliding the jib's fairlead to the middle you'll be tightening the foot slightly and allowing equal amounts of wind to be directed both downward and rearward. *(Boats that don't have an adjustable jib track are often set in this position by the factory as a good all around average.)
Third Gear, (Green in picture).
The faster the boat goes, the more rearward wind you want as less bow lift is needed. Think of this position as shutting off downward wind. Third gear tightens the foot and letting most of the wind escape the jib towards the rear. You'll be getting the most foreward push in this position.
You'll find many other variables effect the jib block position also, everything depends on something else. It your job to figure what the best setting (s) would be for your needs. Just get out there and practice.
While prepping for my homeward trip after a few hours on the lake, I began talking with a powerboater next to me. In his eyes sailboat's have so many things going on that it seemed too much like work. This started me wondering about my times out and the things I've been doing to sail my boat. Here's a quick list of thoughts.
After heading out on the lake I head into the wind, turn off and stow the outboard, lower the swing keel, lower the rudder, lash down the tiller, and then go forward to tend the mainsail.
While at the mast it's a simple matter to pull the locking pin at the gooseneck, raise the main, reinsert the locking pin, look around fror anything that's not right, and scurry back to the cockpit for some serious sailing.
Right about this time the wind has blown me sideways. At near zero speed the helm doesn't respond very much. After setting the jib and main, things finally get working. My sail on the water has begun!
Something tell me that he doesn't know what sailing is really about!
An earlier thought got me to think about what to expect during extreme listing over. One of these days I knew the situation would show it's self. When that time did come I wanted to be prepared for it. You know, find out what it felt like for myself before it unintentionally occurred.
The winds were about 10-15, gusts to 25, (Dwyer gauge readings). The working jib was out full and the mainsail was reefed down about six feet. My direction was port tack and reaching, just short of pinching. During this time I found that everything works well under a constant 25 degrees of list. At times those nasty gust's would push "G Marlyn" to over 40 degrees.
On my own "white knuckle scale" that's allot. At about 25 deg. an occasional wave would splash off the hull and soak the lower portion of the jib. I also started getting a concerned feeling. Above 30 deg. the water covers the rub rail with several waves splashing on the jib. Somewhere up to 35 deg., water starts getting the deck wet and the jib turned into a little water catcher. Up to 40 deg., and with help of a powerboat wave, my windows got an occasional good bath, the jib became a bigger scoop and I found the tiller very difficult to hold course. By then my knuckles are pleading for fresh blood probably because my heart stopped and adrenaline took over. In addition I start to wonder what kind of fool I really am?
Normally you don't use the the topping lift while sailing but I needed to control the amount of max list when certain people were aboard. Roughly speaking, the topping lift became my "poorman's vang", at least it did when the boom was held straight aft.
Position "A" helps me in really slow winds by increasing the initial acceleration.
None of these settings are set in stone. Should you try this method, time and personal experimenting will tell how things work so practice and see what helps you! You could fabricate an adjustable topping lift similar to one found in the "Ray's Project Page" web site.
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