Originally Posted by skrap1r0n
... any rate, my cars lock into the rail with a springloaded plunger, so I cannot really adjust it on the fly, I have to set one when the opposite sheet is loaded. I can see the advantage of having them adjustable while loaded, and I may seriously consider something like that when I replace my running rigging and organize my lines, if it's worth it on a 25 footer.
The ability to adjust the car under load is only of value for hard core racing, you can change the setting under sail simply by a brief luff up whichunloads the sheet...
If you want to improve the performance of your boat, get the car off the rail and onto a inner track to provide a closer sheeting angle. Such an angle will allow your boat to sail 3 or 4 degress closer to the wind, and provide a remarkable improvement in VMG (speed up wind). some race boats have adjustable cars, some don't, but NOBODY races with the genoa trimmed to the rail.