Join Date: Feb 2008
Location: N. VA
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For whatever it is worth, my 30' Islander Bahama 30 has the German setup and apparently was built that way. My setup has no boom vang either, which I really miss. The hatch slides forward underneath the traveller, which is mounted about the forward edge of the hatch. As several have said, it has advantages and disadvantages. For a coastal cruise like the Bahama 30, the advantages it represents are more important than the disadvantages.
The advantages I see are these:
1. The traveller spans the top of the top of the cabin and is halfway up the boom, so travelling the block to one side or the other has more effect than an end boom traveller would. That is simply an effect of the geometry.
2. I can use the setup to flatten the sail by making the mainsheet more vertical or to twist the sail by making it sheeting more sloped. I have used twisting good effect when the steady component of the wind does not require shortening sail but very strong gusts cause excessive heeling or even rounding up. This happened on my transit in mid April when I was reaching in 10-12 knots with gusts to 35 out of the Magothy River.
3. The traveller, the traveller sheets, and the mainsheet are out of the way and do not impede movement of people in the cockpit and companionway.
The disadvantages are these:
1. To adjust the mainsail, one must leave the wheel and move to the cabin top.
2. Violent gybes can indeed do real damage to the boom. It is one of the reasons I never sail dead downwind except in light air.
3. Mid boom sheeting requires stronger sheets and creates more stress and strain at the blocks' mount points. This is simple physics using the laws of levers. I have a cabin top winch and really need it when the wind pipes up.
4. Mid boom sheeting without a vang produces lousy sail shape when running. One can use a vang setup with mid boom sheeting, but if one does then the sail twisting effect is less effective unless the vang is easily adjustable too.
Mid-boom sheeting may provide either faster or slower boom adjustment than end-boom sheeting. It depends on the exact geometry. There is normally one extra loop in the block and tackle in mid-boom sheeting to provide more mechanical advantage -- double the force but half the speed. That M.A. more or less negates the law of levers effect caused by mounting the sheet mid-boom. To calculate the law of levers effect, divide the distance to where end boom sheeting would be mounted by the sheet's distance on the boom, both measured from the gooseneck. If it were exactly in the middle the 2:1 effect would be exactly cancelled by the 1:2 law of levers effect.
Overall, mid-boom sheeting works very well for cruising but is an inferior system for racing and single handing, IMO. It is not as convenient from the wheel as end boom sheeting.
T. P. Donnelly
S/V Tranquility Base
1984 Islander 30 Bahama