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Go Back   SailNet Community > General Interest > General Discussion (sailing related)
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  #11  
Old 05-21-2011
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Puddin,

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.

Tom
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  #12  
Old 05-21-2011
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My San Juan 34 has mid-boom sheeting on a cabin-top traveler with the German mainsheet routing. We have a cabin top winch and line clutch although we have never had to use the winch for the mainsheet, even in heavy air.

The primary advantage to the cabin top traveler is that it frees up the cockpit. Sheeting is a little faster but recently I have been considering adding some finer controls for tweaking because in very heavy conditions it can be a little too fast.

It also puts all of the mainsheet controls in the same place, at the forward end of the cockpit where all of the mainsail controls and halyards are also located. That makes the boat infinitely easier to shorthand but slightly more difficult to singlehand. The area can get a little cramped when racing with a full crew so if I only raced the boat I might consider spreading out the controls so crew are out of each others way.



The primary disadvantage of mid-boom sheeting is the load on the boom. I have a loose-footed main and in very strong winds the boom will get a bit of a bow in the middle because of the single attachment point. In the future I'm planning on changing from a triple block, to three, evenly spaced single blocks spread the load.
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  #13  
Old 05-21-2011
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Quote:
Originally Posted by Faster View Post
Nowadays more people are going to the so called 'German' system... a cabintop or forward cockpit traveller with double ended mainsheet running forward to gooseneck, down to the deck and aft to winches or cleats near the helm. ....
I think good-old Gui would argue that is a Portuguese system...he has the only hotshot boat where I've seen that system...
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  #14  
Old 05-21-2011
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Dacapo and SJ34,
I think there's some confusion on what a 'German' or 'Admiral's Cup' mainsheet system is. Have a look here:

Harken Mainsheet Systems

... and scroll down to the "admiral's cup 2:1 w/ dedicated winches, and the 4:1 example a couple below that. This what I'm refering to, not a cabin top traveller system as you're describing.
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Old 05-22-2011
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For a boat less than 37-40 feet, the Beneteau First 35 has a German system.

Beneteau USA
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  #16  
Old 05-22-2011
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Indeed it does! Thanks!
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