|Topic Review (Newest First)|
|05-22-2011 07:30 AM|
|puddinlegs||Indeed it does! Thanks!|
|05-22-2011 05:54 AM|
For a boat less than 37-40 feet, the Beneteau First 35 has a German system.
|05-21-2011 11:29 PM|
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.
|05-21-2011 04:56 PM|
Originally Posted by Faster View Post
|05-21-2011 01:36 PM|
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.
|05-21-2011 08:26 AM|
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.
|05-21-2011 12:09 AM|
|nolasailor||thanks for all the input,,, would there be better sail trim ability with one or the other,,, I had thought that if i set it up for end of the boom i could alway add a riser to the track and relocate to cabin top if i did not like it at the weel, good point abot the 4 part block for aft, and needing more for mid boom, i did not even think of that,,,,|
|05-20-2011 05:03 PM|
The only major advantage I can see of having the traveler on the cabin-top is the increased distance you can swing the boom. The farther aft the traveler, the lesser the distance of travel. Of course, the comparative distance the boom travels will also be predicated upon the length of the traveler itself.
As for stress on the boom, I would think the ultimate anchoring point of the traveler would be approximately 2/3 aft of the mast. Anything forward of that would likely pose a stress point, while aft of that would lessen the stress to some degree.
|05-20-2011 04:47 PM|
Puddin.. our son has installed this on his Catalina 36 to good effect. I considered it for our own boat but didn't need to use winches so stayed with our cockpit traveller with mainsheet cleat attached (plus a fine tune)
Most mid boom (cabintop) setups on 30 plus end up using a winch, seems like, so the speed advantage is already lost. I suspect you'll see more of these setups for the reasons mentioned... more free space in cockpit and getting sheet to the helm.
On the Niagara 31 the double sheet setup is near the end of the cabin top, a couple of feet further aft than your typical cabin top traveller. I can't recall if there's a bridge deck on the N31 cockpit but that would be a good place if you can live with the intereference with seating and access to companionway. End of boom would probably put the traveller across the cockpit seats in front of the binnacle... again, choices to make.... are there seat hatches in the way.... etc etc.....
|05-20-2011 01:58 PM|
Originally Posted by Faster View Post
To the OP, if you're boat was originally rigged with end boom sheeting, that's what the boom section was designed for. It may not be beefy enough for a mid-boom system.
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