Rolling Rolling..... - Page 2 - SailNet Community
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post #11 of 19 Old 03-22-2010
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Make it simple. ...multiple hulls... ...i2f

20 MPH ain't fast unless, you do it in a 1000sq 3/2 house on 10foot waves
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BORROWED, No single one of us is as smart as all of us!
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post #12 of 19 Old 03-22-2010
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Rolling depends upon a lot of factors, as cited above. It also depends upon how centered and low the weight of the hull is from side to side compared to the center of "rolling reisistance", for want of a better term. Give a push to a bicycle wheel with a 2 pound weight on its outer rim, for example. It will swing back & forth a couple of times, but will then settle down fairly quickly with the weight on the bottom. Move the weight up towards the axle (the center of "rolling resistance", and the same push will get the wheel rocking 'way up & way back for quite a while. Spreading the weight out over the boat has the same effect of increasing the duration of the rolling due to inertia. This is why racers try to concentrate ballast and crew weight all together as much as possible: to reduce rolling and pitching, which slow the boat. A boat with more motion might be more comfortable to sail than a racing boat, and allow better sleeping for the off watch. It's all a big balancing act.
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post #13 of 19 Old 03-22-2010
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A boat with a heavy mast will roll less than the same design with a lighter mast. And a slower less annoying roll as well. Form stability of the hull has a large influence and the more spread out the displacement is towards the ends the less roll all else being equal.

Brian
Living aboard in Victoria Harbour
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post #14 of 19 Old 03-23-2010
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Well, I will also throw in my 2 cents on your old thread here fuzzy. Sorry I missed it.

I have owned 4 boats - with 2 of them I have done a lot of LA and distance sailing on.

The Catalina 380 was a rolly, tender girl. She had a rounded hull. She was a wing keel, moderate draft (5.5). She was an older design, based upon the old Morgans.

My 400, baesd on a newer design, is VERY sure footed and does not roll, almost at all. SHe will stop rolling before most any boat in the marina, including some motorboats. She sails pretty flat and and is slow to heel with a very predictable motion. The 400 has a 'flat' bottom and a wing keel of medium-high displacement (5'10 with the wing).

My feeling is that 'rolliness' and tenderness may go hand in hand. I also feel that it is a combination of factors with hull design (hader chimed hulls are more stable) being the main factor. However, I do not believe it is the sole factor. For example, Dad has a Tayana 42 with a rounded hull and it does not roll. She has a mod-full keel and draws about 6-6'2. She also weighs in dry at 38000 lbs!!! I think the keel and its draft play a large role in sailboats to how stable she is too.

I would look for flat/hard chimed 'bottom boats for LA and cruising. I think the stability and sure footedness make them a better choice. I cannot imagine anyone wanting to LA in a roller (which I have done). I ahve also always wondered if a potential buyer could go to the marina that his potential boat was at, and watch her as the sport fish go by, and have a pretty good feel for how tender she was going to be and how much she would roll. If I saw a boat that rolled as long or longer than other sailboats of comparable length and facing the same direction, I would probably gie that boat a pass. That is how much I hate tender/rolly boats.

Brian
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post #15 of 19 Old 03-24-2010
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Quote:
Originally Posted by tdw View Post
To that end would it follow that a typical IOR hull (fine bow, pinched in stern) be more of a roller than say a modern wide arsed jobby ?
IOR Boats were often designed to break a rule more than for actual speed. IMS has/had designs that also worked that way. Where the newest designs were boats whose measurements gave a correction to their rating, enabling a time benefit. I never understood the use of designing a boat to be slow to win a race. After owning two IOR boats I can tell you that the hull shape is unstable when pressing them hard down wind in a race under full sail. They would 'roll' out of control and broach. In one occasion I managed a maneuver akin to Starsky and Hutch... I wished I had been wearing my brown corduroy trousers.
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post #16 of 19 Old 03-24-2010
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To that end would it follow that a typical IOR hull (fine bow, pinched in stern) be more of a roller than say a modern wide arsed jobby ?

A modern broad transom could compare to a broad IOR beam (don't forget the tumblehome) insofar as rolling tendencies. They could have similar rolling tendencies because of their shapes. Beyond their shapes, however, they might roll differently because of where their weight was placed. Olin Stephens complained to me bitterly about how designers distorted IOR boats to work the rule, lightening their hull and deck structure and scantlings to unsafe levels so that they could put more weight down low, to dampen rolling. A good IOR boat is therefore not likely much of a roller. (Nor, because of all the tweaks and bumps in the hull, trying to fool the rule, is it likely to be very fast.)
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post #17 of 19 Old 10-13-2010
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rollin' tender boats

maybe a good new list for first time buyers would be:

Top 10 most stable and stiffest boats to live on in the 28-40 foot range

That was we can avoid the

Chesapeake Bay area

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post #18 of 19 Old 01-10-2011
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As new owners of a 1995 Beneteau Oceanis 351, Ian McHenry and I have found this discussion quite interesting (and a bit too late). Our boat has a 5ft draft (with a winged keel), 35ft LOA, 12.5ft beam, displaces 5.4T, rolls like she is possessed, even in glassy water. We are liveaboards, and while we are used to it and do not tend to notice, we can't always say the same for guests who join us.

Question: Is rolling inevitable due to some aspect of this design? Is it possible to manage this using a second anchor to ensure the boat will not hang perpendicular to the groundswell (but rather nose-to)? If so, what is the correct procedure for setting two anchors in this situation?

Thanks!

Adam Wible
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post #19 of 19 Old 01-10-2011
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1995 Beneteau Oceanis 351

Get a 'flopper stopper'.

http://www.forespar.com/pdf/F33.1-30...r-brochure.pdf

or

Boat Stabilizers - Ocean Torque Boat Stabilizers Stop The Roll

Alternatively for an more economic solution,

A triangular bit of 3/8" ply say with 2'0" sides and a hole in each corner with a 1/2" rope (equal lengths) with a stopper knot meeting up about 4'0" up and joined to a single rope.
At one corner, a good few pounds of lead or a other weight should be firmly attached.

All this is then is suspended from a spinnaker pole extended out from the mast at the beam.

This will 'help' minimize the rolling. More so if one is deployed on each side of the yacht.

'Maņana' ? Well, down here in the Caribbean islands we don't need a word with that sense of urgency.
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