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Old 02-02-2013, 04:46   #1
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Most Stable Point on a Sailing Cat

Which place in a catamaran has the least motion in a swell? Not counting the helm station of course

I recently sailed a cat in 4.5 m [=15'] aft of the beam swells and could not find a place where I wasn't violently seasick. I could not make it outside as I hadn't been prudent enough to find a bucket to accompany me prior to leaving....

On a monohull in bad seas I find that mast base/middle of keel is the best for sailing and over the prop for motoring. What about being on a cat?
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Old 02-02-2013, 05:18   #2
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Re: Most stable point on a sailing cat

Middle & far to the stern is where I put folk if they getting sick- this keeps them outside with lots of air, and in a place of least movement- I also give them fresh Ginger tea, that has proven to work well- ( I brew a liter so before they come aboard)I get a lot of new people every year & only have 1-2 people a year sick - often time in 3-4 meter seas- But I also always go with the seas with new folks onboard-- Good Luck !!
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Old 02-02-2013, 06:30   #3
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Re: Most stable point on a sailing cat

My trouble was that I snuggled with the baby in the owner's hull bed. Once we left I could not lift my head up from the bed without getting sick... I knew that outside would be better, but could never make it to the stairs.

And just an fyi: I know of two people (including myself) who get more sick from drinking or eating ginger. So be careful with that
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Old 02-02-2013, 11:25   #4
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Re: Most stable point on a sailing cat

Beam seas are the worst case angle on a cat (not pleasant on a mono either, but worse on a cat).

Technically the point with the least movement is the geometric center, usually about where the mast is stepped on most modern sloop rigged cats. On my boat, the galley is located very near this position and I've cooked on the stove top in 6-8ft confused seas with ease and surprisingly little movement. Of course, that is inside the deckhouse so probably not the best place for sea sick crew. I think aft midships in the cockpit or forward by the mast base (if its not too rough for this to be safe and dry).

When my GF is feeling a bit queezy, and weather permitting, she prefers to go forward and crash on the safety nets (tramps). This seems to work for her.
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Old 02-02-2013, 11:40   #5
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Re: Most stable point on a sailing cat

I picked up the information ( I think it was from the multihull designer John Shuttleworth ) that a cat's place of least movement ( CoG) is approx. 2/3 to 3/4 of the overall length from the bow. Seems to work fine on my cat, that's where my cabin and cockpit are placed.
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Old 02-02-2013, 13:02   #6
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Re: Most Stable Point on a Sailing Cat

I find that the boat moves around the CG, which because of engine placement is much more aft than the mast step. It's basically where my cockpit is located. The engines and water tank are pretty much aligned across the beam so the boat tends to pivot around that line or perhaps a little further aft when the fuel tanks are full.
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Old 02-02-2013, 14:38   #7
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Re: Most Stable Point on a Sailing Cat

We find that the seating position which has the least movement is the center of the forward facing bench seat in the cockpit. This seems to be the point visitors gravitate to when they are concerned about the boat's movement. If they are feeling a bit queezie, this location is also outside and allows sight of the horison or any nearby land which seems to help quieten down feelings of sea sickness.
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Old 02-02-2013, 16:34   #8
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Re: Most Stable Point on a Sailing Cat

Also as low as possible; upper decks and raises areas are bad, more soe than monos because of the quicker motion.
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Old 02-02-2013, 16:49   #9
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Re: Most Stable Point on a Sailing Cat

Yes, one big problem in some cats is that the helm station is so high off the waterline that it has a very quick and violent motion. On my 32-foot cat the least motion was in the center of one hull or the other on the floor, but that was not usually where one wanted to lie down, though we did have pretty good ventilation there due to overhead hatches. When feeling sick it was usually best to lie down on a cockpit seat with head facing forward in order to get it closer to the center of pitching. I know it may not be what you want to hear, but my wife got more seasick more often on our cat than on our monos, which is one reason we switched back. My wife seems to be more susceptible to the short quick motions of a cat than the longer slower motions of a mono. When owning a cat we talked to some others that had a similar problem, though I must say that most people report the opposite.
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Old 02-02-2013, 17:57   #10
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Re: Most Stable Point on a Sailing Cat

I know we have only rode on a couple of cats, and have only owned monos, but the couple of cats we have been at sea in seemed to us to have a very hard to judge pitching motion that we had never felt before ! But in reaching or running they were more comfortable! This pitching motion and the cost is what keeps us from haveing one ! LOL mostly the cost !!
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Old 02-02-2013, 17:58   #11
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On the Seawind 1000 the least motion is in the salon, galley and master bunk. Works out well.
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Old 05-02-2013, 00:06   #12
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Re: Most Stable Point on a Sailing Cat

Upside down!
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Old 05-02-2013, 01:31   #13
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Re: Most Stable Point on a Sailing Cat

Quote:
Originally Posted by Tropicyachty View Post
Upside down!
Ha ha ha - thats so funny, I havent heard that one before.

Of course its still better than the most stable point on a Mono, - on the bottom of the ocean
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Old 05-02-2013, 05:31   #14
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Re: Most Stable Point on a Sailing Cat

here we go again !
It amazes me how jealousy breeds contempt
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Old 05-02-2013, 06:43   #15
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Re: Most Stable Point on a Sailing Cat

On any boat, the least motion is ON the centerline, as close as possible to the "axis of gyration", and regarding sea sickness, that would mean put your head there. (Where your inner ear is)...

For most boats, this would be about 2/3rds aft of amidships, at or near the WL.

For our Searunner, We can get quite close. When beating hard to windward in a gale, the off watch "sorta" sleeps on the sterncastle floor, wedged into the footwell with pillows.

I have known monohullers that resort to the cabin sole as well, when it REALLY gets rough.

Cats can't do this as well as tris, but the closer to that point you can get, the better.

Also... moving as much weight as possible from the ends of the boat (or up on the mast), toward this Axis Of Gyration... will improve motion. The pitching might be a bit quicker, but far less of it, with less pounding.

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