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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

Rocking and Rolling

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bsmudd
1st Mate

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61 Posts

Initially Posted - 08/23/2004 : 12:25:07

I had a great trip this june from Solomon's Island MD, up the Potomac to Alexandria. My swing-keel Catalina handled a good range of circumstances. The only thing I didnt like was the amount of pitching, rocking, tossing, and turning, she did in the lower Potomac when the waves and the wind got a little big. After a couple hours it got old.

Is this common for the catalina 25s? Does the swing keel desing exacerbate this effect, placing the bulk of the boats weight so low in the keel? Is there a way to minimize it by packing heavier, lighter, or in certain parts of the boat? What sailing techniques minimize it?

- B.S. Mudd -
on the Chimera

Edited by - on

jwilliams
Captain

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USA
357 Posts

Response Posted - 08/23/2004 : 12:48:41

B.S.,

You have described what it is like to be in a small boat whenever the cross-waves get up.

There are several places on the SF Bay like that, and where I imagine the conditions are similar to the Potomac. Between Angel Island and Tiburon, the Sacramento river current makes a right turn. When the tide is coming in strong it gets really bouncy!

The Bay is oriented roughly N-S. Typical winds in the summer come from the NNW and get lots of distance to build waves. But the bay is relatively shallow, so the waves become 3-4ft but very short duration, often less than 10 feet apart, particularly in the SBay.

North of the Bay Bridge, in the slot between Alcatraz and Angel Island, the wind comes directly through the Golden Gate as do the swells coming through from the Pacific, so you can get the phenomenon of short duration waves on top of 3-4ft swells and the river current against the tide! It makes for some uncomfortable sailing. Add the spray, wakes from the frequent jet ferries, stink boat admirals with their semi-displacement wakes and commercial traffic...ain't it great!!! Who would like to do anything else!!

Jim Williams
Hey Jude C25fk 2958
SF Bay

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ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 08/23/2004 : 13:18:04

- Q - Is this common for the catalina 25s?

Abrubt motion is common for all 'smaller' boats.. the more mass you have, generally the more stable you will be... the motion on a 20,000 lb boat is a lot slower than a 4,500 lb boat.

- Q - Does the swing keel design exacerbate this effect, placing the bulk of the boats weight so low in the keel?

Lower center of gravity, deeper keel mass usually = better stability amd slower roll motion (all other design elements being equal).

- Q - Is there a way to minimize it by packing heavier, lighter, or in certain parts of the boat?

Generally speaking, you want weight in the boat as low and as centered as possible. That said, having weight in the ends of the boat will actually dampen smaller-amplitude pitching motions... but can have other (very) undesirable effects on longer period seas. (hobby-horsing). Usually you don't want to go there.

- Q - What sailing techniques minimize it?

Other than changing your course to minimize uncomfortable motion, you can trim to keep the sail shape fuller... more powered up to drive through the chop. This also has the effect of producing more heeling forces, which will stabilize the boat a bit in the longitudinal roll axis too.

Sails are sometimes referred to as 'dacron stabilizers'. Motion with them down gets a lot worse.

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jtbarrett
1st Mate

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USA
60 Posts

Response Posted - 08/23/2004 : 19:56:28

In that area the currents are extremely strong. We went through them in a morgan 33t on the way to the MD governers cup along with heavy storms and wild seas..Although the smaller boat would rock a bit more..that area is known to give ya a thrill..

Jonathan T Barrett
"hang Loose"
'82 sk sr #3047

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Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 08/23/2004 : 20:17:12

The longer the pendulum the longer the period of swing. You might hang mushrooms over each side.

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ddlyle
Captain

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302 Posts

Response Posted - 08/23/2004 : 21:23:36

By mushrooms I presume you mean anchors.

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ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 08/23/2004 : 23:10:59

"By mushrooms I presume you mean anchors."

ROFL..

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MattL
Admiral

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USA
990 Posts

Response Posted - 08/24/2004 : 02:16:59

yea and they have way coool colors.

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 08/24/2004 : 09:00:52

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by ClamBeach
 "By mushrooms I presume you mean anchors."

ROFL..
<hr height="1" noshade id="quote"></blockquote id="quote">
You guys are starting to sound like the Cruising World forum.

Frank, I think I'd skip the mushrooms and go for speed (to get the hell out of there).

Edited by - on

RichardG
Admiral

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USA
990 Posts

Response Posted - 08/24/2004 : 12:40:08

I don't know that area, but sometimes waves can bounce off steep shorelines at just the right angle to cause a really uncomfortable bathtub effect, with waves seemingly coming from all directions.

About 7 years ago, during the first summer I owned my boat and still somewhat new to local waters, I decided to go to Catalina Harbor (the backside of the island) via the West End. While the channel crossing was relatively smooth and uneventful with regular swells and little wind, while approaching the West End I noticed a big trawler who had passed me start pitching and rolling bigtime off in the distance. About ten minutes later I hit it -- all of a sudden waves were coming from all directions, rolling and pitching the boat violently. The waves weren't breaking over the boat, but down in the cabin I noticed canned food projectiles flying. My wife, previously sleeping in the v-berth and usually pretty sea-tuff, poked her head out with a "why do I feel like I'm in a paint-shaker machine" look on her face. I stayed in it for about 30 seconds longer before turning around to go to Two Harbors. Anyway, someone told me that occasionally the swell can bounce off the West End area just right, causing such a condition, and that you need to head several miles offshore to get around it. It was unfortunate that it happened on my first attempt to the backside of the island, because thinking the condition occurs often, I avoided trying it again for three more years until I could do it with two buddy-boats. Anyway, I've since been back there many more times and have not hit that same bathtub condition, even in much bigger swell/waves/wind.

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 08/24/2004 : 22:08:48

Some might recall from physics classes a phenomenon called the "standing wave." It happens when waves with the same period approach each other from opposite directions--a particularly common event inside an inlet or close to a sea wall or breakwater. The effect is like an elevator going up and down--it doesn't even look like waves--just water jumping up and down in place. Theoretically, the amplitude is double that of the waves that started the thing, but the period is the same. It can be very violent--like a paint shaker! I first encountered it as a kid driving a 14' aluminum runabout through an inlet from Lake Michigan--the lake waves were around 4', and the water was jumping up and down in the inlet between 6' and 8'! My boat was thrown into the air, and I only stayed onboard by hanging on to the steering wheel!

The other time things can get especially exciting is when waves are moving opposite to the current. The period is shortened proportionately, and things get very vertical. It happens all the time just off the point near my boat club--boaters are wise to stay 200 yards or more off the point when the tide is opposing the wind.

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bsmudd
1st Mate

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61 Posts

Response Posted - 08/25/2004 : 12:28:12

Which is more stable in these conditions, sailing on a reach or wing-to-wing? At the time, the wind was actually headed perfectly into the small Bay I was headed to for the night, so I tried to go wing-to-wing. It was bouncy and difficult to keep the wind in the sails right, even though the wind itself was pretty steady and strong. So I switched to tacking on reaches which was less direct, still rolly polly, but there was less boom-swinging to scare my girlfriend (and me).

Combs Creek on Breton Bay was my home that night, after 5 hrs of hot summer motoring and three hours of ducking and weaving in the twilight. I give my love to that Creek for its beauty and its protectedness.

Edited by - on

JimB517
Past Commodore

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USA
3285 Posts

Response Posted - 08/25/2004 : 13:53:32

There is no point of sail LESS STABLE than sailing wing-n-wing directly downwind. Either gybe from broad reach to broad reach, or roll up the genny, sheet the main in tight and motor in. That tight main will be acting as a huge "vertical dacron stabilizer" very difficult for the boat to roll it through the wind.

If you are taking this tactic, its always better to take a course so that you can keep some wind pressure on the main, that will make the boat even more stable.

Once at anchor, I've found that 3 of those orange cone stabilizers on a line tied to a 8 lb mushroom anchor cut rolling about in half. Use your whisker pole to hang them over the side as far out as practical. Make sure they stay fully submerged throughout the roll and don't hit bottom.

I use 3 on one side off the whisker pole and 3 more on the other side either off the boom or usually I just hang them off my winch. They really work and the whole setup only costs $25 or so.

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 08/25/2004 : 13:58:56

I'll offer the opinion that the reach will be smoother. Wing-n-wing dead downwind means the sails aren't really stabilizing you from rolling motions, while reaches will do that, even though you might be sailing a little off the direction of the waves. And you might end up getting there faster as well, even with a couple of jibes (gybes?)--done carefully.

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