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The big spin

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chris wray
Deckhand

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USA
22 Posts

Initially Posted - 11/08/2004 : 19:54:27

All,
I come to you greatly humbled & confused today as this WE I was sailing with 6 friends in SF Bay where I have spent the last 2 years sailing and enjoying this challenging body of water. We were going east bound after trip around Angel Island we had a 10 -12 mph tail wind, were wing to wing and we were riding a flood tide at a point where the tidal flow waters were meeting. I attempted to alter our course about 40 degrees for our across the bay treck home to Richmond and as I did so the boat (formerly the Mary Ellen and now named "Vortex 655321") spun in her length. We had the main set out on the port side and the headsail to starboard. We tried this again the same way and got spun again and then a third time. It was funny and we made comments like "We will never get to America this way" and surmized that "this might be the real reason the early mariners got scurvey". I shifted the boom to starboard and tried it a forth time and we went right on our way just fine. What happened???
I had to buy the drinks when we got in to port.
I have the 3rd generation rudder.
Could the tidal currents, which are hard to read unlike the wind which is interpreted for us by the windvane, have negated the needed force on the keel for forward movement and when we moved the boom across to starboard the needed opposing keel force was restored?
I may have frightened one of them and she may refrain from ever going with me again. The rest were mildly interested in what physics may have been at work but only after I paid for the round drinks.
Any comments so that I may, in the future, avoid a repeat of this would be greatly appreciated.
Sincerely,
Capt'n Spin
250 WK #421, "Vortex 655321" formerly "Mary Ellen"

Edited by - on

Arlyn Stewart
Master Marine Consultant

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USA
2980 Posts

Response Posted - 11/08/2004 : 22:32:52

Capt'n Spin,

I'm guessing that your rudder was being impacted by an eddy from the confluence.

The rudder on the 250 is very large comparatively. I have noticed often the degree of impact on a broad reach for example. As a following quartering wave impacts the rudder it spins the boat. Countering this requires vaning the rudder to the swell just as the swell arrives and stalls the rudder and impacts it. Holding the vaned position a half second, and then throwing the helm back on course avoids the spinning forces brought on by the momentarily stalled and impacted rudder.

Edited by - on

kbq
1st Mate

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USA
99 Posts

Response Posted - 11/09/2004 : 20:06:50

Chris -

Was that in Racoon Straight? I've had some really entertaining times there when tide, current, wind and waves conspire to test the wife's and my skills... Particular fun was had there recently when our son was visiting and sailing with us: the mainsheet wasn't released quickly enough after a gybe, and the resulting violent round-up (about a 75 degree heel for a moment - we were standing on the side!).

Anyway, share whatever you find!

Kevin
"wait for me"
250wk

Edited by - on

chris wray
Deckhand

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USA
22 Posts

Response Posted - 11/10/2004 : 14:58:46

Kevin,
It was near the point where the wind powered generator is placed on the south end of Angel Island. We had gone around Angel counter clockwise and were headed back to Richmond powered by the slot wind. The roundup and heel were just as you described only we did it 3 times. The fourth attempt we made it and I guess it was because we loaded the mast from the opposing side. Arlyn says it might be the rudder. I'm wondering if it might be the rounded bottom design (bow to stern) or something like that??? The "rudder problems" that this boat has had make me wonder. Earlier designs don't have that rounded countenance that we see in the side view pictures in the brochures.
Where to you sail out of?
CW

Edited by - on

ssteakley
Captain

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USA
467 Posts

Response Posted - 11/10/2004 : 21:59:09

"10 -12 mph tail wind, were wing to wing and we were riding a flood tide at a point where the tidal flow waters were meeting. I attempted to alter our course about 40 degrees for our across the bay treck home"

Sometimes it is not always possible to fully grasp the conditions but if you were wing on wing and you altered course 40 degrees then we would all assume you adjusted your sails prior or during the course change. A C250 is tender and would require reefing the genoa or the main even in 10-12 with strong currnts. Maintaining control is the responsibility of the skipper and you owe your guest much more than drinks...
JMHO
Sailing in the San Francisco Bay in a C250 would be great fun but a huge responsibility I am sure.
Steve Steakley

Edited by - on

henfling
1st Mate

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USA
26 Posts

Response Posted - 11/10/2004 : 22:52:11

Cap'n Spin,

I also was sailing on Saturday (11/6) on the SF Bay and I also sailed out of Richmond through Raccoon Straits, around Angel Island heading for Alcatraz and towards the Bay Bridge before heading back to Richmond. The wind was good with the GPS recording a maximum speed of 7.7 knots, but as we were on a beam reach heading home, we too experienced several uncontrollable "weather helm" roundings to find boat facing directly into the wind. Now I should mention that our boat originally came with the second generation rudder but recently we purchased and installed the new high performance rudder from the Chandlery and it works great. We have intentionally sailed the boat close hauled at a 30 degree angle with no weather helm whatsoever. So Saturday's "weather helm" had us baffled until we realized that we were getting significant wave action coming from our quarter deck on the windward side. As soon as we changed course and sailed in the same direction as the waves, the rounding up problem vanished. Also as soon as we got into the lee of Angel Island, we could resume our original course as the island blocked the waves. I also recall surfing and kiyacking in Hawaii and the same problem would occur when a wave would pass by me, it would "push" the back of the board or vessel forward causing the front to swing (spin) 180 degrees around. Anyway, to make a short story long...it was a lesson to realize that sailing on the Bay involves a multitude of challenges including wind, current, tides, large commercial traffic, and waves.

La Dolce Vita
2001 Catalina 250 WK

Edited by - on

kbq
1st Mate

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USA
99 Posts

Response Posted - 11/11/2004 : 13:08:40

Chris -

When we sail the Bay, it's out of the Richmond marina. We usually head over on a Friday night, rig as fast as we can, and head to a rented slip for the evening. That way, we're ready early Saturday for whatever comes up.

There's been some good discussion in this thread on the effect of waves when running. Personally, I've found it difficult indeed to run wing and wing with the afternoon waves around Angel Island - it pushes us too close to an accidental gybe. We generally reef, if needed, and just tack 'til we're in the calmer waters east of the Island.

Steve - on the responsibility of a 250 on the Bay - why do you consider it particularly dangerous? I consider it a big responsiblity any time I'm at the helm of any craft with passengers. I certainly don't see any particular hazards with a 250 on the Bay! (or am I misreading you?)

Kevin
"wait for me"
250wk

Edited by - on

Steve Milby
Past Commodore

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USA
5908 Posts

Response Posted - 11/12/2004 : 10:56:20

Most of us have seen how a power boat wake can knock the bow of the boat to leeward when you're beating to windward. The same thing happens when a big, steep wave overtakes a boat from astern and strikes the boat on its quarter. It causes the stern of the boat to yaw.

In addition, when a steep wave rolls up under a boat from astern, it lifts a transom-hung rudder partially out of the water, in the same way that it lifts your outboard motor and causes it to cavitate. The rudder resists the tendency of the stern to yaw, but when the surface area of the rudder is momentarily reduced, at precisely the same time that the wave is slapping the stern quarter, the rudder no longer provides enough resistance to prevent the stern from yawing, and around she goes.

I think that when the wave overtakes the boat from astern, it also causes the rudder to stall at that same moment, as Arlyn pointed out, so that the surface of the rudder is not only reduced in its area, but its lifting force is also reduced.

While you were running downwind, the waves were hitting the boat more squarely from astern, and the boat was able to hold its course, but when you bore off 40 deg., the waves started to strike the boat on its quarter, and all those yaw-producing effects came into play, causing the boat to broach.

In those conditions, for that reason, it is best to avoid taking the waves on the quarter, and it is also best to avoid taking them on the beam, because that will cause the boat to roll heavily and perhaps dangerously.

Reducing the boat's speed helps prevent yawing and broaching.

If there is a fairly long period between each wave, you can steer parallel to the waves in the troughs, but, as the next wave approaches, turn the bow to meet the wave as it rolls under the boat, trimming the sails as the boat turns. If the waves are short, steep and close you really can't do that, and it is probably better to run further downwind, and then turn and beat back against the wind and waves. It won't be easy or comfortable, but at least you'll be able to control the boat better.

In more moderate conditions a broach just provides a little excitement, but as conditions worsen, the danger increases, and you have to avoid broaching, even if it means an unpleasant beat against the wind and waves.

Edited by - on

chris wray
Deckhand

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USA
22 Posts

Response Posted - 11/12/2004 : 13:54:29

All,
I found Henfling's story somewhat gratifying as we were sailing the same waters on the same day at nearly the same time with virtually the same boats and we had similar experiences. (Don, It was me and my rattled crew that talked with you & your guys at the marina that evening.)

Incidentally, Mr. Steakly, I take the matters of my crew's safety and my boating capabilities very seriously. I thought I was getting fairly nimble at the helm and I was brought up short, indeed, by the spin experience I reported. I don't sail where I sail because it's easy. I lake sailed for 3 years prior to SF Bay sailing and the differences between the two are immence and even astounding and I drive 3 hours one way for this sublime experience. By the bye, what would suggest as a more fitting mea culpa to my crew other than my provision of a nerve-calming libation?

Thanks to all for the input
Chris Wray

Edited by - on

Arlyn Stewart
Master Marine Consultant

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USA
2980 Posts

Response Posted - 11/13/2004 : 14:09:40

Steve, good comments.

One addition relates to auto pilot use with a quartering sea. Very often the pilot is useless because anticipation helming is needed, vaning the rudder to the sea at the moment of impact will prevent the yaw...unfortunately the autopilot can't perform this because it corrects the course only after the boat is yawed and thats generally too late to avoid a broach.

The next cruising opportunity that presents this condition, I'm going to try a warp to see if it will allow auto pilot use.

Edited by - on

Oscar
Master Marine Consultant

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USA
2030 Posts

Response Posted - 11/27/2004 : 12:10:34

The next generation autopilots includes a gyro, and a "smart" processor that allows the autopilot to "learn" from the conditions. I've been told it makes a huge difference in folowing seas. I don't know if the technology is spilling over into tiller pilots yet....

Oscar
C42 # 76 "Lady Kay" (Ex. C250 WB #618)
Georgetown MD/Fort Lauderdale FL

Edited by - on

Jeff McK
Captain

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USA
389 Posts

Response Posted - 11/27/2004 : 22:56:09

Chris,

This is really confusing, but I tend to think Arlyn's on the right track. I've experienced similar events while kyaking when I hit a "hydraulic". You go 'round & 'round like it's a washing machine on spin. Factor in the wind off the stern quarter & you've got a ride worthy of Six Flags. I'm just glad you didn't have anyone hurt or break anything.

OK, I'll go ahead & ask: What is the source/significance of your boat's new & unusual name? I know it's not the coordinates of SF Bay (37 deg 42.3 N, 122 deg 16.45 W).

Edited by - on

chris wray
Deckhand

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USA
22 Posts

Response Posted - 11/28/2004 : 20:46:05

Jeff,
The "name change" was for some comic relief from the day's sail. But the "Vortex" part was, of course, for the spinning and the "655321" part was from Anthony Burgess' "A Clockwork Orange" the novel and movie from the early seventies wherein "Alex", the main character and anti-hero, served time in prison for a most horrific and frightening murder and was given "655321" as his convict number. Our pairing of the two, for our boat's temporary new name was, I'm afraid, just because of all the spinning and frightening things that the boat had done seemingly of its own accord and "Vortex" just by itself seemed, in a poetic sense, just not enough to get the job done. Hence "Vortex 655321"... (spoken "Vortex Six double-five three two one").

Truth be known I've yet to name our 250. But not for lack of ideas and considering a great many. Years ago we had a wonderful little boat that had a wonderful name that fit her like a rubber "T" shirt. That name came to us in a week or so of our getting that boat. Thus our strategy has been to wait until something really fits and then going with it. Thus far we are content to be passively searching. We're not superstitious about an un-named boat because it's bad luck...
Chirs Wray

Edited by - on

Jeff McK
Captain

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USA
389 Posts

Response Posted - 11/28/2004 : 21:19:26

Chris,

I'd forgotten about that movie. Interesting choice. All I can say on the new name is be patient. It'll come to you soon enough.

Stay safe.

Edited by - on

Arlyn Stewart
Master Marine Consultant

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USA
2980 Posts

Response Posted - 11/29/2004 : 09:51:23

Chris... I agree that its better to wait rathter than push the naming. The right name will emerge unexpected in time.

Edited by - on

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