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Old 17-06-2010, 22:51   #31
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Originally Posted by sandy daugherty View Post
Turning down in a gust is ONLY appropriate in ultra-high performance multis sailing below a beam reach, where their boat speed adds a considerable amount to the apparent wind. It is not appropriate for any cruiser. I'm not sure where the trade-off occurs, but I think its limited to boats that fly a hull as a matter of routine, and that doesn't even include Outremer Ultra lights! For our PDQs and Catanas and FP's et al, heading up is the answer for a gust from any point of sail above a run. Easing the sheets should be the immediate response, always!
Sandy although you're correct on easing the sheets "always", that is very bad advice (for a multihull) to write "heading up is the answer for a gust from any point of sail above a run".


Turning down in a gust helps in several ways, in any multihull (aero-rig is the only exception I can think of):
  1. Centrifugal force from weight aloft during a quick downwind turn helps counteract the heeling force and contributes to righting moment.
  2. Turning downwind reduces apparent wind and allows time for recovery either by waiting for a lull, or by reefing when heading down. (Before you counter that you can't reef while heading downwind, try it. If you have a full-batten main with ball-bearing batt-cars you should be able to do it.)
OTOH, doing as you suggest (heading up) should ONLY be done if you are already close-winded enough that easing the sheet alone is sufficient to alleviate the crises. Turning the boat further to windward:
  1. Increases apparent wind thereby intensifying a crisis when you were already overpowered before starting the maneuver.
  2. Causes centrifugal force from weight aloft to increase capsize force, and that might just be enough to be the critical contribution causing capsize.
If you don't think weight aloft is a major factor, try picking up any mast from one end and hold the other off the ground. Add the weight of sails. Cruising cat masts weigh hundreds of pounds. The mass cantilevered by it's length could mean thousands of pounds of dynamic momentary pressure working either for or against you. A quick turn the right way or the wrong way can make the critical difference, even at only 7-10 knots. Think again -- this does NOT apply only to super high-performance boats.
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Old 18-06-2010, 02:37   #32
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Originally Posted by RunningFish View Post
If a cruising cat is in danger of capsize in 3 foot seas and 30 knots of wind simply because it's got a little to much sail up and isn't trimmed well...how can it be safe for offshore sailing?

Thx running fish, that's exactly my point..

Meanwhile some more info for further academic discussions:

-the boat was about 8 tons, carrying 360 sqft of genoa, 600 sq ft of fully battened main, has no dagger board whatsoever but a keel in the central part of the hull, the rudder in this specific model is ahead of the props, hence, closer to the center of the hull, the main was probably over trimmed and I couldn't ease the main sheet as I moved from 2 knots of wind and almost 0 speed to 25 knots and 10 knots of speed in a matter of seconds. I should have done it earlier, but my past experience with cats (easily handling up 30 knots apparent with full sail and in much bigger seas..) and overconfidence caused the trouble. I don't know how many of you have been in such situation but when you start fly a hull, trust me, you are loosing all of yr reasoning..

Buttom line: not every cat behaves the same way and I should never test again the forgiveness of any boat.

Cheers

Yeloya
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Old 18-06-2010, 05:32   #33
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39 feet well known brand and make cat, my wife + two guests with me on board,
What boat - not so I can criticise just want to look at the numbers - eg beam sail area, hull shape etc.
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Old 18-06-2010, 06:41   #34
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yeloya,

The key in this whole picture is where the winds builds to 25+ in 120 seconds from 0 - 2 knots. It sounds as if you were lulled (pun intended) into a false sense of security. Surely in retrospect, you must have seen the wind on the water rushing towards you. Is the area where you were sailing known for this type of behavior?

SailFastTri, while turning downwind has lots of advantages, I have been on any number of boats, mono and multi where you cannot turn down unless the main is eased, the power of the main overrides the power of the rudder.

Fair Winds,
Mike
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Old 18-06-2010, 06:54   #35
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REEF EARLY, REEF FOR THE GUSTS

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Originally Posted by YOGAO View Post
yeloya,
snip

SailFastTri, while turning downwind has lots of advantages, I have been on any number of boats, mono and multi where you cannot turn down unless the main is eased, the power of the main overrides the power of the rudder.

Fair Winds,
Mike
Yes and that's why you need to ease the main as you turn. BTW -- after the turn when you get to the business of adjusting for conditions it would be helpful to sheet in tight again to reduce wind pressure (by not having the main broadside to the wind) and shed more air as you reef.

One more "multihull rule of thumb" is: "REEF EARLY, REEF FOR THE GUSTS". Monohulls are like weebles, and can shed wind when overpowered in gusts. They are more forgiving of bad seamanship. When we see low thunderstorm clouds approaching we drop sail and motor at least until the initial wall of gusts passes and we know just what we're in for.
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Old 18-06-2010, 12:53   #36
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I would have a close look at the rig if it was under that much load. When you load up the rig that much things start looking for the weakest link. The mast tangs and chainplates are not designed to take that much load.
.... there were several contributing factors to actually getting there......in 25- 30 knots of wind, full rig and 10 knots boat speed....plus rounding up quickly ( not recommended ) you could easily see the equivalent of 35 knots maybe more of apparent windspeed...plus if you really turn fast there is significant roll out of the turn...I can get about 4 degrees off level while motoring by giving the boat full helm at 8 knots..... no sails.... so in 35 knots plus 3 or 4 degrees of roll from the round up and it is possible. Most multi hull sailors have all taken the hobbie cat out....rolled off the wind,to see how fast it'll go, sheeted in the main to adjust for the apparent wind moving forward, then pointed back up and found ourselves in that uncomfortable slow roll over as the apparent wind flips us.....regardless of what you do with the helm while desperately trying to get the mainsheet out of the cleat.......this is exactly that and I am sure that it will never happen again to this guy.
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Old 18-06-2010, 14:48   #37
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Originally Posted by YOGAO View Post
yeloya,

The key in this whole picture is where the winds builds to 25+ in 120 seconds from 0 - 2 knots. It sounds as if you were lulled (pun intended) into a false sense of security. Surely in retrospect, you must have seen the wind on the water rushing towards you. Is the area where you were sailing known for this type of behavior?

SailFastTri, while turning downwind has lots of advantages, I have been on any number of boats, mono and multi where you cannot turn down unless the main is eased, the power of the main overrides the power of the rudder.

Fair Winds,
Mike
I'm just guessing here, but looking at Yeloya's base, my guess is he was somewhere in the Aegean, which is infamous for sudden (read immediate) changes in wind speed and direction, leaving little room for reaction.

Even an extremely experienced multihull sailor (and Yeloya certainly is far from being inexperienced) can be caught off-guard in that place.

A little bit of thread drift here: some sailors I've met in the US underestimate the Mediterranean as a whole, not to mention the even-more unpredictable Aegean, just by looking at their size on a chart. Big mistake.
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Old 18-06-2010, 15:06   #38
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25 knts with all sail up in a Seawind 1000

I've only done one longish trip (a 10 day delivery up East coast of Oz) in a cat and it was early in my sailing days. It was a Seawind 1000 and at one stage the skipper had full sail up at a steady 20-25 kts in choppy seas for a period of about 24 hours. I have always preferred monos and still do for opean ocean sailing.

However, I have to admit that the Seawind 1000 behaved impeccably at 25 kts with self tacking jib and full main even if there was significant slamming. It was just that I didn't "feel comfortable" and had no feel of how close the boat was to it's limits. We eventually part rolled up the jib and put two reefs in the main (skipper decided to stop my whinging). It was far more comfortable and we didn't seem to lose much speed anyway. After reefeing I did see gusts in the low 30s.

The scary part is you can't always see gusts coming, particularly at night, so do you cat sailors set the sails for what gusts might come along? - obviously my skipper didn't feel the need to in the previous 24 hours.

This is where I like the little bit more forgivess offered by a mono, but one day I just could be tempted across to the darker side.

Greg
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Old 18-06-2010, 15:52   #39
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The elephant in the room is the simple fact that, yes, every "conventionally" rigged sailing catamaran can be sailed over. And, the capsize force is a function of the square of the apparent wind speed. A cruising catamaran needs to be carefully and actively sailed with consideration for any reasonably probable apparent wind speed. So, for instance, sailing in areas to the lee mountains one might well expect winds to go from calm to very powerful in a short distance. Sailing in squally conditions it is common to see sudden gusts to two or more times the average wind speed. A catamaran sailing downwind with the mainsail up may round up and experience a sudden increase in apparent wind speed (this is even more dangerous as the flow will tend to stay attached or, if stalled, may attach to the main and it may not be possible to de-power the rig). Since the capsize moment is O(V^2) the designer can do little to make a boat that sails well in the lighter apparent winds and also protects the sailor from the heavier without sail changes. So the prudent cat cruiser will be aware of, and rig for, the windiest likely scenario. The sailor who needs a boat that will protect him from gross errors should not sail a catamaran.

IMO the OP made some serious errors that put him, his passengers and his boat at risk. He was unaware of the limits of his boat. He did not recognize the danger of the gusty environment. He did not have a plan for de-powering the rig. He was not in control of his boat.

I suggest:

Making an effort to become more in tune with the boat. As a rule of thumb you will have used half of the available stability of most cruising cats at about 5 degrees of heel. It might help to install a level gauge with a 10-0-10 scale or if you can see you hulls put marks on them to help with awareness of heel. Go sailing and find out in what apparent wind speeds and trims the boat heels to 5 degrees. I suspect you will quickly develop a feel for when to reef without relying on instruments. I would NEVER rely on a boat's true wind speed instrument directly for this. True wind speed is extremely hard to get properly calibrated (errors in apparent wind speed, boat speed and heading are cumulative). Chances are good the TWS reading you are getting is seriously in error. Look to weather and try to make a direct observation of the wind a sea state. Judge your TWS instrument against that and it can be used in the dark or rain as a general guide. Apparent wind speed is more reliable and repeatable.

Be extremely conscious of factors that might suddenly or significantly change the apparent wind speed. Channels, valleys, fronts, clouds changes in temperature, dark lines on the water and so on need to be noticed, judged and acted on. A round up from anywhere with the wind near or aft of the beam will increase the apparent wind speed. Sometimes dramatically. If your sails are over-trimmed and you head up you will be increasing your heeling moment until the boat slows down or the sails luff. On beach cats we use this trick to fly hulls. It is not a brilliant idea on your cruising cat. If you are running with your main against the shrouds and round up two things will happen: the main will go from stalled to attached flow and will produce a lot more force and the apparent wind will increase with it's V^2 effect. Heading up in this case can cause disaster and easing the main will have little effect. Don't get caught in that position. If you do the only answer is to reef. Learn how to reef the mailsail downwind.

This brings us to the next error. You need a plan. Somewhere in the back of your mind you should always be thinking "what should I do if it all goes pear-shaped right now!" You don't want to be thinking about what line to release or which way to steer when things go wrong. You want to act. Cruising cats tend to have lots of volume forward and relatively narrow beams and they generally don't accelerate very quickly. This make their "zone of death" smaller than performance cats. Racing cats tend to flip most often when bearing away from a close reach to a run. The dynamics are different for most cruising cats and it is generally safe to bear off even quickly to reduce the apparent wind. However, be aware that course changes, up or down, while reaching may do little to reduce your heel (and may even increase it). So, make sure you can release your sheets (biggest and tallest first). Learn how to reef.

An out of control boat is a dangerous boat. Any time you are out of control you need to take immediate action. Cruising cats with keels or small boards get a lot of their leeway resistance from the lee bow. As you push the boat harder the leeway increases and the bow is pushed down further which both moves the center of effort of the hull forward and increase the force on it. This creates weather helm. Solutions include reefing (yes the boat is telling you something), and while a little counter intuitive, reefing the jib can help because on many boats the bow will lift and the hull's ce will move aft more significantly than the rigs. In any case reef. Too, weather helm can be a sign that your sails are over-trimmed. Put telltails on your sails and lean how to read them. Over-trimmed sails are not only slow, they can be dangerous. Learn how to trim your sails. Learn how to reef.

Good luck,

Tom.
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Old 18-06-2010, 16:21   #40
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I've only done one longish trip (a 10 day delivery up East coast of Oz) in a cat and it was early in my sailing days. It was a Seawind 1000 and at one stage the skipper had full sail up at a steady 20-25 kts in choppy seas for a period of about 24 hours. I have always preferred monos and still do for opean ocean sailing.

However, I have to admit that the Seawind 1000 behaved impeccably at 25 kts with self tacking jib and full main even if there was significant slamming. It was just that I didn't "feel comfortable" and had no feel of how close the boat was to it's limits. We eventually part rolled up the jib and put two reefs in the main (skipper decided to stop my whinging). It was far more comfortable and we didn't seem to lose much speed anyway. After reefeing I did see gusts in the low 30s.

The scary part is you can't always see gusts coming, particularly at night, so do you cat sailors set the sails for what gusts might come along? - obviously my skipper didn't feel the need to in the previous 24 hours.

This is where I like the little bit more forgivess offered by a mono, but one day I just could be tempted across to the darker side.

Greg
25 knots from behind ,so the apparent is going to be 15 to 17 over the deck, not too much to worry about.

25 knots on the nose, and that's 30 odd apparent. If this was your situations and it was still no worries it goes a long way to explaining why seawinds have a name for being sedate performers. Overweight and under-canvassed maybe?.
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Old 18-06-2010, 17:13   #41
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Dear Tom,

Like every answer I've read yr comments carefully. But in the end, I thought you didn't fully read my notes. Reefing can be and should be done before you fly yr hull .. not after. I don't know yours but I haven't seen yet any cat (trust me, I've seen quite a bit ) that can be reefed while you are 25-30 degree heeled and in a matter of 4-5 seconds.
The waters that I was sailing was a small bay where I sail at least 300 days in a year, race in monohulls every two weeks, make a deliveries up to 200-300 nm once a month on various boats, mainly on cats.
Again as I said, of course I have seen the gust that was coming some 200 m away and estimated to be around 20, max 25 and from 120 degrees. I knew under these circumptances I could be making around 10-11 knots max. And it was exactly like I expected. The problem is I believed the boat could have easily handled these conditions which she didn't. The anemometer was showing 25 knots on 90 degree apparent. This should be about 20 of true roughly. Having wind surfed for 30 years I don't trust instruments but he tip of my ears; if it wasn't 20, it was 23-25 max. On the other hand, I could have understood if I tore the sails, broke the boom or something else. Normally on a cat, you break down something before you fly the hull and this generally doesn't happen on a 2 ft swell at 10,5 knots of speed and 25 knots of apparent. (Let's say 30..)

After all, if you want to be 100% safe, you never leave the port..By being over prudent, you may significantly reduce the risk level but never fully eliminate them..

Yeloya
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Old 18-06-2010, 19:21   #42
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Dear Tom,

Like every answer I've read yr comments carefully. But in the end, I thought you didn't fully read my notes. Reefing can be and should be done before you fly yr hull .. not after. I don't know yours but I haven't seen yet any cat (trust me, I've seen quite a bit ) that can be reefed while you are 25-30 degree heeled and in a matter of 4-5 seconds.
I'm sorry if I misunderstood your situation and I am trying to be constructive. Of course it is much too late to start reefing when you're on the verge of capsize. I was suggesting that mistakes were made to get into that dangerous condition one of which was failure to prepare in good time.

Quote:
...The anemometer was showing 25 knots on 90 degree apparent. This should be about 20 of true roughly.
The true wind speed is irrelevant.

On most boats it is a serous error to have full sail up with 25 knots at 90 degrees apparent. I don't think you can blame the design. I believe this is a case of user error. The designer is limited to what they can do about this kind of mistake. They could design the boat so the rig falls down before the boat capsizes. People get killed when rigs fall down. So, that's not a good idea. Or they can reduce the sail area so that the boat is safe with full sail at higher and higher wind speeds. But, because the force available from the wind is a function of the square of the wind speed a boat that need never be reefed will not be able to develop enough power to sail well in normal conditions.

Quote:
After all, if you want to be 100% safe, you never leave the port..By being over prudent, you may significantly reduce the risk level but never fully eliminate them..

Yeloya
Fair enough. And one person's over prudence is another recklessness. But unless you know the limits of your craft you can't make informed judgments on how much risk you are taking. I think you should not have been surprised to find that you could fly a hull with full sail and 25 knots on the beam. Perhaps the vessel's limits were misrepresented to you but I would not consider them either particularly unusual or particularly dangerous.

Tom.
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Old 18-06-2010, 20:14   #43
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I don't pretend to understand the dynamics of all the forces involved here, but what I'm getting out of this -
the unusual aspect of this is the sudden transition from almost no wind and almost no boat speed to 20-25 knots true wind coupled with rapid increase in boat speed, aggravated by rounding up with a resultant increase in apparent wind, all of which ended up in an elevated hull and doubtless elevated blood pressure.
My amateur theory is that if the boat had been sailing at say 6-7 knots in say 10-15 knots wind then when a 25 knot gust hit the boat would have accelerated in a normal manner but would not have flown a hull or rounded up severely.
I think it was the sudden increase from near zero wind speed that affected what was a near stationary vessel that caused the situation. Individual traits of the particular design (such as the rudders being unusually far forward) may have had something to do with the boat's reaction.
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Old 18-06-2010, 22:39   #44
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I think I'm with Yeloya here. A 20 or even 25 kt puff doesn't sound like anything that should trouble a cruising cat on a beam reach. If the "numbers" say to put in a reef at 20 kts, 25 is still within the margin of safety. I suspect the answer may be a combination of overpowered main and under-trimmed jib that stalled the rudders. The additional forces generated by the quick upwind turn are what lifted the hull, not a gust.

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Old 19-06-2010, 00:31   #45
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I think I'm with Yeloya here. A 20 or even 25 kt puff doesn't sound like anything that should trouble a cruising cat on a beam reach. If the "numbers" say to put in a reef at 20 kts, 25 is still within the margin of safety. I suspect the answer may be a combination of overpowered main and under-trimmed jib that stalled the rudders. The additional forces generated by the quick upwind turn are what lifted the hull, not a gust.

Brett
I would be amazed if the designer or the makers recommend waiting to reef until 20 knots. In any case, 25 knots is much more wind than 20. It is a rare sailboat, multi or mono, that will not be seriously overpowered with full sail sheeted in with 25 knots on the beam. Perhaps my expectations are out of line but I would much rather cruise a boat that will sail well in typical breezes and be required to reef or ease the sheets in a stiff breeze than one that needs to use the motor in average winds so that I don't need to take care of it in higher winds.

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