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Old 12-02-2016, 16:29   #61
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Re: Following Seas and Cock Pit Height

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Originally Posted by duefocena View Post
Fully pooped twice in 24 years on big cats, they shed water like ducks due to aft buoyancy, speed of get away, lack of heel. "Sliding glass windows"? My 42' Lagoon's is 1/2" thick polycarbonate and would stop a train. Scuppers drain to clear air rather than below water line and mine has an additional,"escape hatch/ lazarette" that would drain a swimming pool fast.
Agree that bridge clearance is imperative to reduction of pounding. 5" difference can make a serious difference.
On my Lipari the cover over the cockpit scupper worries me as don't think it would allow enough water to escape fast - plan on modifying it before ocean crossing. Was also thinking of making a plywood washboard to allow door to be left open but would stop water up to about 0.5m high (18").

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Old 12-02-2016, 18:02   #62
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Re: Following Seas and Cockpit Height

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Originally Posted by 44'cruisingcat View Post
Yep. That's exactly why they're here.
I do find it sad / annoying that a straightforward question on the multihull forum ends up with 5 pages (and counting) of which at least 50% is not pertinent to the original question.

I come to this forum to ask questions when I need specific advice, to gain knowledge from others who have been before me on topics that I feel are relevant to my situation(s) and hopefully to contribute with any knowledge I might have on a subject when I can. These are all things that the forum can achieve really well.

Ultimately though I would rather be sailing than reading a forum, and yes I sail a multihull but also have over 50 years of monohull and power boat experience including sailing in conditions when other boats are foundering.

I haven't yet checked whether the level of off topic comments increase when the Northern hemisphere is in the depths of winter, and there are consequently a lot of frustrated sailors who have nothing better to do than add red herrings and diatribe to validly posted questions, but I think there might be a correlation.

Please, if you can't contribute positively and on topic, keep your hands off the keyboard or go work out your frustrations stripping down a winch or in the gym.

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Old 14-02-2016, 13:43   #63
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Re: Following Seas and Cock Pit Height

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Originally Posted by smj View Post
I'm guessing when a mono broaches it's because the single rudder breaks the surface and the boat looses steerage where with twin rudders there would be a better chance of maintaining steerage? When a mono broaches I would definitely consider that a loss of stability, so it wold appear that twin rudders may somewhat ad some stability?
It can be, but it is not the only reason why a monohull can broach. Sometimes the hull design just results in too much of the hull resistance shifting too far forward.
A lot of early "broad beam aft" monohulls were pigs because they trimmed down by the bow when they heeled, and this promotes an increase in pressure resistance at the bow.

On the run, which is the case of interest here, the rudder is normally deeply immersed anyway, unless the boat has already broached. Boats typically broach when they don't/can't accelerate any more. If you accelerate, you tend to stay away from the steepest part of the wave.

When you broach and heel over, you can sort of say that you have "lost stability", but from another angle you haven't, because it is still the same boat with the same intrinsic stability.
It is a matter of not confusing "course stability" and "righting ability". Better tracking reduces the likelihood of overcoming existing stability, but it doesn't improve it.
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Old 14-02-2016, 13:50   #64
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Re: Following Seas and Cock Pit Height

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Originally Posted by ZULU40 View Post
my point also related to cruisers, and they arent hard to find
Those handle very much the same for that matter. You will struggle to get any water over the stern of that boat.
Keep a bit of speed on and they lift the stern and slip away as soon as a wave slope develops.
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Old 14-02-2016, 13:50   #65
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Re: Following Seas and Cockpit Height

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Originally Posted by Red Herring View Post
Hi All,

Another newbie question, but in looking at different boats it has become very apparent that some have a much higher cockpit height or a completely enclosed cockpit, and some have what seems like very low cockpit, with only 1 or 2 stairs on the sugar scoop.

I was wondering if there was any issue in following seas with cockpit swamping with the lower designs.

For example:

A Lagoon 38 has a high enclosure...




Where as a Leopard 38 has a low cockpit egress...



I can't help but be drawn to the higher cockpit enclosures, as I assume they are inherently more sea worthy in a following sea. Is this a valid point?
To get back to the original question, there's no simple answer.

There's a lot more to it than just the height of the rear beam.

There's the overall weight of the boat, the length the hulls extend aft beyond the bridgedeck, the amount of buoyancy aft (compared to weight), the bridgedeck clearance, even the angle the photo is take from!


The reality is, cats aren't easily pooped.




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Old 14-02-2016, 21:36   #66
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Re: Following Seas and Cockpit Height

The danger in saying cats do this and monos do that is all cats are not designed exactly the same and all monos are not designed exactly the same.

A lot of the modern monos with wide flat bottoms have characteristics more similar to a cat.

To the original question, if the only difference was the height of the transom, the higher transom would be less likely to be swamped. Reality is most cats are hard (but not impossible) to swamp.

If we are talking typical cats, they go fast down wave fronts often racing ahead of breaking waves. The sterns lift quickly on waves effectively increasing transom height.
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Old 17-02-2016, 12:02   #67
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Re: Following Seas and Cockpit Height

If there is someone out there on a cat or a monohull who has been pooped, I would like to here about it. Especially the conditions for the cat.
Imo bridgedeck height will have more of an impact on your safety and comfort than most other factors
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Old 17-02-2016, 13:22   #68
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Re: Following Seas and Cockpit Height

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Originally Posted by admiralslater View Post
If there is someone out there on a cat or a monohull who has been pooped, I would like to here about it. Especially the conditions for the cat.
I'v been "pooped" in both a mono (47') and a cat (55'). Conditions were similar - sustained wind mid 40's (which many sailors would call 50, because those gusts showed up on the dial). Wave heights are hard to judge, and shape is more important in any case, so I don't bother trying to guess.

As I mentioned in a post above - the cat case had a meaningful factor of operator error and I could have avoided it if I had not made the mistake.

This is all quite rare on either mono or cat. We have sailed (including in the southern ocean) quite a ways towing a drogue and I can only remember the two times when I would say pooped. It is possible I have forgotten and there were one of two more, but it is still quite rare. Splashes and foam are much more common, but a true solid water pooping does not happen much.

But it does and can happen. So the question is whether you design for this relatively rare case or not. Designing for it does involve costs and compromises. It is a bit like the bendy design question - the answer to what is "strong enough" is not obvious.

I might mention that in the cat case - there was quite a bit of glass in the cockpit forward bulkhead, but it was "marine grade" and not sliding patio grade. It did not break.
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Old 18-02-2016, 05:33   #69
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Re: Following Seas and Cockpit Height

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Originally Posted by estarzinger View Post
I'v been "pooped" in both a mono (47') and a cat (55'). Conditions were similar - sustained wind mid 40's (which many sailors would call 50, because those gusts showed up on the dial). Wave heights are hard to judge, and shape is more important in any case, so I don't bother trying to guess.

As I mentioned in a post above - the cat case had a meaningful factor of operator error and I could have avoided it if I had not made the mistake.

This is all quite rare on either mono or cat. We have sailed (including in the southern ocean) quite a ways towing a drogue and I can only remember the two times when I would say pooped. It is possible I have forgotten and there were one of two more, but it is still quite rare. Splashes and foam are much more common, but a true solid water pooping does not happen much.

But it does and can happen. So the question is whether you design for this relatively rare case or not. Designing for it does involve costs and compromises. It is a bit like the bendy design question - the answer to what is "strong enough" is not obvious.

I might mention that in the cat case - there was quite a bit of glass in the cockpit forward bulkhead, but it was "marine grade" and not sliding patio grade. It did not break.
Thanks for the reply. I realize that it might lead to a lot of bs but would you elaborate on what error you think you made on the Cat
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Old 18-02-2016, 06:20   #70
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Re: Following Seas and Cockpit Height

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Originally Posted by admiralslater View Post
Thanks for the reply. I realize that it might lead to a lot of bs but would you elaborate on what error you think you made on the Cat
I explained it in some detail in a prior post just up the thread. Essentially we caused the boat to decelerate just as a wave rolled up. Scroll up a bit and read the other post if you want more detail.
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Old 18-02-2016, 07:20   #71
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Re: Following Seas and Cockpit Height

Thanks Estarzinfer for sharing your experiences and providing a rational analysis of the risks. To my knowledge, production cats are not using home-style patio doors with non-tempered glass. The fact that the doors on the cat you were on did not implode, even when the cockpit was pooped, should say something about the risks. One wonders if the thin plywood or acrylic drop boards in the companionway of most monohulls would have faired as well.

I also thank you for pointing out that operator error led to the pooping on the cat you were sailing. As you know, the natural tendancy of a cat is to accelerate rapidly with waves from astern and decelerating in those conditions could and did obviously increase the risks.

Although I strongly disagree with your earlier assertion to the effect that condomarans are designed and intended to be safe only when sailed in the lee of islands (and I suspect that in retrospect, you would agree that this was an overstatement), nevertheless you have provided some context. And as you said earlier, if one is concerned about the risk of a very rare pooping, you can buy a boat without large sliding doors. Similarly, on a monohull, you can retrofit a virtually bulletproof companionway sliding hatch and doors from Atkins & Hoyle. I looked into it on my Cartwright 36 pilothouse cutter when I was considering a circumnaviagtion.

Brad
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Old 18-02-2016, 07:24   #72
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Re: Following Seas and Cockpit Height

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Although I strongly disagree with your earlier assertion to the effect that condomarans are designed and intended to be safe only when sailed in the lee of islands.

Brad
I don't think I ever said that, must have been someone else.
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Old 18-02-2016, 07:30   #73
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Re: Following Seas and Cockpit Height

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I don't think I ever said that, must have been someone else.
Yes, incorrect attribution. It was Barnakiel who made that statement.
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Old 18-02-2016, 08:37   #74
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Re: Following Seas and Cockpit Height

Apologies Estarzinger - it didn't sound like you and I should have re-read the thread!

Cheers!

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Old 19-02-2016, 09:40   #75
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Re: Following Seas and Cockpit Height

One of the good things about sailing is the fun, had a friend in college had a P cat that he took to catalina frequently. Steve had fun, at the time I had Cal 20. Not sure I have ever had s much fun with a boat since. Have had faster and much bigger. The only advice I seem to remember is love the boat you have and sail it well..If the storm is powerful enough you will get swamped from the rear. I prefer to think I am smart enough to prepare for the weather I'm in..if not I will have trouble. Biggest problem is there are too many fine boats to choose from and we all want to think we have the best. There is no greater tool fro safe sailing than experience and the only way to get it is to sail..Don Friday Harbor
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