Twister_Ken
Well-known member
Ouch! nm
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Stability and Seamanship, Weather and the Legend
- Thread starter Chris_Stannard
- Start date
AlanPound
Member
Re: Category A yachts
I don't think that the AVS ratings >12m & <12m mean that larger boats are liable to have poorer ratings. Rather that smaller boats need higher ratings, as because of their size they are more likely to be knocked down (or knocked down worse)....
Certainly AVS, Capsize Index, STIX etc., are not ideal bases for comparison, but we are struggling here for ANY meaningful means of comparison, and these types of values, flawed though they are, are about all we have (except maybe 'gut feel' based on experience). (Of course, we could always base our comparisons solely on what the manufacturers claim in their literature.......)
So I say: use the figures, understand their limitations, form any opinion you might form independently, and take a view (what else can you do?)
Alan
I don't think that the AVS ratings >12m & <12m mean that larger boats are liable to have poorer ratings. Rather that smaller boats need higher ratings, as because of their size they are more likely to be knocked down (or knocked down worse)....
Certainly AVS, Capsize Index, STIX etc., are not ideal bases for comparison, but we are struggling here for ANY meaningful means of comparison, and these types of values, flawed though they are, are about all we have (except maybe 'gut feel' based on experience). (Of course, we could always base our comparisons solely on what the manufacturers claim in their literature.......)
So I say: use the figures, understand their limitations, form any opinion you might form independently, and take a view (what else can you do?)
Alan
G
Guest
Guest
Re: Category A yachts
I agree entirely. That's what I was struggling in my inarticulate way to say!
I agree entirely. That's what I was struggling in my inarticulate way to say!
DoctorD
New member
I agree the comments should be published in YM - this thread makes fascinating (and impressively sensible and knowledgeable) reading. My boat has good AVS, Ballast ratio, figures and is "Cat A" - but the only true reason I am confidant in her ability is that we have sailed together in some testing conditions (for my level of ability).
G
Guest
Guest
Re: Oops, try that list again
Interesting question ref multihullls, Chippy, but one for which there isnt a clear cut answer. You wont get someone who is prepared to tolerate a Contessa readily accepting the safety of a multihull, but multihullers are no more dispasionnate .
Certainly, the capsize-at-the-drop-of-a-hat claim is bollocks. In fact, it is way harder to capsize a cruising cat than the same length of mono - heavy or light displacement - because of the beam, the lack of a tripping keel, and the weight distribution. That said, the cat wont ever right itself.
Many inverted monos are damaged and some sink as a result. An inverted modern cat will not sink but will be a huge life raft. Fatalities often happen to those in inflatable life rafts, and more rarely to those who stay with a boat.
In theory, a fast multihull would be more able to avoid bad weather, but a cruising multihull is often no faster than a mono in real life.
A multihull is a much less tiring ride in bad seas, which is as well since you cannot leave it to look after itself. Forget heaving to - you have to sail it.
There have been a lot of multihull circumnavigations, particularly in Prout boats, so I think it would be silly to say that a multi can never be an offshore boat. I wouldnt chose one for sailing in the southern ocean, but then I wouldnt chose a small mono either. Something about QE2 size sounds right to me!
I am not a rufty tufty "just a gentle force 6" type of sailor. I sail with my wife, and we do not even leave port if the forcast contains the number 6 - less, if its on the nose. We dont do trips of more than 36 hrs. For this type of lightly crewed family sailing, and having had a mono in the past, I would unhesitatingly recommend a cruising cat. It is safer because it is a better working platorm ,a much less tiring ride, and has a smaller rig. Dont listen to the club bar prejudice - try one.
Sermon over.
Interesting question ref multihullls, Chippy, but one for which there isnt a clear cut answer. You wont get someone who is prepared to tolerate a Contessa readily accepting the safety of a multihull, but multihullers are no more dispasionnate .
Certainly, the capsize-at-the-drop-of-a-hat claim is bollocks. In fact, it is way harder to capsize a cruising cat than the same length of mono - heavy or light displacement - because of the beam, the lack of a tripping keel, and the weight distribution. That said, the cat wont ever right itself.
Many inverted monos are damaged and some sink as a result. An inverted modern cat will not sink but will be a huge life raft. Fatalities often happen to those in inflatable life rafts, and more rarely to those who stay with a boat.
In theory, a fast multihull would be more able to avoid bad weather, but a cruising multihull is often no faster than a mono in real life.
A multihull is a much less tiring ride in bad seas, which is as well since you cannot leave it to look after itself. Forget heaving to - you have to sail it.
There have been a lot of multihull circumnavigations, particularly in Prout boats, so I think it would be silly to say that a multi can never be an offshore boat. I wouldnt chose one for sailing in the southern ocean, but then I wouldnt chose a small mono either. Something about QE2 size sounds right to me!
I am not a rufty tufty "just a gentle force 6" type of sailor. I sail with my wife, and we do not even leave port if the forcast contains the number 6 - less, if its on the nose. We dont do trips of more than 36 hrs. For this type of lightly crewed family sailing, and having had a mono in the past, I would unhesitatingly recommend a cruising cat. It is safer because it is a better working platorm ,a much less tiring ride, and has a smaller rig. Dont listen to the club bar prejudice - try one.
Sermon over.
G
Guest
Guest
Re: Oops, try that list again
Interesting reply.
Not sure about the bit about people prepared to tolerate a Contessa not accepting the safety of a multihull, though! I can see a lot of sense in the pro-multihull arguments.
I don't have practical experience of large multihulls so can't really comment. But I did own a Hobie Cat before the Contessa, so maybe I'm biased. I used the Hobie for cruising... While a Hobie clearly isn't a stable boat, we found that the only times that it capsized unexpectedly was when it buried a bow and pitchpoled.
I seem to remember reading somewhere (I think directed by someone on this forum) that tank testers of cats had had difficulty getting them to capsize at all. I suspect that the most likely way of capsizing a cat may be if she buries a bow when moving quickish and pitchpoles like my Hobie used to only on a bigger scale. I suspect the tank testers may have difficulty recreating that?
Just a thought, maybe I'm wrong.
Interesting reply.
Not sure about the bit about people prepared to tolerate a Contessa not accepting the safety of a multihull, though! I can see a lot of sense in the pro-multihull arguments.
I don't have practical experience of large multihulls so can't really comment. But I did own a Hobie Cat before the Contessa, so maybe I'm biased. I used the Hobie for cruising... While a Hobie clearly isn't a stable boat, we found that the only times that it capsized unexpectedly was when it buried a bow and pitchpoled.
I seem to remember reading somewhere (I think directed by someone on this forum) that tank testers of cats had had difficulty getting them to capsize at all. I suspect that the most likely way of capsizing a cat may be if she buries a bow when moving quickish and pitchpoles like my Hobie used to only on a bigger scale. I suspect the tank testers may have difficulty recreating that?
Just a thought, maybe I'm wrong.
chippie
New member
Re: Oops, try that list again
Thankyou Howard & Simon for your replies. The easier motion in a multihull must be a positive factor in preventing crew fatigue before things get to the stage where the vessel is hove to and the crew straps themselves into their bunks. As a coastal sailor on my trimaran I hope I dont get to that point.
It can be frighteningly obvious that a multihll doesnt spill wind in gusts as a monohull does by heeling. I think that fast cruising cats have a system where the mainsheet is dumped when gusts are too strong.
Some years ago a trimaran by the name of Rose Noelle made headlines when the upturned vessel was washed ashore on Great Barrier Island over 100 days after she had been capsized. According to the owner's account of events it was a 'rogue' wave that roared out of the night and flipped her over.Possibly coupled with a strong gust at the same time. I dont think there are many ,if any cases where people have survived for that long in a liferaft.
This illustrares the point made in earlier postings that it is the sea rather than the wind that catches boats ,monohull or multihull. Interestingly in this case it wasnt particularly stormy or a violent sea state ; a large swell certainly but one that any well found boat could cope with.
Reading that I have done on the subject tends to suggest that trimarans tend to capsize by either tripping forward or diagonally forward. More modern designs tend to have the outrigger bows nearly in line with the main hull to preclude this as much as possible. Also virtually all modern multihulls have semicircular hull sections to prevent too much 'bite ' on the water when flung sideways thus avoiding tripping. I remember reading in one of Tristan Jones' books about a device he called cool tubes which allegedly increased the windward hulls bite on the water. Nothing seemed to come of these. (Given the later doubt of the veracity of some of his claims I'm not surprised.)
I think both monohulls and multihulls have their own sets of pros and cons in any given circumstances. All IMHO of course.
Thankyou Howard & Simon for your replies. The easier motion in a multihull must be a positive factor in preventing crew fatigue before things get to the stage where the vessel is hove to and the crew straps themselves into their bunks. As a coastal sailor on my trimaran I hope I dont get to that point.
It can be frighteningly obvious that a multihll doesnt spill wind in gusts as a monohull does by heeling. I think that fast cruising cats have a system where the mainsheet is dumped when gusts are too strong.
Some years ago a trimaran by the name of Rose Noelle made headlines when the upturned vessel was washed ashore on Great Barrier Island over 100 days after she had been capsized. According to the owner's account of events it was a 'rogue' wave that roared out of the night and flipped her over.Possibly coupled with a strong gust at the same time. I dont think there are many ,if any cases where people have survived for that long in a liferaft.
This illustrares the point made in earlier postings that it is the sea rather than the wind that catches boats ,monohull or multihull. Interestingly in this case it wasnt particularly stormy or a violent sea state ; a large swell certainly but one that any well found boat could cope with.
Reading that I have done on the subject tends to suggest that trimarans tend to capsize by either tripping forward or diagonally forward. More modern designs tend to have the outrigger bows nearly in line with the main hull to preclude this as much as possible. Also virtually all modern multihulls have semicircular hull sections to prevent too much 'bite ' on the water when flung sideways thus avoiding tripping. I remember reading in one of Tristan Jones' books about a device he called cool tubes which allegedly increased the windward hulls bite on the water. Nothing seemed to come of these. (Given the later doubt of the veracity of some of his claims I'm not surprised.)
I think both monohulls and multihulls have their own sets of pros and cons in any given circumstances. All IMHO of course.
