I've read this term a few times while looking at different boats, could some one please explain to me what it means and what the numbers mean. the 2.37 was used for a Hunter 23. Are these good numbers for this boat ? Glenn
Capsize screen 2.37
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My understanding is under 2 is best
My understanding is under 2 is best for an offshore boat. This boat was never intended for offshore so this rating is probably great and means it is a fast boat but not as stable as larger offshore boats.
My understanding is under 2 is best for an offshore boat. This boat was never intended for offshore so this rating is probably great and means it is a fast boat but not as stable as larger offshore boats.
beam divided by displacement
It tells you about initial stability sort of. The formula is very simple and does not take into account anything about the hull shape or topsides, keel etc. Just the use it to compare between boats but don't not buy a boat just because it has a cap screen above 2.0 The effect of the captain is MUCH more important than the vessels capsize screen. In the traditional sense a good captain can get a rowboat through a hurricane and a bad one can't sail a rubber duck in a bathtub.
It tells you about initial stability sort of. The formula is very simple and does not take into account anything about the hull shape or topsides, keel etc. Just the use it to compare between boats but don't not buy a boat just because it has a cap screen above 2.0 The effect of the captain is MUCH more important than the vessels capsize screen. In the traditional sense a good captain can get a rowboat through a hurricane and a bad one can't sail a rubber duck in a bathtub.
Size does matter.
The capsize ratio is meant to be an index of comparison indicating relative stability among boats. I find this ratio to be rather useless and misleading as it just takes two items into consideration, displacement( displacement of the weight of water in cubic ft) and beam (in feet). It may have some value in comparing boats of same configuration and similar size but most useless in trying to compare a 22' boat with a 40' vessel. It is the recommendation that an offshore vessel should have a CR of under 2 but by no means should it be concluded that any boat with a CR of under 2 is a safe offshore vessel. Believe me I have heard the argument being made by the owner of a 27' production boat claiming that his boat had a better CR than a 32' and concludying his boat would handle better offshore. I like Bill's comparison of captains and that may be a better indicator than this ratio.
The capsize ratio is meant to be an index of comparison indicating relative stability among boats. I find this ratio to be rather useless and misleading as it just takes two items into consideration, displacement( displacement of the weight of water in cubic ft) and beam (in feet). It may have some value in comparing boats of same configuration and similar size but most useless in trying to compare a 22' boat with a 40' vessel. It is the recommendation that an offshore vessel should have a CR of under 2 but by no means should it be concluded that any boat with a CR of under 2 is a safe offshore vessel. Believe me I have heard the argument being made by the owner of a 27' production boat claiming that his boat had a better CR than a 32' and concludying his boat would handle better offshore. I like Bill's comparison of captains and that may be a better indicator than this ratio.
Capsize Screen - History & Meaning
About 20 years ago, a violent storm hit the Fastnet fleet racing between Ireland and the UK. A number of boats, and some crew were lost. This resulted in extensive testing and analysis, much of it in the UK. It was determined that any vessel struck broadside by a breaking wave higher than the beam of the vessel will capsize - roll upside down. Most sailboats are stable upside down, until another wave (usually smaller than the capsizing wave) gives the boat enough of a roll to break out of the inverted stable position, and roll back to right side up. Despite its simplicity, the capsize screen was developed during the research as a pretty good indicator of the likelihood that the boat will right itself after a capsize. It tells nothing about comfort or maneuverability of the boat. But it does indicate survivability in extreme conditions, like those of the fateful Fastnet race. Since boat designers understand this issue , a boat with a capsize screen above 2 has not been designed to survive a severe storm at sea. In fact, its wide beam will probably give it substantial initial, form stability. This means the ability to carry more sail in less than severe conditions. This is a popular choice for a coastal cruiser that can make it to port before the extreme conditions that could cause a capsize can build up. So the Hunter 23 is not a blue water cruiser. But it is a great daysailer or overnighter in coastal waters. What do you want to do with a sailboat? Together with the other performance ratios, capsize screen can help you get tp the boat you want! David :ady Lillie
About 20 years ago, a violent storm hit the Fastnet fleet racing between Ireland and the UK. A number of boats, and some crew were lost. This resulted in extensive testing and analysis, much of it in the UK. It was determined that any vessel struck broadside by a breaking wave higher than the beam of the vessel will capsize - roll upside down. Most sailboats are stable upside down, until another wave (usually smaller than the capsizing wave) gives the boat enough of a roll to break out of the inverted stable position, and roll back to right side up. Despite its simplicity, the capsize screen was developed during the research as a pretty good indicator of the likelihood that the boat will right itself after a capsize. It tells nothing about comfort or maneuverability of the boat. But it does indicate survivability in extreme conditions, like those of the fateful Fastnet race. Since boat designers understand this issue , a boat with a capsize screen above 2 has not been designed to survive a severe storm at sea. In fact, its wide beam will probably give it substantial initial, form stability. This means the ability to carry more sail in less than severe conditions. This is a popular choice for a coastal cruiser that can make it to port before the extreme conditions that could cause a capsize can build up. So the Hunter 23 is not a blue water cruiser. But it is a great daysailer or overnighter in coastal waters. What do you want to do with a sailboat? Together with the other performance ratios, capsize screen can help you get tp the boat you want! David :ady Lillie
Well Done !
Thanks every one, I have a better understanding now. Numbers are nice I guess if your smart enough to understand them and how they relate to things you are using but for an old guy with not too much smarts they can be overwhelming...... Thanks for clearing this up for me. Glenn
Thanks every one, I have a better understanding now. Numbers are nice I guess if your smart enough to understand them and how they relate to things you are using but for an old guy with not too much smarts they can be overwhelming...... Thanks for clearing this up for me. Glenn
Numbers
Glenn, I'm new to sailing and have been amazed how technical it can get. I see that you're in Ventura. I have my H26 in the Ventura Isle Marina and really like it there, Paul
Glenn, I'm new to sailing and have been amazed how technical it can get. I see that you're in Ventura. I have my H26 in the Ventura Isle Marina and really like it there, Paul
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