Does anyone have stability curves or capsize angle for the 75-84 Hunter 27? I tried Hunter Corp. and surprisingly they had no data on record.
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H27 Capsize Ratio
Maybe you can find it or deduce it from the attached website Dave. It has been a long time since I was on John's site but I think my H37C actually shows well there. Maybe your H27 is in there. Or you could e-mail John if you cannot calculate it yourself. And maybe post the result here?
Maybe you can find it or deduce it from the attached website Dave. It has been a long time since I was on John's site but I think my H37C actually shows well there. Maybe your H27 is in there. Or you could e-mail John if you cannot calculate it yourself. And maybe post the result here?
Dave; Why Do You Care?
For a 27' fixed-keel production boat, how far off could it be? Unless the intent is to do a trans-Atlantic, what is the importance to you to post the question? Not being a SA by way of the question, just questioning because it seems this single-point calculation is getting a lot more attention than it seems to deserve. Rick D.
For a 27' fixed-keel production boat, how far off could it be? Unless the intent is to do a trans-Atlantic, what is the importance to you to post the question? Not being a SA by way of the question, just questioning because it seems this single-point calculation is getting a lot more attention than it seems to deserve. Rick D.
That question comes up from time to time.
The answer is that the resulting figure is not very significant. What surprises me is that you were surprised that Hunter did not have the data. They probably never developed it and after all those boats are more than 20 years old. Is the h27 Cherubini a stable boat? Yes it is compared to those in its class. Can it be sailed offshore? Even a canoe can be rowed offshore if the water is calm or the rower foolish. Is the h27 an offshore boat? No it is not.
The answer is that the resulting figure is not very significant. What surprises me is that you were surprised that Hunter did not have the data. They probably never developed it and after all those boats are more than 20 years old. Is the h27 Cherubini a stable boat? Yes it is compared to those in its class. Can it be sailed offshore? Even a canoe can be rowed offshore if the water is calm or the rower foolish. Is the h27 an offshore boat? No it is not.
Estimated around 130 degrees
The website below estimates the angle of vanishing stability based on a formula in "Adlard Coles' Heavy Weather Sailing". I am not sure of the "hull depth" of the h27: at 1.25 feet the angle of vanishing stability is around 127 degrees, at 1.5 feet, it is 132 degrees. Capsize screen is 1.94. These results show that the h27's design is capable of taking its crew through a heavy storm with breaking waves with the capability of rolling the boat. But it was not manufactured with that use in mind. For instance, the ports in our '77 model are simply not strong enough, and a modification is needed to prevent leaks through the lazarette for another example. Improvements to the rig, sails, storage, fuel and water, safety, ground tackle, and communications systems would also be needed. Such improvements would also be needed by most of the production cruisers built over the past 30 years. If your intended use is coastal cruising, then the 75-84 h27 is one of the better designs available for a couple in its size range. Developments in the past 20 years have emphasized initial stability and cabin volume at the cost of stability in extreme conditions. This shows up in capsize screens from 2.0 to 2.3 for modern designs below 30 feet. I believe this accurately reflects the use intended by 97 percent of buyers. I prefer the sailing ride and looks of the 70's boats with their longer overhangs and more attractive lines. And I sail on the Great Lakes where I can make it to port before a big storm can build up waves that could capsize the boat. I'm not sure whether John Cherubini, or any other designer would have calculated the angle of vanishing stability in the 70's. The design of the "Queen of the Fleet," the h33 of that era would clearly make a great blue water cruiser (with all of the need for modifications described above.) But I certainly understand that Hunter does not maintain and publish design parameters for products they shipped 20-30 years ago! David Lady Lillie
The website below estimates the angle of vanishing stability based on a formula in "Adlard Coles' Heavy Weather Sailing". I am not sure of the "hull depth" of the h27: at 1.25 feet the angle of vanishing stability is around 127 degrees, at 1.5 feet, it is 132 degrees. Capsize screen is 1.94. These results show that the h27's design is capable of taking its crew through a heavy storm with breaking waves with the capability of rolling the boat. But it was not manufactured with that use in mind. For instance, the ports in our '77 model are simply not strong enough, and a modification is needed to prevent leaks through the lazarette for another example. Improvements to the rig, sails, storage, fuel and water, safety, ground tackle, and communications systems would also be needed. Such improvements would also be needed by most of the production cruisers built over the past 30 years. If your intended use is coastal cruising, then the 75-84 h27 is one of the better designs available for a couple in its size range. Developments in the past 20 years have emphasized initial stability and cabin volume at the cost of stability in extreme conditions. This shows up in capsize screens from 2.0 to 2.3 for modern designs below 30 feet. I believe this accurately reflects the use intended by 97 percent of buyers. I prefer the sailing ride and looks of the 70's boats with their longer overhangs and more attractive lines. And I sail on the Great Lakes where I can make it to port before a big storm can build up waves that could capsize the boat. I'm not sure whether John Cherubini, or any other designer would have calculated the angle of vanishing stability in the 70's. The design of the "Queen of the Fleet," the h33 of that era would clearly make a great blue water cruiser (with all of the need for modifications described above.) But I certainly understand that Hunter does not maintain and publish design parameters for products they shipped 20-30 years ago! David Lady Lillie
David and Ed, thanks for the information and the excellent web links. I do appreciate that the angle of vanishing stability is just one of many factors in a boat's heavy weather capability. Nevertheless I like to know as much about my boat as I can, and such figures are at the very least useful to have on hand when a guest nervously asks when the rail is dipped, "Just how far over can this thing safely go?!" I come from some tall ship sailing experience, where stability criteria are front and centre after notable ship tragedies and every ship captian knows his vessel's curves by heart. Actualy I was surprised that is is (theoretically, and exclusive of downflooding) as much as 127 degrees. I'll be sticking to Great Lakes and short coastal sailing with this boat.
Kingston
Dave, the Admiral and I spent a great week in Kingston last summer, and then chartered a C&C 30 for a week of cruising in the Thousand Islands out of Kingston. We really enjoyed your great sailing community! (See the link below.) You'll love your h27 - we sure like ours! David Lady Lillie
Dave, the Admiral and I spent a great week in Kingston last summer, and then chartered a C&C 30 for a week of cruising in the Thousand Islands out of Kingston. We really enjoyed your great sailing community! (See the link below.) You'll love your h27 - we sure like ours! David Lady Lillie
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