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Myacht lll
33 Posts |
 Posted - 08/15/2009 : 4:54:03 PM
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Does anyone know the formula for figuring displacement speed. I think mine should be around 6-8 knots but it would be nice to know exactly for those times when you want to relax and not be in any hurry. Might as well be getting the best economy.
Hugh
1988 28 Voyager
Southwest Fl.
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Jimbo Song
238 Posts |
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Myacht lll
33 Posts |
Posted - 08/16/2009 : 4:32:05 PM
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| Interesting. According to that website, my hull speed is about 14 mph. A lot faster than I thought. |
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Bob On This
USA
175 Posts |
Posted - 08/16/2009 : 5:07:38 PM
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Looks like the Voyager at around 27' WL length is a little under 7 knots, or about 8 MPH.
Looks right, ?????
Bob
Diver Down |
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ryanonthebeach
1 Posts |
Posted - 08/17/2009 : 02:19:18 AM
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Guys, the formulas I used on the Boat Speed calculator are from Whyman and David Gerr.
There will obviously be differences in speed based on the hull design. A good reference for this is David Gerr's, propeller handbook, although it doesn't contain Whyman's formula it's a great reference for speed and propeller selection.
There is a good article by David from the westlawn design school which has some more information you may find useful.
http://www.westlawn.edu/news/WestlawnMasthead07_Sept08.pdf
Thanks
RyanOnTheBeach
www.psychosnail.com |
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Jimbo Song
238 Posts |
Posted - 08/17/2009 : 09:26:14 AM
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Not sure what you are looking at. The "theoretical" hull speed for a 28' Voyager is 7.94 kts. Most 27'-28' Carvers Butt Angle is either 6 or 7 degrees. Not sure about the 27'ers but the 28' Voyager weighs 16,000 lbs.
Personally, experience teaches me that my actual hull speed is a bit less, around 7.5 kts.
Bob
quote:
Originally posted by Myacht lll
Interesting. According to that website, my hull speed is about 14 mph. A lot faster than I thought.
1987 Carver Voyager 28
"Jimbo Song"
Palm Coast, FL |
Edited by - Jimbo Song on 08/17/2009 09:30:24 AM |
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Jimbo Song
238 Posts |
Posted - 08/17/2009 : 09:28:24 AM
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Voyagers and Mariners are measured LWL. So, the wetted area for a Voyager 28 is 28'.
Bob
quote:
Originally posted by Bob On This
Looks like the Voyager at around 27' WL length is a little under 7 knots, or about 8 MPH.
Looks right, ?????
Bob
Diver Down
1987 Carver Voyager 28
"Jimbo Song"
Palm Coast, FL |
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Myacht lll
33 Posts |
Posted - 08/17/2009 : 4:49:17 PM
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I'm a little confused about a couple of things. The web site is asking for a quater beam butt angle. Aren't these angles measured to the half beam or from the center line to the outside edge. What about the weight? My 28 1988 28 Voyager is supposed to weigh 10300 lbs dry weight. We we hauled it out at the survey it was 12500 obviously due to gear,fuel, water etc.
Hugh
1988 28 Voyager
Southwest Fl. |
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Jimbo Song
238 Posts |
Posted - 08/17/2009 : 7:16:24 PM
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I think they want the quarter beam due the the chine angle. I'm no expert but they think the quarter beam is more accurate.
I've never weighed mine but the Coast Guard Doc (both original and current) show the weight as 16,000.
Just going by what I've read as far as the calculation goes. I think the best calculator is what we hear and feel when underway. Mine seems to be best just under 8 kts.
Bob
quote:
Originally posted by Myacht lll
I'm a little confused about a couple of things. The web site is asking for a quater beam butt angle. Aren't these angles measured to the half beam or from the center line to the outside edge. What about the weight? My 28 1988 28 Voyager is supposed to weigh 10300 lbs dry weight. We we hauled it out at the survey it was 12500 obviously due to gear,fuel, water etc.
Hugh
1988 28 Voyager
Southwest Fl.
1987 Carver Voyager 28
"Jimbo Song"
Palm Coast, FL |
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Topic |
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Displacement speed
