Charlie Rice
Santa Cruz, California
Boat Name: Carol Anne
Model/Year: 1987 Catalina 22
Hull No. 14097
Hailing Port: Santa Cruz, California |
 06/21/2008 6:30 PM Pacific Time
Just got my Nissan tuned. Top hull speed is now 3.5 knots. Does anyone know what the top hull speed should be? I thought I used to get more like 5. |
Steve Morgan
Bayport , NY
Boat Name: no name yet
Model/Year: 1988 wing keel
Hull No. #14444
Hailing Port: Bayport NY |
06/22/2008 8:12 AM Pacific Time
I have nissan 5. I guess it depends on how high you throttle. I usually dont go over 3/4 throttle and avg. about 3.7 knots on the knotmeter. |
Jim Kuertz
Cincinnati, Ohio
Boat Name: Almost Heaven III
Model/Year: 1989 Wing
Hull No. 14834
Hailing Port: Indian Lake, Ohio |
06/22/2008 2:55 PM Pacific Time
Charlie,
Your prop pitch has a lot to do with top speed. As I recall I can get a little over 5 knots with an 8 hp. on my 22 wing. A good outboard pro should be able to tell you if you should go with a speed prop or a power prop to meet your goal. |
Mike Bracket
Clinton Twp, MI
Boat Name: Gunsmoke
Model/Year: 1979
Hull No. 9150
Hailing Port: Lake St Clair MI |
06/22/2008 7:32 PM Pacific Time
Charlie.
I can normally run 5+ with mine but I have a good bottom and I upgraded to a "power prop" when I bought mine. I think it is an 8 Pitch instead of the standard 7 but otherwise...
Not sure what to tell you. Maybe the bottom is fouled?
Mike |
Charlie Rice
Santa Cruz, California
Boat Name: Carol Anne
Model/Year: 1987 Catalina 22
Hull No. 14097
Hailing Port: Santa Cruz, California |
06/22/2008 8:51 PM Pacific Time
Mike,
Talk to me about the fouled bottom. |
Al Gearing
Burleson, Texas
Boat Name: Torch of Freedom
Model/Year: C-22/'76
Hull No. 6448
Hailing Port: Arlington YC |
06/23/2008 7:14 AM Pacific Time
Hull speed is appproximately the square root of the waterline length times any where from 1 to 1.36. In our C22 the water line length is about 20'. Or about 4.47 to 6.08 knots. Some how I doubt that the upper number is attainable for us. Hull speed in the knee of a curve, below which the speed will increase linearly with an increase in power. After the knee, doubling the power will only result in maybe a quarter increase in speed. I have sailed big boats at above hull speed, it is a real thrill. So if you are moving at 5 knots with a moderate amount of power, any greater speed will take a lot more power to gain on it.
For what it's worth,
Al Ge |
Greg Baker
Charlotte, NC
Boat Name: Sea Sharp Minor
Model/Year: Catalina 22 - 1984 - Swing Keel
Hull No. 11823
Hailing Port: Lake Norman Sailing Club |
06/23/2008 8:28 AM Pacific Time
I would definitely have a competent boat shop check the prop. Most outboards off the shelf do not come with props for sailboats. You probably need to have a much lower pitch (think of a lower gear in your car) so the engine rpm can be at optimum when the boat is moving near its hull speed. Prop selection is done by first making a good guess followed by testing to optimize the guess. Normally you would test by measuring the rpm of the engine at wide open throttle and try different pitches to get the rpm within the engine manufacturers recommended value. Of course you don't often run at wide open throttle but this process usually optimizes lower power settings too. |
Mike Bracket
Clinton Twp, MI
Boat Name: Gunsmoke
Model/Year: 1979
Hull No. 9150
Hailing Port: Lake St Clair MI |
06/23/2008 2:44 PM Pacific Time
Charlie: really depends on where you sail but ANYTHING on the bottom of the boat will slow it down. Even a small handful of weed/grass on the keel cable will make a noticible difference. In many midwest lakes, the water is so fouled with agricultural runoff (nitogen) than the moss, sea weed and slime will grow on the bottom regardless of what kind of bottom paint you use. If you let the boat sit for a week or two, she will not slide thru the water as well as if the bottom were freshly scrubbed.
Mike |
Charlie Rice
Santa Cruz, California
Boat Name: Carol Anne
Model/Year: 1987 Catalina 22
Hull No. 14097
Hailing Port: Santa Cruz, California |
06/24/2008 6:37 AM Pacific Time
Thanks for all the comments. Will proceed with your input... |
