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ContinuousWave Whaler Moderated Discussion Areas ContinuousWave: Whaler Performance Propeller for a 15 Classic with 90-HP
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Author | Topic: Propeller for a 15 Classic with 90-HP |
edwardschnog |
posted 04-12-2007 08:45 AM ET (US)
Hello to all of you... I was wondering who can give me some advice on which prop to use, to get the highest possible speed out of a 15 classic (Alert) whaler with a 90HP 2-stroke Yamaha engine. Data of the 90HP Yamaha engine: RPM range: 5000-5500 Shaft length: 20 inch Gear ratio: 13:26 (2) Weight: 261 lb (119 kg) According to this diagram the ideal prop pitch should be 22". Diameter-Pitch-RPM----Gear/ratio---Slip--Mph Can anyone with practical experience inform me what the best prop for this boat/engine combo is and how to setup the engine to the transom to get the highest possible speed and less chine walking !! Thanks, |
runpasthefence |
posted 04-12-2007 09:08 AM ET (US)
http://continuouswave.com/ubb/Forum4/HTML/005164.html A Yamaha 90 will not spin a 22" pitch prop on a 15' Alert. There are several ways to raise your motor on the transom of your Alert. One is to simply mount the motor in the bottom-most set of holes. Another is to use a manual or hydraulic jack plate/setback plate. These not only raise your engine, they also set the engine back as to create a greater fulcrum effect when trimming th boat. Because the 15' hull's lifting strakes do not extend to the transom of the boat, trim angle has much influence on chine walking as well. If you trim the boat onto the lifting strakes you will eliminate chine walking at WOT. However, you will lose speed as you increase wetted surface. You may also want to invest in hydraulic or dual cable steering as steering input also has much influence on chine walking. |
Tom W Clark |
posted 04-12-2007 10:00 AM ET (US)
Edward, Your calculations are sound, but it is always best to use some baseline data as a point of departure when trying to improve the performance of an outboard powered boat through the use of different propeller(s). What propeller are you using now? What speed are you seeing with it? |
edwardschnog |
posted 04-12-2007 11:44 AM ET (US)
Dear All, Thanks for the sent info. This will really help me alot. Has anyone ever tried the Pro series Yamaha prop?
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The Judge |
posted 04-12-2007 02:59 PM ET (US)
Do a search and you will find that most are running the 19". |
Tom W Clark |
posted 04-13-2007 09:40 AM ET (US)
I suspect the Yamaha Pro Series is made for Yamaha by Precision Propeller, Inc. the maker of the Stiletto and Turbo brands. If so, the 21" Pro Series will perform like a 22" or 23" prop form most other manufacurers. i do not think the 90 HP Yamaha will be able to turn it that high on the slightly heavier Alert 15. |
Fishcop |
posted 04-13-2007 11:15 AM ET (US)
Get the 90hp and a Stiletto Advantage 1 19p. I have the 90hp Yamaha on my 15' with an 18gal tank and it goes faster than you would ever want to go. Lots of power for pulling water toys and people. I put a doel fin on and it lost 2mph, but does not get too bad now with the chine walking. Tom W. Clark can get you the prop, once you have the engine. Oh yeah, use a lanyard for the kill switch! http://img.photobucket.com/albums/v219/Waha/100_0928.jpg http://img.photobucket.com/albums/v219/Waha/100_0933.jpg http://img.photobucket.com/albums/v219/Waha/100_0929.jpg |
Fishcop |
posted 04-13-2007 11:20 AM ET (US)
Sorry, Third hold down from the top, you should expect upper 40's. It will feel much faster! Good luck, Andy |
edwardschnog |
posted 04-13-2007 10:17 PM ET (US)
Nice pictures Mr. fishcop ! If I decide to buy a 90Hp for my Alert15 I would certainly go for the Yamaha Pro Series 13.5x19 prop. I really appreciate all the support I got from this forum.
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an86carrera |
posted 04-13-2007 10:58 PM ET (US)
I would guess that the Alert is a bit heavier But, 90hp on a 15' will be great. Len |
lastmango |
posted 04-17-2007 06:16 PM ET (US)
Edward, Isaw where you were looking for info on props for the 90HP setup on your 15'. I left you some info over on the discusion[1982 sport 15 46-MPH] thread. |
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