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  23 WALKAROUND, Single HONDA 250-HP

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Author Topic:   23 WALKAROUND, Single HONDA 250-HP
acseatsri posted 04-12-2015 07:44 PM ET (US)   Profile for acseatsri   Send Email to acseatsri  
What (fixed hub) propellers will fit [a BF250} V6 Honda outboard? I have someone offering me a 15-1/4 x 17 propeller from a Yamaha 300 HPDI. I also have a Rebel 15.5 x 17 from an E-TEC I can try, if it fits. The boat is a 23 WALKAROUND and no Whaler Drive.

4050-lbs Boat
630-lbs Engine
860-lbs 150 Gallons fuel
1200-lbs Max gear and people

6740-lbs Heavily loaded

Tom W Clark posted 04-12-2015 08:10 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Any large (4.75) propeller, from any manufacturer, will fit a V6 Honda.
jimh posted 04-13-2015 01:06 AM ET (US)     Profile for jimh  Send Email to jimh     
Please post articles about propellers to PERFORMANCE. I have moved this thread here.
jimh posted 04-13-2015 12:06 PM ET (US)     Profile for jimh  Send Email to jimh     
From the information you have given in other threads, I believe you are asking about a Honda 250-HP outboard engine on the 23 WALKAROUND.

Plugging in numbers into my CROUCH'S CALCULATOR:

WEIGHT = 6740
POWER = 250
HULL FACTOR = 180

the calculated boat speed is 34.7-MPH

Using my PROPELLER CALCULATOR and with information from Honda's specifications for the BF250:

RPM = 6000
RATIO = 2
PITCH = (to be calculated)
SLIP = 10
SPEED = 34.7

the calculated PITCH is only 13.6. I wonder how the 17-pitch propellers you are going to test will work for this application.

Working the problem the other way, and starting with 17-pitch, the boat speed works out to be 43.5-MPH. Then going to CROUCH's CALCULATOR, you'd need a HULL FACTOR of 226 to be able to reach that speed with the power and weight. I don't think the 23 WALKAROUND hull is that easily driven.

acseatsri posted 04-13-2015 07:04 PM ET (US)     Profile for acseatsri  Send Email to acseatsri     
Jim--the reason I think it MIGHT work is my friend's Grady-White 23 Gulfstream (with 9.5-foot beam and engine bracket) with a Yamaha 250-HP Ox66 does almost 40-MPH with a 15.25 x 17 propeller of unknown manufacturer. I believe the gear ratio is 1.86, which would require even more power to spin compared to the 2.0 ratio on the Honda. The propellers I mentioned are available for free to test.
jimh posted 04-15-2015 09:35 AM ET (US)     Profile for jimh  Send Email to jimh     
Boat speed is going to be proportional to weight and power. If you can reduce the 1,200-lbs of crew and gear, you will have more speed potential.

If the boat weight is down to about 6,000-lbs (or 740-lbs less than your "maximum") and we assume a hull constant of 200 (which may be reasonable), then we could expect 250-HP to push the boat to about 40-MPH.

CROUCH'S CALCULATOR
http://continuouswave.com/cgi-bin/crouchcalc.pl

To give 40-MPH from the 6000-RPM engine speed through 2:1 gears, the propeller pitch would be about 15 to 16-pitch

PROPELLER CALCULATOR
http://continuouswave.com/cgi-bin/propcalc.pl

In looking at some prior reports of the 23 WALKAROUND performance, I found a mention of 47-MPH with 300-HP, but that was on a boat with Whaler Drive. The claimed weight was 8,500-lbs. Those numbers result in a hull factor calculation of 250, which is just not even believable. Hull factors of 250 are found on racing hydroplanes, not on deep-V hulls with Whaler Drives.


Cf.: http://continuouswave.com/ubb/Forum4/HTML/005281.html

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