prop survey

reelapeelin: I hooked up my merc tach yesterday and ran the 3 blade aluminum 15.5 by 17 and it was a real eye opener. Red line is 5,600 for the Merc 150. I ran it up to a little over 5,400 and the GPS speed was right at 41 MPH solid with a half tank of gas , trimmed up and just me. I am now using the 4 blade comprop as a spare. I think I am going to leave well enough alone...Many thanks for your prop advice , Frank
 
sfprovyn, GLAD to hear it worked out for ya!! ;D ...that size prop seems to be turnin' in best numbers for these V 20s w/ 150s... 8)...
 
I've got a 260hp Volvo I/O 280T with a Michigan 15x19 3 blade aluminum prop.  I feel my numbers could really be improved with a better prop, but I'm having trouble getting numbers for it.  I don't even know what my WOT rpm is.  The highest I've ever taken it was 4000 rpm, the book states 4400 for WOT, but it seems like I have a lot more to give it.  The trouble is, I hardly ever get any flat water here and the boat is coming completely out of the water by 4000.  My cruise is only 28 mph at 3200 rpm and 2500 rpm only gets me 12 mph.  I would like something that holds on to the water a little better at 2500 and would help pick up my cruise some.  I could care less about the top end, I've got no use for that.  I was looking at a 14 3/8ths x 19 4 blade stainless.  There may be a 330-350 hp engine in this boat's future as well (fuel efficiency reasons).  Don't worry about overpowering the hull, the motor will be derated from a 5500 rpm redline to 4500 which should keep me within the 310 horsepower rating for my hull. These numbers are with full gas, gear, and 2 POB.
 
18.5 dia
aluminum
5500 rpm 42 mph

i have a new rebuilt chevy 305 with a 2 barrel.......saves gas!

volvo penta 280 outdrive
 
sfprovyn - Keep your eyes peeled on ebay for

17 Merc Mirage Plus
17 or 19 Mercury Offshore (Vensura)
19 Mercury Laser2
17 or 19 Mercury Tempest

The Mirage, Offshore and Laser 2 pop up on ebay - now and again for under $200. You'll pick up an extra 2-4 mph . . . just by changing to a thinner blade stainless. These are all good designs above.
 
After hangin' on the Honda, I tried a Merc Mirage 15 1/2 x 17...GREAT performance, but a little too heavy and caused a rattle in the gear-case...would probably turn in good numbers on the 150 Merc on a V-20... ;)...
 
I'm with Big Joe, 1980 175 Evinrude and I run a 15 X 17, I do mostly off shore fishing and have never really been that concerned with top end. What I like about the 15 X 17 is that it is more of a power prop, I can set the throttle and the trim and push my way solidly through a 3 foot sea without any slippage and a fairly smooth ride.


steplift20 said:
hmmm i took her out for the first time yesturday with my new prop   15x17  and she ran goood
top speed was about 32mph   no slippage and the tach was about 5700
but how come you guys get moor speed than me
try i need to paint the bottom but maybe i would pick up   what 2 mph more
Click to expand...
 
what speeds are other getting with 200 HP O/B motors.
I'd really like to know what speeds you all are getting with 225 hp O/B motors
 
'73 Center Console

Original motor
Evinrude '75 135hp
max speeds
4900 RPM @ 35 MPH 13x19 SS (old beat up prop)
4600 RPM @ 31 MPH 13.25x17 Alu (new $130 Mich Wheel)

Upgraded motor to:
Evinrude '83 175hp
original old prop SST 14-1/4x21 4500rpm @ 43MPH (max)

replaced with $50 ebay prop, 15x17 SST II
tops out fully loaded at 43mph (GPS) @ 5400rpm
normal cruising speed of 30mph @ 3800rpm

Keep in mind when comparing numbers, the hp rating change in '84/'85 means this 175hp would be about the same as an '85 and newer 150hp.
 
man i'm so glad to see them results Brad great that's the same setup i and building currently glad to know my prop is close or right.
 
Those results are an educated guess. I don't have a gps and you can't trust a boat speedometer. I've owned and been on several boats and it does seem to haul a$$ for as heavy as she is. I try to lighten the load as much as possible only carrying necessary gear, but I always have a full fuel tank.
 
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