speed issue; i/o bowrider

[dimitry]

I am considering purchasing a newer boat: inboard/outboard 130HP 17.5-foot bowrider. Boat is a beaty inside out. The present owner howeevr states that the top speed he observed with 21"-pitch prop was about 30-35 mph. It sounds too low to me, especially considering that my current 115HP Mercury outboard easily gives 55 mpy on a no-bow-rider boat.<br />What speed is reasonable to expect from such a boat?<br />Any comments would be appreciated.

 

[crackerjack]

Re: speed issue; i/o bowrider

Dont expect to get near the 55mph of your outboard! <br />30-35 seems a little slow for a 21p prop. <br />My 18' bowrider with 135hp I/O and 19p prop tops out at around 40 mph.

 

[youmansjason]

Re: speed issue; i/o bowrider

How was he measuring that speed? Was it the boat speedometer or GPS? If it was with the boat speedometer, then it is very likely that the speedometer is wrong. Boat speedometers are notorious for their inaccuracy! The one in my boat is a good 5 MPH off (on the low side).<br /><br />The most accurate way to measure a boat's speed is with a GPS. <br /><br />A boat like that should be running more like 37-40 MPH.

 

[QC]

Re: speed issue; i/o bowrider

How old is the I/O? Older model I/Os were rated at the flywheel and usually delivered about 25 - 30 bhp less at the propshaft which is where OBs are rated . . . So that 130 may actually compare with a 100 OB. It is also about 400-500 lbs heavier. I'd be surprised if it could pull a 21P prop too, sounds like it may be 2 - 4 inches over pitched to me.

 

[craze1cars]

Re: speed issue; i/o bowrider

I have a 18 foot, 1992, 3.0, 115 hp runabout that has a top GPS speed of 36mph on a 17 pitch prop. I can get a couple more out of a 19 pitch but I prefer holeshot. So I let the motor wind up with the smaller prop and sacrifice the top speed.

 

[6 balls]

Re: speed issue; i/o bowrider

i have an 18ft runabout with the 3.0 ltr and a 21 pitch prop with just my wife and i in the boat and low on gas the fastest it has run was 47 mph on the speedo but the motor was running at 5000 rpm (too fast!!!) with an average load at wot i get about 40-43 mph

 

[phantoms]

Re: speed issue; i/o bowrider

What model boat is it? My Brother-in-law has a Tahoe 17.5 ft with the 130hp 4cyl and it will do 40-41mph.

 

[dimitry]

Re: speed issue; i/o bowrider

Many thanks for the input, guys. <br />The boat is 1990 Bayliner with 3L I/O Mercury.

 

[watered down]

Re: speed issue; i/o bowrider

I had the Glastron SX-175, 17' w/135hp I/O. It weighed only 1980# and would top out at 40mph with little weight on board. However, with the two kids, wife & I, it couldn't get over 35 mph.<br /><br />That Bayliner is probably heavier than the Glastron b/c it uses wood. I wouldn't expect to go much more than 35 mph in her with others on board.

 

[ae708]

Re: speed issue; i/o bowrider

My 179 Manta Ray with a 3.0 Mercruiser runs 43mph by the GPS with a 19 pitch Hustler aluminum prop.