Mar 21, 2011 · Re: RPM vs MPH If you change from a 21 to a 19 you have about a 10% change in pitch and should experience about a 10% increase in RPM. (unless there is a difference in the efficiency of the prop) When you change if you also go to a …

May 7, 2009 · Re: Mph, Rpm, Prop Pitch Question Wild, I had a 19 SeaRay with the same powerplant. I got about the same MPH and RPM as you using a 21" pitch Rapture SS Prop. I would be surprized if you could get that boat to 50MPH. The power needed to increase speed on a boat is nearly exponential.

Jul 23, 2009 · The 3 litre mercruiser (1999) (alpha: 115 HP) on my 18 foot Larson does not get up to target RPM (4400 - 4800) even at WOT. Started with a 23 pitch but only went to 3800 RPM and 42 MPH. Went down to 18 and now at 15 pitch (15.25 diameter) but still only get 4200 RPM at WOT (trimmed) and 38 MPH.

Apr 25, 2009 · i have a 96 18 ft sea ray[175 series] with 3.0 mercruiser took it out today and the boat seemed to be flying across the water. only thing i noticed at 35 mph[about 3/4 throttle] rpm was 4500. i thought this was kind of high. what would be normal? or is this ok?. i …

Nov 4, 2009 · At the same RPM the A will move more water but the B or B/C my well be quicker and the A may out mph them but it might take 1/4 mile to find out. BP298 will have a good idea I'd bet. S CP

Jun 6, 2013 · (All RPM and MPH were done via GPS) On to this year. First time out the boat started right up and sounded great. First time out of the hole shot the boat was very responsive just like when I first got it back after the timing was adjusted last year. The boat was very quick out of the hole and planed out at 4800-4900 RPM and 42-43 MPH.

Oct 26, 2010 · Looking into warming over my motor. Would like to stick with the same props and increase the engine rpm, as there is not many props available for my particular outdrive. Its a 415hp 502, and it has a volvo DPX-A DUO PROP outdrive. 1.78 ratio, with "E3" stainless props it pushes my boat (28' cat) right @ 66 mph at 4950-5000 rpm.

Sep 23, 2007 · Re: 7.4L Mag MPI RPM/MPH - prop slip? I started off chasing a CVX23 and a CSS19. I like the inboard/outboard boats. Don't care for working on outboards. The CVX sold too quickly and I couldn't come to a price agreement on the CSS (it needed 2-3k in mechanical work). So I got under the dash...

Jul 24, 2011 · Re: Mercriuser 3.0 only reaching top speed of 25 mph and 3500 rpm, and steering is ti If you have guns, a shotgun barrel brush works well to clean up the aluminum steering tube. Or you could use a small brass brush with a plastic handle and melt the handle straight, so it will fit into the tube, then clean it from both sides.

May 4, 2005 · i have a 23ft 1980 wellcraft with a bb 454 and an alpha 1 out drive .is it normal for the rpm to match the mph? IF not what can cause that problem THANKS