Hi All. I'm wondering if I have the correct size propeller right now. The shop just installed a new F70 paired with a Yamaha aluminum 17-pitch propeller. The engine topped out at 6400-RPM compare to the 6300-RPM recommended. This is with an empty tank under the center console, no gear, and only one person. They were recommending a 19-size propeller, but I imagine later, with extra weight, this [that is, the 17-pitch] propeller may be the correct choice. I won't be going max speed but want that good [acceleration from a standing start].
What do you guys think? Thanks--Simon
Yamaha F70 Propeller
Re: Yamaha F70 Propeller
Simon - At what height is the motor mounted on the transom? How many bolt holes are empty above the top bolt? If two or three [engine mounting holes are empty above the top bold], the motor is at the right height.
Did you revisit the conversation we had with Tim, Dennis and Sailorman from November?
Did you revisit the conversation we had with Tim, Dennis and Sailorman from November?
1992 Outrage 17
2019 E-TEC 90
2018 LoadRite 18280096VT
Member since 2003
2019 E-TEC 90
2018 LoadRite 18280096VT
Member since 2003
Re: Yamaha F70 Propeller
Simon--as you may know, the rev-limiter on your F70 kicks in at 6450-RPM, so an occasional trip to 6400 won't hurt anything. What trim were your running in your test?
Your comments about the test having minimal weight on board and not caring about top speed are very pertinent. Based on them, that [17-pitch] may be just the right size propeller. I definitely would not go up in pitch to another aluminum propeller.
I would advocate considering a quality stainless propeller. The incremental cost is a tiny fraction of what your new motor set you back, and it will give you top performance for pretty much a lifetime. I may have mentioned before that I am very happy with the Power Tech SCD3 I have on my boat. I have it in the 16-pitch and it's a little under-pitched, similar to your reported situation in that I can hit 6400 if running light and trimmed out a bit. I think that propeller would do very well for you.
I will probably be trying a 17- or 18-pitch version of the SCD3, but not until late spring at the earliest. If the new propeller works, I'd be interested in selling the 16-pitch. I mention that because one option for you would be to simply hang on to your current propeller and see how it works in the various conditions you are in, with a more representative load. And then, if the stars align, you could buy mine and save a few bucks over a new one.
Tim
Your comments about the test having minimal weight on board and not caring about top speed are very pertinent. Based on them, that [17-pitch] may be just the right size propeller. I definitely would not go up in pitch to another aluminum propeller.
I would advocate considering a quality stainless propeller. The incremental cost is a tiny fraction of what your new motor set you back, and it will give you top performance for pretty much a lifetime. I may have mentioned before that I am very happy with the Power Tech SCD3 I have on my boat. I have it in the 16-pitch and it's a little under-pitched, similar to your reported situation in that I can hit 6400 if running light and trimmed out a bit. I think that propeller would do very well for you.
I will probably be trying a 17- or 18-pitch version of the SCD3, but not until late spring at the earliest. If the new propeller works, I'd be interested in selling the 16-pitch. I mention that because one option for you would be to simply hang on to your current propeller and see how it works in the various conditions you are in, with a more representative load. And then, if the stars align, you could buy mine and save a few bucks over a new one.
Tim
Last edited by flymo on Sat Jan 30, 2016 6:15 am, edited 2 times in total.
Re: Yamaha F70 Propeller
I did revisit the post back in November and had the shop install the engine 2 holes up. If it weren't for this forum, the shop would have installed very differently.
I have never driven this boat, ever. Only time I've seen the boat in water is from Tony's posts. I have to admit, it looked pretty nice.
The shop went for a test run to see how the boat performed. And the stats that I was given was based on an empty boat with one person on board. So I imagine that with a full load and at least one person on board, then the prop should be the right size. I'll test out other props this spring/summer but right now I just want to use the boat a little. Never even been on it.
The shop said that the boat was crazy, scary fast. Not sure how that really feels. My last boat was a [21-foot of some other brand than Boston Whaler]. It hit 42 mph.
I read a post from Tony that the boat hit almost 42mph on an aluminum 15 pitch with an F60. That's just really fast. I'm looking for more of a hole shot.
Thanks Tim. I might take you up on that offer for the powertech.
I'm picking the boat up tomorrow but probably can't take it out for break in process for another 2-3 weeks. I'll report back once I get more solid stats on how that engine runs.
Thanks for the information. I'll stick to the 17 for now.
Simon
I have never driven this boat, ever. Only time I've seen the boat in water is from Tony's posts. I have to admit, it looked pretty nice.
The shop went for a test run to see how the boat performed. And the stats that I was given was based on an empty boat with one person on board. So I imagine that with a full load and at least one person on board, then the prop should be the right size. I'll test out other props this spring/summer but right now I just want to use the boat a little. Never even been on it.
The shop said that the boat was crazy, scary fast. Not sure how that really feels. My last boat was a [21-foot of some other brand than Boston Whaler]. It hit 42 mph.
I read a post from Tony that the boat hit almost 42mph on an aluminum 15 pitch with an F60. That's just really fast. I'm looking for more of a hole shot.
Thanks Tim. I might take you up on that offer for the powertech.
I'm picking the boat up tomorrow but probably can't take it out for break in process for another 2-3 weeks. I'll report back once I get more solid stats on how that engine runs.
Thanks for the information. I'll stick to the 17 for now.
Simon
1987 15' Sport CC
Re: Yamaha F70 Propeller
Simon, by all means get some time on your new before deciding on a prop - heck, 5 years into it and I'm still experimenting! The 15 is not really all that fast in the grand scheme of things, but it's so light and quick it feels fast, especially in the configurations where you sit low to the water.
If hole shot is high on your priority list, I can recommend the SCD3 for that as well - it's a total rip. With my Supersport configuration it's actually uncomfortable nailing it from a standing start because the bow goes straight up, but with your center console and forward tank I think you'll be better off.
Just to mention it, if the dealer has already taken the motor to 6400 then you're pretty much done with breaking it in. Hopefully they followed the manual, which calls for 1 hour of slow running, before taking it up on a plane.
Tim
If hole shot is high on your priority list, I can recommend the SCD3 for that as well - it's a total rip. With my Supersport configuration it's actually uncomfortable nailing it from a standing start because the bow goes straight up, but with your center console and forward tank I think you'll be better off.
Just to mention it, if the dealer has already taken the motor to 6400 then you're pretty much done with breaking it in. Hopefully they followed the manual, which calls for 1 hour of slow running, before taking it up on a plane.
Tim