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RPM's @ 25 mph on a Horizon 250/260 w/Volvo 5.7Gi DP
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Author:  H250_SC [ Thu Aug 19, 2010 7:56 pm ]
Post subject:  RPM's @ 25 mph on a Horizon 250/260 w/Volvo 5.7Gi DP
Can anyone tell me the approximate RPMs you're getting on a Horizon 250/260 @ 25 MPH equipped with the Volvo 5.7Gi DP?
I thought I'd be below 3,000 but am over that.
Thanks for your help!
Author:  230 Mike [ Thu Aug 19, 2010 10:01 pm ]
Post subject:  Re: RPM's @ 25 mph on a Horizon 250/260 w/Volvo 5.7Gi DP
I'd guess very close to 3K, but not much more than that. What props do you have?
Author:  H250_SC [ Thu Aug 19, 2010 11:02 pm ]
Post subject:  Re: RPM's @ 25 mph on a Horizon 250/260 w/Volvo 5.7Gi DP
Thanks for the reply. I'm going to say mine is around 3,200-3,300 or so. Mine has the dual stainless props, but I know they're the DP's that came on it originally. The original owner only put 70 hours on her when I took ownership in June.
Author:  Flying Sushi [ Fri Aug 20, 2010 7:15 am ]
Post subject:  Re: RPM's @ 25 mph on a Horizon 250/260 w/Volvo 5.7Gi DP
I have a feeling you have a set of F4 props (or even F3s) .... 250/260 is a big boat for 5.7 Gi so the original owner or dealer could put them on where typically F5s.
Author:  JDW250 [ Fri Aug 20, 2010 7:38 am ]
Post subject:  Re: RPM's @ 25 mph on a Horizon 250/260 w/Volvo 5.7Gi DP
What's your RPM's at wide open throttle? I'm assuming you were using your dash speedo rather than GPS to determine MPH. If using the dash, we'll all have different responses as to RPMs at given speeds because the speedos are not that accurate. I don't have your power package, but according to the manual, you should expect to see RPMs at WOT between 4600 to 5000. If you can't hit 4600 @ WOT, then my guess would be the same as Flying Sushi's in that the dealer swapped out the original F5 props to get the boat out of the water faster. Also, you should be able to see the VP size designation on the props (F5, F4, etc).
Author:  M3eater [ Fri Aug 20, 2010 7:41 am ]
Post subject:  Re: RPM's @ 25 mph on a Horizon 250/260 w/Volvo 5.7Gi DP
The Volvo 5.7GiDP (280hp) would have originally had F5 props. According to FW, this produces about 29mph at 3000 RPM. Of course, your mileage may vary , as they say.

Our 97 245 Sundowner, with the 280hp 5.7GiDP and F6 props, once up on plane, would run about 25mph at 2500 rpm, 30mph at 3000 rpm, etc. It also really did not need smaller pitch porps (F5, for instance), unless you were really into boarding or skiing and pulling up two at a time or had a loaded boat and wanted to come up really fast.

Our 268 Vista has the same engine, but has the F4 props. Here, we are turning about 3300 to 3500rpm to go around 25 to 27 mph.

As noted, check your props and let us know what you have. With our experience with the 245 Sundowner, I would say that you should be able to run the F6 props if lower RPM per speed is your goal. However, we must also remember that the gearcase ratios may be different on all of these applications too.

EDIT - JW's post came in just as I was doing mine .... minor correction .... if you have smaller props (F4 instead of F5), you would be able to OVER-rev the max RPM.
Author:  H250_SC [ Fri Aug 20, 2010 9:12 am ]
Post subject:  Re: RPM's @ 25 mph on a Horizon 250/260 w/Volvo 5.7Gi DP
Excellent responses guys and I really do appreciate it. I'm new at all this and the info has been enlightening. I have a hunch he may have had the F4 props put on when new. I will check this weekend and post back. BTW, the speed was via my GPS (not dashboard speedo)....but I've not run her WOT, only because I have my 1 year old on board and my wife will give me the evil eye, :twisted: haha.
Author:  TX H210SS [ Fri Aug 20, 2010 9:36 am ]
Post subject:  Re: RPM's @ 25 mph on a Horizon 250/260 w/Volvo 5.7Gi DP
One other thing to keep in mind- as you near the most effecient speed for your boat the rpm to speed ratio will be reduced......I can't see 25mph being the effecient speed for that boat.......i would imagine that your looking at around the 32 mph range for that boat (just a guess). I can see that boat (24') still squating somewhat at 25 mph so it's taking more rpm to push that extra water.

Even with towing a wakeboarder i'm running around 18 mph and my rpms to maintain that constant speed will vary a lot depending on wind, water, etc...thats why the high end wakeboats have a "perfect pass" option that will constantly adjust the throttle to keep same speed.

My suggestion is to find and run the optimum speed and check your rpm's then. I have never seen a boat run rpm to speed ratio the same thru the entire power band.....ie....2,000 rpms at 20mph, 2,500 at 25mph 3,000 rpms at 30mph. 3,500 at 35mph - That just will not happen becuase the forces on the boat in the water change so much at those speeds.
Author:  H250_SC [ Fri Aug 20, 2010 10:31 pm ]
Post subject:  Re: RPM's @ 25 mph on a Horizon 250/260 w/Volvo 5.7Gi DP
Thanks again guys....and it looks like I'm not so much off the norm for my H250 w/5.7GI DP....At a GPS indicated 25.7, I was just a touch off above 3,000 rpms. God knows why I originally thought it was higher than that....so all seems OK. Thanks again for all the information!
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