Checking out prop, rpm's, etc.

dca2

Cadet
Joined
Jan 30, 2008
Messages
13
I am going this weekend to run around in my recently purchased used boat. All systems work and we have already run it on the water. I am interested in all I have read about the proper prop selection. I will post my numbers after I get back.

Prop is a Renegade Offshore 14 1/2 X 21 on a 2000 John. 150 on a 2000 Triton SF18. Boat and motor have about 200 hours and it was taken in for regular maintenance (Brother in Law does not do his own maint. on anything!)

The boat will be used on inland waters, lakes (shallow and deep, not much rough) and Red River (often fast current in the early spring) for tubing and skiing as well as fishing.

I have noticed a fast hole shot but when I run WOT and trim up the motor for more speed (speedometer reads 57 mph), The boat will really pull to the left and I mean fast if the steering wheel is let go. It does not do this at lower speeds or when the motor is trimmed down.

Things to check:
WOT RPM's
GPS speed
Speedometer just for s**ts and giggles

Is there anything else to note while running around?

Anyone know the recommended RPM's for this motor? (I don't have the manual)

Thanks for reading this lengthy post.

Dave
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: Checking out prop, rpm's, etc.

I don't know the max rpm but I believe it developes its power at 5,000 rpm.
Someone should be along with a max reccomendation.Most reccomend something higher like 5,500.don't make any changes until you give us the specs so the pros can evaluate.
As far as pulling left check the trim tab/anode below the antivent plate.
If it pulls left turn the rear of the tab to the left.tab also serves as an anode
may need replaceing.
I'm guessing from my limited experience that is a fairly light boat or an ideal setup.21 pitch,good hole shot 57 mph (though probably less GPS) seems impressive.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Checking out prop, rpm's, etc.

5500 - 5800 rpm for best performance. Prop calculator shows 55 MPH at 5500 RPM with 10% slip.
 

dca2

Cadet
Joined
Jan 30, 2008
Messages
13
Re: Checking out prop, rpm's, etc.

Actual Numbers:
2000 Johnson 150, Renegade Offshore 14.5 X 21; 2000 Triton SF 18

GPS Speed: 52 mph
Boat Speedometer: 58
RPM's, WOT, motor trimmed up: 5100
Hole Shot. motor down: 2-3 sec.

2 adults, 3 kids, full tank of gas

Boat use:
Year-Round -- Fishing on lakes and some river use (all inland)
Summer -- Skiing and Tubing

Thanks,
Dave
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Checking out prop, rpm's, etc.

Do you consider that your "average" load? If you don't have the three kids along, I'd consider that the average load and the engine would likely run in the 55-56 range at 5500 RPM. I would consider that fairly close on setup. However, if you consider the five people an average load, then I'd look at a different prop to get the revs up in the 5500+ range as you are lugging the engine at 5100.
 

dca2

Cadet
Joined
Jan 30, 2008
Messages
13
Re: Checking out prop, rpm's, etc.

Average Summer Load will be the 3 kids + wife. Fishing Load would be me +1 adult and a live well with 30 gal. of water.

My real questions, I guess, is on a budget, does another prop save enough bread to justify the cost? ($400 = ~125 gal. of gas down here) How much of a strain on the motor will pulling a tube with this set up cause?

Thanks for all the input
Dave
 
Top