Props* 170CC w/F60 Yamaha

[mtty]

A good friend of mine purchased the above boat a few months ago. After having the boat awhile he's now concerned about his prop. Rather than experimenting I thought I'd ask those with similiarly equiped boats. Currently , he's running a 10 X 15 prop and turning 4000 rpms. According to the Yamaha site wide open throttle is between 5000 and 6000 rpms. He obviously needs to go down in pitch and could probably go up in diameter. As a point of reference I'd like to know what size and rpm are you getting out of your 170 equiped with the F60.

[Davekfl]

I have a 170 Bass with the f60. My prop is 10 3/8 by 13 and I can easily exceed 6000 rpm.
I view this as a problem and I am thinking of going up in pitch to get the rpm down.
I remember someone else that got good performance with the 10 by 15 prop which is what your friend has. If you are only getting 4000 rpm you have more than a prop problem. I think the 10 by 15 is probably the right prop for this boat and motor.
Dave K ( Sarasota, Florida)

[mtty]

You may be right Davekfl. As I recall when my boat was new I had a problem with the tach. There was a setting on the back of the tach where you adjusted it for the number of "poles" the alternator had. To this day I haven't a clue what a pole is on a tach. I resolved the issue by adjusting the setting at the rear of the tach and then running WOT and checking the reading on the tach. As I recall I had to do this a couple of times. Once I was in the ballpark of manufactures WOT recommendation for RPMs I assumed it was on the correct setting for "poles". Each setting produced significant changes in the RPM reading( 1500 to 4000 RPMs) so I felt relatively safe to assume I had the right setting. I think I'll recommend he check his poles before he reprops. It'd definitely be cheaper.

I'd still be interested in what prop others are running on their 170 with the Yamaha F60.


As a post script, who knows how I ever broke my engine in. I'd imagine it was at slower speeds/rpms than manufacturer recommends. What a great opportunity for dealers to properly learn something about rigging.

[Putershark]

I say compare your findings performance wise with the Yamaha test data found on this page http://www.yamaha-motor.com/outboard...px?ls=outboard

On steps 1 through 3 just choose "All" then on step 4 choose "Triumph" as the builder and use the data that comes the closest to your configuration.

[mtty]

I was looking at that site this weekend. Problem is that the data is for an F75. I'm looking for info on any 170 series with an F60.

[Putershark]

In reality, I bet the only difference between the 2 engines is more than likely only ECU programming for I think that stroke, bore, and CID on the 2 engines is about the same

If anything you would pretty much only see the 15 horsepower difference in the bottom end (and the ability to swing a slightly larger prop), for prop slippage would come into play long before much of a top end speed loss between the 2 engines could be really found...

I'm running an 11X13 aluminum prop on my 170DC with a 60 Yamaha and at WOT I'm hitting 6100 rpms. I tried different props (14" aluminum and 15" ss) but none of them would run around the recommended 5500 - 5600 rpm. The 14" would turn 5100 rpm wot and the 15" would only turn 4700 rpm wot. I settled for the 11X13. I usually run the boat around 4200 - 4500 rpm anyway, only opening it up to about 5900 rpm for a brief period when I head back in so 6100 rpm at wot has not really been a problem.

[Davekfl]

DeerHunter
Were the 14 and 15 pitch props the same diameter as the 11X13 prop you have? If they were also 11 inch diameter it just doesnt make sense that one inch in pitch would cause a 1000 rpm difference at wot. I read in some mag that a 1 inch pitch up should decrease your wot by 200 to 300 rpm. Certainly not a 1000! Thats why I was looking at getting a
10 3/8 X 14 or 10 3/8 X 15 prop to replace my current prop that is 10 3/8 X 13.
With my current prop I also can do 6100 rpm at wot.
Dave K ( Sarasota, Florida)

Dave,

The 14" was an 11x14, at least that was how it was marked. Like you, I thought I should drop 200 - 300 rpm per 1" of pitch. I can't remember what diameter the 15" was due to an early onset of oldtimers. I've been contemplating a composite prop, maybe that will get the motor into the optimum range at wot.

Tom