which prop mercury

[marcumercury]

I've got a 17' Norris craft with a 60 mercury. The original owner had put a new foot on the motor and hadn't changed prop. It had a 12" pitch on it. It would plane out with one person but put two in and one had to go to front for a second. I have tried a 17" pitch and now want plane off period. Don't care about speed. Any suggestions would help.

 

[jestor68]

Re: which prop mercury

I hope your boat has a tachometer so you can tell the rpm the motor is turning at full throttle. We need to know that.

As far prop selection goes, you totally went THE WRONG WAY in pitch selection. If you want better acceleration and load carrying, you go down in pitch..... not up.

I'm guessing that the dry weight of your boat/motor to be around 1450 lbs.(?)

 

[jestor68]

Re: which prop mercury

Using a total calculated weight of 2164lbs, the Mercury prop selector says:

calculated pitch....10.4
calculated rpm......5500
calculated speed....29.9

These recommendations assume a healthy motor putting out full power.

I believe there is a 10.5 pitch prop available. Close enough. A 10 pitch would work too; maybe even better.

 

[marcumercury]

Re: which prop mercury

Yea the tach works. Do u have any idea how many rpm the 60 is supposed to turn? I'll put the 12 back on it and get wot rpm. See I'm not for sure if its the factory motor. Do u think the 60 is to small for the boat? Do u need any pics ?

 

[steelespike]

Re: which prop mercury

We need the year of the motor. If it is a big foot?
Guessing rpm range as 5000-5500.
Need your present wot rpm and gps speed.
I've found 3 different gear ratios depending on year or big foot.
What is the diameter, this could indicate if a big foot.
Boat may have a tag on the transom indicating max hp.
Motor should be 2/3 of the rating.
From the prop size and performance I'm guessing motor is 78-90.
non big foot.

 

[jestor68]

Re: which prop mercury

See I'm not for sure if its the factory motor. Do u think the 60 is to small for the boat? Do u need any pics ?

Visit the Norris Craft web site and see what others with a 17 are running. If you don't need to go 60 mph, a smaller motor will work. The best you can expect with the 60 is about 30 mph.

 

[jestor68]

Re: which prop mercury

If it's the 3 cylinder 2 stroke; the WOT rpm range is 5000-5500 rpm. Do you know what year the motor is?