What Prop?

Blue197320 · #1 06-08-2012, 07:33 PM

try my 15x17 as a good start. ran good when i had a 150

Blue_Heron · #2 06-08-2012, 08:37 PM

I played with several props on my 20. On a Potter 20 with a 150 Merc, I would start with a Mirage 17p.
Dave

jorgeinmiami · #3 06-09-2012, 02:18 PM

Evan Thanks for the offer when I get ready to hit the water I'll call you maybe we can take both of them out just in case I need a tow...LOL

But anyways is there any way to figure out what size prop I do have?

Right now I have a lot on my plate with family members and their health issues so the boat is on the back burner

McGillicuddy · #4 06-09-2012, 02:58 PM

Jorge,
You prop appears to be an older Yamaha semi-cleaver probably 14" diameter by 17" pitch. Could also be an old Force prop. Unless you find an old prop catalog from the '80s it will be hard to determine exactly as most folks don't document the specifics of their prop. The prop will be a decent match for the MA w/150 Merc combo, but you can do better. It has stern lifting qualities and should turn close to your target 5800 rpms or so.

Probably get you 40 mph at top end +- 2mph. I think a PowerTech MQS3-16 pitch will be your best bet.

To measure diameter, place the prop on a work bench take a square to the edge of a blade and use a tape measure to measure the outer-most point of the blade to the center of the prop hole. That number x 2 is your diameter.

To confirm the pitch a prop shop can lay it on a semi-cleaver repair mold and give you that.

Fr. Frank · #5 06-10-2012, 05:20 PM

Quote:

Originally Posted by McGillicuddy

Jorge,
You prop appears to be an older Yamaha semi-cleaver

That's exactly what it is, Jorge. The 17-M series props are the early Yamaha salt-water props, and provide as much stern lift at high RPMs as the Mercury Mirage. Their weakness is in a reduced rake progression on the outer 1/3 of the blade, which gives them great top-end performance, but weakening their mid-range performance. They run very well as a semi-surfacing prop for WOT/high-rpm performance, with slip ratios that can be down around 8%, but have higher 15%+ slip ratios at greater running depths, at mid-range RPMs.

jorgeinmiami · #6 06-10-2012, 08:32 PM

So I guess I need to be running WOT all the time

Naw It's just the prop that came with the motor.
As the budget get better I will look for a "all around" prop
Most of the time you run in the mid range anyways

I know that you have extensive knowlege on props what do you suggest??

Fr. Frank · #7 06-10-2012, 10:34 PM

Jorge, I think the best easily available all-around prop is used is the Quicksilver Mirage. I would also suggest either the 17" Pitch, or 18" Pitch, assuming you have the 1.85:1 gear ratio lower unit. If you have the 1.65 gear ratio (which would be unusual), then the 15" or 16" pitch is in order.