Prop Pitch, How to tell?

[Blind Bobber]

I really want to thank all of you for your helpful advice. I finally got my new to me boat out on Hagg lake last week. Hooked 3. Anyway my trolling motor battery died after 7 hours. So tried to troll with the 25 Merc. Just too fast even at idle. So my motor came with a spare prop which the seller told me was a slower prop. Slower is fine with me. Truthfully this motor with current prop is much faster than this blind guy should be going anyway. These two props side by side look the same. Where, typically, is the pitch number stamped? Would an untrained eye be able to tell a diffrerent pitch by sight?
BLIND BOBBER
:wave:

[Sensei-san]

It would very difficult to determine propellor pitch by looking at them. You can see gross differences but an inch or two would be hard to detect. Most propellors either have the diameter and pitch stamped on the hub or a part number that can be cross referenced by the manufacturer.

I would take them into a dealer to see what they are pitched at. You might want to investigate getting a trolling plate for your outboard. A lot of freshwater trollers use them instead of a kicker.

[1pump]

My Merc 25's prop is stamped with a part number and the pitch. It's a 13" pitch which is standard for a 25M 2-stroke of that vintage ('87). I troll with mine, but I have a trolling plate.
I doubt the dealer could tell you anything other than what prop it was supposed to come with. It needs to be put on a pitch block to determine the pitch and the only people who have those (as far as I know) are prop shops.
If the spare is a slower pitch it's probably an 11". I think that's the only one available smaller than the 13", at least from Merc. Even if it's an aftermarket wheel it should have a pitch stamped on it, although it might be painted over.

[OutTrolling (ot)]

There is a site www.castlemarine.co.uk/pitch.htm (http://www.castlemarine.co.uk/pitch.htm) that offers a free downloadable program. Plug in some values and it will calculate for you. I have never tried it personally but have seen it on the web. The site also offers some good general info. Might want to check it out and see if it has what you are looking for.
Happy fishing.
OT.

Old fishermen never die, they just smell that way.