How do I...

[NetDoc]

size my prop? Do I have to measure it and calculate pitch or is there an easier way.

In this example, I have a 3.0L Mercruiser engine on a 200 (or 180) Volvo outdrive in a 23' glass 1968 Fibra.

 

[90stingray]

Re: How do I...

Pitch is usually stamped on the hub of the prop. Are you trying to find a prop or replace a prop?

 

[NetDoc]

Re: How do I...

No, I'm just trying to learn about my boat. Thanks for answering the question! Is there anything else that is stamped on the prop? Can I read this number while it's still mounted?

 

[90stingray]

Re: How do I...

Usually the prop part number and pitch is stamped on the hub between the blades. Yes, you can see this while its installed. If its not on the outer hub, look down inside the hub where the nut is... there might be the part number and pitch stamped in there. Anything else you need to figure out?

 

[steelespike]

Re: How do I...

Prop size is written diameter X pitch usually in inches. ie: 14 X 21 .
Numbers may appear near the base of the blades or under the prop nut.
You can measure diameter;measure from center of the bore to the tip of a blade and double.
Diameter is a secondary consideration. If you look up a prop for your drive the diameter
should be right.Usually as pitch goes up diameter goes down.

 

[halfmoa]

Re: How do I...

A bit of a hijack, I'll admit, but what if there are no numbers on the prop? Can a prop shop measure it?

 

[Silvertip]

Re: How do I...

A prop shop can determine pitch using a "pitch block" You measure diameter with a ruller.

 

[halfmoa]

Re: How do I...

A prop shop can determine pitch using a "pitch block" You measure diameter with a ruller.

Thanks! Now all I've got to do is find a prop shop closer than the only one I've located 4 hours away...

 

[steelespike]

Re: How do I...

Our closest prop shop about 5 miles is listed only as "Harter Welding".
There are shops that do it by mail. If its a relatively small prop you may want to consider
new if having to drive many miles or shipping.

 

[NetDoc]

Re: How do I...

All great information! Do we have a picture of a pitch block?

 

[NetDoc]

Re: How do I...

Is this what we are talking about?

 

[steelespike]

Re: How do I...

My neighbor at the river had a set of pitch blocks and all the tools needed to remove
a straight inboard prop ,including a lift to get the boat out of the water, and repitch. He would let anyone he knew and felt was mechanicly inclined to use them.About 40 years ago I had that privilage to repair the drive shaft and repitch my 53 Chris Craft prop. It was kind of exciting ,obviously not something you run into everyday.