Prop Shaft Size

[CapeBob]

I have forgotten the shaft size of my 1979 Prairie36 with twin Perkins 4.236 engines. Many thanks in advance for the answer.

 

[C lectric]

Don't have a specific answer.
Do you have access from the boat inside to measure the shaft?
Use a caliper, a spring loaded inside caliper. Then go down and measure the shaft.

Then you can use a tape to see the diameter.

Amazon, Harbour Freight and many others sell them. They are useful tools.


OR you can use a sliding, digital type caliper BUT you must already have a good feeling for the actual size. These calipers are much more limited in the range of measurement although definitely a bit more accurate although more expensive.

I have several of both types but the digitals were more money and they must be handled and stored more carefully.

 

[Comodave]

My digital calipers go up to 6”.

 

[rgano]

The external beaks of the caliper in use need a depth equal to the the radius of the shaft being measured. Mine are 1/16" over 1.5" deep meaning it could accurately measure a 3" diameter shaft. But in reality, the OP just wants somebody to tell him. I would still want to measure it eventually since maybe there has been a new shaft installed since original or not all Prairie's were built the same. Hmmm.

 

[Comodave]

The shaft on a Perkins likely would be 2” or less. It doesn’t have that much power to need a huge shaft.

 

[CapeBob]

Thanks, C lectric, I have calipers, but no access to the shaft from inside the boat. Thanks to the rest of you who responded. What I need is the cross-sectional diameter of the propeller shaft. I had a man who, while cleaning, routinely examined the zincs. Unfortunately, he passed away.

 

[sailormike]

our 29 that had a gas engine re powered to a 63hp Yanmar has a 1 1/8" shaft

 

[jrd22]

Thanks, C lectric, I have calipers, but no access to the shaft from inside the boat. Thanks to the rest of you who responded. What I need is the cross-sectional diameter of the propeller shaft. I had a man who, while cleaning, routinely examined the zincs. Unfortunately, he passed away.

You don't have access to the stuffing box?

 

[mvweebles]

My 4.236 has a 1.5" shaft if that helps. I think I swing a 26" prop and have a 2.57 reduction gear.

Peter

 

[CapeBob]

Thanks, mvweebles.

 

[CapeBob]

You don't have access to the stuffing box?

Thanks, jrd22. Yes, I have access to the stuffing box, but it connects directly to a coupler that I don't have access to the outboard end of . I'm going to try the other engine.