Thank's Bill just looking around.

Martin555.

Hi Martin.
Great to see you back on the site.
Like you I don’t drop in that often now for various reasons,but it’s great to see the site thriving.
Take care and stay safe,and it’s good to keep in touch in the real world 😀
Regards
Bill.

Hi Martin,
I think you are dead right (saw it on MB Mayhem I suspect😉).
I've been looking at a few boat prop suppliers.
X seems to indicate that both leading and trailing edges of the blades are straight so the plan view looks like an X. Same for aircraft props (sorry - Airscrews😁) apparently.
An S type has a curve leading edge and straight trailing edge, just many 3 blade scale props so the plan view is (you guessed it👍) S shaped.
Pitch doesn't seem to have much to do with it. S types can also be fine pitch (~1.3) like this example -
https://www.modellbau-berlinski.de/rc-boats-and-accessories/model-boat-propellers/plastic/marine-propeller-2-blade-45mm-right-m4
60/45=1.33r. I've also seen some S with 1.6 pitch, yer pays yer money .....
From Roy's comment re angular props I'd guess that the X types are are the surface piercing.
Cheers, Doug 😎

Hi Roy,
Here is another one to through into the mix LOL!!
I have seen it somewhere that a propeller viewed from behind that the 'X' propeller is 'X' shaped and an 'S' propeller is 'S' shaped.

Martin555.

Hi Martin I know that the plastic and nylon props were labelled P for I think 1.3 pitch to prop diameter and the X ones at 1.7.
Maybe S stands for surface piercing? They tend to be very angular props and perhaps a bit bigger diameter. Just surmise on the S.
Roy

Hi garyp,

RE the S on your prop.
I only come across an 'X' or an 'S' on model props and the only explanation i can find is "X" prop is a surface piercing prop.
S props generally speaking have more pitch.

I am sure that someone here could shed more light in this subject.

Martin555.

I have just ordered a new brass prop.. M4 40MM.
I guess the M4 is thread and the 40 MM the prop diameter. Any help? Please..
On the replacement plastic prop package it is replacing it says
M4 40S

Thank you sir.

4mm shaft diameter, 35mm prop diameter.

Thank you .That is great advice..

Hi I am sure others can contribute so part answer is, M4 is the screw size. That is, there is a thread on a 4mm diameter shaft. The 35 looks like the diameter of the prop in mms.. Most times you will get a prop that revolves clockwise when viewed from the back.

The prop when it is giving forward motion will be screwing itself onto the shaft. We also put a locking nut on the shaft before the prop and using a M4 spanner they are locked against each other which prevents the prop from un-doing when going in reverse. I would place a washer up against the bearing at each end as well.

Make sure when the prop is screwed in place that the shaft has plain shaft where it is positioned in the bearing of the prop tube. The other end usually has a U/J or universal joint. Try and keep these as in line as possible also the part attached to the other end of the prop shaft should be as squarely fitted as possible. Sometimes this is a screw thread and sometimes a plain end. You need a U/J to suit.

If you get vibration when running go to the U/J first and make sure it is not canted slightly when it was either screwed or lock-nutted in place. Sometimes a washer placed between the nut and the U/J can help.

I connect it all together with a single battery running the motor and find the sweet spot and screw or glue things in place then leaving the motor running to ensure there are no changes as it is finally attached.
Good luck
Roy

Gary, the details of prop are :- m4 = size of thread on propshaft and in propeller.
:- 35 = 35mm diameter of propeller.
Not sure about the S but could mean sport
Cheers Colin.