Prop slack-how much is ok?

mhb100 · 30 June 2009, 20:53

Guys

I'm just changing the prop due to some slippage.

Before i removed the old prop I noticed that there is some 'play' as you can pull the prop forward/back about 1-2mm on the splines. There is no sideways movement. Is this normal/acceptable?

I'm going to fix a new prop, thrust washer, nut,etc, so is this sufficient or is there something internal i need to check?

I'm not tecnhically minded so I dont feel confident in doing anything more complex than fitting the new prop....any views

thanks Mark

9D280 · 01 July 2009, 08:43

Mark,

assuming you have a new set of everything, the only other thing that would cause that would be a mobile shaft, and I suspectyou would hear the results of that as soon as you engage gear!

If you are repalcing the thrust washers, any wear that was there will be removed. Sometimes you have to back off the nut slightly to get the split pin in - that may start as 0.5mm of movement, but when the prop starts moving every time you engage a gear (& thumps the nut every time you engage reverse), it doesn't take long to unwind the nut to a give a bigger gap.... but that's why you have the split pin!

jyasaki · 01 July 2009, 15:19

I ran (admittedly too fine) a prop with the situation you described, and within about an hour of running had a line of cavitation burn on the rear of the blades. I don't know if it was caused by the play between the thrust washer and nut, or if it was the lack of pitch, but it's not something I would really suggest (unless you like visiting the prop shop.)

A thicker spacer or a couple of SS flat washers will take up the play.

jky

mhb100 · 01 July 2009, 20:03

thanks Guys, info much appreciated
Mark