Question: Should the propeller on my boat fit nice & snug or should it have some in & out play?

(Posted by: ITLNWSGY on 2010-08-29 23:07:49)

Posted by: Richard C on 2010-08-30, 03:39:49

To few details sometimes results in completely wrong answers. In this case that's what may have happened. It is correct that when installed correctly, with all of the correct parts, the prop should be snug to the prop shaft. However I've seen prop shafts that would move quite a bit. If you pulled outward on the shaft. If memory serves me the entire shaft moved but the prop wasn't actually moving on the shaft. In most cases there is a thrust washer that is part of the hardware used to install a prop. No washer can damage the gear case and/ or the prop will move on the shaft. So, It all depends on the design of the drive. Most service manuals will give you a specification on just how much movement is allowable for your specific drive. I'd suggest you walk around your marina and check similar drives to yours and see if theirs move like yours. Or drop by a dealer for your make drive and have them check your prop to make sure it's installed correctly.

Posted by: skip on 2010-08-30, 00:55:34

There should be no play whatsoever.If it slides on the shaft splines when the holding nut or cone is tightened then there is a component missing! You havnt given any detail as to outboard or inboard etc,but most have a fishline cutter that slides on the shaft before the prop,is this in place? Some props also have a spacer fitted inside check that your prop hasnt just got a hollow seat where this should be.when a prop cone is fitted there should be a nylon spacer between prop and cone.Hope this helps.

Posted by: Capt Mac on 2010-08-30, 03:19:09

Hello, As stated in the first answer the prop should have a tight fit on the propeller shaft, however; the prop shaft should have about .010 - .020 free play forward and aft depending on the model of drive unit. The slight amount of slack allows the bearings to float with an oil film once pressure is applied to the spinning propeller. If you have too much play forward and aft you'll start to head a loud "clunk " as you clutch in and out. Too much play must be removed by adding shims to your thrust bearings in the lower unit.

Posted by: erichoare@btinternet.com on 2010-08-30, 04:38:29

A very simple answer her. It should be tight onto the shaft with absolutely no movement whatsoever. all props are designed to fit onto specific shafts, for example, the prop size, taper and key-way match those of the shaft. If any movement is detected then you should have it checked out as the vibration could not only damage both the prop and the shaft but the prop may fall off. If you are out at sea this could be catastrophic. safely is your first priority.