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Hi Grief

The shaft comes with a nut and washer at both ends. Is that to lock to the prop and the coupling?

correct

So what stop the water flooding in through the shaft past the bearing once it is fixed in place?

Use grease/petroleum jelly(vaseline) or light oil such as "Three in One" depending upon your fancy.

Thanks jankers.

Chris

Chris,

I would strongly recommend that you look into an alternative stern tube arrangement using proper ball bearings rather than plain bushes. One of the main reasons for this is that the end of the tube is effectively sealed and greatly reduces the likelyhood of any leakage into the hull. Ball bearings, if properly looked after, will also last considerably longer.

I got mine from the Prop Shop and when the boat is down to its marks and running there is no leakage whatsoever. I filled my tube with waterproof grease.

From what I remember the price was very reasonable as well.

Look into it at least, I fitted the supplied tube before John Hemmens pointed out the disadvantages so I had to dig out the original to fit the new one. You are going to put hundreds of hours into this project so you don't want to end up with something as demoralising as a leaking stern tube when you finish it.

All the best

Richard

True about ball race shafts being 'the best' but I have been running a bronze bush shaft (horizontal) in a tug for 27 years with no significant leakage or bush replacement.
I fitted an 'oiler tube' - soldered to the outer prop tube. Once a month I give it a squeeze of water proof vehicle axle grease. Try to ensure that you have no mis-alignment between motor and prop shaft. Any mis-alignment will cause wear on the inner bush no matter how good the coupling is. I set up prop shaft and motor in the boat with a rigid connection. When all adhesives etc. have set, replace the rigid connector with the flex. coupling.

If you get any 'noise', this means you will get wear. Silent (or nearly so) is good!! You'll also get a better battery life!

Best of luck,
Iain

The Ben Ain kit comes supplied with 'plastic' bushes in the stern tube.

Whereas there are merits of plain bronze bushes care must be taken to ensure that they are bronze and not brass but plastic did not give me sufficient confidence that they would last the life of the boat.

You must also ensure that you have an oiler tube fitted no matter what bearings you are using. Once again the Ben Ain stern tube is not fitted with an oiler so you have to do work on it anyway.

Oops ....... trust me to provide a classic example of a silly answer!!

Iain

Thanks for the great replies.

Where I'm at is.
Bought the brass prop and a prop shaft (with bronze bearings) from the prop shop. The guy was very helpful. I asked him about the shafts and he suggested for a lower revving prop the Bronze bearings should last many years. I think I will add an oiler point

Of the Prop shop. Thanks for the contact Richard. I decribed the motor ( A robbe navy geared 600/24 compact geared at 3.3:1.
I described the prop at 70mm diameter four blades etc.
The shaft and prop arrived next day. The shaft was £7.00 so if its not suitable I haven't fitted it yet. The prop is excellent and came in just under £20.00
I knew the shaft had to be oiled or greased but I wasn't sure if I was missing something else with respect to keeping out the water. I looked long and hard at the rudder shaft for the same reason.

How common is leaking through the prop shaft or is it just a case of regular pre sailing squirt.

I agree the plastic bearing that came with the kit shaft looks a little soft for such a well loaded prop from an engineers point of view.

Going off at a tangent I have ordered a cooling coil to go with the motor. I think if I set this up so the prop pushes water through the tube I can run it back out of the port or starboard side to simulate the cooling water outlet on the old steam versions. It will also cool the motor for me. How does this sound guys?

Thanks In advance

Chris