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Author Topic: prop shaft leak  (Read 12752 times)

HS93 (RIP)

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Re: prop shaft leak
« Reply #25 on: February 17, 2012, 05:09:17 pm »
Quote from: sunnybob on February 17, 2012, 02:28:56 pm
Tailuk.... couldnt find any reference to krishna, or krishnah, on this site. {:-{


hs93.... interesting, but your post doesnt mention the actuall bearing at all. Do you have a link to them?

at the moment, Im leaning towards burring over the rudder ends of the tubes, and redrilling them to a tight fit on the shafts. Plan B would be to add a reducing sleeve somewhere to the tube, but there is so little space that they would have to be fitted outside the boat, between the tube supports.
Looks like I backed myself into a corner here.
you havent stated if it is M4 4mm shaft of a 4 ba shaft and what size the outer tube is you may be able to push the old bushes out and fit modern ones from SHG

Peter
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sunnybob

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Re: prop shaft leak
« Reply #26 on: February 17, 2012, 08:10:58 pm »
Quote from: HS93 on February 17, 2012, 05:09:17 pm
you havent stated if it is M4 4mm shaft of a 4 ba shaft and what size the outer tube is you may be able to push the old bushes out and fit modern ones from SHG

Peter

There are no bushes in my system. just two tubes with two shafts. The only way forward i can see is to cut the tube under the boat, between the supports, make a bushing that will be inserted into each tube, with a smaller hole through the centre to barely accept the shaft.
I dont have measurments to hand, but I recall that the shaft is 4.5mm. I suspect the tubes are 5mm.
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malcolmfrary

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Re: prop shaft leak
« Reply #27 on: February 18, 2012, 09:46:35 am »
If there is sideways play between the shaft and tube, its going to leak.  It does need a close fitting bush (a sliding fit on the shaft, no play) at each end that can be lubricated with water repellent grease.
The only other way out is to provide a sump for the water leaking in to be collected and kept where it won't do any harm until the end of session when it can be got out.
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dodgy geezer

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Re: prop shaft leak
« Reply #28 on: February 18, 2012, 10:17:43 am »
Quote from: sunnybob on February 16, 2012, 04:15:34 pm

there appears to be a fair amount of slop between shaft and tube, what are the chances of necking down the end of a 5mm brass tube to more closely fit the shaft ends?


The easiest way I know to 'neck' down a small tube is to cut it using a pipe cutter. When I have done that with small 5mm sized tubes it has dropped the diameter uniformly, sometimes down to about 3mm. If you have no room to circle the tube with a cutter, you could cut a section off, neck it and fit it back in with a larger diameter tube slid over it...

Alternatively, you could always go here  http://www.mikessubworks.com/page1.html and click on the 'SEALS' section on the left of the screen. These are prop shaft seals for 1/8" and 3/16" diameter shafts, and add as little as 1/4" to the internal end of the shaft...
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HS93 (RIP)

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Re: prop shaft leak
« Reply #29 on: February 18, 2012, 01:23:42 pm »
how about some measurements and some pictures so we are not guessing in the dark.

Peter
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John W E

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Re: prop shaft leak
« Reply #30 on: February 18, 2012, 01:42:16 pm »
aye aye there

I think this may be the model that Sonny Bob is on about :-) its the one (I think) he was renovating?

here are a couple of pics of the tubes and model - if so - mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm - lot of food for thought there.

aye
john
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HS93 (RIP)

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Re: prop shaft leak
« Reply #31 on: February 18, 2012, 02:02:07 pm »
if water is getting all the way up them in any amount after all grease etc he has used he needs to sling them as they are that worn

it may be comming in via the flange he has bolted to the hull with the shaft solderd to it.

peter
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sunnybob

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Re: prop shaft leak
« Reply #32 on: February 18, 2012, 08:48:30 pm »
bluebird... I hadnt remembered posting those pics.  {-) i was trying to get the boat to respond to the rudder. in its original form, the boat had a 40 ft turning circle.

The kort nozzles didnt work, they were scrapped. The shorter shaft is the one now being used, as the blade is much closer to the hull, and also the rudders, which I have enlarged. But I have found the problem, in that somehow the shafts and tubes got mixed up with another set I had and the shaft is 4.5mm, but the tube is 5mm.

Due to minimum space on the tubes, most of the suggestions here wont work. I have tapped the lower ends of the tubes over with a toffee hammer, and have now succeeded in making one side watertight, and the other side significantly less leakage. the other tube needs a second application of hammer  <*< <*<

I'm using some castrol high melting point bearing grease as well. Its looking hopeful.....
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