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Author Topic: Prop tube leak  (Read 6210 times)

Ian

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Prop tube leak
« on: June 20, 2007, 02:25:57 PM »

Hello All,

I am just finishing up my Al Khubar tug, and during some testing I have noticed a little water coming through the propeller tubes. Is a little water normal?  If not, can anyone give me some help on fixing this ?

Cheers,
Ian...
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Colin Bishop

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Re: Prop tube leak
« Reply #1 on: June 20, 2007, 02:37:00 PM »

Yes, a bit of leakage is normal especially if the motor end of the shaft is at or below the waterline. There are ways of reducing it though. One is to put a close fitting washer, say brass or similar, on the ends of the shaft next to the tube. This will bear against the tube and help seal it. Another option is to introduce some grease or thick oil into the tube which will also help prevent water ingress. Don't stuff the tube with grease though as the drag will be enormous. If you do a search on this site there are quite a few entries dealing with this issue. It happens on real boats and ships too!

Have a look at http://www.modelboatmayhem.co.uk/forum/index.php?topic=1153.0
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DickyD

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Re: Prop tube leak
« Reply #2 on: June 20, 2007, 03:46:08 PM »

Just a quick point Ian. If you go the washer route make sure you do not have things to tight.
I did on one of my prop shafts and it got so hot it took the skin of my finger.
I should try the silicone grease first.
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Bunkerbarge

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Re: Prop tube leak
« Reply #3 on: June 20, 2007, 03:54:27 PM »

One of the single most usefull things you can do is to fit shielded roller bearings instead of bushes.  Much better at holding water at bay.

Then a water proof grease is better than oil but it depends on how much power you have available to overcome the drag of the grease.  I don't get a drop inside on the steamer and the tube is full of grease.

When I tried grease in the u-boat tubes the motors wouldn't turn!  Each one is an individual case that you have to evaluate.  By the way the u-boat tubes do not let in any water either now.
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Ian

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Re: Prop tube leak
« Reply #4 on: June 20, 2007, 05:01:31 PM »

Hey, Thanks a Lot to all you guys for your help,

 I have got some work to do and I am sure there will be no more leaks. I think I will try a little grease first, and look for some brass washers too.

Cheers,
And thanks a lot,
Ian...
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kendalboatsman

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Re: Prop tube leak
« Reply #5 on: June 20, 2007, 05:36:12 PM »

Hello Ian,

I built a HFM Deep Dive sub which I was lucky enough to win at a HFM open day. The instructions recommended melting vaseline and injecting into the prop shaft. Seemed to do the trick.

Clive :)

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J.beazley

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Re: Prop tube leak
« Reply #6 on: June 20, 2007, 05:47:13 PM »

Clive ive used this method aswell only problem is when the vaseline gets hot due to friction it tends to melt and run everywhere.

Tamiya grease always does the trick for me now

Jay
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Robert Davies

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Re: Prop tube leak
« Reply #7 on: June 20, 2007, 06:25:29 PM »


Unfortunately Vaseline is also water soluble - or at the very least, readily breaks down in water.

Incidentally, I'm currently experimenting with oil sold for refilling motorcycle Scott oilers - so far so good....

-Rob

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Mankster

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Re: Prop tube leak
« Reply #8 on: June 20, 2007, 07:19:11 PM »

Building mainly submarines, I have to make sure my shafts never leak! You can use an oring or better still a Simmerring seal on the end of you propshaft. Just epoxy it to the end of you propshaft, fit and forget, no more messing with oil, grease etc..

Colin Bishop

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Re: Prop tube leak
« Reply #9 on: June 20, 2007, 07:25:13 PM »

Mankster - are you suggesting sticking an O Ring on the shaft in place of the washer I suggested earlier? If so, is it likely to wear?
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Mankster

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Re: Prop tube leak
« Reply #10 on: June 20, 2007, 07:47:35 PM »

You can use an oring trapped between a washer and the bushing on the propshaft and held tight by a nut on the prop side of the shaft. An oring / cupped seal is hard to stick on the motor end of the shfat, unless its enclosed in a carrier like SBS-2 and BHS seals from Subtech. A Simmerring seal is much easier. Yes I guess they can wear out over time. It hasn't happened to me yet. A Simmerring has a spring to compress the lip onto the shaft, so watertightness is maintained even if ther is wear.  As The bronze bushing in the average model boat propshaft would probably wear out sooner though.

Tom Eccles

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Re: Prop tube leak
« Reply #11 on: June 21, 2007, 09:37:23 PM »

Hi gents.

Could someone please explain the design and application of a simmering seal?

It may be common in naval construction but I have never heard of these seals and I am intrigued.

Many thanks
Tom

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Mankster

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Re: Prop tube leak
« Reply #12 on: June 22, 2007, 09:28:54 PM »

Hi gents.

Could someone please explain the design and application of a simmering seal?

It may be common in naval construction but I have never heard of these seals and I am intrigued.

Many thanks
Tom



http://translate.google.com/translate?hl=en&sl=de&u=http://de.wikipedia.org/wiki/Wellendichtring&sa=X&oi=translate&resnum=1&ct=result&prev=/search%3Fq%3DSimmerring%2B%26hl%3Den%26rls%3DGEUA,GEUA:2006-01,GEUA:en

Shipmate60

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Re: Prop tube leak
« Reply #13 on: June 22, 2007, 11:00:53 PM »

Fill the shaft with fishing reel grease.
Thin and waterproof!!

Bob
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Martin [Admin]

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Re: Prop tube leak
« Reply #14 on: June 22, 2007, 11:06:03 PM »


I'm trying thick Silicon oil ( nicked from the photo copier repair man! ).
I'll water test next week and report back.....
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Tom Eccles

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Re: Prop tube leak
« Reply #15 on: June 23, 2007, 12:44:12 PM »

Hi Mankster,

Thank you for the link. Unfortunately the page does not give a lot of information.

Never mind, I was only hoping for some help.

Tom

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John W E

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Re: Prop tube leak
« Reply #16 on: June 23, 2007, 12:59:02 PM »

HI ya there Tom

as regards simmering seal I must confess I have never heard of them being called this before  ;D its a new one for me - and no doubt others will say 'Of course you have heard of this before - but, Ive always known them as an oil seal' - their uses are mainly in engineering in gearboxes, car engines etc., and as the name implicates it seals the oil in around the rotating shaft keeping the oil in the right place  ;D   I hope this is the information you are after.

aye
john e
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Tom Eccles

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Re: Prop tube leak
« Reply #17 on: June 23, 2007, 03:00:34 PM »

Thanks Bluebird.

As an engineer of some 40 years experience, mainly in the manufacture and servicing of aircraft and aircraft components I have come across various types of oil seal. I have just never heard of a simmering seal until seeing it mentioned on this thread. That is why my interest was aroused.

I am interested to know something of the design and use of this particular type of seal as apposed to others.

Thanks for you help

Tom
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Shipmate60

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Re: Prop tube leak
« Reply #18 on: June 23, 2007, 04:16:51 PM »

I have heard them called "lip seals".

Bob
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Colin Bishop

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Re: Prop tube leak
« Reply #19 on: June 23, 2007, 04:40:20 PM »

Quote
I have heard them called "lip seals".

One or two people on here might find them useful then...
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kayem

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Re: Prop tube leak
« Reply #20 on: June 23, 2007, 04:44:40 PM »

Quote
I have heard them called "lip seals".

One or two people on here might find them useful then...

I think that boxing gloves to stop the buggers typing might be a better idea.
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Mankster

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Re: Prop tube leak
« Reply #21 on: June 23, 2007, 06:36:46 PM »

Hi Mankster,

Thank you for the link. Unfortunately the page does not give a lot of information.

Never mind, I was only hoping for some help.

Tom



Hi Tom, no problem. The Wiki entry exceeds my knowlege on the subject. Maybe you can contact the manufacture http://intl.simrit.de/web/public/contact/callback They should be able to give you all the help you were hoping for.

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Re: Prop tube leak
« Reply #22 on: June 23, 2007, 07:41:09 PM »

They are definately "Lip" seals to the Marine Engineering fraternity.

They are usually fitted in such a location as to require many hours of downtime of a very expensive peice of equipment to enable to exchange of a 2 dollar seal.  More substantial ones have a spring backing to the lip but not always.

The arrangement of the lip seal even extends to the multi-lipped variety used on stern seals where you may have 3-4 lips in one seal of maybe 600mm diameter
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Colin Bishop

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Re: Prop tube leak
« Reply #23 on: June 23, 2007, 08:05:54 PM »

Quote
The arrangement of the lip seal even extends to the multi-lipped variety used on stern seals where you may have 3-4 lips in one seal of maybe 600mm diameter

Sounds a bit like a toilet pan connector then?
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Tom Eccles

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Re: Prop tube leak
« Reply #24 on: June 23, 2007, 09:06:07 PM »

Hi Guys

Do the edges of the seal actually overlap the end of the shaft? (I assume this is the "lip")
If so I also assume that the spring grips on the diameter of the shaft or have I got it wrong?

Thanks

Tom

P.S. the reason for my interest is that I also have a slight water leak problem with the shafts of my Yorkshireman. The problem became pronounced after I fitted a mixer but has diminished a fair bit since I packed the shafts with silicon grease. As always I am searching for another way....

Tom
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