Jump to content

Featured Posts

Hi..new here!!

 

Got a leak on my stern tube, its actually leaking where the welded in tube joints with the brass propellor tube passing thro it,nothing to do with the greaser/packing. It leaks a fair bit more with the motor running(in gear or in neutral) then it settles down to a steady drip when the engine is stopped. How is the seal between the brass insert and the welded in tube made?

 

Any ideas/helpful advice

Link to post
Share on other sites
Hi..new here!!

 

Got a leak on my stern tube, its actually leaking where the welded in tube joints with the brass propellor tube passing thro it,nothing to do with the greaser/packing. It leaks a fair bit more with the motor running(in gear or in neutral) then it settles down to a steady drip when the engine is stopped. How is the seal between the brass insert and the welded in tube made?

 

Any ideas/helpful advice

 

Not much.

 

First make sure any shaft/engine misalignment is sorted, otherwise it may leak again.

 

Then depending upon your bravery, dexterity and the free shaft length -

 

undo bolts holding the gland the the hull bracket (two or four usually).

 

Stilsons on tube and undo it - do not panic - large inrush of water expected.

 

PTFE tale around thread on tube or steel (which ever is the male).

 

Refit and tighten.

 

Well that is the theory, practice may be different!

 

If you wrap cling-film around the shaft between prop and hull it might reduce the inrush of water.

 

Tony Brooks

Link to post
Share on other sites

similar suggestion that i have done twice

1 remove prop

2 get a good heavy duty plastic bag

3 put plastic bag over the prop shaft thru the weed hatch

4 fasten plstic bag around weld in section on the hull withh bungee chords tight

5 remove stern tube inside as described earlier if you have enough room prop shaft as well

no water will come inside if you do it like that

good luck

Link to post
Share on other sites

Hi Andy.

 

An even simpler strategy may be to simply wrap some self amalgamating tape around the joint interface of stern-tube /steel boss on the hull, then fit a jubilee clip on top of that. Sounds a bit crude but the leak will self seal with time anyway.

Link to post
Share on other sites
similar suggestion that i have done twice

1 remove prop

2 get a good heavy duty plastic bag

3 put plastic bag over the prop shaft thru the weed hatch

4 fasten plstic bag around weld in section on the hull withh bungee chords tight

5 remove stern tube inside as described earlier if you have enough room prop shaft as well

no water will come inside if you do it like that

good luck

 

Of course, do nopt forget to remove the plastic bag!!!!

 

Radiomariner

Link to post
Share on other sites

thanks for the advice..

 

I presume from the info that the brass insert is threaded and screws into the welded in steel tube then!

 

Think its gonna be a busy/wet weekend for me next weekend!!

Link to post
Share on other sites
thanks for the advice..

 

I presume from the info that the brass insert is threaded and screws into the welded in steel tube then!

 

Think its gonna be a busy/wet weekend for me next weekend!!

 

Yes, usually screws in a long way, maybe 60mm or so.

You might get away with screwing it most of the way out, & wrapping tape or other sealant on the exposed thread then retightening.

 

These things usually start leaking because whoever assembled it compromised on getting both threads tight because the position of the supporting plate wasn't exactly right. The risk is that whatever you do to seal it may only be temporary, and it will start leaking again sooner or later, unless you can make sure that both threads (the brass tube is threaded both ends) are tightened fully home. THis might involve drilling fresh holes in the support plate, or even cutting it out and rewelding it after the tube assembly has been tightened.

 

Tim

Link to post
Share on other sites
similar suggestion that i have done twice

1 remove prop

2 get a good heavy duty plastic bag

3 put plastic bag over the prop shaft thru the weed hatch

4 fasten plstic bag around weld in section on the hull withh bungee chords tight

5 remove stern tube inside as described earlier if you have enough room prop shaft as well

no water will come inside if you do it like that

good luck

 

I'd be a bit concerned if removing the prop under water was a simple matter. It's mounted on a taper, for good reason, and it should need significant force to remove it. Also reassembling it under water and ensuring it is tight, with the split pin properly fitted (often involves drilling a fresh hole) would be a bit iffy.

You would also want a contingency plan in case the plastic bag became dislodged.

 

Tim

Link to post
Share on other sites

when i was sinking 3 years ago the method i described worked well when you remove the drive shaft and stern tube the water pressure holds the bag in the hole knocking the prop of is a bit of a task but it can be done usually loose the key way without the expense of dry docking

i was a bit worried when i did it but if you look back to the old man o wars if they got shot below the water line they just dragged a sail over the hole and the water pressure held it in place

Link to post
Share on other sites
simply wrap some self amalgamating tape around the joint interface

 

Hi John is that a term normally recognised in a plumbers/builders merchant or do they normally go by a trade name - if so what? Us non-DIY'ers often get intimidated at the trade counter when we don't know what we are on about!

 

David

Link to post
Share on other sites
Hi John is that a term normally recognised in a plumbers/builders merchant or do they normally go by a trade name - if so what? Us non-DIY'ers often get intimidated at the trade counter when we don't know what we are on about!

David

 

 

It is quite common these days, I have seen it in many DIY places and catalogues. Eg. RS Components 227-2932. I have used it for all kinds of jobs including finishing crimped cable ends, as the name suggest it does not rely on adhesives.

Link to post
Share on other sites
when i was sinking 3 years ago the method i described worked well when you remove the drive shaft and stern tube the water pressure holds the bag in the hole knocking the prop of is a bit of a task but it can be done usually loose the key way without the expense of dry docking

i was a bit worried when i did it but if you look back to the old man o wars if they got shot below the water line they just dragged a sail over the hole and the water pressure held it in place

 

 

I wasn't saying 'don't do it', just that it might not be as simple as your little list implied :cheers:

Also the 'contingency plan' might just be a ball of greasy rag to stuff in the hole. Someone who isn't used to that sort of work could easily panic at the sight of water rushing into their boat, it helps to have a 'plan B' if you're not used to improvising in a hurry.

 

Be aware if you do lose the key (the keyWAY is the slot it goes into), that they are not all created equal. Yes, a lot of them are just square section stock, but sometimes the keyway in the prop (usually, though sometimes the shaft) isn't quite deep enough & a new key would need to be filed down to fit (I had to do one on Friday for a new prop, it's not that unusual). If the prop sits on top of the key, instead of on the taper, it will work loose, & I've seen propellor bosses cracked where they have been tightened hard onto a tight key.

If you are determined to take the prop off under water, slacken off the nut without removing it (always a good plan), then when the prop is loose on the taper, turn the shaft until you can feel the key/keyway at the top. Then remove nut & prop without turning shaft, & you should then be able to carefully remove the key with mole grips or whatever.

 

Tim

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.