Stern Glands

[fishfoxey]

Hi As my stern glands are water cooled do I have to winterise them separately from the raw water cooling , or is the pipe that runs to the stern gland linked to the raw water system and as such will get some antifreeze when I pump it through the weed filters?

[Smoggy]

It will probably come from the raw water system somewhere, try tracking it back, if so it will be covered by your antifreeze. 

There is often a vent pipe to above waterline as well.

[marshman]

I always remove the line where it enters the stern gland - I have  bronze nut which I can undo to drain the water and if the boat is remaining in the water, I have a blank nut I can screw back in its place - just part of the wintering process for me. If its coming out, it may drain itself but its an easy enough process.

I have never seen antifreeze coming down it - its a clear reinforced pipe so you would spot it I think.

[TeamElla]

On 29/10/2020 at 15:50, Smoggy said:

There is often a vent pipe to above waterline as well.

Well now, you have certainly set me thinking.

I have never considered the stern gland vent pipe when winterising, but then again our PSS Seal has been there for many years and the boat generally stays in the water all winter. So unless we get a really big freeze, I won't be losing any sleep over it. Food for thought though!

[Vaughan]

I have always heard this referred to as "forced water lubrication" and it is meant to ensure that there is always a flow through the grooves in the outboard bearing - or cutless bearing - which is neoprene, and water lubricated.  It has nothing to do with the inboard bearing - known as the "stern gland".

If the boat is on the water I doubt that frost would have much effect on this and it is possible that while winterising the raw water system with antifreeze, a certain amount will have been pumped through the shaft tube by the raw water pump.

If the boat is stored shore it would be vulnerable to freezing and as Marshman says, if you then disconnect the feed tube, this means that the shaft tube will drain out through the cutless bearing.

If you take it off with the boat in the water, then the boat will leak!

[TeamElla]

3 hours ago, Vaughan said:

I have always heard this referred to as "forced water lubrication" and it is meant to ensure that there is always a flow through the grooves in the outboard bearing - or cutless bearing - which is neoprene, and water lubricated.  It has nothing to do with the inboard bearing - known as the "stern gland".

Sorry Vaughan, 

I respect your knowledge and experience, but I have to take issue with the last sentence in the above statement.

For clarity only:-

A PSS Shaft Seal does need water around the mating static carbon face and rotating stainless steel face to both cool and lubricate them. On a slow boat, this just comes up the stern tube (or shaft log), but in a fast boat exceeding 12 knots the water drains out and has to be fed down the vent tube mechanically.

As far as the cutless bearing goes, many Broads based boats have this totally divorced from the shaft log in a skeg that drops down from the underside of the hull near ther propeller (but you know all this)

By vent tube, I mean the tube that connects to item 4 and has to run up to above the water line in this link:-

https://www.shaftseal.com/pss-type-a-seal.html

On reflection (winter time):-

I suppose that the  very top of the water filled vent tube might freeze with the boat in the water in a severe winter but surely would not freeze up right down to the PSS gland (at bilge level inside the boat under the water line). Would it??

 

 

 

 

 

 

 

 

 

 

 

 

 

[Vaughan]

5 hours ago, TeamElla said:

I suppose that the  very top of the water filled vent tube might freeze with the boat in the water in a severe winter but surely would not freeze up right down to the PSS gland (at bilge level inside the boat under the water line). Would it??

I doubt it!

The water outside in the dyke is not freezing, even if it has ice on the surface.  So until it freezes, it is unlikely to freeze anything inside the boat down in the keel.  I have known very hard winters where the valves on skin fittings have frozen but, whatever you think about climate change, we don't seem to get those long hard freezing winters anymore, like there were in the 60s.  A boat is much more vulnerable to ice damage when it is stored outside on shore.

6 hours ago, TeamElla said:

As far as the cutless bearing goes, many Broads based boats have this totally divorced from the shaft log in a skeg that drops down from the underside of the hull near ther propeller (but you know all this

They do indeed and where they are fitted outside on a P or A bracket, they lubricate themselves.  By no means all Broads boats have forced lubrication but I have seen several that do, as they will also have a cutless bearing at the back of the keel.

6 hours ago, TeamElla said:

https://www.shaftseal.com/pss-type-a-seal.html

 

Here we are clearly talking about different things and yours is obviously a type where the inboard bearing itself needs water lubrication.  I am talking about the conventional bronze stuffing box with gland packing, which does not.  If that gets too warm to the touch, then you have packed the gland too tight!

I have seen your type of bearing before and there is one made by Vetus.  But you don't see them very often on a river hire boat.

[Karizma]

With Karizma being our first boat (my parents had one about 15 years ago) and keen to understand what everything is and what everything does, anybody help me out with this?

I'm use to seeing a grease nipple on the top on the stern tube (if that's what you call it) that needs regular greasing, but this has a copper pipe that goes to the raw water cooling system near the engines exhaust elbow.

I assume cold water is 'forced?' down the copper pipe to cool the stern tube?

Do I need to check / doing anything with this on a regular basis?

PS: you can tell I'm getting ready to go down and check her out later this week 

Steve

IMG_7991.HEIC

[Karizma]

sorry Mac HEIC files don't work on here. jpeg photo below (hopefully )

[Vaughan]

The water pipe is lubrication for the cutless bearing, at the outboard end of the shaft tube.  The stern gland is a stuffing box, which may need tightening with a turn on the two nuts seen at the right in your photo, if the gland is dripping too much.  If the two parts of the bearing get too close together, or you cannot control the drip by tightening, then the gland will need re-packing.  I recommend you have that done by a boatyard.

I notice the shaft tube is electrically bonded. Is that an earth for an inverter?

[Karizma]

Thanks for the reply Vaughan, that all makes sense now 

As for the earth wire - I'm not sure where that goes yet (haven't checked) but she does have an inverter charger on her (Sterling pro combo Q), so might be.

[Cheesey69]

Galvanic protection.

When plugged in to mains stops your prop shaft disappearing if you or your neighbours  have a leaky return and the volts find a return path via your boat . Especially in salty water your underwater metal work turns into a low power battery.

I lost my prop to this when i owned a blue water sailor and my boat acted like an anode.

[Karizma]

Hi Cheesey69, I do know she has a GUEST galvanic isolator on her, so I'll check that the earth wire goes to it - I'm sure it will if its been installed correctly.

every day is  a school day !