Question On Stern Tube

[Tomsdad]

Hi all, new member and first post. I have bought a Birchwood 25 about 1970’s. Ford Watermota Xflow engine mated to a J type gearbox. A common set up on these cruisers and on Freemans. Bought as a project boat and gradually working through all the issues. I have no problems sorting engine and gearbox issues as I have always fixed my own cars but from the gearbox back to the propeller on a boat is all new to me.  I  am a bit confused and concerned with this issue. Please see photos, The prop shaft leaves the gearbox and goes through some sort of coupling. Like a universal joint on a car prop shaft. But then it reaches what is called the stern tube? Sometimes referred to as the stuffing box?  Well my stuffing box has been repacked (by boat mechanic at marina) and there is no drips. My research suggests it should drip. If so why should it drip? But more concerned about there being no grease gland. Other boats of this ilk and age have a grease gland behind the stuffing box. Why do some boats have a grease gland and should I have one. There is no water pipe for water cooling on the prop shaft. But why does the prop shaft need cooling? Sorry to ramble on. Maybe my equating the set up to a car is making me miss something. 
 

[floydraser]

Welcome to the forum Tomsdad. Good question, well explained and good photos. Someone higher up the food chain than me will be along any second with a full and comprehensive answer I'm sure! 

[dom]

It's probably a dripless seal. They usually have a convoluted rubber boot over them, but it's possible yours has had a DIY replacement. It looks like a bit of exhaust hose or similar.

A lot have a water cooling feed, but not all, ie. Volvo Penta lip seals are more basic and lack the feed. It's not needed on low load/speed applications, where water entering from the cutless bearing (prop end) is sufficient to cool the whole assembly.

[Smoggy]

That is not a dripless seal it's a regular stuffing box and the hose is the normal way of connecting to stern tube but it should be a proper hose as it needs to be reinforced, any old rubber hose will tear apart with the drag on the gland and flood the boat.

The drip is to ensure water is getting to the packing to keep it cool and lubricated, if just repacked it will likely settle in and gain a drip, it's not a high speed boat so don't panic.

Not all have greasers, the grease is to stop the drip once you have stopped, grease in the packing can make them get hot so overdoing a grease cup is not good.

[Smoggy]

That's not a universal joint btw,  it's just a regular shaft clamp with a spacer adapter in between, probably different bolt pcd's on gearbox and shaft clamp.

 

[annv]

Hi Tomsdad First off the hose should have two stainless clips on each end with saddles on opposite sides. Next the stuffing box needs the packing replacing and the nuts ned replacing with a nylock nut,this will allow you too adjust the drip which is required both to cool and lubricate the packing. you dont have to lift the boat out of the water to replace the packing as the amount of water coming in is not that much ,providing you have the relacing packing to hand. John

[Vaughan]

2 hours ago, Tomsdad said:

ANNV is quite correct, that the stern gland (stuffing box) needs re-packing.  You can see that the two faces of the gland have come together and the nuts on either side are right at the end of their adjustment.  If you are new to these things, this is best done by a boatyard.

Modern gland packing contains graphite and does not need grease, or a grease cap.  In my experience, it doesn't really matter if the gland drips or not.  What does matter is that if you over-tighten the gland, to stop it dripping, it will overheat and burn the gland packing.  So you are better off with a bit of a drip!

Remember always, that a "stern gland" is not a shaft bearing.  In other words it does not hold the shaft in line in the stern tube.  Normally the inboard bearing (stuffing box) is threaded onto the shaft tube but in your case a short length of hose is added, to take up vibration.  I would guess this is because your boat has a very short prop shaft tube.  This will mean that the alignment of the engine itself is vital, in order to keep the shaft centralised in the tube.  Especially when running slowly.  This arrangement is normally done for high performance, at high engine revs.  So engine alignment is important and should be checked by a boatyard.

A raw water feed pipe to the stern tube (known as forced-water lubrication) is only necessary if the out board bearing (the Cutless bearing) is not arranged so that water passes through it naturally.  The Cutless is a neoprene bearing which is lubricated by water, hence the grooves in its bearing surface.  If you don't have a water feed pipe from the engine to the shaft tube, this means the Cutless has its own lubrication, so no problem.  It is probably fitted on a P bracket or skeg, separate from the end of the keel.

Propshafts and their bearings are a bit complicated and if you are new to this, it is really best to consult a boatyard.

 

[Tomsdad]

Blimey!  What a great response. Really appreciate that. Will work through all the suggestions and rework it as necessary. But it leads me to another issue which maybe connected. I need to post a video and it looks like I can’t do it from this reply box so I’ll open a new thread. There is a noise. A rotational noise ( only there when prop shaft rotating). 
it resonates and whines and I think is amplified by the fibreglass tunnel that the prop goes into ( but don’t let my thinking cloud your thinking). It happens between 1250 and 1500 revs so I  cruise at 1200 revs and it’s just great. After 1500 it’s also great but too fast. 
From your previous responses I think about alignment? But there is no felt vibration. 
everything is smooth except for the noise. It’s been there since I bought the boat so nothing I’ve caused and obviously I have checked other things like alternator bearing. 
definitely coming from somewhere gearbox back to propeller. 

 

[OldBerkshireBoy]

When repacking the stuffing box on water pumps we used to rotate the postion the gland packings cut ends, ie first ring at 12 on a clock face, with next ring at 2 and third ring at 4 and so on plus regardless of what material the packing was they were set up to leak, nice and slowly mind. I dont see why it should be different on slower rotating shafts?

[annv]

Hi Tomsdad It sounds as if the shaft is rubbing on the stuffing box try loosing the nuts so water drips/runs and try again if still present use a very long screwdriver or steel rod with insulated handle to use as a sounding rod which will be amplified by putting one end to your ear and touching the other on to the surface off stuffing box, gearbox etc you can then locate where the whine  comes from.John

[Vaughan]

The Watermota is a Ford Cortina 1200 petrol engine, normally on a Parsons mechanical gearbox.

I have never heard a shaft make a noise like that before so I would look to the gearbox, which can be adjusted, for drive clutch tension. 

It occurred to me earlier that the hose connection on the stuffing box may be there to take up vibration as the engine itself is mounted solid onto the engine beds, without flexible mounting feet.

I hope the noise is not because the engine is "running" a crankshaft bearing.

[Smoggy]

That noise could be the prop "singing", mine did it a bit after refurb till a bit of crud had built up, like a resonance that builds at certain rpm.

Only had a brief listen and been in the pub all afternoon so caveats apply. (Ie could be talking sh1te)

[Vaughan]

10 hours ago, Smoggy said:

That noise could be the prop "singing", mine did it a bit after refurb till a bit of crud had built up, like a resonance that builds at certain rpm.

It does sound a bit like that, but on the Broads it would be caused by cavitation from an over-large prop and would normally only happen when the boat is turning sharply under power.

It is very difficult to tell without "being there", but an engine with worn crank journals will sometimes sing like that as well.

[MargeandParge]

Another place to look is your engine and gearbox mountings as if there is a problem it will show up more with different torque loadings . If the engine moves under load it will make the shaft out of true.

Kindest Regards Marge and Parge 

 

 

[Tomsdad]

So being a believer in trying the easy fixes first. 
1. Visual. Does engine move when under acceleration. Pointing to possible engine mounts. I have checked all mounts for tightness. Including gearbox and prop shaft couplings. 
2. Loosen off stuffing box maybe 1/4 turn at a time till I get some drip of water. Although at present the prop shaft is relatively easy to turn by hand. So don’t think the stuffing box is overly tight. 
3. Long metal bar/ mechanics stethoscope. Try to pinpoint origin of noise. 
what about the cutlass bearing. Could a worn cutlass cause the noise at specific rev points?

4. If it’s crank journals/bottom end wear. It’s not the end of the world. Reconned a similar engine in my cortina oh maybe 40 years ago………

[annv]

Hi Tomsdad If oil pressure is good at tick over with a engine up to temperatures unlikely bearings, crank will give a rumble if throttle blipped from tick over, 1200 three bearing crank petrol engines where prone to crank stretch.this caused piston wear and high oil use. just had a thought try removing the fan belt and see if noise goes dont run for long as water pump won't circulate the water, or dos noise only occur in gear and not out of gear?. John

[Tomsdad]

Not sure what the oil pressure is. Only have an oil idiot light on dashboard. Goes out immediately and doesn't come back on even when hot and ticking over. The engine is a mid 70’s Ford 1600 Xflow which has a 5 bearing crank. Water pump is not driven via the fan belt only the crank and alternator. The noise is only when in drive. Not in neutral. 

[annv]

Hi Tomsdad Oil light sensor is usually set 5 to 8 psi so ok their. 1600 5 bearing crank Ford is as good as they get providing regular oil changes. Fan belts can give strange noises when they get dry and old. But if only in gear tracing it by elimination or sounding rod is the only way forward, dont think cutlass bearing would be the cause as it's immersed in water, but Vaughan is the man with experience on this possibility. John

[grendel]

you said in your first post that the boatyard had already repacked the stern tube seal, however as some have commented it looks a bit tight together for a freshly packed seal, so one has to ask how well it was done, you should have plenty of space to tighten the seal if done properly, several rings of the seal material and you should end up with a very slow drip, if its been under packed and then overtightened, that could be the source of your noise with the seal running dry and squealing.