Stern Gland System Advice Needed

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Gludy

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My new boat has the Aquadrive fitted.
They have also left a lubrication system for the stern gland and I am getting conflicting advice on this - its the rubber hose bit in the photo
de57edb1544c50f3e735e3785eceb0d9.jpg


Fisherman gave me these helpful remarks on another thread:-

"The rubber tube is jubilee clipped to the stern tube, and to the inboard gland which is therefore able to move. As your engines vibrate the shaft movement is accomodated by the rubber tube. Now you have gone over to Aquadrive, which accomodates movement in itself, the thrust bearing presumably holds the shaft firmly, so the flexi gland is redundant. I would have replaced it with a normal gland, screwed to the stern tube. As it is the movement in the inboard gland is no longer required, so the tube will not be flexing, and is unlikely to rupture. However, the sea is on the inside of that rubber tube, and you are floating on those jubilee clips. "

I asked a friend tonight and he said that its just the lubrication system for the bearings instead of the normal stern gland and that if the hose went yes it would leak but not rapidly.

I do not know if the way it has been done is a good thing or not and I would like to throw the issue open tothose who know a lot more than me about it - so what do you think of the system they have installed? How safe is it?
 
Hi,
I agree that the rubber hose is not needed, but if you remove it you could open up a can of worms, It's possible that the shaft might not run true to the tube. Having fitted a number of Aquadrives it's very hard to line them up true and they could use the rubber tube to help. It's double hose cliped each end which is good so it should never give a problem.

What I can't see is some form of lubrication for the shaft, Grease or Water. Water is the most comon on motor yachts as it acts as lubrication and cooling. Have you got a small pipe going from the engine cooling water being pumped somewhere onto the gland! If not it could cause the gland packing to over heat.
 
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How safe is it?

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should be as safe as any boat with a rubber tube there.


presumably you're using the "aquadrive" description as a general term for cv joint couplings? - I've not seen an aquadrive that wasn't painted green & had integral rubber mounts for the thrust bearing housing - like this heavy duty one
Aquadrive%2060780.jpg


lower power versions having only 1 or 2 bolts each side.

I imagine that yours has rubber mounts under the white brackets supporting the thrust bearing housing?


Like ColinBrowne, I wonder where the lubrication is for the sterngland.
 
Yeah, my aquadrive installation is green as your image shows. Photo was taken during the build, hence the sawdust (aft-cabin is hand-built insitu once the deck is on) and unconnected cabling...

50699356_a640b8a6b6.jpg


I also have a similar stern gland to Gludy - perhaps its as recommended by Aquadrive?

Rick
 
You'll see I've posted a suggestion that all I would do is fit better clips, the ones with a bolt and two bushes. I completely missed the lack of lubrication. That gland looks like a stuffing box, as such should have water or grease to it.

Also, I don't know what the situation will be with that boat, but in mine I have very much bigger wires, about 70 amp multistrand, for the anti-electrolysis strapping (the small green ones.)
 
OK - just that the one I showed goes up to 1600hp - perhaps it's not the very largeness that explains the difference, but was made up to Trader's spec..
 
I had Aquadrives fitted because I thought they would greatly reduce noise and vibration but I have done that on the sales blurb and have no practical knowledge to base that on. So would appreciate details from anyone who has experience of beofre/after Aquadrive.

Also if my props gets caught in a fihing net it seems the system prevents the engines being dragged back of their mounts but what else can happen?

Fisherman - I caught the advice on changing the clips on the other thread thank you. However what do you mean by you did not realise the lack of water lubrication? I am a novice on this subject - just trying to learn.
 
I was told that the spec is done by Halyard - they design and supply to fit the particular boat. They have also used the Halyard double silencer system to meet the new noise specs that come into force 1st January.

I have not travelled a single yard in the boat yet and was too blinkin excited when I first saw it arrive to notice noice or lack of it.

As I understand it, what is below the rubber is sea water but only what can leak through the bearing to lubricate it- so if the rubber ruptered there would be a bit of a spurt that could be coped with. Apparantly it saves tightening the stern gland all the time etc?
 
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I had Aquadrives fitted because I thought they would greatly reduce noise and vibration but I have done that on the sales blurb and have no practical knowledge to base that on. So would appreciate details from anyone who has experience of beofre/after Aquadrive.

[/ QUOTE ]

I can't offer a direct comparism, as I've not had an aquadrive retrofitted. What I can say is that the elling is very quiet and the manufacturers fit the Aquadrive as part of the noise reduction. I'm happy with the result /forums/images/graemlins/wink.gif

Rick
 
The water in the black tube is as much as will pass your outboard bearing, prob a cutless. The only other bearing you have is on the inboard end of the black pipe.
A normal inboard stuffing box, fixed to the tube, is injected with grease via a remote greaser which has to be turned each day at sea, and delivers grease via a small pipe. If your shaft runs true the stuffing box will not need tightening very often.

The black pipe is an extension of your sterntube. The problem is to get lubricant to the packing in the stuffing box. One way is to let it weep slightly. It has always bothered me, and someone may know: if you inject grease into the tube, at the outboard end of the flexi black pipe, will the grease be pushed into the stuffing box by water pressure?
 
I'm sorry - I don't know what is specified by the aquadrive manufacturers and the manuals are all on the boat. (I'm coming to the conclusion that 2 sets of manuals would be handy - one here, one on the boat /forums/images/graemlins/wink.gif

Rick
 
Paul

I can't offer a before & after comparison either - but comparing very similar boats with/without aquadrives; it is very impressive.

We have a basic ford truck engine, with not that good soundproofing & ordinary engine mounts rather than the more flexible ones that the aquadrive system allows - yet compared with other steel & grp boats with that engine it is very very quiet & smooth indeed.

we looked at one 36' boat in Holland , again with an old design truck engine - which had an insulated ply enclosure round the engine + the full aquadrive system. You could barely tell that the engine was running (in fact you couldn't until we stopped talking) & when put into gear - the only way to know was that the boat moved. OK, this was exceptional - but still amazing for a 36'er with the engine right under the saloon/helm.


The full deal requires use of softer engine mounts, which is fine - since the cv joints take care of engine movement & all I've seen have rubber mounts for the thrust bearing housing - to reduce noise/vibration from the shaft/bearings



You can get graphite packing for stern glands like yours that "doesn't need lubricating" & perhaps with this & water behind it the cooling/lubrication issues are sorted?, but I've read of it grooving some shafts


Ours has a similar gland, but w/o the rubber tube. this fixed directly to the hull, but then entering a compartment in the keel that's several feet long. A bearing at the back of this, then a very short length of shaft exposed before the prop.

the compartment has a drain screw, since presumably water will get in past the rear bearing, but I spent ages getting off years of paint last Feb. to release the drain bolt & nothing came out at all.

The stern gland has a remote greaser, which is needed. It doesn't get warm at all, but after a couple of hours running we notice a little extra noise/vibration & greasing stops it. Makers reckon grease every 2 hours anyway.
 
Without a aquadrive the stern tube would only have one cutlass bearing on the outboard end plus cutlass bearings in "P" bracket. This would then allow the shaft to flex a little as the engine moves, thats why they fit a rubber hose to stern gland.

If aquadrive are fitted they should put a half cutlass bearing on the inner end and one outter end. With this fitted they can fit the gland onto the tube. No flexing

When you a fitting "P" bracket, stern tubes aquadrives more bearings along the shaft, harder to get all lined up.

I would think all is the same as a standard boat with a aquadrives fitted.
 
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