Aquadrive - watch for loose bolts

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We have recently had a serious problem arise with the Aquadrive fitting in our gearbox-to-propellor drivetrain. If you have an Aquadrive fitting in your boat the below will be of interest - otherwise ignore the following!

Back in 2020 we collected our new to us yacht for the delivery trip home. I noticed a line of splattered grease perpendicular to the Aquadrive that had evidently been spun off the unit by centrifugal force. I also noticed three of the six bolts on the forward hub of the Aquadrive were finger loose and falling out. I tightened the bolts with an Allen key, cleaned up the previously splatted grease and thought nothing further of it.

Fast forward to current day. We had a leaking shaft seal and instructed an engineer to replace the seal. This required dismantling the Aquadrive to push the shaft back. When the engineer removed the Aquadrive he found the internal bolts which serve to fix the shaft to the aft Aquadrive hub were also loose. This had caused the shaft to be loose in the Aquadrive fitting which has caused internal movement and the deformation of the forward end of the propshaft. New propshaft required. As an aside we have also had to replace cutless bearing, thrust bearing and seal housing (and seal) but that’s not directly related to the Aquadrive problem.

The Aquadrive was found to have wear in the gearing and it was recommended that it be replaced. I met with experts on Aquadrive to collect the parts and was given very useful guidance on the fitting of the Aquadrive unit. It is absolutely essential that all bolts are torqued to specification and are fitted with thread locking substance. The consequences of not fitting to specification can be catastrophic. The experts advised that a splattering of grease is always an indication of loose Aquadrive bolts and it is essential that it be rectified immediately.

In conversation with other owners (in our online group ) it seems to be a problem more common than one might expect. It seems from the feedback that where Aquadrive units are dissasembled for shaft seal replacement the unit is then often not refitted correctly. I’m guessing that the engineer doing this work doesn’t have the fitting guidance to hand and consequently the problem arises.

There are various case reports online where the shaft has become so loose in the Aquadrive hub that it has fallen out, slid back through the thrust bearing, out past the seal and jambed the rudder or fallen out of the hull completely. In one instance where the shaft released and jambed the rudder on full lock the yacht could not be sailed or towed (except in circles) leading to abandonment and sinking, it’s a serious issue.

So, if you have n Aquadrive - keep an eye to the bolts. If any are loose then remove, degrease, apply thread locker and torque up.

Hope this avoids a future problem for someone.

Rob
 
That's strange because Aquadrive's own installation instructions for the BV10 Aquadrive that I fitted back in 2003 make no mention of thread locker.
It's performed faultlessly (even with maximum allowed CV shaft misalignment) ever since and I've twice removed the shaft from the coupling for stern gear maintenance and then re-torqued the bolts upon refitting the shaft, instruction - but without thread locker.

Capture.JPG
 
Interesting indeed, but it looks like your fitting is quite different to mine, see here:

Aquadrive.png

So perhaps the thinking has changed. It‘s the Allen head bolts visible in the picture which have come loose but our engineer reports that the internal bolts on the shaft taper lock were also loose.
 
Are you sure that's an Aquadrive.
It looks very similar to my Python drive.
Perhaps it's because they are very similar devices.

I've had very similar problems.
When a yard replaced the cutlass bearing. They didn't torque up the shalf collet clamp. When I removed the gearbox, to have some work done on it, the shaft had slipped back about 15m.
One good burst astern and they shaft would have come out. And with twin rudders there's nothing to stop the saft sliding right out.
 
Ian_Edwards said:
Are you sure that's an Aquadrive.
It looks very similar to my Python drive.
Perhaps it's because they are very similar devices.

I've had very similar problems.
When a yard replaced the cutlass bearing. They didn't torque up the shalf collet clamp. When I removed the gearbox, to have some work done on it, the shaft had slipped back about 15m.
One good burst astern and they shaft would have come out. And with twin rudders there's nothing to stop the saft sliding right out.
Click to expand...
Looks like an Aqua drive to me. At least it looks exactly the same as ours and ours is certainly an Aqua drive. I’ve got mine dismantled at the moment as we are fitting a new engine and so it’s a timely reminder to me that when I install the new engine and reinstall the Aqua drive I need to make sure that everything is tightened to the correct torque.

We had the Aqua Drive fitted to our old engine for the last 16 years and it’s been brilliant. It’s made the engine installation very quiet and smooth and I’ve been totally impressed by its performance. We had one issue about eight years ago where the thrust bearing started to rumble. We consulted Halyard Marine and they referred us to their engineers who replaced the bearing free of charge. The only downside was me having to dive under the boat to release the shaft anode to allow me to move the shaft far enough aft in order to allow me to get the bearing out to send it back to be replaced. We were in Milford Haven Marina at the time and diving with a snorkel under the boat in the cold mucky water was challenging to say the least.
 
Ian_Edwards said:
Are you sure that's an Aquadrive.
It looks very similar to my Python drive.
Perhaps it's because they are very similar devices.

I've had very similar problems.
When a yard replaced the cutlass bearing. They didn't torque up the shalf collet clamp. When I removed the gearbox, to have some work done on it, the shaft had slipped back about 15m.
One good burst astern and they shaft would have come out. And with twin rudders there's nothing to stop the saft sliding right out.
Click to expand...
Yes, it is an Aquadrive, model CVB 15.10. It’s a current model in production.

As an aside, if anyone has problems with their Aquadrive unit then I highly recommend consulting with TW Marine at Furness Vale, High Peak. Very helpful and knowledgeable people, Steve or Nick. T W Marine Ltd
 
Interesting experience. We have the Python Drive version which is obviously very similar. I wonder why loose bolts would allow the grease to escape. I assumed the grease was contained by the rubber cv boots.
 
Keith-i said:
Interesting experience. We have the Python Drive version which is obviously very similar. I wonder why loose bolts would allow the grease to escape. I assumed the grease was contained by the rubber cv boots.
Click to expand...
No, grease is not contained by rubber boots but by steel end caps. Here is a picture of the Aquadrive with an end cap removed:

no%20cap.png


and here with the cap replaced:

with%20cap.png


when the bolts are loose the grease can escape from behind the cap - and splatters perpendicular to the Aquadrive.
 
john_morris_uk said:
so it’s a timely reminder to me that when I install the new engine and reinstall the Aqua drive I need to make sure that everything is tightened to the correct torque.
Click to expand...
And don’t forget the Loctite. Any previously used bolts/threads must be degreased before Loctite is applied. Apologies if I’m stating the obvious, I aM simply repeating the advice received from TW Marine.
 
My Python Drive bolts have non-slip stepped washers. I think they’re called Nord Lock. Very difficult to undo once tightened.
 
Interesting discussion. We are having exact same issue ie bolts loosening. That's the Allen key head bolts on the aft end of the Aquadrive unit.
I'll borrow a torque drive and torque them up
It's been on for a while so may need replacing
Thanks for posting this, very helpful. 👍
 
john_morris_uk said:
Looks like an Aqua drive to me. At least it looks exactly the same as ours and ours is certainly an Aqua drive. I’ve got mine dismantled at the moment as we are fitting a new engine and so it’s a timely reminder to me that when I install the new engine and reinstall the Aqua drive I need to make sure that everything is tightened to the correct torque.

We had the Aqua Drive fitted to our old engine for the last 16 years and it’s been brilliant. It’s made the engine installation very quiet and smooth and I’ve been totally impressed by its performance. We had one issue about eight years ago where the thrust bearing started to rumble. We consulted Halyard Marine and they referred us to their engineers who replaced the bearing free of charge. The only downside was me having to dive under the boat to release the shaft anode to allow me to move the shaft far enough aft in order to allow me to get the bearing out to send it back to be replaced. We were in Milford Haven Marina at the time and diving with a snorkel under the boat in the cold mucky water was challenging to say the least.
Click to expand...
Thanks for your input. Do you mind me asking - how many engine hours do you reckon you've done in those 16yrs?
I'm thinking aquadrive may need replaced after about 7 000 hours.
Thanks.
 
Delboy1874 said:
Thanks for your input. Do you mind me asking - how many engine hours do you reckon you've done in those 16yrs?
I'm thinking aquadrive may need replaced after about 7 000 hours.
Thanks.
Click to expand...
My best guess would be a lot fewer than 7000 hours. Perhaps between one and two thousand? Our current engine has an hours timer and we’ve done a less than a thousand hours despite cruising on the boat for several months at a time each year since I retired.
 
Very timely. Thank you. I am about to change cutless bearing and will be following your advice on reassembly.
 
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