Aquadrives

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colvic

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Now that we are ready to replace our "submarine" engine, have elected to fit an Aquadrive as the flexible coupling to allow for any misalignment.

Any tips for the installation or anything I should be aware of?


Thanks


Phil
 
Suggest you search the archives. I fitted mine a year ago and there were lengthy threads on the problems I encountered.

The main issue is making up the thrust plate accurately and to be a good fit. I started off with a cardboard pattern, then a plywood one with everything bolted up in final position, then cut the metal plate to size and shape. Still required some grinding to get it right. I used epoxy paste to get the position correct, then glassed up once I was sure it was right, when solid.

Performance has been rather disappointing. There is a good deal more transmitted noise than there was without the Aquadrive, despite much effort to eliminate it.

Try a search on Python Drive. It looks to be a very similar device but may be cheaper.
 
After waiting since October to get work started on the boat I went with the advert claims re noise and alignment problems just so that we can get the boat back as soon as possible, and now what you are saying really worries me. What did Halyard say/do re the increased transmission noise, which I have to say we didn't have much of. I've spent over £300 in order to prevent possible problems with Spanish mechanics and perhaps yet again I'm wrong.

I take it that the steel plate you mention takes all the thrust as opposed to the coupling and/or gearbox on the old installation. Hope it can befitted well enough.


Phil
 
Re: Aquadrives, be fair

I found your original thread, it really sounds as though that recent engine change introduced a new and fundamental vibration problem prior to the fitment of the Aqua drive.
 
I bought mine in Holland, not from Halyard. The supplier was just that, no knowledge of the product, just a sales outlet. I could have spoken to Aquadrive in Sweden, I suppose, but didn't bother.

My previous experience was like yours: virtually no transmitted noise with a conventional setup. I fitted the Aquadrive to overcome shaft to stern-tube knocking with the softer engine mountings of my new Yanmar. There is now a continuous rumbling noise that I believe to be the bearing in the Aquadrive. This noise is only isolated by the two relatively small rubber bushes. There also seems to be a shaft critical speed right on 2100 engine revs, just where I want it for cruising speed. The good thing is that alignment is a thing of the past. My engine is in fact still perfectly aligned and it has been suggested to me that this could be the cause of some of the noise. Some have said that they are quieter with deliberate misalignment. I am a little sceptical about this, CV joints on the many Minis I owned knocked at full lock but were quiet straight ahead. Have yet to experiment.

The thrust plate is the only difficult part of the installation. It has to be tailor made for each boat and glassed to the hull. Measurements are fairly critical. My son knows the Spanish agent for Aquadrive, who seems to be competent. Might be worth consulting him.
 
Re: Aquadrives, be fair

I only fitted the Aquadrive to cure the shaft to stern tube knock. The critical speed problem did seem to arrive with the Yanmar, causing knocking at about 2100 rpm. This didn't happen with the Bukh, whose engine mountings are incredibly stiff. With the Aquadrive the critical is still there but I have minimised it as far as possible by being extra fussy with the shaft centring in the coupling.
 
I think I saw, on the Python website, that their drives should NOT be installed in a perfect straight line. I think the Python drives are very similar to Aquadrives.

I did not think they were any cheaper than Aquadrives.

I spent some time checking whether I could by parts (eg agricultiral equipment) to make an artculated joint but concluded it would be too much trouble compared with the money I would save by not buying an Aquadrive - and I will need 2 of them :-(
 
Hi Vyv

Thanks for your comments about the Aquadrive and having already parted with my money they prompted me into checking a few things out.

Today we bought a new engine for the boat and during the discussion the pro's and cons of 3 cylinder versus 4 cylinders was brought up and the engineer said that there is more vibration with a 3 cyl. engine, obviously, but to overcome it they supply a very substantial foot that retails at over £40 each to reduce the problem quite dramaticaly.

Using a steel mounting plate could act as a resonating plate and amplify the sound.

You say that the alignment is spot on, which is what is recomended; if set up out of alignemnt then that alignment is increased due to engine movement or hull flexing then it is quite possible for the permissable degree of mis alignment to be exceeded and then you get noise.

I've been told that Halyard offer a very helpful advice service; I enquired from them as to which model etc. I needed and they were very helpful and no pressure to buy. I bought from ASAP at just over £300 which is a lot less than I was quoted a year ago from a different supplier.

Engine should be in and working by first week in February and I'll let you know how things go. I'm going to use a ply mounting plate, glassed in, to mount it to to prevent any extra noise. The stuffing box is mounted onto a ply former.


Phil
 
I have fitted three flexible couplings to date.One was my own design and made of two old Mini universal joints.The other two were Aquadrives.Never had any special difficulty in fitting them although it can be an awfull lot of work.
For the thrust plate I used 12mm plywood ,fiberglassed over, and then epoxied to the hull.To make sure the whole thing was acurately aligned I bolted the Aquadrive(connected to the shaft) to it and to the engine and stuck the plate to the hull with a bit of epoxy filler.Then,after the filler hardened I fiberglassed the plate to the hull with epoxy and roving.IMHO it is not important to use metal thrust plates as fiberglass laminated plywood is probably stronger and it is much easier to get a good bond to the fiberglass. In the whole it is definitely not difficult and the results that I got in all three cases more than justified the work.
 
It's difficult to know what to do so far as the plare material is concerned. Both Aquadrive and Python recommend metal, indeed, Python sell blank plates shaped for the bearing housing that can be cut to fit the hull. I spoke to a company that fits them to a variety of motor boats and they only use mild steel.

However, for a small power output such as on a yacht I'm sure you are correct that plywood is sufficiently strong. I do feel that much of the transmitted noise that my installation suffers is due to the plate material. Bonding to steel is not difficult, especially if a few holes are drilled in it first.
 
I made a jig to ensure correct alignment. Used 18mm ply heavily glassed in.
A massive improvement. The Yanmar dances about quite happily while the Aquadrive takes the flexing. There is no grumbling or rumbling at all.
I note from the thread that a number of owners have problems with Yanmars on their soft rubbers. This was my problem at about 2000 revs. and start and stop. Strikes me Yanmar need to think about their mountings while I think about why I didn't get a Beta.
Also note that as supplied there is no positive locking on the bushes. They just use nylon lock nuts. Lousy engineering. Aquadrive need to re-engineer the bush arrangement with proper steel sleeves.
 
Re ASAP and VAT; Friday got a price for stern tube, quoted as retail less 10% is £230, written quotes arrives yesterday all of a sudden VAT and carriage are added so price goes to almost £280.

Ver very naughty and have told them so...retail includes VAT.
 
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