V drive and aquadrive

[Benbo]

I am fitting a new 43 HP Beta engine with a Hurth V drive gear box in my Nicholson 40 AC.
Space is a premium.Has anyone had experience using aquadrive or other flexible couplings with V drive units-any advice/help most gratefully received!Any other advice regarding other useful additions to consider at this stage while I have got everything out and the chance to achieve perfection!(most unlikely I know.)

 

[Neil_Y]

We represent these systems but it might be another option worth considering.

The thrust bearing assembly is far smaller than an equivelant aquadrive on larger sizes I believe but I can give you dimensions.

The units are called Seatorque, thrust is taken on an internal bulkhead as with an Aquadrive and this is coupled to the gearbox or V drive with a double UJ cardan shaft.

http://www.h4marine.com/pdf/stm3schematic.pdf
This diagram shows an STM3 where thrust is taken on through hull but the unit is similar.

We need to know distance gearbox to P bracket/or stern tube aft end, engine type hp, gearbox type and reduction ratio to specify.

 

[Benbo]

Hi,
Many thanks. The Seatorque systems does indeed look elegant I had considered it before but dismissed it as too complex and not easy to retrofit, but having looked in more detail it would provide a good solution. I might even be able to fit a quicKutter to the shaft! I presume the Seatorque system replaces the entire existing shaft and cutlass bearing and stern gland.
My problem has been that the existing system is very rigid-a fixed coupling to the V drive and the engine with rigid mounts, as a consiquence I have replaced 3 cutlass bearing in the boat's 24 life! I have been assured that there is no problem with alignment it just because of the vibration and ? due to uneven wear when motorsailing.Not that there are many hours on the engine anyway.
The stern tube is 875mm long & 46mm in Diam with 100mm collar at the in-board end which I would like to get rid of or shorten, and so be able to move the engine further aft giving a little more room in front of the V drive.
The engine is Beta 43 HP with a Hurth V drive (HBW150-V) gearbox with ratio 1.560(1.880):1.950 (1.950).
I will contact you to discuss in more detail as I think this could work.

 

[Neil_Y]

I could give you another explanation for bearing wear, I assume these will have been rubber bearings?

This whole area of vibration/alignment/bearing wear is a bit of a black art, and many companies would prefer it stayed that way.

Much of the conjecture is theoretical but there have been some serious studies on commercial bearings by one of our competitors in composite bearings who seems to agree with us. The study was on larger shafts but was essentially a look at the rates of wear for hard and soft (elastomeric) materials as bearings in water film or boundary water film lubrication.

You can read it here http://www.wartsila.com/Wartsila/gl...ail/2_2007/bearings-for-longer-shaft-life.pdf