Halyard CV drive coupling

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Pagetslady

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Hi Anybody fitted a Halyard CV shaft coupling between their engine and prop shaft, I am installing a new Beta engine this winter and have always wanted to use the prop to push the hull directly rather than through the engine would like to hear from anybody that has fitted one.
Regards Mike.
 
They do what they claim. Downside is that you need to glass in a substantial "floor" to take the thrust and there is a big increase in overall length of the drivetrain meaning there is often not room to fit one in a boat not designed for it. Newer style engines like your Beta are so much smoother than older engines so the benefit from that point of view is is much less than in the past.
 
I know that the system as is has worked for years in fact on my boat 25 years but I just like the idea of the shaft being supported by a 2 fixed bearings which are not too far apart and the prop to be pushing directly through the hull rather than on the engine mounts I need to measure up to see if one will fit but the new Halyard smallest one now incorporates the shaft coupling within the actual mounting plate so is shorter than they were, Bruntons have recommended that I increase my shaft to 30mm which will mean fitting a larger stern tube as the running clearance will be too small, but with a bearing supporting the shaft in a fixed position as opposed to the engine which will move about I thin that a Duplex 25 mm shaft should cope well with out whipping sufficiently to hit the stern tube. It will also make lining the engine up much easier. Rather than just glassing in the bracket for the Halyard I would extend the engine bearers to fix it too.
Any way its some thing to think about this winter.
Regards Mike.
 
I fitted a Halyard coupling to a 1970's boat which had been re-engined with a 2 cylinder Yanmar. My main reason was I thought the stern gland was getting a very hard time from the very flexibly mounted engine. It was a lot of work, but the result was impressive, esp in reduction of noise and vibration transmitted to the hull
My present boat is somewhat similar in layout, but with a 3 cylinder engine. The improvement in smoothness compared to the Yanmar is so considerable that I can't justify a Halyard coupling.
Using the engine mountings to push the boat doesn't really concern me, easy engine alignment with the Hayard is nice though
 
I had to replace my shaft coupling and propellor shaft and had a Halyard drive fitted. A 30 mm thick marine ply bulkhead was epoxy bonded into the bilge about 18" back from the gearbox. The engine is a Perkins 4236 and the 30mm bulkhead was selected to back up a stiffener that had be cut through, rather than the need for such thickness. The bulkhead was only about 18" across the top, 12" deep and 6" across the bottom, so it was very rigid anyway.

If fitting a new engine one may have the opportunity to alighn the shaft and engine perfectly, however Halyard recommend that the CV is mounted with a small offset. Apparently they don't like to run true as it increases the risk of early wear.

Compared to before and after: it's a world of difference as far as engine vibration is considered. If you are going to fit one then make sure all shaft bearings e.g. Cutless, and engine mounts are also new, which I did. So, to be honest I cant really tell how much of the benefit can be apportioned to the Halyard. Still its 100% better than the hard rubber and plastic, rusty bolted coupling that sheared on me.
 
There is also the Hydradrive I believe it may be shorter but can send you a brochure as the download from the website isn't working it seems. We took them on mainly for the marine joint but the Hydradrive is a thrust bearing and CV coupling taking all thrust loads on a bulkhead allowing the engine freedom to move.

http://youtu.be/OAaelKOkxQ4

CV joints need to cycle the balls to spread the wear over a larger surface area hence the need to have them offset, the same goes for cardan shafts.
 
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