Forums, Engine, Gearbox, Stern Gear, etc, Engine Beds

Zoom 495 at 11/09/2015 18:36:41
Hello all.
I am getting a tremendous amount of vibration and the aft motor mounts on my Volvo MD2030 are starting to come adrift. The installation of this unit (by a shipyard no less) is terrible. I suspect it was done poorly as to do it correctly the motor may have to be mounted further forward and therefor needing a longer shaft. Questions are please:
Does anyone have such a beast mounted in their boat, and if so, is it possible to get a photo of it to show relative location of the motor?
Can I effectively install a spacer or flex coupling to potentially extend the shaft length, thus being able to do the re-mount without removing the shaft?
My Contessa was built in 1977. Will the shaft be a metric size on an imperial size?
Thank you and fair winds,kris

Keny at 11/09/2015 19:57:21
Hello Zoom
Are your engine beds solid like your coupling – this would be somewhat unusual in a Contessa ? If so I would suggest that it has just gone out of alignment.
keny

moongirl at 14/09/2015 17:38:25
Am I correct in believing that you are suggesting moving the engine fwd? I can see that this would be a problem as the end of the engine installation is pretty close to the vertical enclosing panel!
Questions:
1 what seal do you have where the shaft leaves the GRP?
2 is there any flexible connection in the shaft?

It is possible to undo the engine mounts + shaft & to slide the engine fwd to be able to lift the engine & renew the mounts. I did just that using old sheets fixed in a loop around the front mounts & mast – I then picked the ropes up like 2 suitcases & the engine slid easily up the beds sufficient to clear the shaft. This was on a Yanmar 3GM20 which may not be quite the same!

Zoom 495 at 20/09/2015 18:24:33
Hello Colin, and thanks for your reply.
Zoom has a traditional stuffing box with no flex coupling, just two mating flanges. The front of the engine is easily 14-18 inches from the forward vertical panel of the engine compartment. I believe Zoom came from England with an older Volvo and perhaps the transmission on that engine was longer enabling the motor mounts to be further forward? Presently, the rear motor mounts are pinched toward the centre line of the vessel at the extreme rear of the engine beds, and so of course, the rubber is broken on both of them. I have not surveyed the shaft or stern bearing and will do that before doing any renovations, but the mounts will need replacing no matter what I do.
All of the help I have received here has made working on Zoom so much easier than it would have been just fumbling through bit on my own! Thanks again,kris

Keny at 20/09/2015 19:17:32
Hello Zoom
I must say that it is not good to have a solid coupling with flexible mounts which is what i believe you have.
I think you’re answer is to fit a proper rubber coupling with a 30mm spacer. The spacer will enable you to change the coupling without disturbing the engine or the rudder.
You should also get a much quieter ride.
keny
p.s. see technical papers 2014

Zoom 495 at 22/09/2015 00:29:30
Thanks Keny.
I read the technical paper and it refers to a Centaflex M127 coupling. It
makes sense to me that an engine with flexible mounts and a very short propeller shaft would be connected via a flex coupling. Is this model the one I should get? With the coupling and the spacer, the engine will be moved forward in the neighborhood of 30 plus a few mm which may give the rear motor mounts the room to be mounted properly. I hope…
Thanks again for the help. It looks like Zoom may go ashore for a few weeks this winter.

doug at 22/09/2015 21:50:22
Hello Zoom,
I fitted a Centaflex M127 about 6 years ago and it has been fine. It uses a collet to grip the shaft and so is easy to disconnect should you need to do so. The boat almost certainly would have left the factory with a 1" shaft but anything could have been done since so it is important to measure it for the correct fitting. Also the correct flange for your Volvo.
A spacer may well do the trick however If you found you had to fit a new propshaft, they are not too expensive if you go to a general engineering shop, rather than a fancy marine one.
This means a lot of extra work but you would have an opportunity to check out your rudder bearings, propshaft bearing and stuffing box at the same time. I found the shaft very wasted under my stuffing box – an accident waiting to happen.
Good luck with it.

George Isted at 23/09/2015 09:14:45
I fitted a Centaflex flexible coupling two winters ago, this was because my 2GM engine seems to bounce around more than I would like in it’s mountings and it did have an almost rigid coupling to the shaft. No problems so far. I can’t remember the exact model but M127 sounds familiar.

Keny at 23/09/2015 09:38:38
Hello Zoom
Just to add to others. You will have to move the engine further forward anyway to provide the room for whatever you fit as a coupling. I have a 3 cyl. also and will measure how forward it is for you next time I visit my boat.
I agree with Doug that the shafts are the easy bit and also wear the most. I knock mine out at £30 a go!
keny

Keny at 26/09/2015 18:20:26
Hello Zoom
As promised the distance between my front pulley and the step panel is about 4 inches. The layout would probably benefit from moving it further forward by another 2 inches which may happen this winter.
keny

Zoom 495 at 27/09/2015 00:49:28
Hello Keny. Thanks for the info. My engine, a Volvo MD2030 3cylinder, is about 14 inches from crankshaft pulley to the step panel. So a good deal further aft of where your engine it sounds like. What make is your engine?
Cheers,kris

Keny at 27/09/2015 11:13:07
Mine is a Beta 20 (20 bhp) – a tad smaller than yours. Total length from front pulley to g/box flange is about 610mm according to Beta web site.
Hope this helps
keny

Zoom 495 at 20/10/2015 16:17:20
Thanks Keny for all the info. It appears that I will have to re-do the engine stools to move the engine forward and therefor get a new shaft. I believe the reason the engine was mounted so far aft by the previous owner was so they did not have to re-new the shaft, drydock the boat etc. Are people fitting some sort of flex coupling in the drive line also? Is the JR supplied tuffnel bearing for the stern tube the best shaft bearing choice? Does anyone have some words for this project as I may as well “do it all” when she is on the hard.
Cheers,kris.

Keny at 26/10/2015 16:03:22
Hello kris
You may have a flexible drive plate fitted to the engine – acts like a dual mass flywheel on a car. Mine has a plastic one but you could fit a rubber one if you’re going to town on it.
You must change the tufnel bush for a cutlass bearing.
p.s. stools mean something different over here!!