Forums, Engine, Gearbox, Stern Gear, etc, Engines and alignment

Zoom 495 at 05/03/2016 06:39:54
I am stuck with the Volvo MD2030 (same as Perkins Perama 20 and 30) that Zoom came to me with. I would prefer a Beta 20, but I have searched for a 2nd hand unit to no avail, and the Volvo has low hours so it stays. The Volvo was very poorly installed by the previous owner and I have removed it to re-install it. The engine beds are in a different plane than the propeller shaft. The MD2030 mounts were spaced up at the front so the gearbox met the angle of the shaft. Upon removal of the engine, it is apparent that the engine beds are at a way flatter angle than the shaft. Did the factory installed engine have a down angle drive on the gearbox output shaft? Do I need to fabricate and laminate in angled spacers (wedges) on top of the present engine beds?
The stern tube has separated from the aft engine room bulkhead. It is not leaking (yet) but I can move it and see the crack around the concentric bond in the bulkhead. Does anyone have experience with this problem?
Any help is appreciated and photos of existing installations or links are welcome!!

doug at 05/03/2016 20:38:49
If you look on the Technical Papers section you will see a piece on fitting a new engine which has some photographs of a Centaflex coupling in use.
It shows a method of lining up the engine using the prop shaft and a short length of bar fixed in the coupling; a steel rule can then be used across the two to measure the vertical and horizontal alignment, as well as judging the relative angles, as you juggle with the engine.
The main drawback of this approach is the high cost of the coupling. The advantages are that the coupling can take up a certain amount of mis-alignment, and it is pretty quick and easy to use.
Sorry I can’t help with the stern tube but I think there is a also a piece on stern gear there, which may be of help.

George Isted at 06/03/2016 09:02:18
The separation of the bronze stern tube from the hull on the inside is not uncommon and if you don’t have any water coming in that means the bonding of the rest of the stern tube should be fine. Engine vibration, particularly if the shaft/engine is miss-aligned, can cause this. I have had to do a small repair in the same area and having thoroughly de-greased, roughened to a good surface and de-greased again it can be rebounded back in place with the resin/fillers if your choice. As you will know, access is not comfortable but it’s an easy repair.

Zoom 495 at 06/03/2016 18:16:07
Thank you George. There is no leak (yet!) and gross miss alignment is surely the cause!! The engine was not even on the same page as the shaft. The engine beds are set on a more horizontal plane than the shaft suggesting the previous engine (original Volvo) had a down angle gear box. I see on the JR spares list there is a set of engine beds available for re-engine. Do you know if these are engineered to make up for this angular difference? Did your Yanmar 2GM sit on the original beds or were they modified?
Thanks George,kris

George Isted at 06/03/2016 20:35:38
I have a 2GM20 that replaced the original Petter-twin. The original engine beds are still in place but they have been modified with large steel brackets to accept the Yanmar engine mounts. I can’t really comment on the Volvo as I have no experience. All the mods do on my boat is bring the engine beds in toward the centre of the boat rather than alter the height.

Hopefully Robin (St Paddy) will see this post and comment as he knows his onions on engines and Co32’s.

Keny at 08/03/2016 14:04:44
Hello kris
I had exactly the same problem aligning my own engine.
Eventually I found it much easier to make a new set of engine brackets which fitted the existing beds
and also aligned the engine correctly.
keny
p.s. there is a picture of one of them in technical papers – ‘cure engine vibration’

Zoom 495 at 08/03/2016 15:54:17
Thanks Keny.
I had a couple large chunks of teak laying about waiting for a purpose and I ripped them on an angle and will fit them to the existing beds to re-align. It won`t be as pretty as your installation looks to be from the photos, but neither are we as refined out here in the Colony of Vancouver Island…
Did you make your own set up for this or did your purchase the kit from JR?
My engine will end up being further forward than it was. I may have room to install a flexible drive as well.
Are you happy with the Centaflex?
Thank you,kris

Keny at 08/03/2016 17:09:40
I’m sure you’re going about it in the right way. Making the brackets was relatively easy. Measuring up and making some drawings took time.
Also I stepped the beds as can be seen in the picture. This had no effect on vibration.
The Centaflex works well and is very popular.
Good luck
keny

Zoom 495 at 09/03/2016 16:44:35
Does anybody know where the technical papers have gone to on the new website?
I can`t seem to find the drawing of the stern gear arrangement.
Thanks,kris

George Isted at 09/03/2016 16:50:43
Hi Kris,
The Technical papers are on the class association website but are only available to member of the association. Once you log in you will be able to find them under the resources menu.

This was also the case on the previous website but they were temporarily made available to all on the new one (now fixed).

Best wishes
Edited: George Isted on 2016-03-09 16:52:20

Keny at 09/03/2016 19:15:34
Hello George
Couldn’t find ‘cure vibration’ in the technical papers. Is there any reason for this?
keny

Zoom 495 at 09/03/2016 22:35:37
Hi George,
I am logged in but for some reason the technical papers bar is missing on the resources tab.
I will just keep trying…

George Isted at 10/03/2016 17:19:16
I’m not sure why but the “Curing engine vibration” paper was not displayed so I have uploaded it again and it is now showing in the list of Technical papers. If you log into the website (not this forum) and go to Resources – Technical Papers in the menu there is a long list.
Edited: George Isted on 2016-03-10 17:20:01

Keny at 11/03/2016 09:39:35
Thanks George – like the new layout by the way
keny

George Isted at 11/03/2016 09:46:46
Thanks.

We have two people looking after and developing the new site so keep and eye on it for new content and functionality.