Flexible coupling?

[pjcomeau]

Has anyone used a flexible coupling other then Vetus Bullflex (go2marine has Bullflex 2 at $523). How about "R & D Marine" flexible coupling (I'm not sure how it fits/works). It looks like it may work with existing coupler.

As for regular coupling, when they ask for "solid" or "split" what does that mean?   I was looking at "Buck Algonquin" coupling selection guide (at www.deepblueyachtsupply.com).

Thanks,

Pierre

[Steve Sayian]

Pierre,

A split coupler has a split in the area where the prop shaft enters the coupler.  There are two bolts that when tightened, clamp around the shaft.  This allows you to also loosen the bolts and remove the shaft without disconnecting the entire coupler from the transmission.
A solid coupler is a one piece of machined metal that requires the shaft (sometimes) to be pressed in and always requires the removal of the coupler from the transmission to remove the shaft.

Steve

[Ron Hill]

Pierre : I have a Uniflex coupling - also from Vetus, which I've had since 1992!!   Vetus also has a Type 6 coupling which is a little cheaper.  A couple of options.   
After all it's only Boat $$ !!!

[Roc]

I have a 'Federal' coupling.  Do a search on this site, and google for Federal and I think you'll find some information.

[Mike Vaccaro]

We have a Vetus Bullflex and have been very happy with it.  With the right engine mounts, it substantially reduces engine vibration.  The August 2004 Tech Notes has a write-up describing the installation.  For boats with the M-25, in addition to the coupling, replacement of the stock mounts with Vetus K75's on the aft and and K50's forward seems just about optimum.  For M-35's, K75's all around (although there is no harm in four K75s [which are slightly stiffer] with M-25 equipped boats either).   

Keep in mind that the installation of a flexible coupling minimizes the concern with engine alignment, but does not eliminate it.  The real purpose of the coupling is to reduce vibration transfered to the hull through the shaft log and strut, not to act as a "universal joint" for the running gear.  The engine should still be aligned following normal procedures after the new coupling is installed.  The Tech Notes article provides a method for changing the coupling with the boat in the water that requires the aft end of the existing shaft (the key way portion) to be cut off.

Cheers,

Mike

[David Sanner]

You might try this site: http://www.yachtsupplydepot.com/
as they seem to have better pricing  (about $70 less but still $455) . 
Also I think you need the studbolt kit.

The Type 6 looks interesting and selling for $109... simple to
install but I wonder how it stacks up to the Type 2 for
reducing vibration.

[tonywright]

I think that the MKII has a problem accomodating a Vetus Bullflex, if you also have a dripless stuffing box.

There is just not enough space for the Vetus, as I recall when I looked at it since it uses more space than the regular coupling. THere is very little open shaft between the coupling and the end of the PSS seal. MK I's don't seem to have this problem. The Federal or similar may be your only option on a MK II.

Of course I am very willing to be corrected by anyone who has successfully installed both a PSS seal and a Vetus Bullflex on their MK II?

Tony

[Roc]

Tony is right, there isn't enough room. The marina that did the work on my boat (new shaft and PSS seal), said the only coupling they knew would work is the Federal, due to the limited space.