Double R&D Coupling

[n.b.Goldie]

While looking at the piccies of a boat for sale on Apollo Duck I was struck by the photo of the drive coupling. It appears to be a double R&D setup. Has anyone seen this sort of thing before? Is it a good idea and what are the benefits/disadvantages?

 

 

 

 

Thanks

Ditchdabbler

[Capt Ahab]

While looking at the piccies of a boat for sale on Apollo Duck I was struck by the photo of the drive coupling. It appears to be a double R&D setup. Has anyone seen this sort of thing before? Is it a good idea and what are the benefits/disadvantages?

 

 

 

 

Thanks

Ditchdabbler

That will be so when one fails (which they do regularly) you will have another to fall back on

[GBBS]

looks like a crown narrowboat. advantages minmal cost, allows more engine movement and softer eng mounts used mostly on Lombardini engines whicha again are cheaper than most. disadvantages if one breaks the other will be destroyed usually. Generally trouble free. IMHO neither good nor bad just different.

 

Dave

[n.b.Goldie]

looks like a crown narrowboat. advantages minmal cost, allows more engine movement and softer eng mounts used mostly on Lombardini engines whicha again are cheaper than most. disadvantages if one breaks the other will be destroyed usually. Generally trouble free. IMHO neither good nor bad just different.

 

Dave

 

Just looked at the ad again, it says the builder is John White but it does have a Lombardini engine. So I guess this arrangement is 'accepted practise'?

 

 

Regards

Ditchdabbler

[Guest]

Ask the makers. I have found them to be extremely helpful:

 

http://www.randdmarine.com/contactus.asp

[Phoenix_V]

We have had a single r and d coupling for about 20 years, no problems, so I guess it depends on the installation, HA3 solid mount in this case

[MikeHing]

When we first had our boat it was built with a single R & D coupling and I was unhappy with the amount of vibration transmitted to the hull. This single type of coupling is pretty useless when combined with an engine fitted to flexible engine mounts.

Very soon after I fitted a second R & D coupling pretty well exactly as shown in the photo. This creates a rudiomentary universal joint assembley allowing a small degree of parallel motion of the drive shaft. The reduction in transmitted vibration was noticeable. I used this set up for several years before finally fitting an Aquadrive unit.

[Roger Crown]

looks like a crown narrowboat. advantages minmal cost, allows more engine movement and softer eng mounts used mostly on Lombardini engines whicha again are cheaper than most. disadvantages if one breaks the other will be destroyed usually. Generally trouble free. IMHO neither good nor bad just different.

 

Dave

Hi Dave

Definitely not one of ours, we never used equipment at "minimal cost", nor did we do tatty room engine installs like the one in the photo.

If you go back to the apollo duck website you can actually see who the boat fitters were and realise that they were at the other end of the market to us.

Regards

Roger

[GBBS]

apologies to Crown!!. I did mean John White. We regularly maintain one with this arrangement and that is indeed a John White.

 

Crown boats are always excellent from our experience no offence meant

 

Dave