Prop shaft drive saver

[gwhastie]

Does anyone have any experience using a drivesaver (picture attached) to create a slightly flexible link between a 4" dia prop shaft flange and a Velvet Drive output flange?

I'm about to instal a marinised Holden 304 EFI engine/Velvet Drive 71C combination in my 16 foot Glen-L Crackerbox hull at an angle of 15.5 degrees and wondering if there will be sufficient lateral movement in the prop shaft at the skeg and or shaft log to compensate for the engine/transmission moving on its rubber mounts and affecting the alignment of the engine/prop shaft while bouncing on waves. Drivesavers are expensive at A$1000 and I'm wondering if one is really needed.

Any advice would be appreciated please. Regards, Gary

[Alan]

Hi Garry, want to be damm good for $1000, I've got no experience with them but don't you have all four (marine style) engine mounts? I would think it will not move enough to be a problem. I have been in some timber boats that I thought the engine was not bolted down it moved so much, and there has been no problems with the flanges.

[gwhastie]

Thank you for the feedback.

Yes, my engine has 4 marine mounts. I was concerned that the Velvet Drive output shaft bearing might get flexed too much.

[Will]

I think the idea of some flexibility is a good one however I wouldnt spend $1000 on what is basically a donut (slightly fancy maybe)
There are many driveline donuts available from several manufacturers -ie Ford, Holden , BMW and many others . Im certain they would handle the power /torque of your application and for prices around $100 or less! Some research required to match bolt centers etc - other advantage is if these is a failure/ wear in the distant future replacements are readily available

[WoodRay]

I've been involved with the use of Fenner drive couplings on the back of diesel engines (A big boot mounted on flywheel roughly the shape of a brake booster diaphragm). Same principle but in reality they still require alignment. Even though they will allow some miss alignment and may reduce related failures, they caused vibrations if out of alignment. I guess the durometer rating of the rubber will be the important factor.

[Paul SA]

I dont use one on Sceamin Eagle skiff and i can tell you when it bounces it looks like the engine lifts up and down 3 inches and sill all good afer all these years and i run a velvet drive behind a 400 chev in my hammond with out one and i beat that boat to death with no problems