Driveshaft lengthening

[typhoontye]

Hello all,

I decided on the flex-o-fold propeller and it has arrived. Installation will have to wait due to re-prioritization of our overall upgrade plan, but…I noticed that the new prop requires quite a bit of exposed prop shaft for it’s installation, maybe as much as eight inches (includes an inch clearance from the forward facing surface on the prop hub to the aft facing surface of the prop support strut). I measured Blue Moon’s, and I have about seven inches measured from the aft most face of the prop shaft to the point at which the shaft exits the prop shaft support strut. My prop shaft appears to be in good condition, stainless steel, so I don’t want to replace it. My question is, has anyone extended their prop shaft by using a spacer of some sort between the V-drive output flange and the driveshaft input flange? Seems like this would be pretty straight forward. Any thoughts?

David Tye
#189, Blue Moon

[Warren Stringer]

Hi David,

You might want to look into a Drivesaver from Global Marine. It would give you the spacing and provides a breakaway joint between the shaft and the v-drive in case you wrap a line around your prop. I have one on my previous boat.

Warren
s/v Adagop

[Warren Stringer]

That would be s/v Adagio. Can’t spell at this hour of the night!

[typhoontye]

Thanks Warren, this looks like an alternative!  I’m skeptical of my math, but using Drive Savers formula, I came up with a torque of 119 ft lbs for my W58, which means I could use the smallest one they sell.  I need to look at the engine specs to see if this is the real number…seems way low to me.  Anyway, it appears this option would give me an extra inch which might be enough. Did you experience any vibration advantage with your Drive Saver?

 

David

 

[bkriegel]

Dave:

Just scanned the emails between you and Adagop; be careful increasing the distance between the strut and the forward end of the propeller hub; ABYC standard P-6.5.5.4 limits this to one shaft diameter –  ie you don’t want the shaft unsupported between the last strut bearing  and prop!

Bob K

SV Acadia

 

[typhoontye]

Copy that,  Bob.  Thanks.  I assume you had no trouble of this sort with your flex-o-prop install? 

 

David

 

[bkriegel]

None; flexofold works like a champ; doesn’t reverse worth a d**m, but that is more a function of prop/rudder seperation/hull design. 

Bob K

[RichCarter]

There isn’t a lot of room in there near the V-drive output flange.  I don’t think you can get a drive-saver shim in there.  Maybe a custom shop could make something.

 

Rich

 

[typhoontye]

Copy that.  I’ll have to look more closely. I have a marine machine shop here I can work with on a shim if necessary.  I don’t intend to tackle this job underwater, so will have to wait till the boat is on the hard…don’t know exactly when, but no later than the Fall.

 

David

 

[Warren Stringer]

Hi David,
It replaced a Yanmar torque limiter which had failed. This was a number of years ago, but as I remember things were a bit smoother. Don’t know if this was a function of the drivesaver or just removing the Yanmar device.

Warren
s/v Adagio

[skipmac]

I had a flexible coupling in my last boat which I liked a lot so looked in to putting one on my Pearson. However, when I was talking to Walter about a V-drive question I asked if there was a brand or model they recommended. Tech support at Walter said they did not recommend using any flexible coupling with their drives. I didn’t quite understand the explanation but didn’t push it as I had already had the guy in the line for a while and he seemed to be getting a bit antsy.

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