feathering props for a mango


Hank rose
 

My 28 year old max prop developed a crack in the body, discovered on a recent haulout. Never caused issues (when I owned it), but It is not repairable, so they say.
Any suggestions or experiences out there? Autostream said they do not make a model that fit my requirements. Considering now: Max prop, Variprop, and Autoprop.
Do I need a shaft brake for the Autoprop? hmm that would it make it more complicated.
I am planning to re-install a prop shaft mounted alternator again (as it came originally with that). Got all the hardware etc for it.
Hank
~take care~


Ron Hynes
 

My max prop has been  trouble free for 23 years so I can’t help with a prop recommendation. The J-Prop marketed by Beta seems interesting as you can adjust the pitch without removing it from the shaft.  However, I am considering driving an alternator with the prop shaft. Can you tell me the pulley ratio or the sizes of each and the amount of power you produce?

Ron Hynes
954.319.0944

On Jul 22, 2021, at 10:09 AM, Hank rose via groups.io <hankonthewater@...> wrote:

My 28 year old max prop developed a crack in the body, discovered on a recent haulout. Never caused issues (when I owned it), but It is not repairable, so they say.
Any suggestions or experiences out there? Autostream said they do not make a model that fit my requirements. Considering now: Max prop, Variprop, and Autoprop.
Do I need a shaft brake for the Autoprop? hmm that would it make it more complicated.
I am planning to re-install a prop shaft mounted alternator again (as it came originally with that). Got all the hardware etc for it.
Hank
~take care~


Hank rose
 

I am working away 3000km away from the boat...... so I can't help form here, but will ask someone to take a photo or 2 and measure. Alternator is a small Motorola, and the belt is a multigroove (?8) serpentine type. When I am visualising from that distance approx .........40 mm, large pulley on shaft over 200 mm, close to 300 mm?
Hank
~take care~


Bill Kinney
 

Hank,

If you have been happy with the MaxProp, I'd suggest you stay with it.  I have had them on my last two boats (over 20 years) and they have always worked well.  They ARE fully compatible with a shaft alternator, even though you will read in multiple places online that they are not.  The only thing I have seen that will damage them is sudden shifting at high RPM from forward to reverse.

I have sailed identical boats that have had Autoprops and Maxprops installed and I have never noticed a difference in performance sufficient to justify the extra cost and maintenance required for the Autoprop.  I am not saying there is NO difference, just it is not dramatic or useful in most sailing situations. Needing a shaft brake has more to do with the type of transmission that you have than the Autoprop itself.  If you have a mechanical transmission (which on a Mango you likely do) there would be no need for a shaft brake with an Autoprop.

As for your existing MaxProp, I once watched a very experienced welder attempt to repair a cracked piece of bronze that had spend 25 years in salt water.  He warned me it was not likely to be successful because the metal is porous enough that salt soaks into it and dramatically alters the behavior of the metal when it melts.  But we agreed it was worth a try.  As he carefully moved the bead of molten metal along the crack, it looked great--until it cooled when the metal that melted just crumbled away. Plus one for his experience and knowledge.

Bill Kinney
SM160, Harmonie
Brunswick, GA


Hank rose
 

Thanks Bill, yes I know that the max prop can lock be locked for a purpose like driving a shaft alternator. However when paying many $$$ I wondered if there were other experiences out there. And indeed Autoprop is more complicated in design, and a little more $$$.

Hehehe, I have asked two prop repair places for a welding repair job, and both answers were an empathetically "no".