Fixed vs. Folding Prop


Bernd Spanner
 

Hi,

I would be interested in your opinion on the following.
I have a SN with the standard fixed propmfor the shaft gen. However the ideling prop goes on my nerves when sailing. Sailinf should be quite and not disturbed by this wowowowo noise. Of course you can put the gear in reverse an stop it. However you lose 0,5 to 1 kt which can make quite a difference in long stretches. And with developments in time the shaft alt might not be top of the game any more.
I consider changing to a folding prop….
Your input and opinion would be highly appreciated.
--
Bernd
SN 119 / Greece


karkauai
 

Hi Bernd,
You will get lots of differing opinions on this.  I have a SM with no prop shaft alternator, but I have solar and a generator.  Many with a prop shaft alternator LOVE its power generation when sailing.  When I am sailing with autopilot, Nav equipment, and radar, I have to run the generator once between sunset and sunrise for 60-90minutes. Solar keeps the batteries up during the day if it's sunny enough.

I see a 15-20% improvement in engine performance and efficiency with my AutoProp compared to the fixed prop, and like the silence of a feathering prop.

If I didn't have a generator I would be tempted to add a prop shaft alternator, and/or wind generator.

Kent
SM243
Kristy

--
Kent & Iris
KRISTY
SM243


Bill Kinney
 

Bernd,

If you install a feathering prop you do not have to make a permanent choice between power generation and quiet sailing.  

If you stop the engine while it is running in FORWARD the MaxProp feathers as you would expect and does not turn while sailing  If you stop the engine while it is running in REVERSE the prop does not feather, and your shaft generator works. This is a feature documented in the MaxProp manual, but frequently missed. Kind of the best of both worlds depending on your needs at the time.

You can do something similar with an Autoprop.  If the transmission is in reverse it feathers.  If the prop is allowed to spin it will power your shaft alternator.  I do not know if your boat has the clearance to install an Autoprop, or which model would be correct.

I confess to being conflicted about the benefits of a shaft alternator.  With one, we would never need to run our genset underway. But that is a lot of wear on bearings and seals... and as you say, wowowowowowo

I have sailed Super Maramus with both MaxProps and Autoprops.  I understand the theoretical and marketing arguments in favor of the Autoprop, but I have not seen any real difference in performance between the two either under power or under sail. My advice would be to go with the MaxProp to avoid the maintenance and fouling issues with the Autoprop, unless you are someone who motors a LOT.

Bill Kinney
SM160, Harmonie
Port Louis, Grenada.


Elja Röllinghoff Balu SM 222 <Bijorka@...>
 

Hello, Bernd
i would definitely be a Maxprop rotary wing propeller because of the better reverse drive
ore one from SPW Germany

https://spw-gmbh.de/de/

we have a Maxprop on our SM
on our old boat an
Euros 39 we had one of SPW both super if you sail you have to take the gas lever 10 sec, then you go to the reverse position then the wings go to the zero position , then again in idle position .
If you don't go back in the reward position, the prop will turn along for the hydrogenerator

Greetings Elja
SM Balu
222

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Ian Park
 

I think every sailor sighs with pleasure when the engine is shut off and your left with the sounds of wind and water gurgling past the hull.
I agree the shaft alternator noise is an annoyance, especially when off watch at night. But we’ve got over it.
There is nothing else that keeps the batteries charged up so well overnight sailing downwind than that alternator. For 21 days our batteries were 100% crossing from Cape Verde to Barbados. During the day our solar panels kept the batteries fully charged and we could put the prop in reverse.
It’s all about personal choice. If you decide to remove the alternator and brackets be sure to keep them for a future owner.

Ian ‘Ocean Hobo’


Bernd Spanner
 

Perfect Elja, thanks so much!
I just spoke to the guys and yes it’s pssible as requested 👍
--
Bernd
SN 119 / NOMAD / Greece


Craig Briggs
 
Edited

Hi Berndt,
My recollection of studies on this are that locking the prop in reverse is actually faster than letting it freewheel, seemingly counterintuitive but actually the case. (I think that was a Practical Sailor study.)
Be that as it may, I changed mine early on to an Autostream feathering prop. That is the Australian "knock-off" of the Max-Prop done in cast stainless steel rather than bronze and about 30% less costly. After 23 years it is still in perfect condition.
--
Craig Briggs - s/v Sangaris / SN68  Tropic Isle Harbor, FL


Elja Röllinghoff Balu SM 222 <Bijorka@...>
 

Hallo Bernd
Where are you in greece now
I am in Kalamata
When you in th aerea let me know

Best Elja

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Giorgio Ardrizzi
 

Hi Bernd
I own a 42-year-old Sharki 
with which I have been sailing around the world for 30 years using intensively the alternator on the shaft.  I never had a bearing or gearbox problem.  For 30 years I have been told that sooner or later something will break! 
Be that as it may, I cannot imagine an ocean crossing without this charging system.

Giorgio
Saudade III - Sharki #1 - 1980
Le Marin - Martinica


   

Il Lun 27 Giu 2022, 20:11 Bernd Spanner <bernd.spanner@...> ha scritto:
Hi,

I would be interested in your opinion on the following.
I have a SN with the standard fixed propmfor the shaft gen. However the ideling prop goes on my nerves when sailing. Sailinf should be quite and not disturbed by this wowowowo noise. Of course you can put the gear in reverse an stop it. However you lose 0,5 to 1 kt which can make quite a difference in long stretches. And with developments in time the shaft alt might not be top of the game any more.
I consider changing to a folding prop….
Your input and opinion would be highly appreciated.
--
Bernd
SN 119 / Greece