Does Revolving Prop trickle charge batteries?

[duke]

My gearbox is hydraulic and the prop is Brunton Autoprop.
There is no mechanism for putting drive shaft on "Hold" or "stop" and not enought space to
fit one.

Looking on the bright side : does the revolving drive shaft add any charge to the batteries
when the engine is off and boat under sail?
The speed of boat , in a good wind is 6 or 7 knots.


Regards,

Duke.

 

[photodog]

No.


But didnt I see some test or report or something about someone who rigged it up to do so and it worked so well it blew up the batteries.....

 

[tt65]

no

Hi, No there will be no trickle charge unless the engine itself is rotating.

If Autoprop is rotating whilst sailing at 7 knots, you would see 8 knots or even more if you could stop the rotation and allow blades to feather. You seem to have lost main advantage of the prop if it autorotates when engine stopped. Reckon you should fit some kind of shaft brake.

I have Autoprop. When sailing I put engine in gear and in my case this stops any rotation. If I put gearbox in neutral the prop auto rotates and it is like putting the brakes on, I lose 1 1/4 to 1 1/2 knots speed through the water.

 

[bobgoode]

The prop will rotate but it will not be driving the engine so the alternator will not be turning hence no charging.

Depending on your hydraulic set up you may or may not be turning the pump attached to the engine.

 

[Bobobolinsky]

Some guys have got a multi million grant to investigate an electric drive with batteries being recharged from the spinning shaft when sailing

 

[nimbusgb]

Bet they are rolling about laughing!

 

[sailorman]

The prop will rotate but it will not be driving the engine so the alternator will not be turning hence no charging.

Depending on your hydraulic set up you may or may not be turning the pump attached to the engine.

Bearing damage in the gearbox may occur due to lack of Lubrication.
for the alternator to charge 1000s of rpm are req

 

[npf1]

you mentioned not enough space to fit a shaft brake. How much space have you got? Some shaft brakes don't need very much.

 

[PCUK]

First check that the gearbox can handle rotation when the engine is off. Some need the engine running to cirulate the oil in the gearbox. If this is OK you can buy a prop' shaft alternator that cuts in at very low revs however, with the autoprop the resistance in the alternator will probably stop the shaft rotating. A shaft brake is the best solution.

 

[bobgoode]

Bearing damage in the gearbox may occur due to lack of Lubrication.
for the alternator to charge 1000s of rpm are req

With a hydraulic drive there is no gearbox, only a pump on the engine and a similar pump on the shaft. The drive ration is obtained by sizing the pumps eg bigger pump on shaft give less rev on shaft for a given rev on engine.

 

[fluffc]

A hydraulic GEARBOX is different ot hydraulic DRIVE.

A hydraulic gearbox is operated by hydraulicaly engaging a clutch on either the forward or reverse gear, as requried. The forward and reverse gears are constantly in motion, and the appropriate one selected by a pair of hydraulic clutches.

 

[Chris_Robb]

My gearbox is hydraulic and the prop is Brunton Autoprop.
There is no mechanism for putting drive shaft on "Hold" or "stop" and not enought space to
fit one.

Looking on the bright side : does the revolving drive shaft add any charge to the batteries
when the engine is off and boat under sail?
The speed of boat , in a good wind is 6 or 7 knots.


Regards,

Duke.

You would need to add an alternator connected directly to the shaft. If you have no room for a shaft brake, I would suggest you had no room for the large pulley needed to get enough revs out of a shaft driven alternator.

Hydraulic gearboxes - some need to be lubricated by the engine running. The Paragon gearbox is an example of one that self lubricates and is therefore ok to leave turning under sail. It is important to find out.

A cheap and efficient shaft lock could be made by a pair of mole grips if you have no room for anything else to fit. Just depends how accessible, and what safety precautions you would put in place to prevent use of the engine whilst the molegrips were on!

 

[bobgoode]

Point well made...you never stop learning.

 

[sailorman]

With a hydraulic drive there is no gearbox, only a pump on the engine and a similar pump on the shaft. The drive ration is obtained by sizing the pumps eg bigger pump on shaft give less rev on shaft for a given rev on engine.

Depending on your hydraulic set up you may or may not be turning the pump attached to the engine

 

[Artic Warrior]

I have a alternator running of a light weight multi v belt of my shaft, and at about 5/6 knots and above the digi read out is showing around 10amps charging, this keeps my beers nice and cold in me fridge, cus its bloody hot out here,,,

 

[duke]

thanks to all

Thanks to all for replies - I had previously checked with Autoprop re suggested prop brake but my space is not sufficient for that one.

Will investigate other makes of brake- otherwise a "heath robinson " improvis.


Regards,

Duke.

 

[WindermereColvic]

Artic Warrior, could you tell me a little more about your system please? ie, what have you done to prevent the lateral load on the prop shaft due to alternator belt tightening from wearing the bearings unevenly? And how do you disengage the alternator from the shaft when you start the engine? Would be interesting to find out as ive been mulling over a system like this for a while.
Oh and Duke, you could always use bicycle caliper type breaks on the shaft, with a bike break handle positioned somewhere you can jam/clip it 'on'. I would think this would be strong enough to stop the shaft but if you accidently started the engine, it would soon wear through the highly replaceable break blocks. Just a thought.
Matt

 

[Artic Warrior]

Artic Warrior, could you tell me a little more about your system please? ie, what have you done to prevent the lateral load on the prop shaft due to alternator belt tightening from wearing the bearings unevenly? And how do you disengage the alternator from the shaft when you start the engine? Would be interesting to find out as ive been mulling over a system like this for a while.
Oh and Duke, you could always use bicycle caliper type breaks on the shaft, with a bike break handle positioned somewhere you can jam/clip it 'on'. I would think this would be strong enough to stop the shaft but if you accidently started the engine, it would soon wear through the highly replaceable break blocks. Just a thought.
Matt

Hi Matt, my alternator is above the shaft so im asuming some of the lateral force is helped by the weight of the shaft..Hope so anyway and i have a switch to disconnect the battery feed to the alternator and flip it on when needed, this is a boat that ive just bought and am studying all these little extras that she has,

Cheers Colin,

 

[WindermereColvic]

Thanks for gettin back to me. Good Luck!

 

[Artic Warrior]

Hi Matt, my alternator is above the shaft so im asuming some of the lateral force is helped by the weight of the shaft..Hope so anyway and i have a switch to disconnect the battery feed to the alternator and flip it on when needed, this is a boat that ive just bought and am studying all these little extras that she has,

Cheers Colin,

Looking again, my alternator is powered from a pully that runs directly on the outputshaft of the gearbox and not on the propshaft, iradicating any wear n tear,,,,