Conversion project - documented

[SaylorMade]

Originally Posted by Bullshooter

Great info SaylorMade, thank you for sharing.

And congratulations for a very good conversion and result!

Thank you very much.

[flpaoli]

Thank you SaylorMade for sharing the build and coming back to report after a year!


Congrats on the conversion, sounds perfect!


Made me think, after seeing how little space the saildrive takes inside the boat, that a larger yacht (for example a 36’) could attempt a different kind of conversion: installing two of these offset a meter each from the center. Sounds like the power would be enough to push the boat forward, but would gain the added benefit of being able to pivot the boat by running one in reverse and the other forward.


And in the space the old engine was install a small diesel generator of acceptable cost. Wonder if this would be similar or close to the spend to put in new diesel engine.

[GrowleyMonster]

Originally Posted by flpaoli

Thank you SaylorMade for sharing the build and coming back to report after a year!


Congrats on the conversion, sounds perfect!


Made me think, after seeing how little space the saildrive takes inside the boat, that a larger yacht (for example a 36’) could attempt a different kind of conversion: installing two of these offset a meter each from the center. Sounds like the power would be enough to push the boat forward, but would gain the added benefit of being able to pivot the boat by running one in reverse and the other forward.


And in the space the old engine was install a small diesel generator of acceptable cost. Wonder if this would be similar or close to the spend to put in new diesel engine.

Actually, pivoting with twin screws is somewhat overrated, since you can simply back and fill with a single screw and spin the boat in not much more than its length. Where twin screws are particularly useful is crabbing sideways, which works best when both props turn inward when ahead. To crab to starboard, put the rudder over hard left, go ahead on the port engine, and astern on the starboard, adjusting to keep the heading the same and the fore and aft position the same or as needed. vice versa for crabbing to port. To the uninitiated it seems like magic, like having bow and stern thrusters. This is routinely done by oilfield crewboats when coming alongside or leaving a crowded dock, or maintaining position under a rig or platform's crane. No reason yachties can't do it, too.

Crabbing or "walking" works best when both screws turn toward each other when going ahead. Pivoting is easiest when they turn away from each other, or outboard. With a quad screw crewboat the rudders are behind the two outboard props and so the outboard screws turn inward, and the inboard ones turn outboard. There are also triple screw and 5 and even 6 screw crewboats, but who's counting? Anyway crabbing sideways while maintaining the heading is the most important use of twin screws with twin rudders, not pivoting,

Another reason for the props to turn inward is that when trailing one prop, the boat will track better if the active prop turns inboard in ahead.

Efficiency is hugely important with EP, though, and with a displacement hull, and dismissing any need to operate in water barely sufficient for the draft of the vessel, the most efficient setup is a single, large diameter, two blade prop running at relatively low speed. OTOH, twin props facilitate smaller diameter props which could be an advantage in shallow water, and provide better redundancy.

[SaylorMade]

Originally Posted by flpaoli

Thank you SaylorMade for sharing the build and coming back to report after a year!


Congrats on the conversion, sounds perfect!


Made me think, after seeing how little space the saildrive takes inside the boat, that a larger yacht (for example a 36’) could attempt a different kind of conversion: installing two of these offset a meter each from the center. Sounds like the power would be enough to push the boat forward, but would gain the added benefit of being able to pivot the boat by running one in reverse and the other forward.


And in the space the old engine was install a small diesel generator of acceptable cost. Wonder if this would be similar or close to the spend to put in new diesel engine.

Thank you !

Well, the cost of a single pod (but larger for a 36') with battery, is roughly in the same ballpark as a new diesel.
If you went with 2 pods (they could each be for example 6 kW then) would be more expensive, and in daily use complicate the control a bit (two throttles).
They would also be off centerline i.e. much more prone to catch stuff in the water.

So I would never go down that route myself.

I think some manufacturers are starting to make rotating pods (like on big ships). That will give you the enhanced manouverability without the downside. But I think they are still very expensive...

With the "normal" pod like I have, you will still experience enhanced manouverabilty due to the high torque from 1 RPM.

[Franziska]

Originally Posted by SaylorMade

Thank you !

Well, the cost of a single pod (but larger for a 36') with battery, is roughly in the same ballpark as a new diesel.
If you went with 2 pods (they could each be for example 6 kW then) would be more expensive, and in daily use complicate the control a bit (two throttles).
They would also be off centerline i.e. much more prone to catch stuff in the water.

So I would never go down that route myself.

I think some manufacturers are starting to make rotating pods (like on big ships). That will give you the enhanced manouverability without the downside. But I think they are still very expensive...

With the "normal" pod like I have, you will still experience enhanced manouverabilty due to the high torque from 1 RPM.

One could integrate a pod at the lower edge of the rudder blade on some boats...

[SaylorMade]

Originally Posted by Franziska

One could integrate a pod at the lower edge of the rudder blade on some boats...

Torqeedo and Hanse did that a few years back.
It never really took off, but it is pretty cool

https://www.youtube.com/watch?v=8oEDUdEDdnw

[Franziska]

Originally Posted by SaylorMade

Torqeedo and Hanse did that a few years back.
It never really took off, but it is pretty cool

Cool, just what I had in mind. Wonder if pod quality is now reliable and good enough for this to work long-term. Thinking predominantly of water tightness and corrosion resistance.



This eliminates large parts of the drive train drag too and the cable can come up a hollow rudder shafts.

Avoids leaky saildrive gaskets too.



Building a suitable rudder is not rocket science either.



With better batteries, solar and charging equipment these days it seems a very clever thing.



I'd team up one of these with a good outboard on a cat. Use the outboard for longer distances and the electric drive in short range or when the outboard does not want to start.



Alternativly two pods and a genset strong enough to drive at least one of them when the battery is flat.

[SaylorMade]

Originally Posted by Franziska

Cool, just what I had in mind. Wonder if pod quality is now reliable and good enough for this to work long-term. Thinking predominantly of water tightness and corrosion resistance.



This eliminates large parts of the drive train drag too and the cable can come up a hollow rudder shafts.

Avoids leaky saildrive gaskets too.



Building a suitable rudder is not rocket science either.



With better batteries, solar and charging equipment these days it seems a very clever thing.



I'd team up one of these with a good outboard on a cat. Use the outboard for longer distances and the electric drive in short range or when the outboard does not want to start.



Alternativly two pods and a genset strong enough to drive at least one of them when the battery is flat.

I think (hope) that Torqeedo always had good quality on their pods, so I don't think that is the issue.

It takes some design consideriations since the rudder is also going to take the strain of powering the boat, but on the other hand, the rudder has to be strong anyway.

I read somewhere that they failed to succeed with this, because this solution was much more expensive than a diesel, which is probably because this was back in 2018.

Today it would be different.

Maybe we are going to see a lot more of this.
Also it makes the propeller very accessible for cleaning !
I like it

[flpaoli]

Originally Posted by SaylorMade

With the "normal" pod like I have, you will still experience enhanced manouverabilty due to the high torque from 1 RPM.

Do you get prop walk when you operate in reverse, in your setup? I read somewhere that sail drives didn't cause it.

[SaylorMade]

Originally Posted by flpaoli

Do you get prop walk when you operate in reverse, in your setup? I read somewhere that sail drives didn't cause it.

No propwalk noticeable compared to the previous sail-drive.

[Franziska]

Originally Posted by SaylorMade

I think (hope) that Torqeedo always had good quality on their pods, so I don't think that is the issue.

It takes some design consideriations since the rudder is also going to take the strain of powering the boat, but on the other hand, the rudder has to be strong anyway.

I read somewhere that they failed to succeed with this, because this solution was much more expensive than a diesel, which is probably because this was back in 2018.

Today it would be different.

Maybe we are going to see a lot more of this.
Also it makes the propeller very accessible for cleaning !
I like it

The boat builders should like it too, much faster to built than aligning shafts or putting saildrives in. A lot less complex than a Diesel installation when it comes to actual boatbuiilding itself.

[Shaneesprit]

The only reason I would want to go EV is the noise or lack of. And the slow take up of drive.

In my case it would mean £1000s extra in marina fees. And the environmental case doesn’t stack up either. I don’t use enough Diesel to warrant a conversion.

Glad to here it’s working - My drive leg is obsolete, so the EV might be a solution one day.

In the future I can only assume that electric will be a connection fee + energy use payments.

[SaylorMade]

Originally Posted by Shaneesprit

The only reason I would want to go EV is the noise or lack of. And the slow take up of drive.

In my case it would mean £1000s extra in marina fees. And the environmental case doesn’t stack up either. I don’t use enough Diesel to warrant a conversion.

Glad to here it’s working - My drive leg is obsolete, so the EV might be a solution one day.

In the future I can only assume that electric will be a connection fee + energy use payments.

I don't think anyone is converting to E propulsion for environmental reasons.

What do you mean it will be a connection fee and energy use payments?
I am not sure how the payment policy is related to the kind of power the engine/motor uses?
If manufacturers would do that, they could just as easily do it on a new diesel.
Let's hope the world does not go that crazy

[Franziska]

Originally Posted by SaylorMade

I don't think anyone is converting to E propulsion for environmental reasons.

What do you mean it will be a connection fee and energy use payments?
I am not sure how the payment policy is related to the kind of power the engine/motor uses?
If manufacturers would do that, they could just as easily do it on a new diesel.
Let's hope the world does not go that crazy

I think he means a fee to charge the batteries. Not everyone has sails and enough space for solar charging.

[SaylorMade]

Originally Posted by Franziska

I think he means a fee to charge the batteries. Not everyone has sails and enough space for solar charging.

Of course electricity is not free, nor is diesel?
I am not getting this - might be a language issue - me being a viking