Did I finally come up withe use for electric drives?

[Stumble]

To start, I have been, and am, highly critical or attempting to replace onboard diesel propulsion motors with electric drives. I don't see them as reasonable, except when tied to massive generators which pretty much defeats the purpose. But I was looking at the new Neel 65' trimaran and got to thinking about how unwieldy that thing must be when trying to dock it.

The conventional wisdom has been to install a very large bow thruster, but that introduces a lot of other issues. My thoughts to eliminate the bow thruster, and install twin 10kw electric motors in the amas on retractable sail drives.

The twin motors would simply repurpose power already onthe boat from its 10kw generator, so no additional power capability needs to be added. This would allow for both substantial manuverability, a bit of low speed propulsion, and regenerative power while sailing.

The major downside I see is cost, since a quick pricing of the system indicates it would be about twice the price as the currently specced bow thruster.

Any thoughts on this idea?

 

[cmckesson]

Yep. That was always my plan for the trimaran of my dreams. Of course, she remains "in my dreams."

But I do have electric drive in my monohull and your proposed installation is still what I would do with my dream boat.

 

[alan craig]

Stumble, you could also borrow an idea which Torqeedo have recently come up with which is a sail drive which rotates through 180 degrees to face the propeller into the slipstream for regeneration. The advantage is that the blades are then curved and twisted in the correct direction for optimum efficiency - although the flow across the blades is reversed, and this means they can never be maximally efficient when used for thrust, since the leading edge becomes the trailing edge. But it's a good compromise. A conventional propeller running in reverse for regeneration is like putting the wings on upside down on a 747.

 

[Stumble]

Alan,

That would certainly be possible. Like I said I have no intention of commercializing this so its just all theory anyway.

But it is the first really valuable use of electric propulsion I have been able to come up with.

 

[powerabout]

I'd be thinking of fold down drives on the arma's with or without propulsion on the main hull but that might be a retractable direct connected to an engine with large flywheel alternator?
I can see a few advantages for a world wide cruiser there especially with regen in the drives.

 

[Stumble]

Powerabout,

My thought on the retractable drives was something like http://www.amartech.nl/products/53-retractable_propulsion mounted in each ama. It would allow for a clean bottom normally but the ability to deploy them when needed.

The primary diesel in the main hull would still be needed for passage making and bad weather issues. So you don't get away from a diesel propulsion engine at all. Instead the electric drives primary purpose is to provide maneuvering capability currently lacking on large trimarans. Not that they couldn't be used for propulsion at some level, but it would take a much larger generator to get much speed out of the idea.

 

[powerabout]

cool
plenty of race yacht yards can do retractable so you can have a std drive line if you need it, maybe the reversing pods like a torqueedo will help get over the poor regen due to the inefficient props issue.
i'm thinking the arma motors could help with manoeuvrability and maybe do the regen which works in a fast boat.

 

[tom kane]

Retractable drives ( Google Pivotal Drives) are cool and have many advantages and would be the ultimate in easy single stick steering and maneuvering coupled to twin drive forward and reversible electric motors. This does not have to be "just a dream" just so easy. You just needs the dough.

 

[Powerconversion]

Alan,
But it is the first really valuable use of electric propulsion I have been able to come up with.

An correctly designed dieselelectric propulsion-system can save 60% fuel under correct conditions versus an conventional system, but no mater how you design them you won't save under any condition. There are tradeoffs like thermal losses in IGBT's and resistance in diodes. Copperlosses as well.

For your use if I understand correct I would go for solar panels in combination with your regenerative propeller. If your regenerative drive where charging battery's in parallel with solar panels and solar controller could guarantee maximum solar penetration and enable the propeller to alter between generating and motoring according to battery voltage.

Because of losses in an regenerative drive solar technology need to improve a lot before they produce much more than what the drive has in losses unless you had lots of them.

 

[WestVanHan]

An correctly designed dieselelectric propulsion-system can save 60% fuel under correct conditions versus an conventional system, but no mater how you design them you won't save under any condition.

Any peer reviewed articles,or boats on the market that can show this?

 

[Powerconversion]

Any peer reviewed articles,or boats on the market that can show this?

Any DP class vessel with diesel-electric propulsion operating in DP mode under calm weathers. In rough weathers the advantage starts to be eaten up and under transit there is literary none.

 

[WestVanHan]

So basically oceanic oil drilling rigs.

What that has to do with a 65" trimaran or thrusters I'm not sure.

 

[Powerconversion]

So basically oceanic oil drilling rigs.

What that has to do with a 65" trimaran or thrusters I'm not sure.

With thrusters it's everything. It's with DP operation on thrusters the whole concept really pay off. With a trimaran for crossing open water nothing. There is lots of dieselelectric vessels that shold newer been buildt because of the userprofiles.

 

[powerabout]

For PSV , rig supply boats
What they do is have lots of gen sets so they only use what is required for the thrust at the time instead of 2 huge engines doing very little

 

[W9GFO]

Couldn't you cut the cost in half by putting a single retractable pivoting thruster in the bow? That, combined with the primary drive would give you excellent maneuverability, the option to use it alone for low powered cruising and it could be used as a hydro-generator. Whilst saving quite a bit on electrical runs.