Electric engines for 53ft motoryacht

[LARRY VALENTINE]

I just got back from Copenhagen where I rode a "hop on, hop off" tour boat of the canals. The tour boat was about 20 x 60 and held about
80 passangers. The boat was electric and was charged over night after running all day. It was quiet,
had no fumes and ran between 4 and 8 knots and was extremely well controlled by the captain in some very tight spaces. We outran some of the diesel powered
tour boats.
I was wondering if anyone has had any experience or knowledge of a Hat being converted to electric power. Cost? Best yard for work,etc.? Could the transmissions
be kept and would a 19 KW generator recharge lithium batteries overnight? Could the lithium batteries offset the ballast weight loss of the DD 6V92TA
engines?

 

[SEVEN]

I knew once they perfected the cars boats would be next but this is the first I heard on them running. I'll wait to hear from the other forum members as to cost. Was Tesal the engine builder?

 

[Boatsb]

No transmissions needed with electric motors . Also the lithium battery banks would need to be huge to make up for the weight.

I use Li Fe Po batteries and the charge faster than lead acid but the time to charge will be dependant on the bank size and level of discharge.

We have a boat here the owner had converted. Not a hatt and not a success either. It's run 2 x in 3 years. Not enough battery bank to make it anywhere at speed. Not enough generator to charge while running.

 

[gpellissier]

This was done a few years ago on a 42 ft Grand Banks. The link gives you an idea of the arrangement and cost...

https://www.atlanticyachtandship.ru/catalog/file/206812/watt_power-grand_banks-english.pdf

 

[Pascal]

Diesel electric isn't new and works but I think it adds as whole new layer of complexity for really little benefits beyond noise and vibration, maybe.

I installed a 10hp electric motor in the 26' classic gaff rig sloop I built a couple of years ago, powered by a 48v bank (8 golf cart batteries). We have a three blade prop, conventional shaft, cutless bearing and dripless log but at the end of the shaft we have a thrust bearing and a pulley with timing belt to the motor. it works well for us as we just use it to assist with docking, picking up the mooring if the wind is too strong to do that under sail, or get back home when the wind dies. Never ran it more than an hour so range is unknown. We recharge the bank once in while either at the club dock or by tying the boat behind the hatt which is docked 1/4 mile away

In our case there was no room for a diesel inboard, in part due to the centerboard but we really don't need long range for a day sailor. And anboard, while cheaper and simpler woudl have ruined the looks of the boat.

I'm happy with the decision. Throttle is a custom made mahogany slider under the tiller and always handy without having to reach down. Power is always on standby, just a finger movement away so if we screw up a tack in close quarter it's there.

Now, it works for us but once you're talking powering a larger power boat with longer range, I don't think electric is there yet.

 

[Walter P]

Pascal, Do you have feathering props on your sail boat? It sounds like a pretty good arrangement and an excellent use of aux. electric power.

Walt

 

[Pascal]

No I went with a regular 3 blade prop as in theory the system is supposed to regen when under sail. Turns out that theory is one thing, real world is another and 5 to 6 kts under sail isn't even close to get the prop to turn the motor and recharge. I don't think I ll bother switching to a feathering prop, we don't care about that extra 1/4 or 1/2 knot

 

[rtrafford]

I really like the idea of electric drives and large diesel power generators as opposed to big banks of batteries, but as that technology continues to advance, the options become even more interesting.

Short hauls, great to be able to run solely on battery power. Long runs, weather, etc would need power generation aboard suitable for the load.

Samsung phones are catching on fire.......

 

[jim rosenthal]

I think at the current state of the art (no pun intended) you'd be spending HUGE money just to prove that the technology isn't there yet. Which is unfortunately already known. I don't know if the recharge time and battery energy density will get there in our lifetimes. I think the motors are available, but the rest of the pieces aren't up to it yet.

 

[krush]

Electric motors and batteries would work great for those that just do an annual trip to the gas dock and pump out station....well, I guess the former could be skipped!

 

[rtrafford]

I think at the current state of the art (no pun intended) you'd be spending HUGE money just to prove that the technology isn't there yet. Which is unfortunately already known. I don't know if the recharge time and battery energy density will get there in our lifetimes. I think the motors are available, but the rest of the pieces aren't up to it yet.

The technology is there, used on large ships. It just needs to be reduced to the private scale in a cost effective manner. Hydraulic drives are a good example of that process transition. I don't know that i could find comfort aboard with that level of DC reliance, amp demand, but a diesel power generator large enough to run the engines and house would be a good first step. Tie that to pod drives to eliminate drag, and you've got a good beginning that can transition as battery technology improves.

 

[krush]

Certain ships do diesel electric. But, ones that just put miles under them, like container and tankers, do not use diesel electric. It all depends on the application.

 

[rtrafford]

Right, but economies of typical operation, having a diesel provide power for house and propulsion plus a unit for house and emergency propulsion would seem to make a ton of sense for a pleasure boat that only runs 2-300 hours per year. Consider we put more than 3-4 times that load on the generator aboard...

 

[Boatsb]

Cruise ships with big house loads and multiple pods use diesel electric. It's probably more efficient in some ships than others based on needs.

 

[rtrafford]

Cruise ships with big house loads and multiple pods use diesel electric. It's probably more efficient in some ships than others based on needs.

Right, so I was suggesting that your twin engine vessel have one large generator for both house and propulsion loads, and one or two small gensets for house load on the hook.

Electric to pod drives. Dramatic loss in weight and drag. Lose an engine, two transmissions, running gear while adding pods. Add lithium batteries as desired, as technology advances, and implement a switch for propulsion power source to shift from battery to diesel.

I'd seriously consider building this now if I was in the mood to start yet another project. Propulsion setups typically start at around 500 HP, designed for marine use. You'd be providing 480v from your diesel propulsion generator, so you'll have a transformer to allow that motor to provide house power.

 

[krush]

somwhere on here there was chat that the spinning shaft in the water creates a LOT of HP loss due to friction.

 

[rtrafford]

somwhere on here there was chat that the spinning shaft in the water creates a LOT of HP loss due to friction.

...and then throw some shaft zincs in there just to add some interest....

 

[Byresch]

I saw a converted sailboat in San Diego that had all kind of power problems with the motor and batteries. Once they finally got it working it was fine until it hit a current head on, then it lost most of its battery power because of the motor's power drain trying to fight the current. Based on seeing that experience I am not a proponent of electric power for boats.

 

[Boatsb]

Just for argumentsale sake.

2 x 500 hp motors require about 750 KW.

House load is probably 12 to 20 KW.


How would you power this vessel?

Even at half that power it's still close to 400 KW to run.

Cruise ships have huge house loads.

That's how they find the economy in those systems.