The mass of the motor itself isn’t really important. The main problems are:

• The battery mass and cells management. 21700 lithium‑ion cell cells are quite sensitive when soldered into a pack. A few cells for an RC model or a trials motorcycle are easy, but when you have several tens of thousands of them, you can definitely expect quite a few defects—both in the joints and in the cells themselves. How do you repair that…?
• Sealing the motor so that condensation absolutely cannot get inside. And it will be a bigg temp. changes there.
• The mechanical design of the drivetrain to be light and strong enough.
• Choosing the drivetrain layout — direct drive or drop-down.
• Cooling of the controller and the motor.
• The construction of the powerboat hull, from the battery section to the drivetrain, so that it can handle the additional mass.

In my opinion, you can expect the final cost of the conversion to be at least €200,000, and that’s a very expensive project for such an old hull.

For that kind of money, you could buy new engines, drives, and enough gasoline for the rest of your life. And you would probably still cause less environmental damage than by using:

• An electric motor who containing environmentally problematic materials for permanent magnets.
• Li-ion batteries, whose production is also environmentally questionable. (In China—Inner Mongolia—I saw with my own eyes what lithium extraction does to the surrounding environment!)
• Electricity from Germany, which is in reall actually in wery high % generated from non-renewable sources: a significant portion is bought from Poland (coal) and France (nuclear-ok for me, but not for your politicians), as well as from gas.

I think this would be a very expensive and inefficient toy, which unfortunately might still be used to obtain EU non-repayable funding.

Hi Plavutka,

you are with most thoughts right I think.
Battery pack manufacturing is not easy, ah and you forgot it’s also dangerous because there is always voltage. The Battery management is also a nightmare. I had the luck that I could develop and produce the bms circuit boards in my company. My experience was that the cells were always good even over the years. When a battery pack was dieing it always started with a broken BMS. Also as usual the guy who made the development of the bms quit the company. 😠
the welding of the cells was actually not that big problem. I will attach a video where if possible, a CNC router did the welding. I just found this video now the speed was much faster after some time.

Unfortunately I can not upload a video.
https://cimg6.ibsrv.net/gimg/www.off...83b498f13d.png

I know cells 21700, I use EVE INR 21700 50PL in my RC airplanes on the cells limits which it is in reall on 125 A. For the small hotliner with 1-2 S prop work I go over 200A.

Conerning the motor design, my thought was that the motor should have similar torque and motor speed then most boats with Z-Drive have at the propshaft. The problem is that all motors I found on the market have higher motor speeds. If you take a Tesla Motor eg. it has about 15,000-19,000 rpm, so gears are needed to get the propeller shaft speed down(3500 rpm) and torque up. As far I understood from my motor bike experience gears take efficiency and most times gears do funny sounds, also gears have a live time and need service like oil changes. I just repaired my rock hidden TRS lower gear housing on my 33 cougar and the oil situation was a real mess. Back to the motor, the only motor I found was the EMRAX which has also lower speeds. But the design is not really what could be under water. The price of the Emrax is also not really cheap and then I would need to build around another housing to use it under water.

@ Andrew and Smarty: I will attach the offer and the datasheet of the Emrax. Probably you know it already. Offer can be automatically generated at the Emrax homepage (www.emrax.com). Without controller!

To put the motor outside the stern in the water would have some advantages I think. No separate cooling, no impeller pump, the old engine room will be free for batteries, no joint shaft. Drives could be also trimmed up. If I crash the propeller and the finn it will be easy to repair!

https://cimg6.ibsrv.net/gimg/www.off...a502960c7f.jpg

https://cimg2.ibsrv.net/gimg/www.off...de21e30c52.jpg
https://cimg3.ibsrv.net/gimg/www.off...4c3497b5d3.jpg

@ Plavutka: Concerning China. I was always a fan, but since I orderer a metal laser cutter and laser welder in China which was was cought from German Custom and sent back I think different. The Chinese send me the wrong CE-Declaration so all went back and money was gone. Anyway I was asking Suzanne to offer me some Chinese 300 hp electric Outboards. I attache pictures. I just saw that the chinese calculate in the 1200hp system with a consumption of 7,5 kWh per km.
If I go on with this project then I would like to it without china. Batteries from Corea or Japan. The only thing I will order would be permanent magnets for the motor.
https://cimg1.ibsrv.net/gimg/www.off...b02dfdc859.jpg
https://cimg2.ibsrv.net/gimg/www.off...ccdadd2e1f.jpg

I mentioned China because practically all rare earth elements used for electric motors with stronger permanent magnets, and practically all the materials for manufacturing Li-xx batteries, come from there, regardless of where the final product is made. Even these 21700 batteries are actually from there. Unfortunately.

And this datas from outboard broshure are classic bull****!

1.) 360 KWh it is like 480 Hp. Gasoline engine with 480 hp use less than 145 l/h with this power. It mean that 360 KWh batery it is equivalent to 145 l or less l gassoline.
2.) 540 KWh it is like 725 hp. Gassoline engine with 725 hp use less than 220 l/h, probably less than 200 l/h, but ok. It mean, that 540 KWh it is equivalent to 220 l or less l gassoline...
3.) 720 Kwh = 945 hp = 280 l of gassoline and not 480 l.

And you can not take out 100% energy from batery.
Al this datas are like bad joke for boat wit si high instaled weight only for propulsion. It is limited ok for displacement boat
And wery high weight of batery also take a lot of energy by planing.
Electric power=no go for planing boat, except for speciall conditions, lakes, green fanatics...

I have an electric robotic mower that works great. Got rid of a crummy old zero-turn rider with a 20 hp Kohler Magnum and never looked back.

Blowing leaves is so energy inefficient, though, that electric blowers need too frequent battery changes when you need to move large amounts of leaves, e.g. when clearing a road through a forest in the fall. I bought the biggest backpack gas blower that money could buy at the time. It sucks down fuel at a rate which people not used to supercharged big blocks would consider amazing.

In regards to the motor mounting.

I thinking you may want to add something to the bottom of the motor for side load support, much link the gimbal ring flanges on an Alpha/Bravo drive are used for

Hi JaayTeee, you are right side load I forgot yet.

To All:
I would like to come back to the energy discussion. Is sombody here who has a boat with eg. Mercury 500R's and knows exactly how much fuel it need in one hour with 6600 rpm WOP?

My LS376-480 with just under 500 hp burn more than 130 and less than 140 l/h at full throtle.
And 430 hp: https://navaboats.com/wp-content/upl...30-DPS-EVC.pdf




p.s.
What maximum speed, what cruisse speed and what weight of fully rigged boat do you expect?

It might also be worth considering using drives from another manufacturer instead of developing your own, because there will be a lot of “burns” before they become usable.

For example, in Germany you have drives from MSA Marine Systems that allow a bit of bow trim and place the motors inside the hull.
Each year we build several dozen machines that operate outdoors in nature, each equipped with two electric motors. Temperature differences can be very unpredictable, and here you also have water involved — and heaven forbid the Adriatic.

For instance, a motor rated for 15 kW of installed power can handle 18.5 kW in our application without damage. But without a small modification, it will start smoking already at around 12 kW after roughly 500–1000 operating hours. And you will likely run into a very similar problem.

Look:
Even if the motor has 97% efficiency, you will still have to remove about 11 kW of heat from that small motor with very little cooling surface when it is loaded at 360 kW. That is more than a single-family house consumes in the coldest winter. The heat is dissipated through the housing, while the rotor runs significantly hotter...

Plavutka, thanks for your Volvo data sheet. So following calculations:


430 hp/h means 130l/h
1 liter fuel contains 9.3 kWh Energy
130l x 9.3 kWh = 1209 kWh
30% efficiency of the V8, then we need 1209 kWh x 0.30 = 363 KWh to bring a boat running one hour with with 431hp.
363kWh x 1,1 = 400 kWh

So if your Volvo Penta runs one hour full throttle at 430hp it would be the same you run an electric motor using 400 kWh.

No!

On the cranchshaft you have by VP 430 hp and this is the same like 316 KW on the el. motor shaft.
In one hour you burn 130 l/h by VP 430 at full throtle.
In one hour you burn 316 Kwh by electromotor by using 316 Kw.

Conclusion:
130 l it is equivalent to 316 Kwh + motor and regler efficiency.
In real it is 130 l gassoline equivalent to aprox. 330-360 Kwh.

By gassoline engine you do not need to calculate any efficiency, becouse you have power 430 Hp on the cranckshaft and 130 l/h. This two informations includes all losses.
By the electromotor you must add efficiency for el. motor and regler.


If you want to play with efficiency of gassoline engine and electromotor, than:
- you must calculate betwen 16 and 26% efficiency for gassoline engine. Depending of engine regime, but always lit is less than 30%. This 32, or even 30% it is just for marketing!
- by electromotor you must calculated eficiency by the electricity production. In Germany it is mostly less than 32% for gass powerplants, efficiency for batery loading, efficiency for regler and efficiency for motor. At the end you have less efficiency like by old Wartburg.

Correct. The gas engines fuel burn rate and HP is already measured after the 65-70% loss to heat.

My boat burns about 50gph to make 600hp at WOT. Burns 20-22gph at 4000rpm cruise.

My boat performs the same as this.

https://cimg1.ibsrv.net/gimg/www.off...c2aebd6f95.png

I’ll burn between 20-50 gallons on a pleasure boating day. 675kWh-1685kWh.

My boat can cruise slow, 30-40mph.

My boat holds 200+45 gallon reserve, 6740kWh-8257kWH.

Its much lighter and more efficient than your boat will be due to weight and hull design.

I’d guess your 10k lb straight bottom boat would get 1mpg on gas power. 300kWh would take you maybe 10 miles.15 if your lucky

We knew this isn`t going to work 50 posts ago but I guess we`re still at it .. okay then.

Hi Hogie_roll, I think it would be this way: Your boat go with 50 gallons fuel at 3000 rpm (50gal x 1.96 mpg) 98 mls. When you go WOT it would be (50gal x 1.15=) 57,5 mls
50 gallons fuel equal 500 kWh . Would be enough to go one end of the lake of Constance to the other and back. Actually not so bad?

https://cimg6.ibsrv.net/gimg/www.off...98f821662e.jpg

Using common sense, without overcomplicating things:
A 430 hp engine at full throttle consumes about 130 liters of gasoline per hour.
An electric motor drawing 360 kW will, in one hour, consume 360 kWh of electricity.

Since a 430 hp gasoline engine is roughly equivalent in power to a 360 kW electric motor, it’s clear that comparing 130 liters of fuel to a 360 kWh battery is entirely reasonable.

There’s no need to calculate thermal efficiency or other engine losses here, because all the necessary information is already in the basic data.

A gasoline engine is actually even more efficient in practice, because such a setup has a lower overall mass.

Yes how ever we calculate it, but 10 gallon fuel powering a V8 would equal 100 kWh battery electric power is easy to remember and would be not so wrong.

Plavutka are you actually German as well?

No, but I have some business partners there, and I’m there a few times a month, mostly in Bavaria.