Here are my 2 cents
First of all
engine is a marine
conversion of the Mitsubishi L3E engine. This engine was used in tractors, construction machines and what not ?? all over the place and replacement engines to spares are easy to find and dirt cheap
. This is a very good engine if maintained properly and fuel consumption
is close to nothing. The two 18 gallon fuel tanks
will give You a very nice range for Coastel, ICW
THE EV ROUTE
Following is the web site from Sillete, the manufacturer of the Sonic Type 2 drive that is installed on the Gemini
together with the 27 Hp Westerbeke
Watch the rated HP ratings = Torque Loads !!!
A 50 Kw motor has way too much torque and even with 25 KW you are getting close to the upper limits.
As You can see they also have an electric sail drive version but itīs a little different then the outdrive version. However the parameters as far as motor sizing, torque loads, reductions and prop size to match with the Sonic drive are similar.
They are working with Lynchmotors in the UK and they use a very cheap
and high efficient DC pancake motor. Even so the motor has not a high IP insulation
rating in case of the Gemini 105
with a totally dry engine compartment this will not be a problem. This lower IP rating on the flip side will give You a much better heat dissipation/cooling, which is Your mayor concern for electro motor efficiency. It is also a brushed motor but here are YT videos to give You an idea what You are up to in case of trouble shooting and repair......
In any case.... since these motors are so cheap and easy to repair and replace. I would always keep a complete spare motor on board.....
The Lynch Motor
A very unique design with a lot of history
and definitely a legend
What You also definitely wanna evaluate on a Gemini
is the weight of the motor, weight of the total installation
and weight distribution. The Westerbeke with the transmission
according to spec sheet is 274 Lbs + 36 gal of fuel
So here is the Lynch motor Mod. LEM 200 up to 15 KW.....
As You can see the best efficiency rate is around 4100 RPM
. That is way higher then the Westerbeke shaft power curve. So with the proper reduction You should have no problem to match the Sonic drive to Your desired spes even without changing the prop which is a lot cheaper. Here is a close up photo
on the bottom that shows the easy principles of designing Your own motor mount set up with the proper gear
and also here
Here are some suppliers for the " TIMING PULLEYS & BELTS " which is a lot more flexible and simpler power tran then using gears > easy change, no lube, no maintenance
, cheap .......
You can also check on Amazon...
However depending on where and how You wanna use the boat. You can also go to a higher KW motor.
Here is the Mod. LEM 2x2.....
This is the same motor but with two identical motors mounted on the same shaft.
This will give You two motors in one for added safety
when one motor fails but the mounting to the Sonic Drive will be still as simple as with only one motor.
Of course now You also have double power but with less heat.
If You should decide to go with Lithium here are my preferd sources for reasons of price
Winston Battery, CALB, LiFePO4 Battery - Evlithium
I like the BMS 123 Smart from EV-Power for itīs simplicity. Also has Bluetooth
Carefully watch the details on this YT channel and form Your own opinion
He did an of the shelf conversion with those motors many years ago and now upgraded to 72 Volts with a new controller with way much better results.
As You might realize he built this system by himself. Now go to all them beautiful YT channels here mentioned and ask Yourself. What are You going to do if there is a problem. Can You fix it Yourself ? Where do I get the spare parts
. What tools do I need on board ? What will Your situation look like if You canīt fix it Yourself ?
!!! Further considerations...... there is different legislation "DEPENDING ON COUNTRY ".... in ref to boat safety
,insurance cover etc. for EV installations on boats for up to 48 Volts and over 48 Volts.
In regards You should also pay VERY SPECIAL ATTENTION to the facts that standard in the Gemini the propane
gas bottle sits right next and all open to the engine compartment and standard the fridge also is 110 V /propane with a constant open flame.
Of course there is also the less spectacular but very valid conversion to an electric outboard
engine as You mentioned.
And of course there is always the big question. How will You charge the batteries ???
On the Gemini there is comfortable space for ca. 400 w of latest solar tech + maybe some additional panels on the life lines. Thatīs barely enough for consumers on board. I donīt see space for a lot more green dreams without the help of some dino fuel on board.
So things are adding up. If You wanna start a YT channel I am sure there will be a lot of attention. However if You wanna get on the water
and go sailing I am sure the Mitsubishi lawnmower engine might be worth while thinking.
Further more ..... make a VERY VERY deep inspection
of the Sonic Drive. There are issues with the reverse release and other little tricky tid bits. Sillette has a good customer Service
but spare parts
for the Sonic Drive are unique and expensive. I also heard some unconfirmed rumors that Sillette will stop to manufacture the Sonic Drive.
Good Luck and Cheers