Conversion project - documented

[sailorxyz]

Hi SaylorMade,


What made you change your mind and go for the Torqeedo rather than the ePropulsion that you originally had in mind? Asking as I'm about to install an ePropulsion Pod Drive 6 in my Badger 34.

[SaylorMade]

Originally Posted by sailorxyz

Hi SaylorMade,


What made you change your mind and go for the Torqeedo rather than the ePropulsion that you originally had in mind? Asking as I'm about to install an ePropulsion Pod Drive 6 in my Badger 34.

Well it was several things:

1. It turned out, that when I chose a folding propeller and the different add-ons, the price was about equal, and I've heard a few not-so-good stories about service if something is wrong with the ePropulsion, but I think that comes down to the local dealers/dealer network

2. The new torqeedo has a five year service interval, and the mount is made, so it is extremely easy to slide out the motorpart and leave the actual mount on the boat. This will also make it a lot easier, if worst happens a long way away from home. Get a new motor unit shipped and you can swap it out in literally minutes.

3. The local dealer have made a pre drilled stainless steel plate, that fits the old saildrive hole, so I don't have to mess with getting the hole closed by a yard.

[GordMay]

Originally Posted by sailingharry

...
I am a strong proponent of not undersizing the motor. A big electric motor run at low percentage of capacity is just as efficient as a small one, with the same range. But the big one gives you the short bursts of high power, such as docking maneuvers in bad wind, or tricky channel entrances.
....

I am/was a proponent of correctly sizing an electric motor - neither under, nor over sizing.

Most electric motors are designed to run at 50% to 100% of rated load.
Maximum efficiency is usually near 75% of rated load.
Thus, a 10-horsepower (hp) motor has an acceptable load range of 5 to 10 hp; peak efficiency is at 7.5 hp.
A motor's efficiency tends to decrease dramatically below about 50% load. However, the range of good efficiency varies with individual motors and tends to extend over a broader range for larger motors (which, generally, have higher efficiency, than smaller motors).

Thanks for this tread, SaylorMade.

[Pete7]

Originally Posted by SaylorMade

Motor size I don't know about. The one I am installing is 6 KW = 9,6 HP, which is more than this type of boat originally was fitted with.
But I must say that we have never ever used much of the old diesels actual capacity.
Again it's about the waters you sail in.

Thought you might like this article about an electric pod conversion. Now Ian is a Epropulsion dealer, so obviously didn't pay the retail price for a prototype 10kW pod, also he has decided to change down to the 6kW pod which is now available to buy.

https://www.facebook.com/page/879091...ch/?q=electric

Could we do it? perhaps. The only thing putting me off is the cost at the moment. So very much something to keep an eye on.

Pete

[Shaneesprit]

Hi
I will read more later especially about how far you can travel and recharge tímes.

But my question is what’s the weight difference?

[PineyWoodsPete]

Originally Posted by SaylorMade

Good question.
We never sail that long.
The longest trip on the engine we made was 42 nm, that's why I ended on the 12 KWh battery :-)

99,9 percent of the time, we are at a berth during night, so charging is done with shore power.

I realize that this pattern is different from other places, but here in Denmark, thats how 90 percent sail. (Berth every night).

YMMV (litterally )

Hi Saylor, an interesting project, lovely boat! But methinks that you're a bit too optimistic about your 50nm range, even under ideal windless, currentless flat sea conditions. Let's say you can get 3kts from 1 kW power, and draw the 12kWh bank flat. That's 12hrs runtime @3kt = 36nm. And at 4kt, even @ 1.5kW (very doubtful!) 32nm. I'd add a sculling oar or another 6kWh!

[Statistical]

Originally Posted by SaylorMade

I do plan on beefing up the 12v system though with a LiFePo4 battery as well, since we can no longer charge that system while underway.

Another option to consider if your daily 12V power needs are modest which I presume on a 27 ft boat they are would be 48VDC to 12VDC charger or simply converter to power those loads directly.


48V bank -> DC converter -> 12V panel

OR

48V bank -> DC charger -> 12V battery -> 12V panel

[Statistical]

Originally Posted by PineyWoodsPete

Hi Saylor, an interesting project, lovely boat! But methinks that you're a bit too optimistic about your 50nm range, even under ideal windless, currentless flat sea conditions. Let's say you can get 3kts from 1 kW power, and draw the 12kWh bank flat. That's 12hrs runtime @3kt = 36nm. And at 4kt, even @ 1.5kW (very doubtful!) 32nm. I'd add a sculling oar or another 6kWh!

1 kW @ 3 knots in calm conditions for a 27 foot boat would be a lot. In calm conditions it should be around half that. 4 knots would be around 1 kW.

Granted those are in calm conditions, current, rough surf, winds, etc would adversely affect range. That being said will be interesting to see his speed vs power graph once he has it back in the water.

[GrowleyMonster]

Originally Posted by sailingharry

Saylor,

I am a strong critic of most EP conversions. In my opinion, the vast majority go in understating their needs and over estimating the results.

Your case, on the other hand, is a poster child for an appropriate install. Sufficient range (if 50nm is the absolute maximum), dock every night. Another 50% is easy to add later if needed. Because you are docked every night, house battery is no worry. Not counting on regen or solar means you won't be dissatisfied when it doesn't measure up.

I am a strong proponent of not undersizing the motor. A big electric motor run at low percentage of capacity is just as efficient as a small one, with the same range. But the big one gives you the short bursts of high power, such as docking maneuvers in bad wind, or tricky channel entrances.

Sounds like you have really nailed an ideal application for EP. Hope you give us an update after the first season of operation -- we tend to hear lots of optimistic enthusiasm during installs, but little operational follow up.

I repowered a Cal 2-27 several years ago, and put my own EP system together from off the shelf components, after considerable research. Total cost, including 10.2kwhr bank of golf cart batteries and a lot of 2/0 copper cable and assorted connectors and hardware and metal was about $2400. I had no problem motoring across Lake Pontchartrain but no way would I get 50nm under average conditions. The OP is going with 12kwhr bank of LiFePO4 so he can discharge a little more deeply and has a bit more capacity but still I doubt it would do 50nm at any reasonable speed. BUT, after all, it is a sailboat.

For day sailing, docking with shorepower every night, and fairly small boat, EP is the PERFECT propulsion system. Not requiring onboard charging makes it even better. Short ins and outs, even more better. Low maintenance costs except new batteries every 7 to 10 years. low noise. No smell. No spills. Instant on, instant power, no warmup or crossed fingers while mashing the start button. No minimum idle speed. That sounds like no biggie until you get used to ghosting into a slip at 50 RPM. I LOVE having no lower idle speed limit. That's one thing I miss a lot, with my current diesel powered boat.

Agreed, most who envision a perfect world to come, after changing to Electric, are counting on pie in the sky, especially the regen fanboys with smaller or slower boats that never spin the prop hard enough to generate a lot of charging amps. But daysailing is the perfect use case, and the perfect engine for a day sailer is electric, for so many reasons.

Agreed, a motor bigger than "needed" is a no brainer. It will last longer due to better heat dissipation, and there is almost zero efficiency penalty for upsizing the motor, unlike with a diesel. I started out with a 5kw motor and later upgraded to 12kw.

Resale value for E-boats has often been picked on. A diesel boat has much higher resale value and potential than an electric boat. But an electric boat has much higher resale value than a boat with a dead diesel or no engine at all. And the Torqueedo has pretty good brand recognition vs the typical (like mine) mix and match and owner designed system. I just don't like the initial cost of the turnkey systems.

The average small diesel engine with reduction gear weighs what, around 300 lbs. The average guest weighs about 180 lbs. Carry three fewer people than the max, keep motor and controller and reduction gear weight down to about 40lb, get rid of old diesel, along with the fuel tank holding probably 100 lbs fuel, and you have 300 + 100 + 180 * 3 - 40 = 900 pounds to play with, for the weight of batteries. Everybody gets their knickers in a knot over battery weight but it's no big deal, and with a 12kwhr bank, the owner could easily add a second 12kwhr bank for not only longer range, but redundancy. 50nm range would be easy sneezy, with that much storage and that size boat. Or greater speed. E-boaters like to go around 3kts to extend their range. No need for that, with so much battery. The LiFePO4 batts are a lot lighter than my old GC2 FLA batteries, too.

[GrowleyMonster]

Originally Posted by Statistical

Another option to consider if your daily 12V power needs are modest which I presume on a 27 ft boat they are would be 48VDC to 12VDC charger or simply converter to power those loads directly.


48V bank -> DC converter -> 12V panel

OR

48V bank -> DC charger -> 12V battery -> 12V panel

Yes, get a few cheap Chinese 10A DC/DC converters, one for each essential circuit, and a couple of spares, cause, hey, Chinese. No need for separate 12v bank. If anything, install a secondary 48v bank, emergency get-home and emergency 12v stuff like backup bilge pump and a VHF, maybe redundant power supply for nav lights.

[PineyWoodsPete]

Originally Posted by Statistical

1 kW @ 3 knots in calm conditions for a 27 foot boat would be a lot. In calm conditions it should be around half that. 4 knots would be around 1 kW.

Granted those are in calm conditions, current, rough surf, winds, etc would adversely affect range. That being said will be interesting to see his speed vs power graph once he has it back in the water.

Well, I'm coming from the perspective of a 33'/32' WL 5-ton hybrid MV, with a semi-displacement hull, and a water-cooled 7kW/5kW motor/gen inline with the 165HP diesel, driving an efficient 5-blade 17x14" prop through a 2:1 red. gear. In flat harbor conditions, 3kW gives me about 4kt, and at the full 7kW, 5.4kt. Drawing the 48V, 11.7kWh lithium bank down to 20% I would have a realistic range of about 12nm @ 4kt.

[GrowleyMonster]

Originally Posted by GordMay

I am/was a proponent of correctly sizing an electric motor - neither under, nor over sizing.

Most electric motors are designed to run at 50% to 100% of rated load.
Maximum efficiency is usually near 75% of rated load.
Thus, a 10-horsepower (hp) motor has an acceptable load range of 5 to 10 hp; peak efficiency is at 7.5 hp.
A motor's efficiency tends to decrease dramatically below about 50% load. However, the range of good efficiency varies with individual motors and tends to extend over a broader range for larger motors (which, generally, have higher efficiency, than smaller motors).

Thanks for this tread, SaylorMade.

I was unable to detect significant difference in energy usage, between a 5kw and a 12kw motor, both running at the same speed, same voltage, pushing the same boat with same prop and same reduction. Perhaps you are thinking of ordinary synchronous motors? I would agree with you, there. E-boat motors in that size range are mostly axial flux BLDC/PMAC type motors, three phase, with commutation occurring within the controller. Different animule altogether. The only reason to prefer a propulsion motor just barely big enough, is price. For a couple hundred bucks more, and a few extra pounds, I would say a bigger motor is a good purchase.

[Statistical]

Originally Posted by PineyWoodsPete

Well, I'm coming from the perspective of a 33'/32' WL 5-ton hybrid MV, with a semi-displacement hull, and a water-cooled 7kW/5kW motor/gen inline with the 165HP diesel, driving an efficient 5-blade 17x14" prop through a 2:1 red. gear. In flat harbor conditions, 3kW gives me about 4kt, and at the full 7kW, 5.4. Drawing the 48V, 11.7kWh lithium bank down to 20% I would have a realistic range of about 12nm @ 4kt.

Your boat is heavier and bigger with more wetted area. I agree though he is unlikely to get 50 nm @ 4 knots I assume it was 50 nm goal was @ 3 knots.

Even your boat I presume should need only 1300W @ 3 knots (3/4)^3 * 3000 W = 1265.

Still I will be interested to see the real world numbers.

[SaylorMade]

Originally Posted by Shaneesprit

Hi
I will read more later especially about how far you can travel and recharge tímes.

But my question is what’s the weight difference?

Out of the boat:
Starter battery 20 kg
Diesel 35 kg
Old engine+saildrive 181 kg (According to Volvo datasheet)
Hoses, exhaust, gaslever, instrumentpanel etc. 10 kg
Total out = 246 kg.

Into the boat:
Engine pod 17 kg
Cabels, throttle etc. 5 kg.
Battery 12KWh LifePo4 73 kg.
Total in = 95 kg.

So about 150 net out of the boat.
Weight distribution very close to the same, i.e. under the cockpit.
It's a good place to lose 150 kg (220 lbs)

For how far I can travel, we will see. Recharge time is known though.
The charger is 25 amps, and it's LifePo4 which will accept that, so from completely depleted back to full is about 10 hours.

[sailingharry]

Originally Posted by GrowleyMonster

Low maintenance costs except new batteries every 7 to 10 years.

This is a serious question, not a snarky one. Low maintenance, coupled with no fuel cost, is an oft quoted benefit of EP.


Let's assume average EP daily range is 10 miles, with speeds af under 4 kts. A diesel capable of that (even running a larger diesel at that speed) should be good for 1 gallon per day. Assume a generous 50 day year, and $5/gallon, or $250 per year. Add $100/year for oil change and winterization, or an annual operating cost $350.


A 12kwh battery is probably $3K.


Recharge is almost always going to cost something, usually much more than basic utility rates. Assume 15 cents per kWh and 10 kWh per day, or $1.50/day (marinas charge$5 a day just to connect), and that's $75/year.


One option will obviously be cheaper than the other at the end, but I'm not sure I'd bet on which! The more you use it, the better the EP looks.