Conversion project - documented

[sailorxyz]

Originally Posted by SaylorMade

So the first consumption data are ticking in for you guys.

Today after the mast was raised, we took a short trip outside the harbour.
Wind was 10 kts. from the east, so right on the nose and some chop, since easterlies have quite a fetch here.

I aimed for 5.2 knots which was the sweet spot with the Volvo, and it did that with exactly 3 KW on the pod. (50 % if it's max capacity)
Which mean we could have been doing that for 4 hours.
Quite impressed. It would have been much farther in calm weather.

So with a clean hull and prop, it exceeds my range expections.
4 knots in calm water is at least the 40-50 nm I had hoped for.

Fun "problem" with the torqeedo display though. When we putter along with 2.5 to 3.0 knots the range goes above 100 nm, and the range counter goes to zero, so they did not expect that
I think I'll let them know and see if they can fix it in a firmware update.

So, so far totally pleased.

Oh, and manouvering in the harbor is fantastic, so much power immediately.

All good info! Makes me feel more settled about my own choice, although I've gone for the ePropulsion POD Drive 6 EVO. I'm using my own battery so there won't be any regen but since I have a Watt & Sea unit, that is not going to be an issue,

[SaylorMade]

Today, first real trip to a nearby island.
Mostly becalmed, so it was a great oportunity to meassure consumption at different power settings.

No current, seastate flat, and close to zero wind.

I compared the consumption data in the Torqeedo display with the BMS app, and they match the battery BMS data 100 percent. In other words, when the Torqeedo says it draws x amps, the BMS says that exact amount is drawn out of the battery. They were also completely in agreement on the percentage of battery left.

I intitially stated that I was expecting 40-50 nm miles at 4 knots, and some in this thread has alluded that I was overly optimistic. Well I have to say, that I was spot on


So here are the actuals:
1 KW = 4.2 knots which means 50,4 nm range
2 KW = 5.1 knots
3 KW = 5.7 knots

We sailed most of the way using the motor today, and arrived with 89 percent still in the tank. One and a half hour after arrival we were back at 100 percent.a

Oh and it was also a free ride, the harbour here has a flat rate on shore power, no matter how much you use, and we always have shore power anyway. (about 3 USD)

[s/v Jedi]

Originally Posted by SaylorMade

Today, first real trip to a nearby island.
Mostly becalmed, so it was a great oportunity to meassure consumption at different power settings.

No current, seastate flat, and close to zero wind.

I compared the consumption data in the Torqeedo display with the BMS app, and they match the battery BMS data 100 percent. In other words, when the Torqeedo says it draws x amps, the BMS says that exact amount is drawn out of the battery. They were also completely in agreement on the percentage of battery left.

I intitially stated that I was expecting 40-50 nm miles at 4 knots, and some in this thread has alluded that I was overly optimistic. Well I have to say, that I was spot on


So here are the actuals:
1 KW = 4.2 knots which means 50,4 nm range
2 KW = 5.1 knots
3 KW = 5.7 knots

We sailed most of the way using the motor today, and arrived with 89 percent still in the tank. One and a half hour after arrival we were back at 100 percent.a

Oh and it was also a free ride, the harbour here has a flat rate on shore power, no matter how much you use, and we always have shore power anyway. (about 3 USD)

Winner winner, chicken dinner

[Statistical]

Originally Posted by SaylorMade

Today, first real trip to a nearby island.
Mostly becalmed, so it was a great oportunity to meassure consumption at different power settings.

No current, seastate flat, and close to zero wind.

I compared the consumption data in the Torqeedo display with the BMS app, and they match the battery BMS data 100 percent. In other words, when the Torqeedo says it draws x amps, the BMS says that exact amount is drawn out of the battery. They were also completely in agreement on the percentage of battery left.

I intitially stated that I was expecting 40-50 nm miles at 4 knots, and some in this thread has alluded that I was overly optimistic. Well I have to say, that I was spot on


So here are the actuals:
1 KW = 4.2 knots which means 50,4 nm range
2 KW = 5.1 knots
3 KW = 5.7 knots

We sailed most of the way using the motor today, and arrived with 89 percent still in the tank. One and a half hour after arrival we were back at 100 percent.a

Oh and it was also a free ride, the harbour here has a flat rate on shore power, no matter how much you use, and we always have shore power anyway. (about 3 USD)

On your next trip out curious about power consumption and velocity all the way up to motor peak output. Obviously you would never be cruising at that but still curious. Also power consumption at 3 knots for extended range. Also will be curious to see a comparison in heavy seas. Obviously consumption will be more but how much more.

Love to see observations matching theoretical models. I said this upthread.

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.

[donradcliffe]

Sounds like you made a great choice for your usage envelope. Keep us informed of any new developments. I can't remember, any plans to tap the big battery for house power?

[PineyWoodsPete]

Originally Posted by SaylorMade

Today, first real trip to a nearby island.
Mostly becalmed, so it was a great oportunity to meassure consumption at different power settings.

No current, seastate flat, and close to zero wind.

I compared the consumption data in the Torqeedo display with the BMS app, and they match the battery BMS data 100 percent. In other words, when the Torqeedo says it draws x amps, the BMS says that exact amount is drawn out of the battery. They were also completely in agreement on the percentage of battery left.

I intitially stated that I was expecting 40-50 nm miles at 4 knots, and some in this thread has alluded that I was overly optimistic. Well I have to say, that I was spot on


So here are the actuals:
1 KW = 4.2 knots which means 50,4 nm range
2 KW = 5.1 knots
3 KW = 5.7 knots

We sailed most of the way using the motor today, and arrived with 89 percent still in the tank. One and a half hour after arrival we were back at 100 percent.a

Oh and it was also a free ride, the harbour here has a flat rate on shore power, no matter how much you use, and we always have shore power anyway. (about 3 USD)

This pessimist congratulates you on the accuracy of your predictions! And a very slick and efficient installation!
Pete

[sailorxyz]

Originally Posted by SaylorMade

Today, first real trip to a nearby island.
Mostly becalmed, so it was a great oportunity to meassure consumption at different power settings.

No current, seastate flat, and close to zero wind.

I compared the consumption data in the Torqeedo display with the BMS app, and they match the battery BMS data 100 percent. In other words, when the Torqeedo says it draws x amps, the BMS says that exact amount is drawn out of the battery. They were also completely in agreement on the percentage of battery left.

I intitially stated that I was expecting 40-50 nm miles at 4 knots, and some in this thread has alluded that I was overly optimistic. Well I have to say, that I was spot on


So here are the actuals:
1 KW = 4.2 knots which means 50,4 nm range
2 KW = 5.1 knots
3 KW = 5.7 knots

We sailed most of the way using the motor today, and arrived with 89 percent still in the tank. One and a half hour after arrival we were back at 100 percent.a

Oh and it was also a free ride, the harbour here has a flat rate on shore power, no matter how much you use, and we always have shore power anyway. (about 3 USD)

That's great results! Hope mine will be similar. Would love to know your consumption at 3kts as that is the electric "extended" mode.



Idle curiosity would also love to know what you get at 6kW..... although apart from momentary use when manoeuvring, there'd app-ear not to be much need for so much power.

[SaylorMade]

Originally Posted by sailorxyz

That's great results! Hope mine will be similar. Would love to know your consumption at 3kts as that is the electric "extended" mode.



Idle curiosity would also love to know what you get at 6kW..... although apart from momentary use when manoeuvring, there'd app-ear not to be much need for so much power.

At 3 knots the range goes to ludicrous range

I also expect to only use max throttle in a pinch against wind and waves for a short while.

I don't like to max out any systems unless I have to.

[SaylorMade]

On another note, I am also a "a horsepower is a horsepower" guy, but I have to admit that I am a little stunned that this electric thing can push the boat at 4.2 knots with only 1.6 HP.
I am not sure that is equivalent to the old disels power curve.

[Statistical]

Originally Posted by SaylorMade

On another note, I am also a "a horsepower is a horsepower" guy, but I have to admit that I am a little stunned that this electric thing can push the boat at 4.2 knots with only 1.6 HP.
I am not sure that is equivalent to the old disels power curve.

Horsepower is horsepower BUT

what matters is horsepower at the prop shaft. The engine rating is nominal peak horsepower before any auxiliary belt loads (like that shiny upgraded 150A alternator cruisers like to bolt on) and losses from transmission. Since your boat had engine upgraded from 8HP to 17 HP entirely possible it was underpropped and thus producing less than its rated output at 1500 rpm.

When cruising at 1500 rpm do you recall the fuel consumption?

[SaylorMade]

Originally Posted by Statistical

Horsepower is horsepower BUT

what matters is horsepower at the prop shaft. The engine rating is nominal peak horsepower before any auxiliary belt loads (like that shiny upgraded 150A alternator cruisers like to bolt on) and losses from transmission. Since your boat had engine upgraded from 8HP to 17 HP entirely possible it was underpropped and thus producing less than its rated output at 1500 rpm.

When cruising at 1500 rpm do you recall the fuel consumption?

The boat was not upgraded later on, it was delivered with the 17 HP, but the boat type in general was delivered with 8 HP. This particular customer, had the boat delivered with a bigger engine from the yard, so I am pretty sure that it was the correct prop.

I believe it was around 1.5 litres an hour at 1500 RPM. It already seems like a long time ago

[SaylorMade]

Originally Posted by donradcliffe

Sounds like you made a great choice for your usage envelope. Keep us informed of any new developments. I can't remember, any plans to tap the big battery for house power?

I don't plan to, since it will make the range indication incorrect.

I might install a switch and a dc-dc charger so it can be activated in an "emergency" to let it charge on the house battery.

What I am going to do though, is to replace the Lead acid house battery with a LifePo4 12v battery.

[GrowleyMonster]

Originally Posted by SaylorMade

Today, first real trip to a nearby island.
Mostly becalmed, so it was a great oportunity to meassure consumption at different power settings.

No current, seastate flat, and close to zero wind.

I compared the consumption data in the Torqeedo display with the BMS app, and they match the battery BMS data 100 percent. In other words, when the Torqeedo says it draws x amps, the BMS says that exact amount is drawn out of the battery. They were also completely in agreement on the percentage of battery left.

I intitially stated that I was expecting 40-50 nm miles at 4 knots, and some in this thread has alluded that I was overly optimistic. Well I have to say, that I was spot on


So here are the actuals:
1 KW = 4.2 knots which means 50,4 nm range
2 KW = 5.1 knots
3 KW = 5.7 knots

We sailed most of the way using the motor today, and arrived with 89 percent still in the tank. One and a half hour after arrival we were back at 100 percent.a

Oh and it was also a free ride, the harbour here has a flat rate on shore power, no matter how much you use, and we always have shore power anyway. (about 3 USD)

Let us know when you actually motor 50nm at 4.2kts, will you please? Extrapolation from using a small percentage of your stated power capacity is valuable data but not as conclusive as a full discharge test of the system. I like EP. I like it a LOT. But I am also about halfway between being a cynical realist and a pessimist even on things that I like. Worst case scenario and results are better design waypoints than pie in the sky, even if a particular limited data set supports it.

Congratulations on your test run, anyway. You have a good system there and it should serve you well for many years of trouble free use. But I would keep quiet about how many kwhrs of juice you use from shorepower! They might decide to throttle or meter you!

[sailorxyz]

Originally Posted by SaylorMade

On another note, I am also a "a horsepower is a horsepower" guy, but I have to admit that I am a little stunned that this electric thing can push the boat at 4.2 knots with only 1.6 HP.
I am not sure that is equivalent to the old disels power curve.

That may well be but torque also comes into the equation. A diesel only produces maxim torque at one particular rpm. Nor do maxim torque and maxim HP usually align. An electric motor produces maxim torque from zero revolutions. That is the main reason why seemly small electric motors consistently out perform an apparently bigger diesel.

[sailingharry]

Originally Posted by sailorxyz

That may well be but torque also comes into the equation. A diesel only produces maxim torque at one particular rpm. Nor do maxim torque and maxim HP usually align. An electric motor produces maxim torque from zero revolutions. That is the main reason why seemly small electric motors consistently out perform an apparently bigger diesel.

But low RPM produces exceptionally small torque from the propeller. A propeller only achieves maximum torque at maximum rpm, which closely aligns with a diesel engine's maximum torque. At 100 shaft rpm, you could probably turn the propeller by hand! Probably not really, but close. At idle rpm, a diesel engine can deliver many times more torque than a propeller requires, as evidenced by the fact that when you shift into gear at idle, the engine doesn't load up. An electric motor's high torque at zero RPM makes for stunning 0 to 10 in electric cars but is of no value in a propeller.