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Next to nothing I would imagine. Boats, unlike cars, use most of their power output at cruising speed beyond hull speed.
 

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My 150 on a 21ft boat - just about one of the most economical 150's you can buy, did about 3nmpg - less than a 10th of what a car does - there's a big difference in how far the same amount of energy will take a boat to a car.

Interesting that this engine uses an Evinrude Etec body - I wonder what they will do now that Evinrude have stopped production.
 

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All comes down to battery technology.

When worked on the Jaguar IPace (I was inverter lead engineer) we had to run the motor at 94% efficiency and the inverter at 96% efficiency to get 200miles from the battery pack.

The same battery pack that was part of the chassis and floor on the car.....

I’m not sure how feasible an electric boat would be unless it’s additional propulsion to petrol via solar or something but it’s a hell of a lot of weight to package in a boat......
 

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Discussion Starter #6
All comes down to battery technology.

When worked on the Jaguar IPace (I was inverter lead engineer) we had to run the motor at 94% efficiency and the inverter at 96% efficiency to get 200miles from the battery pack.

The same battery pack that was part of the chassis and floor on the car.....

I’m not sure how feasible an electric boat would be unless it’s additional propulsion to petrol via solar or something but it’s a hell of a lot of weight to package in a boat......
Not sure but I doubt they will be using lead batteries. Most people are moving to lithium for their ellectric motors such as Minn Kota and motorguide, with even these now improving to lithium phosphate batteries.

I bought a lithium phosphate battery about 2 months ago ($1250) which only weighs 7kg compared to the equivalent lead wet battery that weighs about 30kg. Another big difference is the power distribution from the lithium, where it gives full power untill it is totally discharged. It's also fully charged in about 1 hr from home power or 3-4 hrs using the car, boat or solar. I'm able to run my 45lt dometic fridge freezer for around 3 days without charging it but supplying it with a bit of solar or power from a cigarette power point on a running vehicle I can keep it running indefinitely.
 

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I suppose those of us that don’t have access to shore power will have to have a generator on board. Kind of defeats the objectives of electric power. However I’m 75 so my time will soon be up, the young ones will have to row or sail. Could use steam but then your back to burning thing. THE END IS NIGH!
 

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No ones gonna say it then? Unless the tech becomes significantly better and we find a truely perpetual/renewable/ 365 a yr available energy source, the only way to have a totally green boat is to become a wafi. 🥴
 

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I've heard people suggest they use wind power to capture energy to power an electric motor in a boat! I made the suggestion of building a tall mast and hoisting up a large piece of cloth to capture the wind power instead :)

I don't know how I'd cope with that real PIA feature that you can't go exactly where you want though!

Back to the article above - I wonder how careful they were to line up the photo of the pod so that it had a Mercury 400R outboard in the photo!

What's also interesting is the efficiency graph for a propellor which shows a massive drop off above 35 knots - I assume that refers to the additional amount of power required to add extra speed rather than the efficiency of an individual boat - if anything my boat feels more efficient at the top end - push the throttle forward from say 4000rpm and you can really feel the surge forward.
 

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I've heard people suggest they use wind power to capture energy to power an electric motor in a boat! I made the suggestion of building a tall mast and hoisting up a large piece of cloth to capture the wind power instead :)

I don't know how I'd cope with that real PIA feature that you can't go exactly where you want though!

Back to the article above - I wonder how careful they were to line up the photo of the pod so that it had a Mercury 400R outboard in the photo!

What's also interesting is the efficiency graph for a propellor which shows a massive drop off above 35 knots - I assume that refers to the additional amount of power required to add extra speed rather than the efficiency of an individual boat - if anything my boat feels more efficient at the top end - push the throttle forward from say 4000rpm and you can really feel the surge forward.
You are probably reaching the field weaking region of the electric machine at the 35knts. I’m not sure what top speed is, but an electic machinecan supply full torque from zero RPM until it reaches a point where the back EMF is equal to the applied voltage so then the torque drops off...

However as power is torque x speed you can use clever control to maintain constant power, the issue is it’s less efficient.
 

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You are probably reaching the field weaking region of the electric machine at the 35knts. I’m not sure what top speed is, but an electic machinecan supply full torque from zero RPM until it reaches a point where the back EMF is equal to the applied voltage so then the torque drops off...

However as power is torque x speed you can use clever control to maintain constant power, the issue is it’s less efficient.
I was referring to the traditional prop graph - the electric seems much more efficient at high speeds according to that article - just I was surprised at the way it shows a massive drop off above 35 knots for a traditional prop - your boat must have a pretty high top speed - in my experience that last 1500 or so rpm gives you quite a noticeable surge forward.
 

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Discussion Starter #13
My 150 on a 21ft boat - just about one of the most economical 150's you can buy, did about 3nmpg - less than a 10th of what a car does - there's a big difference in how far the same amount of energy will take a boat to a car.

Interesting that this engine uses an Evinrude Etec body - I wonder what they will do now that Evinrude have stopped production.

Mercury do seem to be good performers, shame about the paintwork though, how's the leg on yours looking ?
 

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Mercury do seem to be good performers, shame about the paintwork though, how's the leg on yours looking ?
On the engine I was referring to (2011 model), it wasn't brilliant - very orange-peely and a few spots of corrosion that I nipped in the bud (but Merc is far from the only culprit with bad outboard paint), I resprayed it with Merc's excellent rattle cans a couple of years ago (pic below). On the Merc I have now, massive improvement as is the general build quality, the leg is looking pretty good, but it's only been in the water for just over an hour!

MercuryLeg_zpsvelco3be.JPG
 

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Discussion Starter #15
On the engine I was referring to (2011 model), it wasn't brilliant - very orange-peely and a few spots of corrosion that I nipped in the bud (but Merc is far from the only culprit with bad outboard paint), I resprayed it with Merc's excellent rattle cans a couple of years ago (pic below). On the Merc I have now, massive improvement as is the general build quality, the leg is looking pretty good, but it's only been in the water for just over an hour!

View attachment 1358573
Is it actually a proper mercury paint then ? I will try to get some as the top of her engine is like new but the bottom is shocking for such a new motor, it's not just what you can see in the photo but the whole bottom gearbox section.

The rig my daughter recently bought has a two year old Mercury with just 38hrs on it is looking pretty blistery and flakey already but its its certainly pretty gutsy and economical. The gearbox for such a new motor is pretty harsh, it really demands a swift engage when putting into gear or it clunks and scrapes in. We sold the other rib with the Yam which looked and performed faultlessly after clocking just under 1000hrs in the short time we owned it.

IMG_4896.JPG


tempImageYGumkY.png
 

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Is it actually a proper mercury paint then ? I will try to get some as the top of her engine is like new but the bottom is shocking for such a new motor, it's not just what you can see in the photo but the whole bottom gearbox section.

The rig my daughter recently bought has a two year old Mercury with just 38hrs on it is looking pretty blistery and flakey already but its its certainly pretty gutsy and economical.
Yes, it was the Quicksilver branded stuff from the Mercury dealer - it's expensive for a rattle can, but worth it - it sprays much better than most rattle cans, and is the correct Mercury black - you don't realise what a deep black it is until you try to touch it in - the black touch up stick that I use for the black alloys on both our cars, looks very black on the wheels but looked charcoal against Mercury's black. I had a few spots like that bit by the trim tab bolt on her engine - previous owner hadn't bothered touching them in as soon as they were chipped or scratched.

I sanded down the corrosion spots very thoroughly until you could only see bright metal and got a good key on the rest of the black paint. Then a bit of red oxide on the bare metal, then a bit of high build primer on any low spots - a good wet sand again, then a bit more red oxide to give a better base colour over the high build primer.

Another good sand all over, then three coats of black, letting each one flash off with a final very wet coat. Then left a week to harden off, a good wet sand all over with 1200 wet and dry, plenty of washing up liquid and a very light hand.
Finally a good hand polish with Farecla G3, then G10 (a machine would be too viscious on the new paint and I did the whole engine with this), finished off with a resin sealer (I used NuFinish) followed finally by a coat of hyrbrid ceramic.

The gearbox for such a new motor is pretty harsh, it really demands a swift engage when putting into gear or it clunks and scrapes in.
Yep, mine was like that too - felt very agricultural after my Etec - but you get used to being swift with the handle - quite a lot of in and out of gear to get off my mooring and back on to it. The new generation of Mercs are smooth as silk.
 

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God I used to love the smell and sound of seagull engines in the morning!!!!!
 
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