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Discussion Starter #41
Update, 1/3/19.

I've spent the last couple of days pulling parts in preparation for the motor removal tomorrow morning.

Removed: Batteries, inverter, inverter control panel, transmission and throttle linkage, exhaust system, motor cockpit panel, including all gauges, alternator, all motor hoses and fuel lines.

Going tomorrow - motor, diesel tank, any remaining parts pertaining to the motor that I may have missed.

Staying - water heater, engine raw water intake and filter. The water heater will still work, but will run either with the inverter or when on shore power. I don't think I've ever used it before.

Changes to design - since all electrical systems converge in the starboard aft rear compartment, I'm going to place the bulk of the new systems in the two aft compartments. The starter cables are thicker than I expected, rated 00, so they can carry all the current I need to the motor controller, which will still be in the engine compartment. This will greatly simplify the wiring changes for the new system.
 

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Just to offer some encouragement - I converted a 32' TomCat catamaran from twin Yamaha 9.9's to Torqeedo Cruise 4.0s over four years ago. I used just the stock Torqeedo components so I can't claim to have accomplished much of an engineering feat but I can tell you it's been great to have an electric system. Quieter (not silent), reliable, and maintenance free.
 

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The motor I'm going with, the Motenergy 1115, weighs 35 lbs. I could run it as a direct drive, but since it's only going to turn at about 1000rpm, it won't turn fast enough to cool itself and I could easily burn it out. So I'll put a gear reducer on it so it runs about 4000 at hull speed, keeping itself cool while giving me what I need. I could go with a water cooled model, but that adds more complexity that I would like for this project. Once the system's finished I can always retrofit if I find that cooling is an issue. The motor comes with a built in temperature sensor so I can monitor it via the motor controller.
Howdy Captain. Being in the middle of an Ericson 29 refit (rebuild?) that includes going to an electric prime mover (same one you are looking at!) I'm on your side. However --

I caution you to test your new motor/controller at your intended voltage before you buy/lock yourself into a gear ratio. Brushless motor speed is based on its KV rating (rpm per volt). You're expecting/designing for 96+v rpm from a 48v power bank, from what I gathered reading the thread. You will not see the rpm you are expecting.

So fire up your no load motor at 48v, measure the RPM (i believe the clearview will tell you the RPM..) knock about 5-10% off of that for load, then figure out your gear ratio.

Thunderstruck recommends a 2-1 gear reduction for a reason with controllers defaulted to 48v.

:2 boat:

Sean
 

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I agree with Sean in regards to RPM of the electric drive. I bought a 1115 drive & clearview display from Thunderstruck. At 48 volts the drive will spin approximately 2400 RPM. At a 2:1 ratio that puts 1200 RPM's at the prop which in all likelyhood is close to what she spun when the ICE was at full throttle.

Far as running the electric drive at full throttle for hull speed, you may get 10 minutes if you're lucky before your battery bank hits 50% DOD. In addition to the clearview I also have a victron battery monitor on my bank. At 3.5 knots I'm pulling 20-25 amps out of the bank. At 4-4.5 knots, 35-40 amps. The faster you go, the faster the bank goes.
 

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Discussion Starter #45
Sean and misfits,

Thanks for the info. The voltage to RPM ratio is a wrinkle I hadn't considered. Good to know before I purchase anything. Can you run the me 1115 at 30kW at 48V, or are you limited to 15kW?

I'm not keeping the ICE prop. I'm going to swap it out for a bigger prop that I can turn much more slowly and efficiently to generate the same thrust. This, coupled with the voltage, will dictate my reduction ratio.

I'm still considering if I should run 96v or 48v. There are a lot more options for accessories (like DC/DC converters and DC/AC inverters) in the 48v space.

I won't be concerned with 50% DOD. I'll be running Lithium batteries, so 80% DOD will be by cutoff. I always thought Peukert was a wanker.
 

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Discussion Starter #46
Status update, 1/4/19.

Removed: Throttle, shifter, and linkage, primary fuel filter, motor.

Still to go: Fuel tank, which was probably installed before the boat's deck was installed. I have no way to reach in and unscrew the brackets on one side without cutting through something. Ugh. Plus, I have to drain the tank - I have a lot more diesel left in it than I thought. I'm going to have to rig up battery to the fuel pump and full up my 5 gal can a couple of times to empty it.

I also discovered today that the shore power connection has been replaced... and whoever did it used home-grade romex instead of tinned stranded wire. Not a big deal, since I'm rewiring some of the AC side anyway, but still a pain in the ass, as removing the shore power face plate is damn near impossible single-handed.

On the plus side, the motor went to a good home, to repower a 70's era boat that is obviously loved by it's owner.

Once all the removal is done, I'm going to have a *lot* of cleaning to do.
 

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Sean and misfits,

Thanks for the info. The voltage to RPM ratio is a wrinkle I hadn't considered. Good to know before I purchase anything. Can you run the me 1115 at 30kW at 48V, or are you limited to 15kW?
The limit on a motor is the amperage that the windings can handle. The specs I see from Thunderstruck EV https://www.thunderstruck-ev.com/motenergy-me1115-brushless-sin-cosine.html (I trust them) are 125a AC (180amps into the controller to achieve 125 continuous through the motor)

It's a brain-twister to explain RMS and back EMF and motor phases and etc so i'll skip that -- let's just assume you can put 180 amps into the controller continuously. That means: 180x48v = 8640 -- 8.6KW continuous, or 11.58hp. And -- because of the Kv constant, you'll only be able to reach that if you are propped optimally. You might think of a max prop or kiwi prop so you can adjust pitch such that at max throttle you are also at max amperage. 96v is double that, but the higher voltage presents more every-day risks and a whole different class of ABYC wiring/grounding/etc requirements. Best to avoid that in my opinion.

You may want to rethink your "biggest most efficient two-blade prop" plan too. Not to pooh pooh on the efficiency parade (I'm a big fan of efficiency, it's a fun mental exercise. I've done it before on a 1-man solar powered fishing pontoon boat..) Unfortunately, efficiency matters little when you're fighting a 22kt wind on the nose gusting to 30 and you're making .7kts headway in the gusts with your really efficient propeller. Better to back off of max efficiency a touch and design a little extra slip/torque into your prop in order to make reasonable headway against sh!t assed conditions before your power runs out. Just a suggestion, of course. I'm just a dumb redneck and I don't know much, so you should take this with a grain of salt.

I won't be concerned with 50% DOD. I'll be running Lithium batteries, so 80% DOD will be by cutoff. I always thought Peukert was a wanker.
He was! you're absolutely correct! I prefer LiFePO4 to other chem's because of the safety factor, but you pays your money and you takes your chances, as they say. My practical experience comes from my 24v 100ah (so 2.4kwh) LiFepO4 system on my Macgregor 26s in a slip at the local lake for the past few years -- it's 2hp electric outboard treats me well, and the 480 watts of solar keeps it charged. The lack of peukert's interference REALLY helps the solar keep up with the refrigerator keeping the beer cold.

The Ericson 29 I'm refitting will have a somewhere between 5 and 10kwh bank, and a 5kw diesel genset for range. Not interested in hull speed here. It's a waste of power. Shoot, most diesel aux boats can't make hull speed unless they're under sail.

:2 boat:
Sean
WK7R
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Discussion Starter #48
Hi Sean,

Thanks for all the great info. I really appreciate it. I have some questions, though.

If I'm going to run at 48V, there might be a better choice of motor out there. I'll have to do some digging. I hadn't considered the ABYC requirements, but I guess I'll have to sell the boat eventually. One of the reasons I'm doing this is to gain experience for the next boat. I fully anticipate screwing things up at least once. I find turning a wrench is worth a thousand technical manuals.

Hull speed is more of a personal design challenge. I'm not looking to skip along the water on my wing keel, or maintain it for any period of time, I just want to be able to touch it and say "yeah, the boat can do that". I realize that I would suck the battery dry in no time. I'm going to start with 8kWh and see how far I can get with that. If I need more, I can always keep adding until I run out of space.

I have a basic knowledge of electricity, but I'm not a professional, and my knowledge of hydrodynamics is about as complete as someone who's two weeks into their first college course. What I don't understand is why the speed of the prop is an issue. If I get X thrust from a prop spinning at 1200 RPM, and the same thrust from a prop spinning at 800 RPM, what's the difference, regardless of weather conditions, other than the gearing necessary? Won't both props push the boat equally well? You can even argue that fewer RPMs means less wear on all moving components.

What more risks are there at 96v vs 48v? I don't know much about DC, but surely the risks can't be as high as the risks for the 120VAC that the boat also runs? Are you talking about undersizing your cables, or is it something else?

Thanks for your help. I appreciate it.
 

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Hi Sean,

Thanks for all the great info. I really appreciate it. I have some questions, though.

If I'm going to run at 48V, there might be a better choice of motor out there. I'll have to do some digging. I hadn't considered the ABYC requirements, but I guess I'll have to sell the boat eventually. One of the reasons I'm doing this is to gain experience for the next boat. I fully anticipate screwing things up at least once. I find turning a wrench is worth a thousand technical manuals.

Hull speed is more of a personal design challenge. I'm not looking to skip along the water on my wing keel, or maintain it for any period of time, I just want to be able to touch it and say "yeah, the boat can do that". I realize that I would suck the battery dry in no time. I'm going to start with 8kWh and see how far I can get with that. If I need more, I can always keep adding until I run out of space.

I have a basic knowledge of electricity, but I'm not a professional, and my knowledge of hydrodynamics is about as complete as someone who's two weeks into their first college course. What I don't understand is why the speed of the prop is an issue. If I get X thrust from a prop spinning at 1200 RPM, and the same thrust from a prop spinning at 800 RPM, what's the difference, regardless of weather conditions, other than the gearing necessary? Won't both props push the boat equally well? You can even argue that fewer RPMs means less wear on all moving components.

What more risks are there at 96v vs 48v? I don't know much about DC, but surely the risks can't be as high as the risks for the 120VAC that the boat also runs? Are you talking about undersizing your cables, or is it something else?

Thanks for your help. I appreciate it.
My recommendation is to not only consider ABYC for resale value.

Quite frankly, who knows what impact an electric vs diesel propulsion system will have on it. If you can find someone who wants electric, maybe it will be OK. For someone like me, who wants a diesel (for the range and rapid refuel capability) I would completely pass on the boat, else devalue by the cost to install a diesel (and all supporting equipment) and an amount to cover my time, trouble, and risk to convert it back.

ABYC standards are designed to help prevent people from setting their boats on fire.

These are the minimum.

There is skill and craftsmanship required to make a boat safe and reliable that no standard, books reading, or YouTube watching can impart.
 

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Sailing Uma did a 3-way chat comparing electric setups with them, Sailing Saoirse and Learning the Lines. It was all over my head when they started talking about which motor and battery set up they went with

Electric Motors, An Honest Discussion — Sailing Uma [Step 140] - YouTube
Yes they did.

I'm a subscriber to their channel.

IMHO, some of the things they do is OK, and some is ill-conceived.

It appeared that the intent of the episode was to help validate their decision to covert to electric.

I believe the real motivator was the 40 year old diesel was baffed and they believed an electric motor would be lower cost.

They ran into all kinds of trouble with the drive system, and it was quite noisy. Perhaps not as noisy as the diesel, but certainly no where near "silent".

They had a severe problem with speed and range.

Once, they had to hunker down and sit through a hurricane at anchor, risking his life (she left him their) because they did not have speed and range to escape the forecast path, in the calm before the storm.

Often they are forced to sit at anchor longer than desired to wait for favourable wind, where most cruisers with diesels would just motor to get where they want when they want.

Then they had an electrical problem due to a high current, high impedance connection.

This left them propelling the electric boat with the gasoline outboard on the dinghy strapped to the mother ship.

They explained that the electric was NOT to replace the diesel, but to replace a sculling oar, that they would otherwise have if they did not replace the diesel.

The other two couples who were in that episode touting the benefits of electric propulsion were either about to, or in the process of a build, and had no actual life experience with an electric cruising boat.

Then a couple episodes later the crew of UMA burned who knows how much gasoline turning countless donuts in an abandoned marina.

Kinda blows the primary factor to reduce carbon footprint outa the water.

Then, they changed out the electric motor, drive, and batteries after a couple years (obviously it was not living up to their expectations) for a much more expensive system including a bunch of LFP batteries (likely donated or sponsored) that would cost much more than putting in a used diesel, or about the same as a new.

The last episode I watched, their dinghy gas outboard failed (from admitted lack of proper maintenance) and they put on a Torquedo they had aboard that was donated by a Patreon.

(Wait a minute, they have a Torquedo aboard that one could claim was reducing their carbon footprint but they are using a 5 HP gas outboard? Why?

Then they advised that the Torquedo was unsatisfactory due to limited speed and range, and they are going to replace it with an even bigger gasoline outboard.

Long story short, I give that episode and their reasoning for electric propulsion an "F" grade on the sincerity scale.

I'm not suggesting electric propulsion is bad, in fact I recommend it to clients where it is a viable technology for their use case.

But there are a lot of factors to consider.

On my cruising boat, after motoring 30 hours at 5 knots, I start looking for a marina with diesel as I have about 4 hours left.

If I converted to a turnkey commercially available electric system (with only 8 hours at 5 knot range) ) I would have as much money and weight into it as I would a diesel system with 34 hours at 5 knot range.

What's more, the diesel system can be refueled very inexpensively in about 10 minutes, whereas the electric system will take at least 24 hours, and cost at least one night of marina fees.

If one will be doing a lot of motoring, like down the ICW, or just getting from one anchorage to another between norther's, an electric propulsion system is not a viable option, without an ICE generator onboard, and then what is the point?
 

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I haven't had my coffee yet, so f'give me if I don't make any sense.

Hi Sean,
If I'm going to run at 48V, there might be a better choice of motor out there.
You're looking at one of the best compromises of speed/torque/efficiency at your boat's requirements. Short of a switched reluctance motor and controller suddenly becoming available in the 5-10kw @ 48v range. And at <50v ABYC wiring standards. e-10 I think, you really are pushing a lot of current at 10KW. ~200 amps. 2/0 awg is expensive. 10kw is roughly the upper practical limit unless you want do deal with the isolated grounds and relative danger of higher voltages.

Hull speed is more of a personal design challenge. I'm not looking to skip along the water on my wing keel, or maintain it for any period of time, I just want to be able to touch it and say "yeah, the boat can do that". I realize that I would suck the battery dry in no time. I'm going to start with 8kWh and see how far I can get with that. If I need more, I can always keep adding until I run out of space.
You can still get to practical hull speed with the above system by going above the continuous rating of the controller & motor. Thunderstruck says 600 amps for 1 minute into the motor. I imagine that means 300 for 2 or more minutes, then. Their recommended Sevcon 72/80 550 controller is rated for 2minutes @550 amps. So you have plenty headroom to overprop/overpitch the system for brief periods of hull speed, so long as you size your wiring safely. Set it up, and play with the props. Again something with variable pitch will be cheaper long run, props are expensive. You never know, maybe you have a slippery lightweight hull and can get the hull speed on flat water without over currenting... stranger things have happened. test test test!

I have a basic knowledge of electricity, but I'm not a professional, and my knowledge of hydrodynamics is about as complete as someone who's two weeks into their first college course. What I don't understand is why the speed of the prop is an issue. If I get X thrust from a prop spinning at 1200 RPM, and the same thrust from a prop spinning at 800 RPM, what's the difference, regardless of weather conditions, other than the gearing necessary? Won't both props push the boat equally well? You can even argue that fewer RPMs means less wear on all moving components.
Specifically to address your 1200 vs. 800/same thrust question. Thrust at what speed? The efficiency curve of the 1200 rpm prop will not peak as high as the 800 rpm prop will at the particular speed you've optimized for but it will be broader and take less of a hit in different wind/wave conditions it's not optimized for, since the slip will vary less over that range of conditions (Simply because of the higher RPM/lower speed of advance/ratio against actual speed of vessel in prevailing conditions)

At another level you seem conflicted on what you want. You want hull speed -- by definition, inefficient. And you want biggest 2 blade prop for efficiency. wahh? Hey I get it I want fast cheap quality stuff too. :) But down here in reality we can only do one at a time. Experimenting is fun, and I'm all for it, knock yourself out if you've got the $$ to do so. Report your findings, we all want to know!

For me it's easy, my e29 has enough room for MAYBE a 14.5" prop. May have to modify the rudder to get enough aperture. So I have to go 3 blades. I'll do a kiwi prop, and optimize for headway against crappy conditions, and get my speed fix from my sails.

What more risks are there at 96v vs 48v? I don't know much about DC, but surely the risks can't be as high as the risks for the 120VAC that the boat also runs? Are you talking about undersizing your cables, or is it something else?
Vs AC/shore power/inverter? You can't shut batteries off at the breaker when you're working on the interconnects. They're always on. Always a hazard. They never forgive you when you forget to take your watch off, or drop that wrench you were tightening that bolt with. Add to the 'always on' bit with you're quite a bit more likely to achieve a lethal current through your body's internal+skin resistance than at 48v. And you're in an environment (salt wet) that lends itself to testing the theory quite handily.

The arc gap is twice as long as it is at 48v, and you put twice the current into a given resistance, generating twice the heat into any 'accident' that occurs.

Oh and, by the way, you're welcome. Hope it's useful.

:2 boat:
Sean
 

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Long story short, I give that episode and their reasoning for electric propulsion an "F" grade on the sincerity scale.
I agree with you on Uma. They went into it kinda ignorant but at least honest cheapskates. I cringed a lot as they made what were obvious to me mistakes though, and then it went sideways when they didn't report honestly what they learned (Which would have dampened the enthusiasm for electric and their whole cooky eco warrior theme they have going on) But that tends to be the way I guess. Their system, originally, for all its flaws, WAS cheap and did work. objective reached! Admirable in that.

I'm not suggesting electric propulsion is bad, in fact I recommend it to clients where it is a viable technology for their use case.

But there are a lot of factors to consider.

If I converted to a turnkey commercially available electric system (with only 8 hours at 5 knot range) ) I would have as much money and weight into it as I would a diesel system with 34 hours at 5 knot range.

What's more, the diesel system can be refueled very inexpensively in about 10 minutes, whereas the electric system will take at least 24 hours, and cost at least one night of marina fees.

On my cruising boat, after motoring 30 hours at 5 knots, I start looking for a marina with diesel as I have about 4 hours left.

If one will be doing a lot of motoring, like down the ICW, or just getting from one anchorage to another between norther's, an electric propulsion system is not a viable option, without an ICE generator onboard, and then what is the point?
I think there are some advantages to this arrangement -- Electric prime mover for the reliable quick anchor set/docking/get out of the way/short hop, and diesel genset for induction cooktop, microwave and air conditioning at anchor, and longer 30-40 hours of motoring @ 5kts. It's the direction I'm going.

:2 boat:
Sean
 

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Discussion Starter #53
Sean,

Electricity is like the sea. If you give it a chance, it will kill you. I'm pretty careful with my wiring, having learned it from a friend of mine who's been a professional electrician for over 30 years. He's helped me reno three of my homes. I've also had to go through the OSHA safety training course a couple time for various contracts I've worked on. I don't consider myself an expert, but I am extraordinarily cautious around electricity and am a firm believer in "too much safety is just enough". I will be testing the hell out of the system I build long before it gets on my boat. If anything is going to melt down, I'd rather it do so on my concrete workshop floor rather than inside my boat.

I think I'm not explaining myself well. Thrust dictates speed. Once the water resistance matches the thrust from the prop, acceleration stops and the speed remains steady. Whether that thrust comes at 800 RPM or 1200 RPM is probably irrelevant. I guess I'll find out. I can't put Khaleesea on the hard until some space frees up, so I don't even know how big my prop is right now. Probably 16x10 or thereabouts. Hopefully I'll be up on the hard soon so I can take measurements.

Point taken about overdriving the motor temporarily. The DC cables on Kahleesea are already 2/0. From what I've read, at 48V that's over 200A, more than enough for cruising speed. Since DC and AC systems converge in the starboard aft compartment, that's where I'll put all electric connections. Looks like the charger and the inverter are going to have to be separate, since I can't find an inverter/charger unit that works with lithium batteries.

Are you putting your genset where your old diesel was? I can't imagine there are too many places in a 29' boat where you can put something like that. I'd also be interested to see your wiring diagram if you have one.

I find it interesting that you're going with the Chevy Volt model of hybrid propulsion. If I needed a longer cruising range, that would be the direction I would go too, but with as much solar as I could cram overhead.
 

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Your project is interesting and i appreciate your goal. Gotta learn and try new things...to reach further.

With your lifepo4 batts...
Any tool i use that goes down into where those batts reside is taped except for the extreme working ends.
I might sneeze or fumble...:)
 

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Thrust dictates speed. Once the water resistance matches the thrust from the prop, acceleration stops and the speed remains steady.
I will take a stab at trying to explain why the above statement makes me cringe.

Thrust is not static. A given prop/rpm does not create say "500lbs of thrust" and when you reach "500 lbs of water resistance" you achieve equilibrium. This is not at all how this works, and is an especially misleading train of thought if you are attempting to armchair/roughly calculate efficiencies or select the correct prop.

A propeller thrusts a boat foward due to the lift generated by its blades' angle of attack relative to the water column it is spinning in (the AoA often times indirectly referred to as 'slip,' or the speed of advance of the propeller VS. the speed of the water column it is advancing in). Thrust, the force pushing forward on the prop shaft, is a dynamic force and depends on RPM, pitch of the propeller, speed of the boat. As the the boat speeds up, the angle of attack at a given RPM is reduced, and so is the lift, and so is the thrust. When the boat is not moving, at the same RPM the blades can begin to stall, create turbulence and possibly cavitate, generating very little thrust. When optimizing for efficiency, you can only optimize for a single point in the speed/thrust curve. Everything slower or faster than this particular point will not be at max efficiency of power in vs. power out of the system, and for thrust can be wildly different from what you expect.

A perfect example of this is the lowly trolling motor, which may have 100lbs of thrust at zero speed, but at roughly 4-5 kts, is generating zero thrust. You can put 5 100lb thrust trolling motors on the same boat and it will not go any faster. It can't. The propeller blades are effectively at zero AoA to the water column they are moving in.


SO let's say max efficiency is roughly 50% slip (Just throwing a number out there but this is a fairly commonly used point), you prop your boat so that at max RPM the props are going twice as fast as the water column. You're aiming for hull speed at say, 7.5kts, so you pitch it so the speed of advance of the prop is say, 15 knots. This will give you maximum thrust at 7kts, and will be great for your ideal speed run in calm water with no wind. however... when the 30knot winds on the nose are blowing, the chop is reaching 3-4 feet in the bay, your boat has slowed down, the propeller at max RPM will be at various states of stalled and will NOT generate maximum thrust where you now need it the most, to make meaningful headway against the conditions. It's like oversheeting your mainsail. You keep pulling but the boat doesn't go.

The conservative angle would be to pitch the prop for say, 10kts speed of advance. Maybe now you can't go faster than 6 kts, because you are not generating enough thrust to overcome your wavemaking resistance. But when the crap hits and forces your boat to slow.. you have a lot more thrust at 4-5 kts headway to push through the wind and chop, and your prop is not operating in a stalled speed regime.

When designing for a system with limited power -- speed is great, but it comes at the cost of low end grunt. Low end grunt comes at the cost of speed. This is the compromise you have to make when designing for efficiency, speed, or power.

Whether that thrust comes at 800 RPM or 1200 RPM is probably irrelevant. I guess I'll find out. I can't put Khaleesea on the hard until some space frees up, so I don't even know how big my prop is right now. Probably 16x10 or thereabouts. Hopefully I'll be up on the hard soon so I can take measurements.
The higher RPM means that the change in AoA across the speed regime is less drastic, so the efficiency peak, while lower, is more broad (it's over a bigger range and you are less likely to stall at the lower end of the speed range than the higher pitched, slower prop)


I can't find an inverter/charger unit that works with lithium batteries.

Are you putting your genset where your old diesel was? I can't imagine there are too many places in a 29' boat where you can put something like that. I'd also be interested to see your wiring diagram if you have one.
The boat came with an atomic four (ugh). I'm opposed to explosive things in a cave so want to avoid propane/gasoline/etc. The thunderstruck motor + belt drive take up little enough room that I can fit a 5kw genset roughly in the engine bay in front of the motor, if i build out the front of the engine bay out far enough to comprise the second step of the companionway 'ladder'. ;) Since i had to rip the floor out to get the oil cleaned up from the ranwater flood that allowed me to pick up the boat for cheap... i'm rebuilding that, the galley, the bulkheads, etc. The new engine stringers are in now, though, and i'm rebuilding the compression post step/cabin sole now. Exciting! Take a look at the Victron Quattro/Multiplus/whatever they call them. They can adjust charging voltage in .1v increments, plenty close enough for lifepo4 @ 90-95% charge regime, and you dont really want to top lifepo4 off anyways.


Okay off to dinner...

:svoilier:
Sean
 

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Your project is interesting and i appreciate your goal. Gotta learn and try new things...to reach further.

With your lifepo4 batts...
Any tool i use that goes down into where those batts reside is taped except for the extreme working ends.
I might sneeze or fumble...:)
You are a smart man!

Sean
 

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I won't be concerned with 50% DOD. I'll be running Lithium batteries, so 80% DOD will be by cutoff. I always thought Peukert was a wanker.
You can discharge AGM's to 80% also. Lithium batteries big investment.
 

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Yes they did.

Kinda blows the primary factor to reduce carbon footprint outa the water.
I think the conversion to electric (for many) is less a "solution" and more an "intention" to move forward.

Here in coal-fuelled Alberta, owning an electric car is actually more carbon producing than a Honda Civic. Next door in hydro-powered BC it is way, way less. Doesn't stop concerned Albertans from buying electric cars, and IMHO it shouldn't—the more common it becomes the more likely it is that it will eventually make a significant difference.

So more power to the electric boaters!
 

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Discussion Starter #59
Sean,

Thanks for the great info. I really appreciate it. No idea why I though the water would be a constant, but when I read it was dynamic I had a serious "duh" moment. OF COURSE it's dynamic. It's WATER. Too many years of car work, I guess. Anyway, thanks for snapping me out of that and pushing my knowledge just a little bit farther forward.

Looks like I should be making my most efficient point cruise, (say, 5kts) and leave about 25-35% more on top for emergencies. That sound about right?

Did you manage to sell your atomic 4? Seems like people either love or hate them.

Good on you for getting a scrapper and doing a total reno. That's a lot of work. I doff my hat to you, sir.
 

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You can discharge AGM's to 80% also. Lithium batteries big investment.
Big investment, but much cheaper than lead acid in the long run, with a much longer list of advantages than disadvantages. My two favorites are much less weight and giving Peukert the finger.
 
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