Update on electric C-Dory

Yes Tom, I read your yesterday's post on "Balancing"--but still don't understand how your access each cell individually to give specific current to that cell. Are you saying that the 1000ma of current is balancing each cell as it needs it? What voltage are you applying to "balance" the cells? And the next question is how is this "high voltage" different than achieved during each cycle of charge as done with a programed charger. I was under the impression a specific current and voltage had to be applied to a cell if it was not equal to the others. Thank you.
 
Bob, The way balancing works in a normal BMS is that there is a little circuit board attached to each cell that shunts the charging current to a resistor when that cell has reached its maximum voltage. The BMS reads the total voltage of the bank and shuts charging down when the maximum voltage is reached. If all the cells are balanced then they all reach the same voltage that adds up to the max at the same time and no balancing is required. If one cell however reaches its individual maximum V before the rest do, the charging current is shunted to the resistor while the other cells keep charging until they too reach the max voltage. This is called "passive" balancing and is the usual type. Some newer BMS have what they call "active" balancing when the current from the fully charged cell is shunted back into the charging current and the next cell in the series. In either case, the maximum balancing current I have seen is 1000mA (1A).

As the cells age and are used, each changes slightly differently from its cohorts and the 1A balancing current is no longer adequate. There are two situations that can occur. In the first, once cell charges to its maximum much faster than the others and the BMS that is monitoring all cells shuts the charging down when that one cell reaches is maximum and the other cells are not fully charged (their voltage has not reached their maximum). The larger chargers (15 -30A) taper the charge down to 2-3 amps which is greater than the balancing current of that one cell. Thus the voltage in that overcharged cell keeps increasing and shuts the charging. The other situation is where one cell is slower to fully charge than the others. With only one cell with a slightly lower voltage than the rest, the charger and/or BMS will think the maximum V has been reached and shut down. Since the capacity vs V curve in the Li batteries is so straight that one cell will slowly be less and less charged on each cycle.

So how do I correct this? I use a bench top power supply and set the maximum V at 0.1 to 0.2 V less than the shut off V for the BMS. I set the maximum current at 100 mA (0.1A) less than the balancing current (for me that is 0.9A). I connect the power supply to the battery and charge it until the data on my phone shows that all the cells are at the same V. The power supply acts as a charger with its current set below that of the balancing current so the BMS does not see any spikes in voltage in individual cells.

This is why it is important to be able to monitor the voltage in each individual cell. You can check to see if you need to manually rebalance the battery.
 
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I am quite interested in your C-Dory electric propulsion. We also are doing electric propulsion, a Navy 6 on a 17 foot Montgomery sailboat (overkill, could have used a 3kW but wanted the new 2024 motor design of the Navy 6). Using a 10.6kWh battery bank and 600 watts of CIGS solar, we motored from Chicago to Alabama (1100 miles) on the Great Loop route, only using our Tohatsu 6hp gas backup for a short stretch on the Ohio river against 2.5 kt current.

Anyway, we are going to expand our bank to 19kWh for the next leg and drop the gas motor altogether, and we are now very interested in a larger all electric power boat for cruising in the Puget Sound, maybe doing the Snake/Columbia river run, possibly the inside passage, and other stuff we could trailer it to. The C-Dory 22 looks promising.

Our 17 foot Montgomery has a 600 pound lead keel and yet we are still able to fit 19kWh of LiFePO4 in there. If we did do a C-Dory 22, I would aim for 50kWh as this is only about 800 pounds of battery. I think the C-Dory normally comes with a 50 gallon fuel tank, which if full of gas would weigh 300 pounds, so net 500 pounds. 50kWh running a Navy 6 at 3kW would give about 16 hours at 5mph, or 80 mile range. We actually managed to do a 115 mile stretch on the loop in our 17 foot boat with our 10.6kWh bank and 600 watts of solar, but we had to limit ourselves to 500 to 700 watts and pray for sun. Probably could do the same stretch in the C-Dory 50kWh no sweat at 4.5mph. 2000 watts to the motor.

Was it difficult to convince the factory to sell you a incomplete boat (no motors or tanks)?
 
The idea of cruising the great PNW fully-electric is compelling. Many, if not most, people that do it are limited to hull speed or less (trawlers and sailboats), though typically with longer boats and thus somewhat higher hull speed. Trawlers can only motor. Practically, sailboats almost always motor, and rarely actually sail except in a local area. A C-Dory hull is designed for planing, and thus likely not as efficient as your Montgomery. You will often encounter tides, currents and winds that keep most boats waiting for changes in conditions, sometimes for days, on a summer inside-passage trip.

Tom has significant experience with a fully-electric C-Dory, but seems to be charging his batteries primarily with 110 VAC. Therein lies the "rub". IMHO, the beauty of the PNW region, like the Chesapeake, is the availability of places where you can gunkhole at anchor. I sometimes have wonderful recollection dreams of anchorages, a recent one up a fjord in BC where we watched 8 grizzles play together on the shore as sockeye salmon jumped all around us. We were the only ones there. I can't recall such dreams about mooring at docks.

I've cruised in protected waters (lakes, rivers, south Puget Sound and the Everglades) with several iterations of gear, finally arriving at a 19.5 ft long Wenonah kevlar canoe, a Torqeedo 1103 (overkill), two Torqeedo batteries, and 175 watts of solar as my ideal. Of course, I can also paddle this rig. This setup works well for long trips in protected water, except where the sun is uncooperative. However, canoes have legendary efficiency, motorboats do not. I was able to run my lightly-loaded CD22 at 4.5 statute mph using about 1550 watts of power, 450 from my Minn Kota bow mount (the max it would sustain), and 1100 from the Torqeedo. Tom was able to get about 4.0 with his rig at 1500 watts. This seems workable, though moving at 5 mph would be ideal.

This is the math problem I see with your proposal. First, you have to fit 600 watts of solar. I currently have 350. I have CIGS on my campers, since I often park in partial shade. The CIGS panels I do have seem to have more surface area per watt, and less "shapes" are available to fit the C-Dory 22. I'm really excited about seeing you fit all of these panels, and I'll follow your lead after you do.

So, 600 watts. At 100% efficiency, something I have rarely achieved, you'd need 83 hours to charge your proposed system depleted to fully, which is not a good idea. Even at 1200 watts, you'd need over 40 hours. One advantage of PNW summers is that days are long, but a recent August (the best weather here) trip from Prince Rupert to south Puget Sound saw many days that were overcast, several raining on us. Good fishing though.

So, how to regenerate those watt-hours? You could carry a Honda 2200 generator. If I could manage to get all 2200 watts as available in batteries (impossible according to the laws of Thermodynamics), it would take 23 hours from depleted to charged. Charging with my Victron is limited to about 1440 watts, which at 100% efficiency would be 35 hours. If 110 VAC is available, I guess one could divide into multiple battery banks, and use multiple chargers. Perhaps also more than one generator, or move to a larger system, but if you don't plan to charge with AC, it looks to me that you will need to limit your electric motoring to a few hours per day and pray for sun.

My plan is to put one 5000 watt-hour battery under the galley (done), and one where the water tank used to be (tank removed, battery under consideration). I'll necessarily limit electric motoring to a few hours per day in the most interesting places. I'll often limit motoring to hull speed, as it more than doubles my mpg from 4-4.5 on step to 9-10 mpg. Carrying 100 gallons of fuel, I can motor nearly 1000 miles at hull speed.

It is hard to discount the advantages of the huge energy density of fossil fuels, which is quite available along the inland passage.

Right now, I'm trying to decide whether I want to move to a 48 VDC system from my current 24 VDC.

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Rob, on our just finished 1100 mile leg of the Great Loop, we employed 600 watts of CIGS (bougerv yuma 200watt with grommets). We rolled them up in bad weather (only once) and put all three in a 14 inch diameter duffel bag. Try that with glass panels!

Shade tolerance was awesome. They were always shaded by the mast, rolled up jib, or backstay, yet we routinely saw 350 to 400 watts and sometimes near 500 watts. Even on total overcast no sun days we got 95 watts. We produced a total of 58kWh, averaging around 2kWh per day. This is mounted on a flexible boom tent, pulled down and curved, not ideal but it held up in 10 to 20mph winds just fine.

Seems if a 17 foot boat could have 600 watts, a 22 could have a bit more?

mastboomtent.png
 
Practically, sailboats almost always motor, and rarely actually sail except in a local area.
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We did the inland passage to AK 4x in 4 years in the Cal 46. We sailed over 50% of the distance. We had rollerfuringon the 150% genoa and a sock on the cruising spinaker. All sail controls led to the center cockpit, so hoisting or dousing sail was easy and fast. One finds that the the "reaches" (narrow passages between islands) the wind was either dead against you or dead behind you. Wen the wind was behind, it was easy to reach our target speed of 6 knots with just the cruising chute.

Our cloud cover/fog over all was more than 50% so you would have to reduce your effeciency of solar panels. To my knowledge only one all electric boat with no auxillary power has made the trip to AK. Wayward Sun (27 feet long) has a large (1,730 watts) solar array, with a hard top extending over most of the boat. She is Sam Devlin designed and built for this use. She used a Torqeedo Cruise 4.0 pod drive, and six Torqeedo 24-3500 lithium batteries for power, averaging about 3.2 knots. The majority of days were overcast or raining.

One of the major disadvantages of electrict power, is a factor we also had in the sailboat, even though we could make 8 knots under poer or sail under ideal conditions. The multiple passes and races one must traverse, must be timed to avoid head currents. So they were transited at high slack water, and would have positive currents coming and going to the pass. But with this limitation, only one pass per day was usually possible. Doing most of this same route in a C Dory 25, we were able to make it through at least 2 if not 3 of these passes per day. If you have limited time, the electric, or sailboat with limited auxillary power, is going to be a limiting factor, and keep the distance traveled per day much less than the planing power boat.

If I would wanted effecient speeds under solar, I would want a long narrow boat, with fine lines and an easily driven hull or a catamaran with narrow displacement hulls. I had a friend who built a 32' cat which would have been ideal. It weighed only 1200 lbs (hull , cabin and deck) weight. It would do 15 knots with a 15 HP outboard or with a Prindle cat sailing rig. That would have been ideal for electric--but it had limited accomidations (sitting height cuddy on top of the bridge deck, and standing only in each hull, under the cuddy). The single bunks were narrow. As pointed out the C Dory is not an effecient hull in low displacement speeds.

I suspect for the price of a new C Dory 22, one could have a custom built or build it yourself, boat which would be far more effecient and suitable for the electric power. There are production boats in trailerable size lengths which are more easily driven at low speeds. Another thought along that line, would be a centerboard sailboat in short length, which would be rebuilt/modified cabin/deck, which there are hundrreds of for sail at very cheap prices or free, which would be easily converted to electric, and be far more effecient hulls, for less work and $$ than a custom built or even used C Dory.
 
I had given some thoughts to hacking a monohull sailboat into a electric power cruiser, possibly adding a outrigger to give a large area for solar. Cats are rare compared to mono but there is the option of scratch building....add years to the project though.
 
That is so cool. If you put a level camperback over the CD22 cockpit, that could probably double the area. I fixed one 175 watt semi-rigid panels on the CD22 over the roof, and one over the camperback, with bungies. The one over the roof is quite stable, and I bring the one over the camperback and put it under the V-birth cushions when I'm not using it or it is flexing in the wind. I'd really like to have more watts.

I glued my CIGS panels down on my truck campers, but then I have huge alternators when I motor, so unless I'm sitting for days, I rarely need them. In the CD22, I'm limited to 30 Amps with my Honda 100 motor, though that can be substantial. I think draping panels over stuff when conditions are good (as I do on my canoe rig), might work fine.

I'll wait to see how you accomplish this. Bringing panels inside during the violent conditions we sometimes have around here would then be possible. Also, when you are moving around in the PNW saltwater, you become extremely aware of tides. Its easy with current equipment, you can even get estimates of speed. In my experience, tides were a consideration, but only with canoes and kayaks on the Chesapeake and Everglades.

The tides can reach 6-7 MPH just north of me in the Tacoma Narrows, so even large boats wait it out. They are often 3-4 mph within the region. Of course, the winds are famous too, as it was winds that destroyed the original Tacoma Narrows Bridge (aka. "Galloping Girdie"). If you scuba, you usually do it at high or low tides. You don't even try to move if you are in a kayak or canoe, and wait for a change, preferably one that will move you in the direction you want to go. Deploying sails are common with kayakers and a load of fun, and I've used them to great advantage at times, and when I couldn't, prayed for one to start up in my direction.

Electric motoring is going to be for people that have substantial patience, and don't mind waiting out conditions: weather, wind and tide. I wonder about deploying a temporary sail from a C-Dory. I sometimes see wind that it might use.

I'm curious, for the Miss River, you would have current with you, and then up the Tenn against or flat. For the Tombigbee waterway down to Mobile, you sometimes have current in either direction?, and dead water in other places. How much advantage/disadvantage do you estimate you had on your trip?
 
Speaking of sailing...just peeked out my window and saw this in the outer part of Oro Bay. Gone in a few minutes. Greenland-style paddles too! These guys were really moving, maybe getting ready for the WA360 or Racd-to-Alaska. Anyone ever deploy a sail on a C-Dory? It could work today, as long as you were moving N...steady 10, 20 gusts from the S.

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robhwa said:
I'm curious, for the Miss River, you would have current with you, and then up the Tenn against or flat. For the Tombigbee waterway down to Mobile, you sometimes have current in either direction?, and dead water in other places. How much advantage/disadvantage do you estimate you had on your trip?
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From Chicago down to the Mississippi (which is mostly on the Illinois river) we had a little current helping us but not an insane amount. We did around 4.5 knots on 500 watts, so probably 0.5 to 0.7 kt current. There were quite a few marina. We were meandering but traveling mostly west and so the sun was coming across the backstay only, which meant we had some good solar days. One day we managed 2.79kWh, our best day of the trip.

Once we turned onto the Mississippi, we had quite a bit of current, 2 to 3 kts. 500 watts was then able to get us to 7kts or even a tad more at times depending if we were on the inside bend or outside bend. Fun! We charged up at a barely floating old barge called Hoppies (only had room for 2 boats because most of it has sunk) and then did the rest of the Mississippi to the Ohio just using our battery bank charge and what solar we could scavenge. That was our longest leg with no charging at 160+ miles.

Coming to the Ohio we left the wonderful 3 kt current of the Miss and suddenly were going 1 kt at 500 watts. Since we had not charged up since Hoppies, our battery banks were around 30% each. Quick math showed there was no way we would make Paducah, KY without beaching a couple days and letting the solar do its thing, so we fired up the Tohatsu and used about 2 gallons to get past Olmsted locks and about 10 miles from Paducah, doing about 3.9 kts at half throttle. Once we were 10 miles away from the marina (well, city tie up with power at least), we switched back to electric (which solar had recharged to around 40%) and finished the Ohio with maybe 15% to 20% left in the electric tank.

We thought we would sail the Kentucky lake but the wind was on our nose constantly and we didn't feel like taking down the boom tent every time there was a breeze only to have it dissipate and be luffing in the hot sun going 0.2 kts, so we just electric motored, marina hopping our way down the 200 miles, about 30 to 40 miles each day, not really conserving power and doing 4.5kts at 1200 watts or so. Must have been about 0.5 to 0.7 kts of current against us, which makes sense, you are still going upriver until you get to Pickwick lock, even though you are going south for 200 miles.

At Pickwick, we locked (like 60 foot drop!) and then scooted down the Tennessee river to the start of the Tenn-Tom, where we had a tiny bit of help from the current, but not huge. We could do 4kts at 500 watts. It is narrow! but there was no barge traffic to speak of because Whitten was closed until October 3 for major refit. We made our way down to Whitten, drove back to Chicago in a rental to pick up our truck and trailer, and locked ourselves around Whitten and Montgomery, then did 190 miles to Demopolis as the only looper. They were all in 40+ foot boats and didn't have a spare lock like we did.
:)

Here is a nice shot of us beached on the Tenn-Tom, Wolf island I think.

beach.png
 
thataway said:
We did the inland passage to AK 4x in 4 years in the Cal 46. We sailed over 50% of the distance. We had rollerfuringon the 150% genoa and a sock on the cruising spinaker. All sail controls led to the center cockpit, so hoisting or dousing sail was easy and fast. One finds that the the "reaches" (narrow passages between islands) the wind was either dead against you or dead behind you. Wen the wind was behind, it was easy to reach our target speed of 6 knots with just the cruising chute.

Our cloud cover/fog over all was more than 50% so you would have to reduce your effeciency of solar panels. To my knowledge only one all electric boat with no auxillary power has made the trip to AK. Wayward Sun (27 feet long) has a large (1,730 watts) solar array, with a hard top extending over most of the boat. She is Sam Devlin designed and built for this use. She used a Torqeedo Cruise 4.0 pod drive, and six Torqeedo 24-3500 lithium batteries for power, averaging about 3.2 knots. The majority of days were overcast or raining.

One of the major disadvantages of electrict power, is a factor we also had in the sailboat, even though we could make 8 knots under poer or sail under ideal conditions. The multiple passes and races one must traverse, must be timed to avoid head currents. So they were transited at high slack water, and would have positive currents coming and going to the pass. But with this limitation, only one pass per day was usually possible. Doing most of this same route in a C Dory 25, we were able to make it through at least 2 if not 3 of these passes per day. If you have limited time, the electric, or sailboat with limited auxillary power, is going to be a limiting factor, and keep the distance traveled per day much less than the planing power boat.

If I would wanted effecient speeds under solar, I would want a long narrow boat, with fine lines and an easily driven hull or a catamaran with narrow displacement hulls. I had a friend who built a 32' cat which would have been ideal. It weighed only 1200 lbs (hull , cabin and deck) weight. It would do 15 knots with a 15 HP outboard or with a Prindle cat sailing rig. That would have been ideal for electric--but it had limited accomidations (sitting height cuddy on top of the bridge deck, and standing only in each hull, under the cuddy). The single bunks were narrow. As pointed out the C Dory is not an effecient hull in low displacement speeds.

I suspect for the price of a new C Dory 22, one could have a custom built or build it yourself, boat which would be far more effecient and suitable for the electric power. There are production boats in trailerable size lengths which are more easily driven at low speeds. Another thought along that line, would be a centerboard sailboat in short length, which would be rebuilt/modified cabin/deck, which there are hundrreds of for sail at very cheap prices or free, which would be easily converted to electric, and be far more effecient hulls, for less work and $$ than a custom built or even used C Dory.
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Bob; You are another class of waterman than me, obviously, in both skill, experience, and patience. I worked 35 years with another forestry professor that had a 57 ft, 15.5 ft beam 100+-y-old wood sailboat (Mary Hillyer) he bought as a derelict and restored beautifully. He had re-rigged the sails to make it easier for his family to sail the inland passage, and made yearly trips from Anacortes (later Keyport) to SE Alaska, the farthest place depending on weather and desire. They took little food and ate primarily what they gathered or caught. He anchored almost every evening and often several days if fishing, crabbing, shrimping, oysters, etc. were good. He sailed most of the trip. That with paper charts and dead reckoning, to boot, something I only had a few years with before GPS became available. My own experience is that I nearly always see sailboats motoring. I believe you were an exception in your trips, or maybe it was just the way things were in earlier times. I'll be making a trip with my canoe rig to the Everglades this January, and I hope that I can visit you. I missed a couple of years ago due to my wife getting Covid. Best regards and I really appreciate the posts you make.
 
Roland said:
From Chicago down to the Mississippi (which is mostly on the Illinois river) we had a little current helping us but not an insane amount. We did around 4.5 knots on 500 watts, so probably 0.5 to 0.7 kt current. There were quite a few marina. We were meandering but traveling mostly west and so the sun was coming across the backstay only, which meant we had some good solar days. One day we managed 2.79kWh, our best day of the trip.

Once we turned onto the Mississippi, we had quite a bit of current, 2 to 3 kts. 500 watts was then able to get us to 7kts or even a tad more at times depending if we were on the inside bend or outside bend. Fun! We charged up at a barely floating old barge called Hoppies (only had room for 2 boats because most of it has sunk) and then did the rest of the Mississippi to the Ohio just using our battery bank charge and what solar we could scavenge. That was our longest leg with no charging at 160+ miles.

Coming to the Ohio we left the wonderful 3 kt current of the Miss and suddenly were going 1 kt at 500 watts. Since we had not charged up since Hoppies, our battery banks were around 30% each. Quick math showed there was no way we would make Paducah, KY without beaching a couple days and letting the solar do its thing, so we fired up the Tohatsu and used about 2 gallons to get past Olmsted locks and about 10 miles from Paducah, doing about 3.9 kts at half throttle. Once we were 10 miles away from the marina (well, city tie up with power at least), we switched back to electric (which solar had recharged to around 40%) and finished the Ohio with maybe 15% to 20% left in the electric tank.

We thought we would sail the Kentucky lake but the wind was on our nose constantly and we didn't feel like taking down the boom tent every time there was a breeze only to have it dissipate and be luffing in the hot sun going 0.2 kts, so we just electric motored, marina hopping our way down the 200 miles, about 30 to 40 miles each day, not really conserving power and doing 4.5kts at 1200 watts or so. Must have been about 0.5 to 0.7 kts of current against us, which makes sense, you are still going upriver until you get to Pickwick lock, even though you are going south for 200 miles.

At Pickwick, we locked (like 60 foot drop!) and then scooted down the Tennessee river to the start of the Tenn-Tom, where we had a tiny bit of help from the current, but not huge. We could do 4kts at 500 watts. It is narrow! but there was no barge traffic to speak of because Whitten was closed until October 3 for major refit. We made our way down to Whitten, drove back to Chicago in a rental to pick up our truck and trailer, and locked ourselves around Whitten and Montgomery, then did 190 miles to Demopolis as the only looper. They were all in 40+ foot boats and didn't have a spare lock like we did.
:)

Here is a nice shot of us beached on the Tenn-Tom, Wolf island I think.

View attachment 128649
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Sure looks like a Montgomery 17 to me. I miss my M15.
 
@Roland What electric motor are you using? And please describe your battery bank.
 
I guess this is a hot topic. Great conversations all within a few hours. First, to answer Roland. NMI was willing to build a C-Dory 22 cruiser for me without motors, fuel tanks etc. I had them install their standard shore power add-on and the raised cabin. They were very interested as this was their first all electric. NMI has a list of standard items provided in the basic build and then a list of possible add-ons. I went through the list and identified only those items I wanted, additional non-standard items like the modified cabin, and then they quoted a price for me. I brought the motors and batteries to them and they helped install them. They were also willing to modify the design of the interior cabin so I could put in a second berth instead of the sink etc. I have pictures of how I modified the cabin in my album WATT NOW.

Now to some of the other comments: I have been able to install 360 watts of GIGS panels on the cabin top. I have a 200W on the top and an 80watt on either side. I had to shave about 1/2 inch off the 80W panels to make them fit. Luckily that did not impinge on the active part of the panel. 2000W will let me cruise at 5 mph and the maximum speed I can get at 5800W is 6.8 mph. From my experience a planing hull at these low speeds is not that much less efficient than a displacement hull. I think I lose more efficiency because the Epropulsion motors only have a two bladed prop with too high revolutions. My power requirements fit David Gerr's equation quite well though it was developed from data on displacement hulls. (see my album)

My 20kWh of batteries fit in the same area as the fuel tanks and weigh about the same as full fuel tanks so the boat is relatively balanced. I would be careful about adding more batteries and weight. Right now my wife and I cruise at a weight of about 4000 lbs so we are using 500W/1000lbs. Adding 350 lbs would increase power consumption at 5mph by about 175 W. Increasing the weight would also require better towing capacity.

As mentioned previously, long distance cruising using electric would require a different design than the C-Dory unless you are willing to take it easy and spend a few days at at anchorage to recharge with solar. As mentioned, the flexible CIGS panels are a great way to add to your capacity. Also, rather than adding a generator on board I would suggest getting a 9 hp kicker. That will let you cruise at the same speed as the electric when your batteries are running low. The data posted by folks on this site suggest you could get 8 miles/gal. I do wonder, however, how many miles per gallon one would get if one were to use a 3000 W inverter generator and a 30 amp 48v charger.
 
Roamad, we use a ePropulsion Navy 6 2024 model (redesigned to be 66 pounds instead of the previous 80 something pounds). It is a 6kW motor that we have never taken above about 2900 watts (when we realized that passing two 900 foot barges that were passing each other in a 200 foot wide channel makes the Columbia river bar look calm). Tom looks like he uses two of the Navy 3, so same potential output power (actually he has more static thrust I bet and redundancy...I think each Navy 3 is 160ish pounds static thrust and the Navy 6 is 230 pounds).

Tom, which CIGS are you using? I used three of the 200 watt Yuma and pretty pleased with them. They stood up to 30+ days of the wind beating on our boom tent and seem no worse for wear. A semi flexible panel would have been destroyed. The output was amazing when partially shaded and they are 6 pounds each. Seems like the Dory could handle six of them easy for 1200 watts and you would get 200 to 300 watts when overcast and maybe 900 watts in full Puget Sound sun in the summer.

Oh, and our battery banks currently are two sets of four 12.8V 100AH group 24 bluetooth LiTime batteries (so each bank is separate and 51.2V nominal. We have a 17 amp LiTime charger for each bank, a single Victron 150V 35A solar charger that charges whichever bank is active and a Victron 20 amp 48V to 12V DC-DC for running boat stuff (lights, VHF, depth sounder). So we have 10,240 watt-hr now and I am planning to add four more of the new group 31 12.8V 165AH LiTime smart batteries at the very bow (will balance out the boat). This will add 8,448 watt-hr giving us a total of 18,688 watt-hr. It will be an additional 132 pounds but we will be dropping the 65 pound Tohatsu and not carrying 44 pounds of gasoline. We also plan to not take the 40 pound 12V compressor cooler fridge as it consumes 500+ watt-hr each day. Sardines FTW!
 
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This is my first attempt at a movie on this site. I was taking the Black Ball Ferry from Victoria, BC to Port Angeles, WA. Hopefully, this link to Youtube of a movie I made of the electric harbor boats will post OK.

Try clicking the link below...

Electric Harbor tour boats in Victoria, British Columbia
 
First, to answer some of Roland's questions: Yes I have two of the Epropulsion Navy 3.0 rather than one 6.0. I chose that for its redundancy. Each motor has its own battery bank (two 48V 100AH Bestgo batteries) and I charge them separately. Epropulsion also has a dual throttle available so I can use each one separately. This way if anything goes wrong with one system I have a fully independent back up. My 20kWh of batteries weigh 360 lbs and fit exactly in the space for the fuel tanks. By having the batteries next to the motors I avoid having to use much heavier gauge wire. You can check my calculations, but a 6 kW motor can pull 125 amps. Estimating the distance from the bow to the motors as 20' and 20' return, you will need a 4/0 cable according to ABYC E-11.

With regards to the solar panels: I have a 200W Allpowers GIGS that fits almost perfectly on the high part of the cabin top. It also has the advantage of having pre-installed grommets that let me tie the panel down with webbing straps to the railings. Below that on the side platforms I have two 80 watt Rich Solar CIGS panels. Again the fit almost perfectly to the available space. I don't understand where you could install 1200 watts of panels elsewhere on the deck (unless you are thinking about placing them on top of the cockpit canopy).

Also, I installed the panels with a sheet of 4mm corrugated plastic under them. This is to increase the cooling in bright sunshine, and thereby also increasing their efficiency. This is a hack I found on an RV website and find it really works! The columns in the corrugation run perpendicular to the long axis of the panel.

I posed a question yesterday whether using a 2200 or 3000 watt charger would more efficient per mile than a regular outboard. Surprisingly the answer is yes. C-brats have posted data indicating gasoline consumption at 5mph is about 8 mpg. A 2200 watt Honda inverter generator has a 0.95 gal tank that will last 3.2 hrs at maximum rated capacity (1800W) according to info found with Google AI. So, it will produce 5.76kWh/0.96 gal or 6 kWh/gal. That is equal to 3hrs of cruising at 2000W (5mph) or 15 miles/gal - almost twice that of an outboard. A 3000 watt Honda inverter generator is slightly less efficient but still more efficient than an outboard even when including the loss of efficiency in the charger.
 
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