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I can’t see how long Faith has been a member, but her messages have hit many of the boat related groups that I belong to. The groups are typically hit within a 5 minute window. The other groups hit are not particularly electric boat related. Since every one of her messages is just about the included link, as far as I can tell, this is just trolling for clicks. It might be different if “she” gave any information about her interest in our group, or made a post that was relevant to one of our topics. Fair winds, Eric

By their nature, larger catamarans are exceptionally safe offshore. It is not unusual to sail through mildly uncomfortable conditions, such as a gale, only to arrive in port and hear sailors on keelboats talk of “surviving” horrendous weather. A large modern catamaran has plenty of buoyancy and exceptional roll inertia. Together these make a capsize, or inversion, highly unlikely. A 30-foot breaking wave hitting a cat abeam will simply make the boat surf sideways. Regardless, anyone venturing offshore in a multihull should be prepared to handle the worst. https://prezhost.com/2020/05/08/heavy-weather-strategies-when-sailing-a-catamaran/

Before I get to the calculators that are relevant to an electric boat conversion project, let’s discuss the purpose of the calculators and how they work. There are all sorts of calculators available, ones to plan retirement, manage our weight, make home improvements, etc. etc. All of these calculators are based on known values and assumptions for the values that are not known, put into formulae that calculate the interaction of the data input and produce an answer to whatever question that we asked . We use these calculators to predict future performance of a new system or changes to an existing system. This allows us to try different components or actions and see how those changes might influence the outcomes. These calculators are limited by both the quality of the data, i.e. accuracy of the known data and validity of the assumed data, and the quality of the formulae in modeling results in the real world. Simple calculators using only known data work very well, like converting standard measurements to metric, there are single constants and they always work. Calculating miles per gallon is done with measured input, but the results are dependent on how accurate the distance (miles) or consumed resource (gallons of gas) are measured. Estimating your retirement wealth 20 years in the future is harder, because the assumptions of available income, investment returns, and inflation are guesses at best. We can validate how well a calculator works by checking the predictions against objective measurements of the system after implementation. A 59” board will measure to 150cm every time (149.86cm to be more precise). If my car gets 39.6mpg (2014 VW Jetta Sportwagen TDI) and I plan a trip of 500 miles, I should use 12.7 gallons. But traffic, terrain, and how the car is loaded, influence the outcome, so the real answer might be +/- up to a gallon (36 to 42 mpg) and I would find that acceptable. Alternatively, I could make assumptions about the additional influences and add them into the formulae in an effort to make the prediction more accurate, but at some point there are diminishing returns for the additional effort and complexity. Ok, so what about the calculators for our boat conversions? They predict power needed, suggest components (like props) and predict performance of your completed project. Some of these calculators are based on very complex models of hydrodynamics and some assumptions of how power is translated into movement. These calculators work fairly well for their intended audience, boats being powered by internal combustion engines operation near 90% throttle (look, we’ve already made some specific assumptions). And we know that they work fairly well by checking the predictions against the thousands of boats than meet that criteria. We can tell if a boat is under-powered, and nobody is particularly concerned about an overpowered installation. But even then, picking a propeller is still more of a fuzzy art, than a science, and dialing in a propeller selection when you don’t have an identical example installation is still often trial and error. Still, thousands of boats are re-powered with diesel or gasoline inboards and outboards every year and the owners are usually satisfied with the outcome, i.e. the resulting performance is close enough to the calculated predictions. Unfortunately, these calculators don’t work very well for our projects. Most of these calculators today are based on the work of Dave Gerr who published “The Propeller Handbook” almost 20 years ago. It is an excellent reference and many of the guidelines and suggestions are as true for us as other boats. But, in my experience, the “power needed” predictions are not even close for our use case. In the case of the Vicprop calculator, it predicts that my boat needs 15hp at the propeller to motor at 6kts, and that 7hp will only push the boat to 4.5kts. You can see my measured performance results in other posts. The energy used is measured as it comes out of the batteries, before any losses in the cabling, controller, motor, gearbox, or bearings, theref

I am converting my 24 volt solar powered boat over to LifePo4 from lead acid batteries. My bank today has a shunt in the negative and through my MPPT solar charger I can monitor power both in and out of the batteries. I only use an external charger at the end of the day so I am at no load condition. If I switch to LifePo4 and add a BMS I have to make a decision whether to use a common port or a separate port BMS. I want the solar panels to still charge while I do have some load going such as putting along. I am thinking a common port solution would be best but does anyone have an opinion on this? Thanks Phil

Ill try to make this a short read, LOL Impossible. Found this older Sail Craft in St. Pete Florida, discovered its has three phase PM servo motors, 2000 watts of solar, regen, 2 ac units, no genset, and a 240v charger, uses 12 group 31 AGMs, all below floors in each hull, twin systems with cross tie for charging both sides at the same time. 8 more AGMs for two 12v house systems, 3 inverters. older style catamaran @ 44 LOA and 20 Beam. Apache 40' modified to 44'. So, I added the Fisher Panda mini digital 9 Kw, it contributes 46 amps in 220v configuration, so I can run one reverse cycle AC and the charger or both AC units, plus galley. 50 gal of diesel lasts about week. Inside helm shows voltage of each bank, outside helm displays each motor's amp draw plus or minus, I have no idea what SOC or charger out put is, BTW is a Zivan 144v. I'm going to include my motor plate for all you electrical engineers out there to run the math, I'm looking for feed back. Heat is my main concern, Servo amplifiers do not heat up, the TENV PM motors will get warm after an hour or so. Let me back up. When I bought her, the boat would not accelerate, I splashed her after the big gen install new battery's, (Duracell AGM 105 AH) and a 2.5 hr stress test tied to the dock I fried the starboard amp, so I pulled the motors sent them for inspection, new bearings, new Hall effect sensors, insulation, then contacted Advanced Motion Controls (Nash Dingman) for new amps, after a few months of schooling and no fires or sparks we were moving again. I added huge heat syncs to the amps and pancake fans, I did not have a O scope to tune the drives, I did it by the seat of my pants, its not perfect, nor am I, it works! Its tuned in Duty Cycle mode. Which meant it will quit on low voltage, 36v and high175v. I turn on the rear Ac unit and have box fans blowing into the motor compartment's because I'm worried ill over heat, the highest motor case temp I've reached is 146 degrees, taken with a thermal laser, I don't think that's HOT but I'm not sure either. I've never pushed the amps over 18, and when I engage the motors it shows about 3.2 average amps after a spike to 6 on start up and the boat moves about 3knts in ideal conditions. I want to know how hard I can push with out blowing fuses or melting wires? I want to install a BMS so any brand names please post links if you have them? I want to convert the TENV NEMA 180 cases to TEFC (fan cooled). Cameron @Power Tec will someday answer my emails where to get the fans. Props are 15 inch, I don't know the pitch, I think the boat is 13 tons displacement I could be wrong. I would like to know what my range is, mathematical theoretic calculations will do. Thanks all, attached are the

I came across one of my posts from 2010 where I did some regen calcs that may be helpful. Eric 11/29/10 #16381 Larry, As the most visible "regen naysayer" here, the link that you provided completely supports my previous premise. According to the Whoosh site "... And since we average 5-6 kts, that's over 100 amp/hrs/day – for us quite possibly 150 amp/hrs/day – that is available for running the radar at night, making water with offshore water quality, feeding the SSB radio, and keeping the iPod charged..." So what does this mean? They get 100-150Ah at 12V in 24 hours, that's 1200-1800Wh in 24 hours or 50-75W at 5-6kts. They do say that the harvested water power is sufficicient for house loads, a statement that I wholeheartedly agree with. My statement is (and always has been) that regen at speeds around 5kts is not a viable source of charging for a traction battery bank. The speed is important because most displacement auxilliary sailboats between 27-32 feet (optimal for a 5kW electric drive) have a hard time hitting sustained runs above 6 kts. For this size boat, average sailing speeds of about 5.5kts is more realistic. So let's say that you use 4kWh of energy out of your 10kWh battery bank, that's about 10-12nm at 4kts in most of our boats. How far would you have to sail using the system described by Whoosh to bring your batteries back to full charge, assuming that you are using no electrical power in the mean time? Generating 75W at 6kts, that's 12.5Wh/nm. So 4kWh will take 320nm of sailing at 6kts and will take over 53 hours. Slow down to 5kts under sail and the recharge distance is up to 400nm and will take 80 hours. If you have a 12V house load of only 2A, the recharge times and distances double. Ignoring house loads, the ratio of drive distance (at 4kts) to regen distance (at 5kts) is about 1 to 40. Motor one mile at 4kts (15 minutes) and you need to sail 40 miles at 5kts (8 hours) to get the charge back. If you use a radio, autopilot or lights, the ratio gets worse. So regen works, but is not as effective at recharging your traction batteries as some drive vendors would like you to believe. Fair winds, Eric Marina del Rey Hide quoted text

Here's the link to the spreadsheet where I transcribed my performance test results in 2011. This is another piece of info that is already in the electric boats group files. /g/electricboats/files/Eric%27s%20files%20-%20Serenity

And two years later. The conversion was still performing like new. You can also see that while performing a brute pull test at the dock, I was able to load the system to 7.5kW, but those loads will not happen during normal boating conditions... Eric 04/04/13 #23215 Last weekend I realized that it had been about 2 years since my last performance test, and I wondered if anything had changed over time. I was at the marina on Easter morning and the conditions appeared to be ideal for another performance test. I ran through the same process listed below in about 100 minutes, covering a little over 7nm in total. Here's this weeks results: 497W = 3.1kts 1000W = 4.0kts 1500W = 4.5kts 2500W = 5.2kts 3975W = 5.7kts 5000W = 5.9kts So there have been pretty minor changes, well within testing errors. Like before, the max winding temp was 72C and that temperature had dropped to 53C by the end of the last slow speed pass. 2 years later, the drive, prop, hull, batteries, etc. seem to delivering consistent performance. If I average the three different testing sessions, the numbers look like this... Here's the overall average results: 499W = 3.0kts 1000W = 3.9kts 1500W = 4.4kts 2470W = 5.0kts 3935W = 5.7kts 5115W = 5.9kts This data collectively represents more than 3nm at each speed, in calm conditions, in multiple directions. On another note, I did a full throttle run at the dock. Average amp draw was 158.8A DC at 47.24V or 7.5kW! Compare that to the 5.1kW noted above at full throttle in open water. Since I was starting with 80Ah already used of my 128Ah of usable capacity, the 160A load was rapidly draining my battery pack. After more than 5 minutes at full throttle, the motor windings had climbed to 85C, well under the manufacturer's rated limit of 150C, although the temp had not stabilized yet. I decided to stop the experiment as I quickly approached having only 30% of my usable capacity left and I didn't have too much time to get some electrons back into the pack before I had to leave. Perhaps I can do this again with a fully charged pack to see where the ME0913 motor temps will stabilize while pulling 7.5kW in the bilge of my boat. In spite of what some of the component vendors might say, I'm pretty sure that running that motor in boat at 10.5kW will cause it to overheat in relatively short order. I appreciate that my vendor conservatively rated my entire drive system, I'm sure that it will continue to perform well for many years. Anyway, I collected the data and I thought that some people here might find it interesting... Fair winds and smooth seas, Eric 1964 Bermuda 30 ketch, 5.5kW Propulsion Marine drive, 8kWh lithium batteries Marina del Rey, CA

This was 2 weeks later, without residual tsunami surge... Eric 03/28/11 #17893 Hi everybody, I did another set of performance trials yesterday. I started at 12:00 noon, after the last rain shower passed. The process took about 90 minutes and I covered 6.35nm during the tests. I ran the same process as before, 1 pass in either direction at a particular throttle setting, progressively climbing through 6 settings and then repeat the process descending through the same settings until done. There was some wind by the end of the trials, but that should be offset through the pass in each direction. The results were more consistent than the last trials which had apparent tsunami surge that skewed some of the numbers. Here's this weeks results: 495W = 3.0kts 1000W = 3.9kts 1500W = 4.5kts 2450W = 5.0kts 3905W = 5.7kts 5165W = 5.9kts Slightly better at the low end and a little worse at the top end, but fairly close (+/- 0.2kts) to the previous tests. Because we had a conversation in the interim about motor temperatures, I recorded winding temps during the second half of the trials to see how quickly the motor would recover during the lower power settings. With a max observed winding temp of 74C at the end of the fourth pass at full throttle, the motor dropped to 52C by the end of the last 500W pass. Right after the trials, I set the throttle to about 2500W and headed out of the marina, around the detached breakwater in open seas and then back in. 45 minutes later, at a constant power setting, the motor was stable at 60C and I had covered an additional 3.85nm. Apparently, the speed boost downwind is greater than the penalty going upwind resulting in an average speed of just over 5.1kts. After messing about for 30 minutes or so at slower speeds, I brought her back to the slip. The entire day was 10.9nm with a 4.0kt average. The battery meter showed 107.7Ah consumed. After 15 minutes rest, the battery bank was resting at 52.35V. 4 hours on the charger, and she was fully recharged. In a couple of weeks, I'm going to try a range run on the open ocean at about 1400-1500W to see how the batteries match up against their specs. I'm predicting about 18nm at 4.3kts out of 6.4kWh of usable capacity, that should take a little more than 4 hours. I know that all this info is more interesting to me, so thank you for your time... Fair winds, Eric Marina del Rey, CA

This was my first measured performance post from tests run on March 14, 2011 Eric 03/14/11 #17620 So I finally got a chance to do some controlled performance trials over the weekend. I headed into the main channel of Marina del Rey at about 11:00 AM to measure system data while travelling a 400 yard course in opposite directions. Unfortunately, there appears to have been some residual tsunami surge that skewed some of the runs. From nearly no difference between the 2 runs to 1kt faster speed southbound, 1.4kt faster northbound 10 minutes later and 0.5kt faster southbound 15 minutes after that. So I'll have to repeat the tests sometime in the next few weeks. The boat is a 1964 Bermuda 30 ketch, 8'9" beam, 24' LWL and 10,200# displacement. The conservatively rated 5.5kW electric drive was purchased from Propulsion Marine in Santa Barbara. I assembled my own battery pack from 16 Thundersky 160AH LiFePO4 3.2V lithium cells for a pack rating of 8kWh @ 50V nominal. I measured pack voltage, motor RPM, southbound speed and average amperage, northbound speed and average amperage. Then I averaged the results for the 6 major speed settings. The pack voltage and current was measured with a E-xpert Pro HV battery monitor, and the speed was measured with a Garmin 60CSx GPS. But here's the quick recap of my boat at 6 different speed settings, 4 runs per setting. 500W = 3kts 1000W = 3.8kts 1475W = 4.3kts 2460W = 5kts 3910W = 5.7kts 5170W = 6kts The funny thing is that my old diesel maxed out around 5.5kts at full throttle. While I don't intend to motor places at 5kw, it's nice to know that I've got the extra power if I get into a tight spot. The system worked great and now I get to re-work my range estimates for the better. This system exceeds my expectations, and I want to thank James for guiding me through the conversion. It has been a real partnership, again more than I expected. The only negative that I can see so far is that the new prop has more prop walk in reverse than the old one, so I've got to spend some time practicing backing down so that it becomes second nature again. That's it for now.... Fair winds, Eric Marina del Rey, CA

I hope this isn't considered to be spam, but these prices seem pretty amazing. They also have 400w panels for $200.

31’ 1977 Bombay Clipper pilothouse sailboat. Recent 10kw 48 volt Electroprop Islander electric engine conversion. Four Northstar 12V batteries. Designed for around 8hrs run time in calm conditions at about 3 or so knots. Have not put the new four blade larger prop on yet to verify this, but have run her at 6 knots with the orig smaller diesel three blade prop. Recharges on shore power in about 6-8 hrs depending on depth of discharge. Helm inside and out in cockpit. Roller furling main and head sail, self tending storm jib. Large v-birth, roomy head, wide open pilothouse views. Unique solid built sailboat with much potential. Perfect NW cruiser. $9999 obo

I’ve got an O’Day 30’ with a Thunderstruck 10K motor, 2:1 reduction and 4 AGM batteries. I’ve got the original 16” pitch 9, 2 blade prop that was powered by a 16HP Universal when the boat was built. I’m convinced there must be something more efficient. I can’t even maintain a course into a 15mph wind. I’m with Jeff looking for suggestions tom@... 850 259-8600 tom@... 850 259-8600 Thos. Stein Inc. 78B Ricker Ave. Santa Rosa Beach, FL 32459 Florida underground utility contractor license RU0058046 Florida plumbing contractor license RF0057995

I'm using a 48V E-bike battery pack in a proof of concept type experiment. The battery pack is rated at 20Ah, with a discharage of 50A, and max discharge of 100A. The electric motor can pull up to 100A - so I'd like to put a circuit breaker in line with the battery, with the idea being that if someone accidentally gets too excited on the throttle, the circuit breaker would trip long before the BMS does. (This is especially after the relevant post about the BMS protection circuits being an unknown quantity in sealed battery systems!) Questions: 1) What is a good circuit breaker for a 48V system? I'm thinking around 25-30A. Most seem rated for 12V, some up to 48V. I've only found one so far that is rated for 72V. 2) Can I use a "48V (max?)" rated circuit breaker? Is that intended for a 48V system that really goes up to 56-58V at peak charge, or is it really strictly limited for 48V (and intended for 32V systesms)?? 3) Is a standard 30A blade fuse ok to use in a 48V circuit? Many don't seem to have voltage ratings... Thanks, John

Hello everyone, Over 10 years ago, you guys helped me to convert my 24' pontoon to electric. I ended up with a Torqeedo Cruise 4, four group 31 AGM batteries and a 4 channel DualPro charger. I've had ten great summers using this configuration on some inland lakes in Ohio. Last summer, I started noticing the battery capacity wasn't what it was when the batteries were new. The Torqeedo would shut down due to "depleted batteries", but I was always able to turn it off and then back on where upon I could return home at a slower pace. That is one of the things I like about electric vs gasoline. I have never been stranded. Anyway, I suppose it is time to replace the batteries. I can't complain about getting 10 years out of them. As I see it, I have two options: 1. Buy another set of AGMs - a little under $1000 2. Buy LiFePo4's - at least double the cost, but less weight and more usable range. As an engineer, I like using new technologies so I lean toward the LiFePo4's. However, many of the posters I follow on this forum bought them directly from Chinese suppliers. With all the COVID 19 disruptions to business and our government threatening to raise tariffs, I worry about placing an order that never gets filled. I would appreciate any opinions on which way to go and any recommendations for low risk suppliers for batteries. Thanks, Pat

Greetings, Reposting this topic the new group location with some photos. Hopefully some feedback or suggestions., Looking for advice on a 15kW 48V electric motors to fit to a Yanmar SD25 sail drive (new model of the SD20). Application is an under construction 52' sailing catamaran. Some broad boat parameters: Ocean going world cruising catamaran – composite epoxy structure. L 52’, Draft 2’ Weight approx. 8500kg / 19,000lb Full electric propulsion, galley and other services including hot water. Motors retractable: 2 x 15kw 48v + regen Battery bank: circa 16kw 48v House loads: 24V DC – Estimated peak approx. 3kw Solar: circa 3kW. 16kW 48v DC gen set. The plan is to fit motor to a Yanmar sail drive SD25 and complete unit be retractable. This involves a wet lower tube and a watertight inner tube with hull closure plate below the prop – motor and sail drive leg fitted to this at their join. We should be able to couple motor shaft to SD25 upper gear box shaft with a coupler and bolt units together without too many modifications. Be great to hear of others experience with this. We are trying to limit motor voltage to 48V – makes batteries & solar easier plus ability to share bank via DCC converters & battery for house loads at 24V. The boat will be light and shallow draft = easily driven. A similar 62’ catamaran was fitted with 2 x OV SD15s and achieved over 9 knots in flat water so we believe 12 to 15kW motors will be adequate. According to Vic Prop boat specs, twin 12kW (16hp) motors with RPM max of 2200 (2:1 gear reduction on SD25 so prop speed 1100 max.) & 3 blade 15" x 13" prop will yield a top speed of 8.92 kts which is fine. We have looked at turn-key offerings from Bell marine, Oceanvolt & Electric yachts but none tick all our boxes so would like to have a crack at customizing our own solution. Some motor options Ive stumbled across include: 1. Motenergy ME1302 or ME1616 Liquid cooled 2. Parker GVM210-100-DPW 3. Go cart or Elec motorcycle motors: Revolt, Zero, ??? Bearing in mind 48V supply and max RPM of around 2400, be grateful to get your thoughts on best motor and associated controller and any tips or constructive suggestions for our project.

Hi there, I'm new here and I wonder if you could give me any hints on this question that I have been unable to answer (in the positive) by using google and sending questions to manufacturers. I have a 30ft sailing catamaran that has twin petrol outboards sitting in wells in the cockpit. As the cat has daggerboards and retractable rudders, I would not like to fit pod or saildrive type motors to the hulls, but instead replace the existing outboards. However I felt with the lower range of the electric motors - not to overload the boat with batteries - it would be necessary to recharge on long sailing passages - hence my question. Many thanks in advance! Caio

But What If They Capsize? “I have heard concerning stories about cats flipping in strong winds”. This question comes up more often as more people are sailing and chartering catamarans. People generally love the comfort, space and performance of a catamaran, but are concerned about the safety of a catamaran versus a monohull on the open ocean. Here, experts give some safety guidelines. https://prezhost.com/2020/04/22/how-safe-are-catamarans-for-blue-water-sailing/

A friend of mine with a Tesla sent me this info from a study done. https://electrek.co/2020/02/21/journal-of-energy-storage-studies-ev-owners-manuals-compiles-best-practices-for-batteries/ Talks about good practice with LiPo’s Steve in Solomons MD Lagoon 410 S2 E

It may be useful to everyone to know if you've ever experienced your LiFePO4 batteries becoming too warm while charging or while they were under load. Frankly, I've begun to wonder if the demands of any kind of boating activity on a battery bank would ever push or pull enough amps to raise the temperature of the typical LiFePO4 pack into a hazardous range. However, if you've had this experience, I would ask that you reply to this message and please describe your setup and conditions for us. One might say, for instance, you use 100Ah prismatic battery cells in a 16S1P configuration, bound with end-plates and held in a heavy plastic box with lid, and you were {charging|discharging} at a rate of approximately {__ Amps}. Batteries were measured with a {________} at a temperature of {_______}. This won't be a statistically a meaningful survey, of course, but if anyone *has* had an overheating experience, it could make for safer boating for everyone if the rest of us were to know the particulars. Thanks so much! [-tv] Tom VanderMeulen "Grace O'Malley" Cape Dory 27, #257 Monroe, MI