Electric Leisure Boat Design II

Discussion in 'Boat Design' started by slboatdesing, Aug 9, 2022.

  1. slboatdesing
    Joined: Aug 2022
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    Location: Maldives

    slboatdesing Senior Member

    Hello again.

    The purpose of this thread is to explore design options for a low - cost electric leisure boat design. I know I am a 'junior member', with limited knowledge. Once I have come up with a design, more experienced hands will no doubt guide me to a successful implementation. In any case, I will produced a design, whether it is a bad one or good one remains to be seen, either by myself or the rescue persons.

    If the design is feasible, then it could lay the ground (bad metaphor for a boat) for any company to produce in hopefully large numbers. Let me say right here that anyone is free to adapt the design for their use.

    If you have followed the previous thread, I was somewhat frustrated with paddling a kayak in shallow seas - turns out I was paddling too hard. Nevertheless, I wondered if there was a better way - an electric boat or a solar powered boat? I explored options here: and will leave things be for now. If my local boat club buys an electric kayak and rents it out I will try that out. Meanwhile I will be paddling.

    Even in I am not producing anything more than a design, there are commercial considerations : this post about starting a boat-building business has information which I will use here.

    Let me read it through now.

    I will leave you with a picture of my favorite design - the image was taken in Male, Maldives yesterday, from a double-decker bus.
     

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  2. kerosene
    Joined: Jul 2006
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    Location: finland

    kerosene Senior Member

    what you pictured is unfortunately the worst candidate for an electric boat.
    Boats unlike eg. cars use big portion of their available power in simple cruising. A car with 200kW engine will only need 20kW or so to cruise at 80-100kph and less than 10kW in city speeds. A boat you pictured can need 100kW to cruise at a decent clip - after all it is design to be a fast boat.
    LiFePO4 batteries - which are safer and best DIY batteries (and now used by many Teslas and BYD electric cars etc.) have per google energy density of 90-160Wh per kg. Lets pick a number from the optimistic side of the range: 150Wh/kg = 0.15kWh/kg.
    If we want our boat to have 100kW (~135hp) available for an hour it comes to 100kW/0.15(kW/kg) = 667kg. This is assuming now losses from battery to shaft power which is not the reality. At best you can expect 80% or so for controller + motor. That puts your battery cells at 830+ kg. And even this is on the optimistic side of thing.

    That is the 1st problem. The weight will put you in a spiral where you need more power to carry the weight needing even more power for acceptable range.

    The second is the cost.

    When it comes to planing boats, read elsewhere but basically 8 knots / 15kph+ speeds, only very short range leisure boats are possible with current battery tech. And very expensive. The second factor is the absolute environmental pointlessness. Leisure boats - despite being huge fuel hogs are better environmentally using gasoline than battery electricity. The batteries take large amount of energy to create and use somewhat limited resources - to put these resources in a boat that sees a few dozen hours of use per year is very bad use of these resources.

    Electric boats _can_ make sense. IMO following ones make sense:

    1. Utility ferry that has a short route and drive cycle and can charge at ports. See picture below of one in Finnish archipelago. Diesel backup.
    2. Slow moderate range day campers/launches. Displacement speeds (6 knotts, 11kph and below) Elco and similar, also photo below
    3. Skinny and low displacement multihulls, but even these have very low range if the displacement goes up. See Orphie boat (2 pics) below. Note the range.



    [​IMG][​IMG] upload_2022-8-9_10-48-46.png [​IMG]
     
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  3. slboatdesing
    Joined: Aug 2022
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    Location: Maldives

    slboatdesing Senior Member

    Many of the electric vehicles I see are either luxury yachts which cost the equivalent of many tons of diesel and maintenance or concept vehicles, again with expensive and environmentally resource intensive materials. Not very environmentally friendly despite being solar or electric powered.

    Ok , so let's talk about what makes sense.

    Electric boats _can_ make sense. IMO following ones make sense:

    1. Utility ferry that has a short route and drive cycle and can charge at ports. See picture below of one in Finnish archipelago. Diesel backup.
    2. Slow moderate range day campers/launches. Displacement speeds (6 knotts, 11kph and below) Elco and similar, also photo below
    3. Skinny and low displacement multihulls, but even these have very low range if the displacement goes up. See Orphie boat (2 pics) below. Note the range.

    The utility ferry is interesting but I am not interested in designing one. The 6 knots or so boats are the ones that will fit the sort of compromise I am looking for. That is an awfully nice boat. Elco goes back a long way - an electric boat in 1893?

    "Elco, the original electric boat company, redefined pleasure boating in 1893 with the introduction of the original production electric-powered boat. Quiet, reliable, impeccably crafted and environmentally friendly."

    The Orphie is an amazing design, the designers have done a nice job, and handling heavy seas at 15 knots? I am not thinking of heavy seas in any case - you have to be going a little faster in heavy seas apparently. We took a short trip for skuba diving in what seemed like 2 foot waves and waves of nausea as well. I go the chance to bob up and down in the water holding on to a float - not a lot of fun but a great experience. I will post a picture.
     
  4. slboatdesing
    Joined: Aug 2022
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    Location: Maldives

    slboatdesing Senior Member

    Here is the concept. The design uses pontoons that are made out of PCV pipe. The pontoons are connected using a flat board made out of plywood or plastic. This is the main load-carrying structure. In order to make it look like a boat, the cabin structure is constructed out of tube and canvas, and these are non-load bearing.

    PVC pipe may not be the best material, an alternative material may have to be used. There are some boats out there that use PVC pipe and I post a few examples here.

    Zhao Ming Diary: The PVC-pipe boats of Linyuan http://zhaomingdiary.blogspot.com/2006/03/pvc-pipe-boats-of-linyuan.html




    As for the canvas sides - the famed Kitfox light aircraft uses such a structure. I have looked at one close up and found it hard to believe everything was covered with canvas - wings, fuselage, tail. There is a picture here that shows the finish that can be achieved. Structural integrity is critical to an airplane, and it travels at over 80 knots so it is quite up to the task.

    http://www.itsys3.com/kitfox/images/fuselage/explabel.jpg
     

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  5. slboatdesing
    Joined: Aug 2022
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    Location: Maldives

    slboatdesing Senior Member

    Lets look at battery capacity again. 2nd post from kerosene

    LiFePO4 batteries - which are safer and best DIY batteries (and now used by many Teslas and BYD electric cars etc.) have per google energy density of 90-160Wh per kg. Lets pick a number from the optimistic side of the range: 150Wh/kg = 0.15kWh/kg.
    If we want our boat to have 100kW (~135hp) available for an hour it comes to 100kW/0.15(kW/kg) = 667kg. This is assuming now losses from battery to shaft power which is not the reality. At best you can expect 80% or so for controller + motor. That puts your battery cells at 830+ kg. And even this is on the optimistic side of thing.

    Instead of 100kW let's go for 10 kW, which means the batteries weigh 68kg. Instead of one hour let's put it down to half an hour: 34 kg worth of batteries. 34Kg can be lifted by one person. An outdoor solar charging station could keep about 5 of these batteries charged or they could be charged overnight. A smart controller that allows 10 minutes of 'high power mode' at full power and then cuts to a 'economy mode' for the rest of the half hour would be acceptable since the user won't be going at full power all the time and in any case a pedal boat or kayak will have a maximum speed of 3 knots or so, this one should be able to do 6 knots in 'power mode'

    The target customer group are the water sports boat and floating rides operators, offering a 30 minute ride on the lake, with or without an operator. This will be an alternative to the $10 per hour Kayak rental. $10 per half hour, which is double the price. If the operator can afford to buy an $800 Kayak, then he can certainly afford the boat as designed.

    It comes down to the batteries and motor which run in the thousands of dollars as described in plug boats:

    Electric Saildrive and Pod Boat Motors - Plugboats https://plugboats.com/guide-to-electric-saildrive-pod-boat-motors/

    At $2500 a piece this seems to be ok far as I can tell it is electric.

    The BSE-2A looks good, no mention of range.

    Small Electric Boats for Sale - Electric Boats for Lakes from Beston https://bestonpaddleboats.com/small-electric-boats-for-sale/

    $700 for an electric boat? Can't compete with that

    Leisure Battery Lake Electric Boat - Buy Leisure Battery Boat,Leisure Lake Electric Boat,Lake Leisure Boat Product on Alibaba.com https://www.alibaba.com/product-detail/Leisure-Battery-Lake-Electric-Boat_60495427509.html?spm=a2700.7724857.0.0.3f1f51e1InoZHX
     
    Last edited: Aug 9, 2022
  6. kerosene
    Joined: Jul 2006
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    Location: finland

    kerosene Senior Member

    your links don't work.

    Kayak style boat will do with less. 1kW motor is already too much, 600W is probably plenty (look at Haswing brushless models for example). A 2kWh battery already gives 3 hours of full blast driving. And that is pretty compact battery that barely impacts the boat balance.

    I'll look for my solar boat video, a sec.
     
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  7. kerosene
    Joined: Jul 2006
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    Location: finland

    kerosene Senior Member

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  8. slboatdesing
    Joined: Aug 2022
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    Location: Maldives

    slboatdesing Senior Member

    I had a look at your design - so it a leisure boat design along the lines I was thinking. From your post:

    Goals for design:
    -easy to make
    -family camp cruising on nearby lakes
    -30 nm range @ 5 knots
    -typical summer day solar would cover range requirements

    How much will it cost is the thing.

    Electric boats will replace IC engines at some point, at least partially. I want to make that happen quicker and help make boating less costly at the same time, maybe getting a prototype built that will inspire copies.

    It should be easy to make but if I ever make a boat I will be subcontracting the work for sure to a boat builder and electric car company. If the water sports industry is willing to buy it, then it will proceed. If not, it will stop.

    Get these two companies together:

    Ideal Motors unveils Sri Lanka’s first home-grown electric car - Adaderana Biz English | Sri Lanka Business News http://bizenglish.adaderana.lk/ideal-motors-unveils-sri-lankas-first-home-grown-electric-car/

    Our Products : Pio Marine (Pvt) Ltd : Fibreglass boats rafters http://www.piofibre.com/our-products.php

    Classified as a four-wheeled electric quadricycle, the Ideal Moksha is fitted with a 22.46 kWh Lithium battery that provides a range of up to 200 kilometers on a single charge by plugging into a 15-amp domestic charger overnight. With a weight of just 870 kg, the powertrain provides a speed of 1080 rpm



    I do not like the smell of diesel either.
     
  9. slboatdesing
    Joined: Aug 2022
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    Location: Maldives

    slboatdesing Senior Member

    There are two separate paths to take here: one is the DIY boater who gets a boat and adds a motor of some sort, and floats it in a nearby lake or beach. If we proceed along this path, options are limited to low-cost boats and motors. My personal requirement is that it looks like a speedboat, and it if it moves at walking speed that is OK.

    Inflatable boats are fairly affordable, either used or new $100 or so.

    Bestway 65046e Hydro Force Caspian Pro 91 Inch Inflatable 2 Person Boat Raft Set With 2 Aluminum Oars And Hand Pump For Lakes And Fishing : Target https://www.target.com/p/bestway-65046e-hydro-force-caspian-pro-91-inch-inflatable-2-person-boat-raft-set-with-2-aluminum-oars-and-hand-pump-for-lakes-and-fishing/-/A-76026396#lnk=sametab

    This looks promising: tested, it seems fast enough. Did he say 1 km range?



    Ultra Light 55 lbs Brushless Electric Trolling Motor for Kayak, Inflatable Boat, KaBoat or Canoe https://www.boatstogo.com/brushless-electric-trolling-motor-12v.asp

    $249.00 That's a good price.

    Best 5 Inflatable Boats with Electric Motor: Pros, Cons, Reviews - Simple Inflatables https://simpleinflatables.com/inflatable-boats-with-electric-motor/

    Modified inflatable:
     

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    Last edited: Aug 10, 2022
  10. Flotation
    Joined: Jan 2020
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    Location: Canada

    Flotation Senior Member

    Have you given a thought about subcontracting the design? You will need to study a very broad range of topics before you can come up with an efficient, cheap and easy to build design of your own. To be blunt, so far you have shown not to understand the differences between hull shapes optimized for high planing speeds and those for lower speeds and less power, you seem to have a lot of reading to do. When talking about efficient design for production in larger quantities things get even more complicated.

    On the lower end of the spectrum a simple canoe with an outrigger and trolling motor seems very close to what you want. Those components are available off the shelf.

    Single Outrigger Kit for Swagman Canoe made in Australia by Australis Canoes and Kayaks https://www.canoes.com.au/index.php?dispatch=products.view&product_id=228

    I mention the outrigger as it will make the boat much more stable and as such a more suitable option for clients not used to being in a canoe. Outriggers can also be bigger like the ones on the lower half on this site: Easy Riders Canoe Outriggers http://www.easyriderkayaks.com/outriggers-c.htm

    I more open waters reserve buoyancy could be installed in the canoe's.

    To be clear, I'm a big proponent of the development of more electric water craft and wish you the best of luck.
     
    Last edited: Aug 10, 2022
  11. Flotation
    Joined: Jan 2020
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    Location: Canada

    Flotation Senior Member

    You want something with long thin hulls instead of a planing hull. I'd not be surprised if a planing hull for your application would be 3-4 times less efficient, read you'd need 3-4x times more expensive batteries and a bigger motor. And you will get into a design spiral of ever increasing costs.

    Apart from the outrigger canoe i mentioned i'd look at examples like these for inspiration on efficient hull shapes and how they could be used for a rental boat in the leisure market:

    5-Meter Power Cat with 6kW Outboard https://www.boatdesign.net/threads/5-meter-power-cat-with-6kw-outboard.66683/
    Double Catamaran Pedal Boat https://directboats.com/docapebo.html
    FunCat Electric Catamaran https://waterventures.com/catalog/index.php?id_product=214&id_product_attribute=0&rewrite=funcat-electric-catamaran&controller=product
    “Ceclo” The Hybrid Pedal Catamaran - NAUTICA NEWS https://nautica.news/ceclo-the-hybrid-pedal-catamaran/

    Solar direct drive kayak https://www.boatdesign.net/threads/solar-direct-drive-kayak.61434/
    Solar catamaran https://www.boatdesign.net/threads/solar-catamaran.65560/page-3#post-908277
    Multihull Structure Thoughts https://www.boatdesign.net/threads/multihull-structure-thoughts.62361/page-166#post-926169

    A multihull configuration has the added benefit of providing more space and stability for solar panels if you would like to go in that direction.

    I am very sure there have been posts by a forum member who made a small solar powered catamaran out of mostly standard parts. It had laid back garden chairs and a collapsible roof with solar panels. I can't find it anymore, if anyone could provide a link I would be very happy.
     
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  12. slboatdesing
    Joined: Aug 2022
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    Location: Maldives

    slboatdesing Senior Member

    I will have to subcontract part of the design or at least build on a proven design. The outrigger canoe with a trolling motor would be fine, good price all around.

    I don't get the business model of this water sports establishment - they have several unused Jet-skis and two boats without motors simply lying there. They are heavy though, very heavy, about 10ft long so they would not want that to close to swimmers and children and out of control.

    Open waters? You know I have never been out of sight of land in a boat. Unnerving concept.

    Electric water craft seem to be viable and cheap - just saw this post:

    Small recreational electric catamaran https://www.boatdesign.net/threads/small-recreational-electric-catamaran.66328/
     
  13. slboatdesing
    Joined: Aug 2022
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    slboatdesing Senior Member

    I understand the difference between planing hulls and displacement hulls. Planing hulls have to get up to a certain speed before they ride on water and then the power requirement goes down. Is this is what is meant by 'on step'.

    I like the catamaran design, thanks for the links.
     
  14. rnlock
    Joined: Aug 2016
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    rnlock Senior Member

    PVC as a structural material is about 2 steps up from bubble gum, although of course it's much less water soluble.

    We've seen, in this thread, a bunch of proposed designs which would use far more power than necessary. As far as I can tell, the typical high speed runabout is designed to use as much fuel as possible, as quickly as possible, and is NOT at home at 6 knots. In the case of electric boats, inefficiency means shorter range, or bigger batteries and a bigger motor. In other words, MONEY. Money that doesn't actually have to be spent.

    I don't know if a typical trolling motor can go 6 knots. No one goes that fast when trolling, at least that I'm aware of. Instead, the typical use is to push a heavy motorboat at a knot or two. For 6 knots, a different propeller with more pitch is appropriate.

    If I'm not mistaken, this link from Flotation shows a catamaran like the one I rented. It was reasonably easy to pedal, but I suspect 6 knots would have required maximum effort, though I'm sure 4 knots would be very easy. 6 knots under electric propulsion wouldn't be out of the question, I think. Note that this catamaran, even though it's made out of relatively heavy plastic, doesn't have a lot of extra junk built in, unlike some of the electric cats we see.
    Double Catamaran Pedal Boat https://directboats.com/docapebo.html

    While rowing a single scull, I was chased by someone making a video, in one of those little rubber boats. I doubt if I was doing over 6 knots, but the rubber boat had it's bow up in the air and was making as much wake as it was capable of. I'm sure an electric would be sucking up far more electrons than a nice double kayak. Here's a single scull, rowed by someone who I'm sure is far faster than I've ever been. You can tell he's a serious rower by the way his thighs are bulked up.

    If you really wanted to make 6 knots with a trolling motor, your best bet would be to tie two of these together, or, possibly even faster, one and an outrigger. Unfortunately, you have to be pretty careful with a boat like that, so it's not likely to be a good choice for renting.

    If you can get by with only 3 or 4 knots, a really good rowing boat is easy. Oars and oarlocks are simple and cheap. There's nothing inherently expensive about the shape, and the weight of fiberglass construction won't ruin it. I think the only reason they're expensive is because the demand is low.

    I've only rowed a real peapod once, but I think it's a realistic option. It was wood, and heavy, but it would go remarkably fast with moderate effort. This video gives some good views of their shape.

    Note that these are probably a good shape for making of fiberglass in a mold. They'd probably require quite a bit of skill and time to make just one at home.

    Dories are also said to row very nicely, but they're a little tippy until you sit down. Much faster for one person to make, though. The Gloucester Gull is supposed to be a good one, though I hear it's mostly a 1 person boat. I don't know where you'd put a motor!
    https://www.woodenboat.com/sites/default/files/boat_launchings/gloucester_gull_hemenway_4.jpg
    I seriously doubt any of these are going to make 6 knots on a reasonable amount of power though. You probably need something long and skinny and light for that. Maybe a double kayak.

    BTW, even a really long skinny boat that hardly makes any waves will need over 3 times the power to go 6 knots than it needs to go 4. That's the nature of turbulent flow. Maintaining laminar flow over most of the hull isn't realistic, as one little flaw will cause turbulence. If you want to worship the boat on a regular basis with spot putty and fine wet or dry sandpaper, it's conceivable there's a shape that would allow a fair amount of it.

    BTW, I've seen so called wakeless launches like the following, and they really make very little wake. Presumably that means they make very little power. Especially at 6 knots, since they're faster. They have to be able to go at least 12 knots and maybe a little more. Even at that speed they leave very little wake. This one has more capacity and weight than needed for the task we're talking about.
    Duo 18 – Still Water Design http://stillwaterdesign.com.previewc38.carrierzone.com/?page_id=12
    I'm wondering if that's one of the ones I helped make. It was just for a week, so I'm no expert.
     
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  15. slboatdesing
    Joined: Aug 2022
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    Location: Maldives

    slboatdesing Senior Member

    Not electric but convertible, and a nice pedal only boat as it is.

    Double Catamaran Pedal Boat https://directboats.com/docapebo.html

    Also this:
    FunCat Electric Catamaran https://waterventures.com/catalog/index.php?id_product=214&id_product_attribute=0&rewrite=funcat-electric-catamaran&controller=product


    Nice design, but at $ 16,000 not feasible.

    “Ceclo” The Hybrid Pedal Catamaran - NAUTICA NEWS https://nautica.news/ceclo-the-hybrid-pedal-catamaran/

    This is half the size I want, but I like the idea. No word about range:

    Mini Boat - A mini but full-sized electric boat - Tech News 24h https://www.technews24h.com/2018/02/mini-boat-mini-but-full-sized-electric.html

    This boat here is close to the perfect boat as far as I am concerned. Uses a conventional outboard. Half an hour endurance with two battery replacements is fine with me.

     
    Last edited: Aug 11, 2022
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