Electric Leisure Boat Design II

Your efforts are highly appreciated.

 

I think some clarification about the design goals is needed here, however let me digress a little.
Let's take some real world experiences. I was asking about electric boats in the Maldives and I was told that powerful boats are needed to cope with the wind and the currents. So we have the wind, waves and current.

For any journey, planning is important, so if we are looking at a leisure boat, we have to look at the possibilities of the wind and waves picking up during the course of an excursion. Do we need to have a boat that will battle gale force winds? Are currents predictable? Is this a deep-see boat or a lake bound floater?

A look at boat certification may give some indication: failing that, and the book has not been ordered yet, let's see this:

10 Common Types of Small Boats https://www.triumphboats.com/types-of-small-boats/

Class D:

Category D – Coastal water, inland, and sheltered waters:
Boats in this class include those built for rivers and small lakes and are designed to stand up to Force 4 winds (11 – 16 knots) and wave heights of a foot and a half (18 inches).

Types of Boats: A Complete Guide https://www.boatsetter.com/boating-resources/types-of-boats-guide

Design goals:
So the type of boat I am looking at is the fishing boat, skiff, or pontoon boat. I am not looking for performance, I am not looking for efficiency. A motorized pedal boat, running on batteries, and travelling just as fast, that costs about twice as much to rent, and can only be used on lakes and reefs on calm days is what I am looking for. This is the design part. Production costs are something else, but I think it is possible for a manufacturer to come up with something at twice the cost of a Kayak or pedal boat: $2000. Maintenance is an additional cost of course. If the end result is something everyone wants to drive, then rentals will cover the cost. If instead, everyone wants to ski, jetski and ride on inflated bananas then really this is a niche market that I am looking at.

Power requirements:
Again, going to the real -world videos (unless they are deep fakes) 1 KW seems to be the magic figure.
For this we have to look at a real-world example (well I have to look because I do not have any experience with calculations of this sort. ) That will be next.

 

Let's just take a motor at random from a search engine. The Torqeedo seems to be quite popular, so lets look at the specs from the site: It evens costs close to $3000 which is very good value for this sort of performance.

Kayak Trolling Motor - Ultralight 1103 AC -Torqeedo https://www.torqeedo.com/us/en-us/products/outboards/ultralight/ultralight-1103-ac/1408-00.html
$ 2,899.00
plus shipping charges

Product description

• Weight: 15.3 kg complete with battery
• 3 HP equivalent
• With 915 Wh high-performance lithium battery
• Comes including charger, throttle, onboard computer, GPS-based range calculation and emergency magnetic kill switch
• New angler mount with tilt and park mechanism, plus simple integration with the kayak’s steering unit.
• Easy to mount on fishing kayaks
• Range of up to 50 km

So we have a close to 1kWh battery, running a 1 kW motor that should give us 1 hour of running. How does it get 50 km range? Clearly we need a mission profile here: 10 min at full power, 6 km/h, which will take us 1 km , then trolling around for half an hour and 1 km back. Not bad. Next ride.

There is someone doing a range test also in a video:

Torqeedo Travel 1103 C speed and distance test

 

Another real - world test. Is it just me or are sailing boats utterly beautiful? Is the design functional or aesthetic? If starting from scratch and designing and building a boat hull then a long, narrow one or a catamaran would be best, but when buying an used boat there does not seem to be much of a choice. In the following thread, the author has purchased a large sailboat and is converting it to electric.

1/4" balsa core construction https://www.boatdesign.net/threads/current-situation-diy-efficient-solar-electric-powered-newport-17-project.64961/

" That being said, with my little 12v trolling motor, tired lead batteries and an 11x6 APC prop, this boat runs a little over 3 MPH pulling only 180 watts. "

I could start of the same way Dan has done, a small trolling motor, 12V and then 3 mph. For me, the experimentation is the journey, the final product may be interesting for a while, then next project.

After some upgrades, Dan has had the perfect electric day: nice mission profile:

Another successful trip! Knocked down almost eight hours of run time exploring parts of the lake I've never seen before, ran the accessories all I wanted and made it home with 60% capacity left. Let's keep going!

 

DIY is an impossibility at the moment, so is do it by contract. I have to hang around until the local water sports fixes their boats or buys new equipment.

I am willing to change the design to a smaller, longer, single -seat racing boat type.

There is also this: about 1.5 times as large would be best. At least the kid will have fun. I think the project closed.

JimBoats 6.5 Is A Sea-faring Ride-on For Kids That (Some) Adults Can Ride Too https://mikeshouts.com/jimboats-6-5-mini-electric-boat-for-kids-and-adults/

JimBoats 6.5 : The coolest tiny eBoat EVER ! https://www.indiegogo.com/projects/jimboats-6-5-the-coolest-tiny-eboat-ever#/

Other designs:

Wooden Race Boat 16-Canada One Design (COD) - Good Old Boat https://goodoldboat.com/advert/wooden-race-boat-16-canada-one-design-cod/

Case of The Mondays: JetKart is The Single-Seater RXT-X 300 You Never Knew You Wanted - The Watercraft Journal | the best resource for JetSki, WaveRunner, and SeaDoo enthusiasts and most popular Personal WaterCraft site in the world! https://watercraftjournal.com/case-of-the-mondays-jetkart-is-the-single-seater-rxt-x-300-you-never-knew-you-wanted/

 

Getting tied up with knots

I took the ferry this morning from Male to Hulhumale (see map). A large vessel, comfortable and air- conditioned, but then it was a calm day. I enjoyed being on water once again, and were were really making waves, it seemed, I counted 5 bow waves behind me, and I thought to myself this must be what 11 knots looks like. My Google speedometer was not working properly, so I made some measurements and calculations. But I was to be pleasantly surprised.

Assuming the trip was 20 minutes and covered 1.04 nautical miles, this works out to a blistering speed of 3.12 knots. Assuming 5 minutes to get in and out of the dock at departure and arrival, this works out to 4.16 knots or 7.6 km/h. Checking with the time stamps on the photographs taken on boarding and after disembarking the time elapsed is 22 minutes, I think there was a delay of about 2 minutes before we left.

Do these calculations seem correct? I thought we were cruising along at a fair clip. What this all means is that a leisure boat that can cruise at this pace is fine with me, this is quite fast enough for my enjoyment at least. I have my design speed now: 4.16 knots.

The ferries here FERRY TRACKER LIVE MAPS | Marine Vessel Trafic https://www.marinevesseltraffic.com/ferry-tracker average about 11 knots or more, which is nice.

Several questions -

• Is a top speed of 4 knots sufficient to navigate the high seas, or is the ferry have reserve power to go faster?
• What if there is a headwind of 20 knots or more?
• What about currents, can these be circumnavigated?

The image is taken after docking an Hulhumale ferry terminal and en route (video).

Fascinating all round.

 

Here is an interesting design: it never came to fruition, however the concept is interesting.

Torqeedo: Revolutionary electric boat propulsion – Hotelier Maldives https://hoteliermaldives.com/torqeedo-revolutionary-electric-boat-propulsion/

 

Here are some boat models in 3D, hull shapes and all, which one is best - I know, long slender twin - hulls? What about shapes?

Top 500 3D Models - 3D CAD Browser https://www.3dcadbrowser.com/3dmodels.aspx

 

Nature Of Boats ordered. Downloaded and Running FreeShip.

 

Could anyone suggest any software for modelling hull drag based on shape? FreeShip only imports from VRML97 so I cannot input any 3D shapes into the program.

Some free software links here:

Free or Low Cost Yacht Design Software : the Boat Design and Boatbuilding Directory https://www.boatdesign.net/Directory/Software/Free_or_Low_Cost/

 

Boat design software does not calculate drag based on shape the way you probably think it does. It does resistance estimates based on methods that only give a valid result when applied to a specific type of hull under specific conditions.

To calculate drag for random shapes or unconventional hull types you need very complex CFD software and even then you will only get a valid result if an expert uses the software.

If you want to import IGES files you may give Delftship a try.

 

Thanks. So for lesser mortals build the boat and see how fast you can go.

Here is a nice alternative to a jetski.

Home - ProGliderBoats https://boating-fun.com

 

I have re- read the thread from the beginning, and I have changed some of my goals. The thread is about designing a boat, and implicit in that thought is that it is going to be built either by me or someone else.

The Sneakeasy is a nice boat, but must be difficult to build. I have been looking at easy to build plywood boats and I think I could manage one with some help. I have used a jigsaw and built some simple things like a TV table and speaker boxes. So I will create the plans and get as much information as I can until the day I can actually build one.

The design is then going to be narrowed down to a long, narrow, 2 seater boat.

Here are some plans and built photos from a Sneakeasy:

Fritz Funk's Sneakeasy Construction Log http://boats.backwater.org/Sneakeasy/SnekCNote.htm

Here is a build video of a Jon boat.

Here is my current favorite:

 

I did a reality check with the dimensions of actual boats, many of the small boats are 10ft long, for example the Jon boat described here. A walk along the beach and inspection of some of the boat hulls there made me realize the boats I had in mind were about 10 ft in length, from the abandoned 'speedboat' to the paddle boats. A jet-ski would also be about 10 ft in length depending on model. The 3D drawings I had originally posted were for a design was too big, being a 23 ft boat, which is too large and will be heavy.

I created a human-representative figure 5ft 5 inches or so tall. The width was measured to be about 56 cm or 22 inches width, and length of a person seated in a low seat 4ft long or 120 cm long, and with a 3ft or 1 metre in height. I first then started with correct dimensions for the human figure on a 10ft by 50 inches or so, the typical Jon boat I posted the link to being 56 inches in width.

Checking with Chine Hull Designer, the dimensions were about right, the Hull Designer uses a larger human figure in upright position.

I am trying to get a hold of a 2D cad program, when that is in place I will use that for dimensions.

 

Ferry speed measured as 21 km/h or 11.3 knots using gps speedometer. Running speed, not walking speed.