Electric boost for a camping rowboat

[rgthom]

EDIT: Moved to Building/Repair, 'cause I started working on it.

I'm thinking about adding electric power to my cruising rowboat. Hopefully folks have done something like this and can let me know if I get off course.

The boat is John Welsford's Walkabout, stretched to 18 feet and powered by slide seat rowing. Cruising grounds are primarily the Sacramento Delta and San Francisco Bay. Speed under oars is typically 3 kts for long term loaded cruising, up to about 4 kts for some of the 5 to 10 mile races I've done on the Bay. I cover 10 to 20 miles in a day when camping, about 100 miles for a week long cruise.

I'm happy with the performance as a rowboat, and have been pretty stubborn about sticking to the oars and getting to the destination on my own power. I also used to be stubborn about doing cycling trips on my own power, and considered electric power on a bicycle as cheating or something for when I was too old to ride. Last year, though, prodded by a thread in the bilge here, I put an electric kit on an old bike of mine. Turns out this works really well. I can still ride the bike, but go much farther and faster than on my own power alone. Now I do my 70 mile round trip commute by bike a couple of days per week, could not do that without the boost. So, maybe adding electric power on the boat could open up more range and expand the options for camping trips.

The general goals for the project would be to increase loaded cruising speed from 3 kts to 4 kts, with boost available for 20 to 30 miles in a day. This will likely require some kind of motor, a battery, and an overnight charger. Eventually solar panels could be added to gain independence from shore power charging. There are a few options I've been researching, will post on those soon.

[Chip-skiff]

Since I think the Walkabout lacks a transom suited for a motor clamp, you might cobble up this sort of mount—



My Bolger Gypsy has a sealed rear compartment and rope steering, so I built a motor mount that fits the gudgeons on the transom. For open water, I set the throttle and slide forward for better trim, using the rope loop to steer. There's also a tiller extension for the motor so I can steer and control the speed that way.

The skiff is easily driven and half-throttle with a 30 or 40 lb. thrust motor is as fast as I care to go. I've run a battery (AGM 925 amp) for a day, 1-2 hours continuous operation, and not run out of juice. Whether a solar PV charging setup would work for you is basic math.

[rgthom]

Perfect, that is very much what I had in mind. In fact, my rope steering is pretty closely copied from yours already.



The drive unit I'm planning to use is an EP Carry electric outboard. This is significantly more expensive than the Minn Kota type trolling motors, but it has advantages in efficiency and battery type. This is my biggest decision, is the EP Carry worth the cost. Do you have any speed vs setting measurements with that motor?

[Clarkey]

I suggest that this would be a very informative place to start:

http://vinegar-stroke.blogspot.com/

Seems to be quite close to what you are planning.

[rgthom]

I suggest that this would be a very informative place to start:

http://vinegar-stroke.blogspot.com/

Thanks Clarkey. I have seen that, part of what got me interested. Gus used a bigger motor and more solar than I was thinking my boat needed. He did not say where he got the Torqueedo, but these are also expensive new. The Torqueedo Ultralight kayak motor is more to the scale, but the long range kit runs about $2300.

Joe Grez (owner of EP Carry) did a solar boat for the Salish 100 last summer. He did the trip on only solar, not rowing or sailing, using his motor and 200 W of solar panels. https://www.electricpaddle.com/downl...tival-2019.pdf

[Chip-skiff]

I'd probably get an inexpensive trolling motor for the first season, and test how it fits into your cruising style. I've got a 30-lb MinnKota and a 40-lb MotorGuide, both dependable and trouble-free. You could keep the battery and sell the motor if you thought a better one would be worth the cost.

[Clarkey]

Thanks for that EP carry solar link. These systems are really coming together now and beginning to have palatable prices too. For some reason pure solar doesn't really appeal to me but the concept of augmented rowing as described in the Vinegar Stroke blog I find absolutely fascinating.

[rgthom]

I'd probably get an inexpensive trolling motor for the first season, and test how it fits into your cruising style. I've got a 30-lb MinnKota and a 40-lb MotorGuide, both dependable and trouble-free. You could keep the battery and sell the motor if you thought a better one would be worth the cost.

This is the sensible way, and probably what I should be talked into. I'm leaning toward the EP Carry for a few reasons:

It's a US made unit. I've met Joe and some of the developers at Pt Townsend, they are making this work and I want them to succeed. Joe has been very helpful providing data and doing some modeling. One of the tests he forwarded was on efficiency:

Blue is the EP Carry drawing 220 W, orange is a Minn Kota Endura 30 drawing 280 W. The more expensive motor should take a smaller battery/solar panel for similar speed.

The EP carry battery is 24 V, but I learned that it can run much higher (up to about 60 V). I already have a 48 V e-bike battery that would run it, so would not need to buy a battery to get started.

[rgthom]

The e-bike battery I already have is 48 V and 17 Ah, total stored energy 816 Wh. At full power the EP Carry draws 220 W, so that battery should power it for over 3 hours full blast. That would allow me to do testing of the motor right away. The e-bike battery is a lithium chemistry, it has higher energy density but does not last as many charge cycles, is not waterproof, and is not as safe as lithium iron phosphate. I would go with a LiFePO4 battery after proving the motor works as expected.

Joe Grez ran some solar power simulations on my boat. For the following graphs, the daily sun angle is for the latitude of the Sacramento Delta in June and the solar panels are assumed horizontal. The solar power goes into the motor, no battery storage for these curves.

This first one is the boat at 450 lb (no camping gear), using 300 W of panels:


The Delta is almost always full sun in June, so the blue curve would apply. The flat top means the motor has reached full 220 W power, so extra solar would be available for charging. My goal of 4 kts looks possible on solar alone for 8 hours per day, not including my rowing input.

The next graph is a full camping load at 600 lb displacement, and only 200 W of solar panels:


There is enough solar to power at 3.5+ kts for about 6.5 hours. With my rowing added, this looks about right to get enough energy to go 30 miles at 4 kts.

In use with a battery, the power would of course be dialed to get the speed over the whole time. Solar would top up the battery as it depletes.

[hawkeye54]

Have you reviewed the 'solar kayak' thread by whiskeyfox in 'Building / Repair ' ? -- lots of good information there



Rick

[rgthom]

Have you reviewed the 'solar kayak' thread by whiskeyfox in 'Building / Repair ' ? -- lots of good information there



Rick

Yes, thank you, I was going to mention that. Whiskeyfox has gone a lot deeper into the components than I was planning, building his own motor nacelle and MPPT circuits. It's very impressive and looks like fun, but I don't have the time at the moment. At first I was thinking of taking a stock e-bike motor and making either a long tail or mating to some outboard lower unit, but that would still take a lot of work and probably not be as efficient.

For the solar on mine, I should just need an off the shelf boost charge controller to mate to the battery. Those are not too expensive.

Rick (also)

[Chip-skiff]

As far as the cockpit/deck space taken up by the PV panels, I was thinking about adding hinged mounts to the coamings or rails so the panels would swing outboard, not taking up space, and could also be dismounted and stowed. Some sort of ratcheting or locking device (such as that for a hatchcover) would allow changes in the angle of each panel. You'd need waterproof connectors of course.

With the panels more or less parallel to the water surface, they'd not add much windage.

[rgthom]

As far as the cockpit/deck space taken up by the PV panels, I was thinking about adding hinged mounts to the coamings or rails so the panels would swing outboard, not taking up space, and could also be dismounted and stowed. Some sort of ratcheting or locking device (such as that for a hatchcover) would allow changes in the angle of each panel. You'd need waterproof connectors of course.

With the panels more or less parallel to the water surface, they'd not add much windage.

So far I'd been thinking of the rear deck as open space that would not interfere with the tent over the cockpit. My boat has about 1200 sq inches of rear deck in a trapezoid shape, not really enough surface even as a custom shaped panel. Typical panels run about 10 sq inch per watt.

This sketch is two Renogy 100 W flex panels over the deck. They would have to be raised enough to fit the motor under, and with a hinge in the middle to fold them up it might work:

[Thorne]

Rick -

I'd suggest fabbing up a standard electric trolling motor pod in a swing-up rudder blade, then connecting that to your steering system. You've probably seen these, but the general design has the rudder kicked fully up when rowing, partially up when sailing, then released (the weight of the motor pulls it down) when used for motoring.

Here's one from a sailboat on the 2008 Gunkholing trip -


But if you go for the EP Carry or other integrated motor, then having it on a rudder-like mount makes more sense - but you'll have to raise and lower it when switching from rowing to motoring.

[rgthom]

Merry Christmas Thorne. Yes I had seen those rudder mount motors, Gig Harbor sells one commercially if I remember. The EP carry tilts up by pulling on its tiller. Without the tiller, I'd have to come up with a way to tilt it for weeds and such, probably just a pull line.

I made the rudder for the boat already, but for rowing it's just not needed. Remember this is for motor assisted rowing, not one or the other. I am actually hoping that the motor does not act like much of a rudder, so I can steer by oars most of the time.

[rgthom]

Since nobody was convincing enough to talk me out of this, and I need some sort of project in the winter evenings, I went ahead and ordered an outboard motor unit from EP carry. It's the same motor as comes in their system for dinghies, but will be without battery as I will use my own. The tiller will not be installed, since I'm going to do Chip-skiff's rope-steered mounting. A cover plate will be mounted instead. There will be a USB connector on the motor to link up to a remote mounted control head in the cockpit. The motor should arrive in a couple of weeks, maybe I can start run testing in February using my e-bike battery.

[timo4352]

I'm up for following a new project.
Good luck with it.

[rgthom]

I'm up for following a new project.
Good luck with it.

Thanks. This will make the Walkabout my first boat with a motor. A 1 hp equivalent electric motor, that maybe gets the boat to hull speed, may not be too exciting to most of you but it's a new world for me .

[rgthom]

OK, started working on this. Since I need to find out how much power the motor uses, I got a cheap volt/current meter on Amazon. The display is powered from the measured circuit, the range is 4.5 to 100 V and 0 to 50 A, and it comes with a 75 mV current shunt. That should work for this setup. Plus, it's a genuine Drok . https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Quick check of the voltage function, using the e-bike battery. Compared to my Radio Shack DMM it looks pretty accurate. I will check voltage and current readings at work against calibrated meters.

[rgthom]

I made a breadboard today to hold the battery, fuses, shunt, meter and terminal strip. This really is a breadboard, it's going to be replaced when I get a better battery. I know myself, though, and will probably wind up using it for longer than planned, so it's slightly better than just a piece of wood. It has a dowel to hold it at a good angle in the second footrest location, so I can see the meter easily and can grab the whole thing and toss it overboard if the battery acts up. Remember this is an e-bike battery, not as safe as a LiFePO4, and they do on occasion catch fire (lots of YouTube videos on that happening).

Breadboard:


On the boat:

[rgthom]

Checking the cheap meter against a calibrated DMM. Voltage is quite accurate, but current has a 0.2 A constant offset (does not read any current until 0.2 A is flowing). Not too bad, I can just adjust readings.

[rgthom]

Today I started on the motor mount, using a set of sturdy pintles from Duckworks and some leftover redwood and oak. The sheaves will get bent metal brackets over them and removable pins, so the rope steering can be hooked up without running the rope all the way through the boat.

[rgthom]

The motor mount and electronics are done as far as I can until the motor is ready, so I started thinking about the rope steering again. The rope runs all around the cockpit and is easy to grab from anywhere, but it's a bit cumbersome to steer constantly by holding the line. Possible improvements could be:

1) Put a handle somewhere in the line, just to hold on to. Simple, and a slight improvement.

2) Make a lever that hooks onto the line, something like this grabbed from a forum post:


That could work, but with enough throw to work the steering the handle would be pretty long. It would get in the way of the already made tent.

3) Put a steering wheel in that works the line. This is what I'm having a go at.

[rgthom]

I was looking at boat steering wheels online, to get an idea of how to make one. There seems to be a standard tapered hub, to mate to a tapered shaft, with spokes and a rim added in various materials. I could have made something, but while searching a small stainless one popped up on the Bay for $20. So now I have this:

[rgthom]

For a shaft, I already had a piece of solid fiberglass rod at the correct 3/4" (19 mm) diameter. I've drilled a 5/16" hole 3" deep at one end, epoxied in a 5/16-18 full thread stainless bolt cut off to make a stud, and tapered the end to match the wheel hub taper:

[rgthom]

Several years ago I made a mast gate for the boat, this one:


The steering line passes just under the gate, making it a good place to put the steering. To support the shaft, I first drilled a 1" hole with a step drill:


Then epoxied in a bronze bushing with 3/4" ID to match the shaft:


A simple wood block will be made also to support the other end of the shaft.

[Ben Fuller]

Rope steering was not uncommon in small work and recreational craft in pre-outboard days. I've seen it rigged with one and two steering wheels with the line taking a couple of turns around a drum. Side levers were also common in work boats; you still see it in launches. Much faster to go from lock to lock than spinning a wheel. Some of the ones I've seen had blocks on the tiller not unlike you see on some modern cable steered outboards.

[rgthom]

Thanks Ben, good to know this has worked before. Do you have any pictures of rope steering using a wheel? I did not find much on the webs.

I found a length of heavy rubber hose to use as a "drum". It's 3/4" ID which fits on the shaft, and 1.5" OD (actually made as sandblaster hose). On a quick test last night, that gave 2 turns of the wheel each way (4 turns lock-lock). That seems about right.

[Chip-skiff]

The proper name for the stick dealie is a whipstaff. If you use it as a keyword for a search, you'll find all sorts of info and discussions.

[Breakaway]

You can buy stick steering in a kit, as well. Just one example:

https://www.boatid.com/ez-glide/14-c...SABEgLlefD_BwE

Screen Shot 2020-02-06 at 3.04.09 PM.jpg


Kevin

[Ben Fuller]

The proper name for the stick dealie is a whipstaff. If you use it as a keyword for a search, you'll find all sorts of info and discussions.

Here in Maine the old open lobster boats that had them called them struggle sticks. Interestingly they just had the bottom end unpinned in a little trough so that they could lay the stick down when they were hauling traps. On the launches I've seen and driven we just called it a steering lever.

[Ben Fuller]

For a different take on using rope and a yoke to steer a rowing boat, a friend rigged lines from his yoke to cross and had turning blocks low about where his rowing thwart was set. They were rigged in such a way that they crossed under his calves, touching. So when he wanted to turn he just dropped his calf a little. He was using the rudder as a trim tab really to counter weather cocking. I expect you could rig lines to your outboard the same, although I'd lock the motor ahead and use your rudder if you have both.

[rgthom]

Thanks everyone. Searching for whipstaff steering does turn up a lot, including Chip-skiff's boat.

I have this steering wheel pretty much working now. My hope is that the wheel can be set for straight ahead when motor rowing. For motor only facing forward, I turn around in the seat and drive by wheel. We will see if this pans out as planned....

[davebrown]

I bought a used Torqueeda or however it's spelled for my Wayfarer. Significantly speedier than my trolling motors. It has a standard marine battery conversion so not using the original battery--advantage is they (marine batters) are cheaper and laying around...disadvantage is weight.

[rgthom]

The Li e-bike battery is very light, 10 lbs for 3+ hours full speed run time. Plus, I already have it.

Here's a view of the steering hooked up. This works, but the shaft should have a support at the far end and I need to add a clamp to secure that piece of hose on the shaft, it can slip.


From the cockpit, steering wheel in place: