Motor thoughts

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Motor thoughts

Postby jboright » Fri Mar 12, 2021 12:51 pm

I'm looking for thoughts/experiences with electric motors (electric outboards and/or trolling motors) for my DS1... new to me late last summer. I managed to borrow an electric outboard last summer from a neighbor but alas it isn't available this year so I'm shopping for a new solution. I've been looking around and will will likely go with the Minn Kota Endura 55 trolling motor (C2 or MAX?) but I have a few questions and am curious if anyone here has input:
- What's the right shaft length for a DS1? (Guessing 36" would work)
- I notice that there are more powerful motors (70# or 80#) but they require 24V. Is the extra power worth the extra weight?
- are there other brands or types of (electric) motors out there I should be looking at? I don't think I'm ready to make the price jump up to a Torquedo... but are there other 'electric outboards' that might be more reasonably priced?
Thanks in advance!

Jon
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Re: Motor thoughts

Postby Anstigmat » Fri Mar 12, 2021 3:45 pm

This does not answer for cost reduction but there is another brand called ePropulsion which has an outboard which has some advantages over the Torqueedo. Same extremely high price however.

I'm reluctantly buying one of those low-cost Chinese outboards this spring. The Torqueedo or ePropulsion would be a perfect compliment to the Daysailer assuming you don't need to go extremely long distances without the aid of sail.

Check your used listings regularly. I saw one come up for $700 once, but did not have the scratch on hand. Kicking myself a bit about that.
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Re: Motor thoughts

Postby tomodda » Fri Mar 12, 2021 8:48 pm

I have an EP-Carry and love it. Answering your questions one by one:

- What's the right shaft length for a DS1? (Guessing 36" would work): Pretty sure mine is 30", I'd have to re-measure it. 36" is fine.

- I notice that there are more powerful motors (70# or 80#) but they require 24V. Is the extra power worth the extra weight?: No.. see more below

- are there other brands or types of (electric) motors out there I should be looking at? I don't think I'm ready to make the price jump up to a Torquedo... but are there other 'electric outboards' that might be more reasonably priced?: Define reasonable......

On the last question, I don't mean to be flippant and I'm not asking how much you can afford. I'm wanting to point out that any auxiliary power choice is a tradeoff of initial price vs total cost of ownership vs convenience/does it do what you need it to do? So, to be absurd, the cheapest aux. propulsion is a used canoe paddle. The most expensive is a brand-new 100hp gas engine. Both have their pros and cons (100hp engine is going to make your boat get up on a plane, then be totally uncontrollable and flip). So, WHAT are you trying to do? Power the boat all day while transiting from X to Y straight upwind or on a windless day? Do you expect to be fighting against currents? Or do you just want to get out of the marina/away from the boatramp and head upwind while you raise the sails and want to putter back to the dock after dropping the sails? I suspect most DS sailers want the latter ability and that's it.

If so, the EP Carry is a GREAT option, check out my post on it (search for EP Carry). But it's $1600 initial cost. On the other hand, that's ALL it will cost, except maybe for an $80 prop change a few years down the line. You really don't need a lot of power, a 70# or 80# trolling motor is way overkill. But before we get into that, answer the question, at least to yourself, of what are you REALLY looking for in aux power?
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Re: Motor thoughts

Postby tomodda » Fri Mar 12, 2021 8:48 pm

I have an EP-Carry and love it. Answering your questions one by one:

- What's the right shaft length for a DS1? (Guessing 36" would work): Pretty sure mine is 30", I'd have to re-measure it. 36" is fine.

- I notice that there are more powerful motors (70# or 80#) but they require 24V. Is the extra power worth the extra weight?: No.. see more below

- are there other brands or types of (electric) motors out there I should be looking at? I don't think I'm ready to make the price jump up to a Torquedo... but are there other 'electric outboards' that might be more reasonably priced?: Define reasonable......

On the last question, I don't mean to be flippant and I'm not asking how much you can afford. I'm wanting to point out that any auxiliary power choice is a tradeoff of initial price vs total cost of ownership vs convenience/does it do what you need it to do? So, to be absurd, the cheapest aux. propulsion is a used canoe paddle. The most expensive is a brand-new 100hp gas engine. Both have their pros and cons (100hp engine is going to make your boat get up on a plane, then be totally uncontrollable and flip). So, what are you trying to do? Power the boat all day while transiting from X to Y straight upwind or on a windless day? Do you expect to be fighting against currents? Or do you just want to get out of the marina/away from the boatramp and head upwind while you raise the sails and then at the end of the day want to putter back to the dock after dropping the sails? I suspect most DS sailers want the latter ability and that's it.

If so, the EP Carry is a great option, check out my post on it here: https://forum.daysailer.org/forum/viewtopic.php?f=8&t=5936. Yes, it's $1600 initial cost. On the other hand, that's ALL it will cost, except maybe for an $80 prop change a few years down the line. I also got an extra battery for $60 (by scouring the internet for refurbished wheelchair batteries, I got the exact same make as what EP Carry uses. And even got some tech tips on it from the company, they are very good on working with their customers). You really don't need a lot of power, a 70# or 80# trolling motor is way overkill. But before we get into that, answer the question, at least to yourself, of what are you REALLY looking for in aux power?
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Re: Motor thoughts

Postby jboright » Sat Mar 13, 2021 1:42 am

Thanks for your thoughts @Anstigmat and @Tomodda. Good points and you're right @tomoda I should have led with what I'm trying to accomplish... Getting away from the boat ramp and out into open water pointed upwind will be the main duty, but would also like the ability to go out (or farther out) even if I'm not 100% sure the wind will hold to get me all the way back home. Like most of us I'm sure, the opportunities I have to get out on the water are fewer and for shorter duration than I'd like, so I want to take as much advantage of them as I can. Knowing that I have the ability to get back to the dock if the wind totally dies just enables me to squeak more fun out of the time I have.
Also good to hear your good review of the EP-Carry. I was actually on their website earlier and it looked interesting. How would you compare it to a 55# thrust trolling motor? It looks lighter and easily managed... but I wonder how the power and battery life compare. I've found other good threads on this site (thanks to you and GL) and my general take-away is that the power (i.e. the ability of the motor to push my DS1 through the water) of the EP-Carry is similar to what I could expect from a Minn Kota 55# trolling motor but the battery life is significantly better with the EP-Carry as is the general ease of use (including mounting and dismounting)? Does that sound right?
Thanks again,
J
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Re: Motor thoughts

Postby GreenLake » Sat Mar 13, 2021 5:11 am

For years I used a 40# trolling motor, with two 12V deep cycle batteries. That gave me something like 1h20 at full power. Speed was a bit under 3 knots. (Often measured with sails still up because of traversing limited calm spots).

Every seven years a new battery. Total outlays with charger and batteries under $500. Not sure anymore what charger and new batteries cost, but I also sprung for a set of very heavy duty cables from the batteries forward to the motor at the stern. (I used a collapsible sack cart to get the batteries into the garage for charging - I happened to have one, but I found it a required item, so happy to include it in the total cost). Also included is an upgrade to a high-thrust propeller made by Kipawa (sp?).

I've now switched to an EP Carry. Like the one Tom describes.

Top speed is 3.5 knots (under bare poles, and sitting very far forward, for better boat balance).

The battery that's included gives 1h at full speed. Which is a bit less. But it is easily removable, and on many trips that I like to do I'm able to charge it on the other side because I'm tying up at a dock, so I have full range for each leg. It's a 24V system, incidentally.

The battery plus motor are lighter than the trolling motor alone. That helps the boat not to "squat" so I sail better, even if both battery and motor are on/at the transom.

The motor has an extra long tiller arm so I can sit further forward, even though, I often just set it to a fixed direction/speed and control steering from the regular tiller (sitting even further forward).

A simple tug on the tiller arm lifts the motor out of the water (nothing to release). That's ideal for situations where you need to alternate between sailing and motoring. (Calm patches, under bridges, short stretches in the marina).

Recently I had to take my sails down because the winds suddenly kicked into the 20s and I didn't have the crew to sail in those conditions. The motor was perfectly adequate to keep the boat pointed into the wind to take the main down. (I later raised the jib to sail dead downwind back to the ramp and jib alone made the DS go well over 4 knots, just to give an indication of how much wind there was that day).

In calm conditions, if you are patient and go less than full speed, you might eke out a bout 5nm of range (at 2-2.5 knots). Or a bit over 3nm at full speed. That works out to be enough to get me home: I rarely find a dead calm that extends the full distance. It's more common that I can somehow sail at least 50%.

There's enough power there to get the boat moving short distances against stronger winds, such when setting/taking down sails, or perhaps to get out of a marina.

What I wouldn't plan on is motoring very long distances or motoring against currents (with a 3 knot current you would be standing still over ground). (For tides, I tend to plan things so I can return with the tide - even if I've to wait a bit, on a river, I'd not recommend this motor).

I balked at the price tag at first, but I met the guy who sells these at my launch ramp one day and he suggested he'd give me a loaner. (He was concerned that the DS would be a bit much boat for his motor). I took him up on it, but at the end of the season, I had gotten used to the convenience of not having to use sack carts for the batteries and as the speed, operating and sailing characteristics of that motor were all at least somewhat better than for the trolling motor, I decided to make the upgrade. (I've not looked back, but at some point may ask Santa for a second battery, so I can go out on a certain extended cruise that involves traveling up a bit of a canal).
~ green ~ lake ~ ~
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Re: Motor thoughts

Postby tomodda » Sat Mar 13, 2021 12:44 pm

For what it's worth, Joe, the owner/inventor of EP Carry, rigged his boat for solar and went on a multi-day cruise with her. All documented on the EP Carry website. I know that for solar, you need a few hundred dollar controller box in addition to the panels. On the other hand, I believe he says that in the right conditions of full sunshine and not full throttle, you can move without drawing down the battery at all. Anyway intriguing, maybe one day. In the meantime, I'm happy withy spare wheelchair battery. It's still running fine, of course I've only had limited opportunities to use it. Hopefully more THIS year!
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Re: Motor thoughts

Postby GreenLake » Sat Mar 13, 2021 4:35 pm

The battery has just under 10Ah at 24V and because it's a Lithium one, it can be discharged almost fully. So you get around 220 Wh. As the battery lasts for 1h at full power, the max power draw would have to be around 220W. If you can fit a solar panel that gives you, say, 100-150W (in actual, not nominal power) you should be able to cruise at partial power (e.g. 100-15oW) continuously.

So that seems utterly believable.

The charger that comes with the batteries delivers nominal 2A, so you'd need at least 5h to recharge a fully depleted battery from an AC outlet.

If you only need to motor in short stretches (but, say, part of every day) a solar panel should allow you to go on a multi-day cruise, while motoring at times with full speed. Or longer, at reduced speed (because power requirements aren't linear, half the speed gives you more than double the range).
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Re: Motor thoughts

Postby GreenLake » Sat Mar 13, 2021 5:01 pm

Quick online search found some portable solar panels (folding). Those might be a reasonable option. Most were for 12V, but I've seen some 24V ones. Tom, if you were to add a solar charging system, which one would you get?
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Re: Motor thoughts

Postby tomodda » Sat Mar 13, 2021 9:51 pm

Call Joe, he'll be happy to work with you.
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Re: Motor thoughts

Postby GreenLake » Sun Mar 14, 2021 4:35 am

Joe's great. However, I'm just blue-skying a bit, because I'm far from a situation where I'd be ready to install anything.
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Re: Motor thoughts

Postby tomodda » Sun Mar 14, 2021 9:36 am

When I ran a pencil thru it, the big expense was the controller. But it's been a while, pretty sure I also was looking at 24v panels. I wonder where to put them, is there enough space on the foredeck? Seems the logical place, but it's an awkwardly shaped place, and the jib sweeps over it. No problem if only motoring, but what if you want to recharge the battery while you sail?
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Re: Motor thoughts

Postby Shagbark » Sun Mar 14, 2021 11:57 am

If Greenlake is correct that the EP carry has only 220 wh and with a price of $1,600, you're paying $7.27 per Wh. With the torqueedo 1103 at 915 Wh and $2,700 , you're paying only $2.95 per Wh. Although more expensive up front, you get far better range with the torqueedo for less expense (by the time you add battaries to get to the same Wh as the torqueedo). I checked the EP Carry website and didn't see the stated watt hours so my analysis could be wrong. I have not owned either one so I'm just basing this on the information I provided above. I use a trolling motor with a single battery which has proven less than optimal. Yes it works as I need it 75% of the time, but there were times when I couldn't push to windward during a strong breeze in the marina to get back to the ramp and other times when the wind died and I wanted to get in to beat daylight and couldn't. I will be upgrading to something better this year.
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Re: Motor thoughts

Postby GreenLake » Sun Mar 14, 2021 6:08 pm

@shagbark: power required for boat propulsion is not linear. Especially when approaching hull speed. You back off on speed a bit, and your range increases disproportionately. That makes comparing range so tricky. If you know the max speed at full power, and max battery time on full power, you can multiply these to get the "fastest range". But half power would give you better than half the speed, and therefore your range is greater than at max speed. (For lead acid batteries, you can get noticeably more power out of a battery at slower discharge, so you get that bonus as well at half power. Not sure whether this effect is as strong for Lithium).

Then there's motor, propeller and drive-train design. The EP-Carry is super optimized compared to a trolling motor. Joe did some measurements on my boat and computed that his motor was using 1/3 the watts per knot of max speed than the trolling motor I had used before.

I have no idea where the Torqueedo fits, because actual data would depend on comparing it when used on a DS.

However, looking at their specs, even the smaller 603S should better the thrust of a 55# trolling motor (they state 44# for thrust, but claim that when comparing to trolling motor ratings that one needs to add 50%). That motor uses 600W at full power. The EP Carry uses a bit over 220. So, let's say, we assume that the 603S delivers the same speed at half power as the EP Carry. Torqeedo give 1:45h for their 500Wh battery discharged at "half throttle". For their (unspecified) test boat, they give 3.23kn at that power setting. That would be in the ballpark of what you can get as max speed from an EP Carry (I can get up to 3.5kn, but only with a perfectly balanced boat, not when sitting with a hand on the throttle).

Looks like comparing like for like (roughly same power setting, same boat speed) you can get 5.5nm range at a bit over 3 knots out of a Torqeedo 603C. And it should have just a bit more thrust for going upwind than an EP Carry. (Price for the 603S: 2K).

The 1003C or 1103C have the larger battery (915Wh over 500Wh) but also can deliver more power. At the same 3.2kn boat speed, you would have throttled them down to less than half, but as long as there aren't any differences in motor efficiency you'd expect them to draw the same power to move your boat as the smaller motor. So, the battery should then last an extra 80%, for a 10nm range. Or you can burn the extra power going faster.

As power vs. speed is a cube law, it's really easy to trade lots of range for even a bit of speed.

That said, if you need the extra oomph to deal with surf or wind (short distance) then one of those motors despite their 2.5K+ price tags might make them worthwhile. I see them occasionally on small racing keelboats

To round out this comparison: if I get a spare battery for the EP-Carry ($400) I'd have a bit more range than a 603S for about the same price, but w/o the ability to trade that range for more speed. Having the capacity spread over two batteries is an inconvenience, but also a potential plus from a safety perspective. I've had batteries die on me before.

In summary, it looks like your conclusion that you get more range for the buck with the larger motors is correct - unless you end up trying to go 4 or 4.5 knots, because you can.

Finally, you get to also compare other design features: the EP-Carry is 2/3 the weight of a 603S (and even less compared to 1003/1103C). As I'm happy with a minimalist setup from my other requirements, reducing weight on the transom is a big plus. If i want to go on an extended cruise, I'd have to add a second battery or figure out solar, or both.
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