Trolling Motor Recommendations

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Trolling Motor Recommendations

Postby bdpvt » Wed Jul 14, 2010 2:54 pm

Thinking about buying a electric trolling motor for getting in an out of the boat launch and back home when the wind dies. We mostly sail on Lake Champlain and other lakes around New England. Looking for recommendations on motor size.
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Postby GreenLake » Wed Jul 14, 2010 3:26 pm

The deluxe variant would be the Torqeedo Travel. Nearly as powerful as a small outboard, but unfortunately, costs as much as a typical DS. Look it up on Google. Would be the one I would get, if I didn't have a budget.

Standard trolling motor. The 40lbs thrust model gets my DS to something close to 3kn on full power, with each battery lasting about 40min, or around 2 to 2.5nm range. (Assuming no wind).

If you are willing to go even slower, the range should actually increase some.

Usually, the 3kn is so slow that I don't ever motor when theres any noticeable wind.

I've often wondered whether I should have gotten a 55lbs thrust model instead. It promises somewhat higher peak speeds, at a cost of reduced range, but in going under bridges and through canals I sometimes wish I could be out of traffic sooner.

Those models also have different types of regulators, so it might be that low-power operation extends the range of the motor further than for the 5-speed controller on the smaller motor.
~ green ~ lake ~ ~
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Postby Alan » Wed Jul 14, 2010 7:17 pm

Roger did some tests with a 55 lb thrust motor and posted the results on a thread, not sure where.

I took my best guess and bought a Motor Guide 80 lb thrust motor (24 volts, so it requires two batteries). With the stock propeller, I was getting passed by kayaks being paddled in a leisurely fashion. With a three-blade prop from Kipawa Propeller, I go a lot faster and leave a very small wake. It's still not very impressive, though.

I've yet to try the 55 lb thrust motor (Minn Kota, with open water propeller) that we bought for our canoe.

One consideration is the weight of the motor. The 80-lb thrust model weighs about 30 lbs, according to my bathroom scale, while the 55-lb thrust model weighs only about 17 lbs. This makes it a lot easier to stow.
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Postby Alan » Wed Jul 14, 2010 7:21 pm

Oops, got the brands backwards. The Minn Kota is 80 lbs thrust. The Motor guide is 55 lbs thrust.
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Postby GreenLake » Wed Jul 14, 2010 8:39 pm

I think it's worth teasing out the requirements. If the need is solely for getting off the lake in case of no wind, then you are optimizing for long range and low weight (or weight that you can store forward while sailing).

There's no particular need to go have lots of power or to go fast (other than impatience). Having Kayaks pass you or not shouldn't be an issue, because even under sail Kayaks can pass you when the wind isn't ideal (like up-wind, or in lighter winds).

I'm confused about your comment about having less of a wake with a three-blade prop. That sounds like you were seeing the propwash and not your wake. Was your motor mounted too close to the water surface?

With my smaller motor, the only wake I see is from the boat, and that would increase if I were to go faster. The wake I see is totally the same as if I was sailing the same speed. (I have the two bladed "weedless" prop). The problem with stock trolling motors is that they are designed for trolling, not cruising. So I'm not that surprised that a propeller upgrade improve the situation.

I happen to think that a slower motor has the advantage of encouraging you to sail, rather than motor, whenever possible. Where I sail, it's not uncommon for the wind to die down in wide bands. I've learned that it usually comes back in less than half an hour, so instead of frantically motoring into the next wind band, I just take a nap. :)

Now, if you have currents (rivers or tidal areas, or long lakes where the surface water returns to the other shore when a strong wind stops suddenly) then you might need more speed, or you will never reach any upstream destination. Also, if your requirement included motoring against the wind, you'd need more power. But these were not included in the way bdpvt defined the problem - he asked explicitly about how to get off a lake when the wind dies..
~ green ~ lake ~ ~
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Postby jdubes » Thu Jul 15, 2010 10:46 am

I agree with GreenLake, it's all about requirements. I've gone through this exact throught process, should i use a troller or gas motor. I already had 50lb thrust trolling motor to start with, the question was should i switch to gas. I sail on lakes and Buzzards Bay. My main goal with the motor is to launch and return the boat to shore. I try not to use the motor when the sails are up unless i have to. I'm more comfortable moving with sails power than with motor power. It has to do with all the steps of working the rudder, the motor, and dealing with any wind picked up in the sails while i'm motoring. Not a fan.

I ended up purchasing a used 2.0 Suzuki that's almost exactly like what i've posted. I find the compactness and gas tank combo of this motor far superior to troller and battery power line combo. With the troller there's to much setup and cabling. You've got to mount the battery and run lines. I've also found through experience that Trolling motors and batterys don't like water. I recently dunked my suzuki and was back up and running in 15 minutes, i won't go into how the dunking occured, It hurts the ego. :oops:

For bay launching it's just right, 9-13knots of wind with a good chop it moves the boat. A 2.5 or would be even better. For lake launching it's perfect, I've never had any problems and the wind blows between 6-10 with a little chop. The troller on the lake was ok, i had no issues. On the bay, it was dicey. If someone is on the boat with me, i instruct them to not move while leaving lanuch site. Movement can scrub forward motion.

Good luck working through this.

Jason
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Trolling Motor Recommendations

Postby ChrisB » Thu Jul 15, 2010 10:51 am

In response to a question from me, Minn Kota recommended a minimum of 65 pounds thrust. After reading posts both here and elsewhere, I decided that a trolling motor would work fine to push you away from and back to the dock in a lake, but would not provide enough push against any significant wind or current. I went with a slightly used 3.5 hp gas outboard.
Chris B.
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Battery recommendation

Postby Baysailer » Thu Jul 15, 2010 10:58 am

On a similar topic is the battery recommendations? I rarely use the electric sail but when needed I have a 36 pound thrust minnkota and use a garden tractor battery. The 36# is OK since it's only used in dead calm but the battery might be a different Q. I went with small and cheap but would certainly think there's better recommendations.

Last night without a motor or paddle on board I had a good evening sail then spent the last hour+ trying to get the final 1/4 mile back to my mooring.

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Battery Recommendation

Postby ChrisB » Thu Jul 15, 2010 11:18 am

Baysailer,

That was one thing I left out. Minn Kota also recommended (insisted really) that the trolling motor be paired with a deep cycle battery of about 120 amp-hours. Deep Cycle batteries hold their cell voltage until almost fully discharged where conventional "starting" batteries see their cell voltage decay much sooner.
Chris B.
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Postby GreenLake » Thu Jul 15, 2010 1:37 pm

For running an electric motor you want a deep-cycle battery. Those are designed to be discharged down to 50% of capacity. Starter batteries are designed for quick discharge of a few %. All lead-acid batteries should be recharged immediately and completely.

Since you should never discharge a lead acid battery fully (or risk it dying on you), a 120 Ah battery gives you a usable charge of 60Ah. If your trolling motor draws 100A, so you would get 40min. At lower speeds, you get more range, because the power needed, and the power supplied by the battery change in a way that results in a longer range for slower speeds. Substantially longer range, by the way.

There are various grades of deep-cycle as well, some types I would describe as a kind of cross-over from starter batteries. I've used 80 to 100Ah of both types for very occasional use (for every 10 times I take the batteries and motor out, I use them maybe two times). With that kind of use, and my not perfect record of keeping them charged (they discharge slowly when not in use) they've lasted about 6 years now.

I do use a charger designed for deep-cycle batteries, not a car battery charger.

I have two main uses for the motor. One is as dead-calm insurance, where I need to go longer distances without wind and the other is for restricted channels where sailing is not an option (a slightly stronger motor would be nice for this second purpose). For routine docking, I use paddles - they are more versatile and the motor can remain in the cuddy until it's really needed.

My favorite launch areas are pretty sheltered, but have just enough wind so that I can usually sail away and dock under sail power - over the years, I find that my use of motor has peaked and then firmly declined. I rather figure out how do do a maneuver under sails, than rig the motor.

Recently I was caught 8nm from the launch with the winds getting light. Out of range for the trolling motor. With a gas engine, I might have sat for 1-2 hours of constant noise (and we would have been mighty tempted). Instead, we sailed, gliding smoothly, leaving a silver wake in the small ripples, watching the sunset, then spent time looking at the Milky Way and looking at the stars with binoculars. It took four hours, got us home late at night, but was worth every minute.

All the while, the trolling motor was in the cuddy, ready to help us across a real dead spot, or, in the extreme case, get us to a nearby shore in case the tide should turn against us. ("Currents weak and unpredictable" according to the chart).
~ green ~ lake ~ ~
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Postby Alan » Thu Jul 15, 2010 1:55 pm

GreenLake,

Just to clarify, the small wake with the three-blade prop is compared to no visible wake at all with the two-blade weedless prop. And that's with at least 18 inches of water above the propeller. With the stock propeller, the boat barely moved.

The 80 lb motor did reasonably well on Jackson Lake, in Wyoming, on a September afternoon, when the weather started to look so ominous that we decided to turn the sailing adventure into a motor test.

By the way, it has ferocious prop walk in reverse. Anybody got a solution for that?
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Postby GreenLake » Thu Jul 15, 2010 3:00 pm

Prop walk should not be an issue when you can turn the motor to compensate. When you have a motor that's fixed, you are stuck with getting a thrust vector that's a combination of thrust and prop walk, but with a trolling motor you should just be able to aim the combined vector any direction you want.

Got your explanation about the wake. You want to leave a "small" wake, because generating the wake is where most of the energy goes. For a "low power" motor, you should stay below hull speed, but I think you should be able to get closer to 4 kn with your 80lbs.

If you don't have GPS, drop something off the bow and measure how long it takes until you can pick it up at the stern. After a while, you'll be able to tell from the wake how far you are going - which is nice to know for sailing as well.
~ green ~ lake ~ ~
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Postby MrPlywood » Tue Aug 17, 2010 4:40 pm

I was curious about how fast I was going with my outboard, so I borrowed a friends GPS this past weekend. I have a 1983 4HP Evinrude longshaft. Peak speed on smooth water was 11kph (~6kn). That's nice when we've spent the day on our favorite island and just want to get back. In choppy water – from wind and wakes – I probably average about 8 to 9kph. It's also nice to have for exploring areas that would be difficult to get to by sailing.

The other day we didn't even rig the sails, just motor cruised around the lake, stopping to see friends, eat dinner at the marina, etc. We were under power for at least two hours and it used 3 liters of gas at the most.

Like jdubes I've also use it for launching and docking. I rig the boat at the dock, motor out into the wind, then raise the sails while the motor keeps the forward motion going.

The motor came with the boat, so I didn't have to make a decision. It is a bit cumbersome, but more than suitable for me.
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