Engine Mounted Electric Trolling Motor

S

Sea Wolf

New member
I've recently finished installing an electric trolling motor on the main motor of my CD-22 Cruiser as an alternative to a gas powered kicker trolling motor, although it would be possible to have the gas kicker as well. Here is the link to the photos in my album:

(Be sure to read the comments under the photos for explanations.)

http://www.c-brats.com/modules.php?set_ ... _photo.php

I did this partially because I was tired of dealing with the second gas motor and its controls, complications, and limitations. I also wanted a motor that would allow me to troll below 1.75 mph and do so very quietly. I did not want to add a trolling plate to the main motor, nor drag a drogue chute, buckets, or whatever. I did not need a big thrust kicker with which to come home off a big water fishing trip, although one could have all three on the same boat.

I choose an engine mounted trolling motor mostly because the steering problem is solved by mounting it directly on the main engine above and behind the motor's anti-ventilation plate. No need for any other link rod, handle extension, or steering wheel. Shifting and throttle control are easily done from the regular helm with a small electric control box.

In addition, the motor can troll with its 44 lbs of thrust ultra quietly from 0 to a little over 2 mph, overlapping slightly the main motor's 1.5-1.75 minimum trolling speed. Both are controlled simply from the helm, and the transition from one to the other is as effortless and seamless as possible.

The very quiet nature of the electric motor also is very stealth like, helping minimize the presence of the CD-22, which otherwise has somewhat a startling and scattering effect on spooky species of fish such as trout and walleye when trolling nearer the surface. While no one worries much about the boat's effect when trolling with downriggers at 50 or more feet, working closer to the surface with a boat the size of a 22 implores one to use long lines, outriggers, side planners, and the like to minimize the effect of the presence of the boat. While an electric trolling motor won't make your CD look like a canoe to the fish, it will make it just about as quiet.

I added two extra group 27 deep cycle marine batteries under the forward dinette seat to increase the capacity of my boat to 440 Amp-Hours from half that. You really don't have to do this, the motor will work fine on one of the existing group 27's for three hours without charging, but I liked the idea of having lots of reserve power so I could wait to re-charge batteries at the marina with shore power and the built-in charger in the boat, rather than relying on the 25 amp output of the 2005 Yamaha EFI 90. While the motor draws a max of 36 amps for 44 lbs of thrust, it typically uses 15-25 amps when trolling, so every hour of trolling would take 35-60 minutes of motor operation above 1500 or so rpm to recharge. We actually run the bigger motor quite a bit to reposition the boat before trolling downwind and to get to different areas, so the loss is pretty quickly made up and we don't go into too deep into the battery reserves. I do, however, like the security margin the extra batteries provide. No need to worry about fan motors for the heater or anchor lights at night, either. The extra 120 lbs also helps balance my weight at the helm, and pushes the bow down into the chop when on plane. With two battery switches in parallel, any single or combination of the 4 batteries can be used or charged as desired.

In my case, I was also able to get rid of the 77 lb 15 hp Johnson kicker and 45 lbs of th separate gas storage tank at the same time from the starboard side of the boat, which also helped redistribute weight.

The only flaw in the system I didn't anticipate was that the reverse thrust of the trolling motor is rendered partially ineffective because the water from the reverse thrust strikes the transom, and the force created partially cancels out the bite of the prop. But it still works ok, and we generally start the big motor up when we get hung-up to back up more quickly and free the snag.

For those who might be concerned with hydrogen and oxygen being released during the charing process, most new batteries are sealed, don't require water to be added, and don't release these potentially explosive combination of gases into the air.

In the event of a loss of the big motor, I should be able to run quite a ways electrically to get home on an inland lake:

440 a-h x 65% = 286 ah, and 286 a-h / 30 amps = 9.5 hrs, and

9.5 hrs @ 1.5 mph = 14 miles. The numbers can be re-approximated, but the results come in about the same. Ok for Shasta Lake, but I wouldn't want to come home from the Farallones on it. For that, we'll add the kicker back in the equation.

Let me know if you have questions. There's more to this than what I have discussed here. Joe.
 
Had the rig on my Trophy 1802 and you are target on for the real quite stealth mode of trolling. We trolled 4-8' of water for crappie in the freshwater lakes and my take was ALWAYS higher than those in the same location trolling with small gas motors. We all used the same baits, same lines, fished the same "lanes"... If they caught 5-10, I'd catch about 8-14... and more larger ones too. We did one time test running parallel, with me in the center and two gas powered on the outside to "spook them" into the center lane... Yes, I really caught more that time, but it could have been just luck or the brand of beverage my boat had on it. We figured that out on the last day of a trip that the motor worked. I did have a problem with longevity of the motor. They had not gotten the electric motor to seal good enough to handle the "fast forced" water during take off and slow down. But, that was about 10 years ago and I feel sure Mokota I think was the brand, has fixed that. A side note is they did refund the purchase price 100% after the 2nd try. Hind sight, we really only stealth trolled about 2 to 3 weeks out of the year and mounting and dismounting could have been a bit of effort that could have saved the motor for those few weeks of the year. Good luck and keep us posted..
 
Sea Wolf.... I had considered that type of setup and always thought one could get a small Honda or Yamaha generator to take aboard in cases where one might need to use an auxilliary for long distances. That way, no need to carry the extra weight on small water, but easy to carry a small gen set aboard on the bigger stuff. Thanx for sharing the pictures, John
 
Byrdman- Thanks for the reply! The stealth feature is no doubt real and effective as we recently caught limits of 3-5 1/2 lb trout at Eagle Lake here in California a couple of weeks ago with the new set up. When fishing with my 12 ft Gregor aluminum boat, I always used to use the motor to lay out the line, then row down wind as silently as possible, slowing to let the troll drop into suspected holes and ledges that held fish. Seemed like rowing was at least twice as effective as trolling with the motor on small lakes, both because of the quietness, and the slower speeds attainable. This new set up is particularly relaxing as well, as it gets rid of the constant putt-putt distraction. See you at the SBS and SBC next month!

drjohn71a- Yeah, that small generator sounds attractive. We once rented a 17 foot square ended canoe on Maligne Lake in Jasper National Park in Alberta with a trolling motor and two giant 12 volt batteries in series. Ran about 8 hours before the inevitable. They wouldn't let you use a gas motor on the lake, but used a diesel tour boat for tourists, and a 25 ft Thunderbird to transport fishermen into the reaches of the lake where they rented you the electric set up on a canoe. A generator in the canoe would have increased the range to days until the gas supply ended. No gas or oil in the water, so I think it would have been ok.

I subsequently thought about a similar set up for use down here for trout trolling. Could have even used a partially gutted small retractible keelboat (sailboat) that would have held a ton of batteries, generator, solar cells, wind generator, and all the galley and sleeping facilities. The long, sleek sailboat hull would be very easily driven, and a great floating camper to boot.


For a generator, one can't beat the small 1000 or 2000 watt Hondas or Yamahas. They're four cycle clean, and run only at enough rpm to generate the power needed, turning the 12 volt output into 120 via an inverter instead of generating the 60 cycle AC through engine rpm. For this, of course, you'd only need the 12 volt output.

On a CD-22,TC-24, or CD-25, a permanent place to mount the generator would be a great solution to moving it around all the time in the cockpit, on the transom, etc. With a little ingenuity, a large cooler could be mounted on a bracket on one side of the transom exterior with the generator inside and equipped with a gas feed line, exhaust port, and blower intake and exhaust ports for cooling. Some detailed sealing for operation in rougher water would of course be necessary. Probably couldn't be sealed well enough to be used in rough salt water. With a 2000 watt unit and the right RV style air conditioning unit on the cabin roof, one could have a first class heat and humidity proof mobile summer cabin on the water!

Fun to speculate! Joe.
 
SeaWolf: Yep, catches were larger too..... I guess there is a reason that bigger fish are bigger....they don't eat things with a gas motor runing in front of them??? :smileo Especially nice when laying out on the front deck just stairing up at the stars with no noise at all except the slap of the water against the boat.
 
Just to update this thread, I've just in the past several weeks added a Honda EU1000i generator to my set up. It sets on the top of the cooler at the rear of the cockpit, held firmly by a bungee cord attached to two rod holders on the motor well inner edge. The exhaust points backward into the well so the carbon monoxide goes into the motor well and out.

After about 5-6 hours of electric only trolling, I usually start up the generator and let it recharge the 2 group 27's, for a half an hour or so.

I've also up-graded the on-board battery charger to a four stage 40,20,10, and 5 amp unit that automatically tapers the charge and can charge all four simultaneously from the 120 volt output of the generator. The built in 12 volt battery charging circuit on the generator is limited to 8.3 amps.

All of this, of course, allows me to run the electric trolling motor continuously to get home should the need arise if the big motor were to quit. Joe.
 
Here's a respone to a series of very good questions in a private message that I wanted to post so that I wouldn't have to answer the questions from scratch again later!

Joe,

Take me through your setup. You have batteries two and three under the rear port dining seat. Where's the first battery? Do you have 4 total? Three to run the troller and other things and one for the engine only? I'm going to try and duplicate your setup. Also, what about a solar panel on the roof to help with recharging? I'm not that crazy about a generator on board. What size troller do you recommend? I'm lake fishing at Almanor, Bucks, Eagle. Thanks for the help!
..........

Have you looked at the pictures in my C-Brat album? They have captions under them that have a lot of this information, and the pictures are a lot easier that verbally describing everything.

There are 4 batteries on board, all group 27's.

Two came with the boat when I bought it. One is in the starboard lazarette, and another one in a box on the floor between the gas tanks. These two have a 1,2,all, off switch to control them in the lazarette. Some people have 2 in the lazarette, but my boat had an oil tank for the big motor in there with the first battery, so the second one was mounted on the floor by the original owner.

I decided to add two more for plenty of power for the MinnKota EM-42 trolling motor. I put them in boxes in the compartment under the FORWARD dinette seat, mostly to hide them out of the way and also balance my weight when fishing alone. There's another 1,2,all, off switch on the side of the compartment you can see in the pictures. The 6 gauge wires from the switch lead out of the compartment through a hole in the bulkhead, then up over the v-berth companionway (doorway), and tie into the 6 gauge wires on the windlass controls behind the helm. These windlass controls are connected to the power out side of the 1,2,all, off switch in the back of the boat. Thus my new wiring had to only go to the back of the helm, not all the way to the rear of the boat, since wires already led forward to the windlass, and I could simply tie into them.

The electric motor is mounted with four bolts on top of the cavitation plate of the big motor. I wanted a hydrofoil of some type, so I chose an aluminum "The Edge" type from Cabela's. It's about $50 + shipping, and mounts under the cavitation plate rather than on top of it. I think the Permatrim foil would also work for this application. You can align the two to match hole patterns pretty much.

The main pulse modulation/power box for the motor is mounted in the starbord lazarette behind the battery, with the power supply wires tied into the original 1,2,all,off power switch's motor supply terminals. The second set of wires, out to the electric motor, exit the motor control's rubber boot to the engine well, then down to the motor itself. The wires to the speed/direction/on-off switch lead forward along the starboard gun whale to the motor controls area at the helm station, where they're mounted between the controls and the helm seat, being screwed into and mounted on the wood panel that is under the seat and on top of the ice box.

A couple of discussion points:

I choose the port dinette storage area location to balance my weight when fishing alone. The two batteries together weigh about 125 lbs! If your boat is already balanced well, you might chose to put one there, and one under the galley station. In that case, you'd have to move the switch over to the helm area to do so. If you don't use the Porta Potti, you could mount both of them in that area after removing the P-P unit to your garage storage. I'd suggest you check the boat balance with the unmounted batteries, bricks, or a couple of 5 gallon water buckets before you permanently mount them.

The engine mounted trolling motor requires 13 inches of water above the cavitation plate so it's prop will stay covered with water. I have to tilt the motor down all the way to keep mine submerged. Take a ruler and measure from your plate to the water level at rest for your boat as indicated by the oil and/or scum line on the transom. If it's less than 13 inches, the little plastic prop will cavitate and make bothersome noises!

You could also mount the two extra batteries in the stern, say in the port lazarette, this would help cover the little prop with water, holding the stern deeper in the water. I would have done this except I didn't want to give up the livewell built in there.

One more thing- even with the 6 gauge battery cables, there's a voltage drop from the front batteries to the transom. The amount depends on the amperage. At 36 amps (full throttle, load all on front batteries), the drop is 0.72 volts. At 20 amps, it's only 0.4 volts, and at 20 with half the load on the rear batteries (all batteries "on"), only 0.2 volts. But if you try to start the big motor with a draw of 100 to 150 amps on the front battery alone, the voltage drop at that amperage is 2.0-3.0 volts! So don't start your big motor on the front batteries alone, use them in parallel (all in the "on" position). The lower voltage doesn't turn the motor as fast to start, and results in more heat being generated in the starter motor. But as far as the trolling motor is concerned, they are fine up there as long as you use them in the same parallel fashion.

A solar panel is a nice idea for recharging the batteries over a longer time period, but will not keep up with the electric motor in continuous usage. The typical panel, at a cost of about $600, will produce 75 watts, or about 5-6 amps of power, while the trolling motor will be consuming somewhere between 15-36 amps, so you'd need 3 to 5 hours of charging for every hour trolling.

That's why I added the Honda EU 1000i generator and a 40 amp 4 level automatic multi- stage charger to be able to keep up with the discharge rate after the first 5-6 hours or so. Actually, because we run the big motor some to reposition the boat, we start recharging after 5-6 hours, and at that point can run the generator about 20 minutes for each hour the trolling motor is used, although this is somewhat dependent on the wind strength, etc. I'll have to look up the brand and specific model of the charger, but it's the best one Wall Mart handles and costs about $90.

So how much does the system cost? (approx.)

EM-42 trolling motor = $550
2 gp. 27 batteries = $110
1 battery switch = $30
2 battery boxes = $25
6 gauge wire = $40
terminals = $15
battery charger = $90 (you may not have to add this)
________________________________
Subtotal $860

Honda Gen. $625
______________________________
Total with Gen. $1485***

***BUT REMEMBER THAT ADDING THE GENERATOR OPENS UP A WHOLE NEW WORLD OF POSSIBILITIES FOR OTHER GOODIES ON BOARD IF YOU WANT TO OPEN THAT DOOR!!!

I set mine up for just under $1000 total by buying most of the components on ebay, except for the generator, which I bought very slightly used for $500 locally.

I'll look at the pictures in my album and add more if I can see that any are necessary. Be sure to read the captions under the pictures.

Good Luck! Write if you have further questions!! Joe.
 
I read your messages with great interest and after a lot of consideration purchased a new Minn Kota engine mounted trolling motor model # RT80EM to mount on to my E-Tec 90 h.p. outboard on my 1985 22'-0" C-dory angler. I do have however some reservations and I suppose second guessing my decision re my selection of the electric motor size. I'm going to use the motor in saltwater around Vancouver and the Gulf islands. In your opinion do I have sufficent power? I will be installing a third group 27 battery in order to provide sufficient power but my question relates mainly to thrust. I see that the suggested size for this length of boat is a motor with 160lbs of thrust. My decision to purchase the RT80/EM was based on the "weight" of the boat and the "hull design" thus ignoring the requirement based purely on "boat length". I'm hopefully going to use this electric motor primarily for ocean fishing. I do have a 2004 9.9 Johnson but like you I was trying to avoid the hassle of useing the arm to connect the main engine with the kicker, being able to safely handle the boat from the helm. Naturally I won't be fishing in rough waters but again, do you think it will be enough to move the boat in a slight chop? Any advice or suggestions would be greatly appreciated. Regards, Tom McIntosh
 
I really like the idea of an elec. trolling motor, since I was planning on adding a small quiet generator anyway. This is really looking like the way to go. It'll be interesting to see other replies over time. Thanks.
 
Tom McIntosh":3m1byc72 said:
I read your messages with great interest and after a lot of consideration purchased a new Minn Kota engine mounted trolling motor model # RT80EM to mount on to my E-Tec 90 h.p. outboard on my 1985 22'-0" C-dory angler. I do have however some reservations and I suppose second guessing my decision re my selection of the electric motor size. I'm going to use the motor in saltwater around Vancouver and the Gulf islands. In your opinion do I have sufficent power.

I will be installing a third group 27 battery in order to provide sufficient power but my question relates mainly to thrust. I see that the suggested size for this length of boat is a motor with 160lbs of thrust. My decision to purchase the RT80/EM was based on the "weight" of the boat and the "hull design" thus ignoring the requirement based purely on "boat length". I'm hopefully going to use this electric motor primarily for ocean fishing. I do have a 2004 9.9 Johnson but like you I was trying to avoid the hassle of useing the arm to connect the main engine with the kicker, being able to safely handle the boat from the helm. Naturally I won't be fishing in rough waters but again, do you think it will be enough to move the boat in a slight chop? Any advice or suggestions would be greatly appreciated. Regards, Tom McIntosh
Click to expand...

Tom-

Your RT80EM has 80 lbs of thrust, much more than my EM-42. I can troll in moderate wind and chop on an inland lake. Best to troll with the current and wind for ease, and most folks say that's much better fishing strategdy too!

Only trial and experience will demonstrate to you what the range of thrust you have will accomodate in your specific trolling style and various conditions. You just have to give it a try and find out with real time experimentation.

I do think the Minn Kota recommendations for thrust are pretty high, just to cover all their bases (and maybe sell bigger units!)

Your RT80EM requires 24 volts, not 12. Are you set up for this with two 12 volt batteries in series? How about figuring out a charging circuit? One of the reasons I chose the RT42EM was to avoid the 24 or 36 volt requirement of the larger units, just to keep things simple.

Here a news release by MInn Kota regarding these Engine Mounted Trolling Motors.

Give 'er a try and let us know how it works out!

Good Luck!

Joe. :teeth
 
I wonder where Joe got this 40 amp battery charger for $90!

You do need a substantial battery charger if you are going use a trolling motor--all in all, the gas engine is more effecient, than running a generator, thru a battery charger, to batteries, to a trolling motor.

Not sure what the power requirement of the battery charger, but I do know I have to cut off my 40 amp battery charger when I start my generator and turn on the water heater (1500 watts). (Eu 2000 generator)

I might consider a 50 amp battery charger if I was going to run a trolling motor which pulled 35 to 40 amps. That way, eventually you should charge up the battery...

My experience with the trolling motor is limited to the Golf carts, charaged from shore, and running a 43 lb thrust trolling motor in a lighter boat, which I use regularly.
 
thataway":3288trma said:
I wonder where Joe got this 40 amp battery charger for $90!

You do need a substantial battery charger if you are going use a trolling motor--all in all, the gas engine is more effecient, than running a generator, thru a battery charger, to batteries, to a trolling motor.

Not sure what the power requirement of the battery charger, but I do know I have to cut off my 40 amp battery charger when I start my generator and turn on the water heater (1500 watts). (Eu 2000 generator)

I might consider a 50 amp battery charger if I was going to run a trolling motor which pulled 35 to 40 amps. That way, eventually you should charge up the battery...

My experience with the trolling motor is limited to the Golf carts, charaged from shore, and running a 43 lb thrust trolling motor in a lighter boat, which I use regularly.
Click to expand...

OK, Bob, here's the LINK to the battery charger. Mine is a slightly earlier model with 2/10/20/40 amp charging rates. Yes, it isn't a marine unit, so it isn't 100% spark protected, but I keep it up in the v-berth behind the helm station where we don't anticipate any gasoline or propane vapors.

The Honda EU 1000i generator can drive the unit at the 40 amp output level, and can keep up with the electric consumption of the trolling motor.

Joe.
 
Thanks Joe,
Interesting charger (and several others on the site--one 75 and one 100 amps (probably boast rather than charge).

The pulse battery minder type of desulfator is a nice feature.

But..I am not entirely sure I would leave this turned on in my boat all of the time--permently installed. I guess I am concerned about fire and overheat risks. I may have to buy one to try out, and see how it works...

Thanks.
 
thataway":14aui24b said:
Stuff clipped.....

But..I am not entirely sure I would leave this turned on in my boat all of the time--permently installed. I guess I am concerned about fire and overheat risks. I may have to buy one to try out, and see how it works...

Thanks.
Click to expand...

Bob-

Thanks for the comments!

I usually don't leave the charger on except when I'm on board and on shore power, or when I'm running the generator. I don't let the four group 27's ever get discharged very far. Probably would be better to routinely run them down a bit and recharge!

Joe.
 
Actually lead acid or AGM batteries are not like the Ni Hy or Nicad and will have longest life the lest they are discharged--ie if each discharge is 20% it will last much longer than each discharge is 50%.

Regards.
 
Hi Seawolf!

You helped me years back with my trolling system. It has worked pretty well, but I need new batteries and wondering what you use. I use 2 12 volt sealed batteries wired together to run my 24 volt trolling system.
 
Lane":20b2cay2 said:
Hi Seawolf!

You helped me years back with my trolling system. It has worked pretty well, but I need new batteries and wondering what you use. I use 2 12 volt sealed batteries wired together to run my 24 volt trolling system.
Click to expand...

Lane-

I know some will disagree, but I use Costco or Walmart batteries and do just fine with them, getting 5-6 years of service before I routinely replace them.

I do very religiously re-charge them, and try not to discharge them too deeply, never more than 50%.

I also use them in my Sea Ray, where they do not get as carefully managed, as sometimes more time elapses between re-charging than I would like, and the batteries drop down into voltages (>12 volts!) that are hard on them, but they don't seem to mind too much (!)

I personally can't see paying 2-3 or more times as much for sealed high-end batteries, myself, either. The boats are not airplanes doing acrobatics, nor are they in sealed living compartments without ventilation.

Simply put, the lead-acid deep cycle batteries are the most economical form of readily available stored amp-hours available.

I make my choice on price and return/warranty policy, though I've never had to return any.

Call me Mr. Cheapo if you want, but I'd rather spend the money saved on something else!

On a positive note, we have an Interstate deep cycle marine battery in our pontoon boat that came with the 2005 boat when new that is still going strong!

On the more negative side, I can't seem to ge the starting battery in our motor home to last more than a year or so, even with a cut-off switch installed. Shows you what storage with little and infrequent charging can do to a "Starting" type battery with thin plates designed for high amperage output. Probably should be removed from the vehicle and take home to the workbench to be monitored and re-charged frequently!

Batteries are really no mystery, they just require careful care and frequent re-charging to keep them from self-discharging and certain death!

Good Luck!

Joe. :teeth :thup
 
I have used a variety of batteries. The A G M inside the cabin. Regular flooded lead acid batteries for most applications. Generally they last at least 4 to 5 years.

I rarely discharge to a voltage of less than 12.2 volts. I also monitor the amperage draw.
 
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