I've never owned a boat before, but I'm about to buy a Tracker 1436 jon boat. I usually fish on lakes that allow electric only. I found a good deal on a Minn Kota Endura 46# transom mount motor. Would that be enough power to move the boat with two anglers and gear? Thanks.

46# Thrust is definetly enough for a jon boat.

I fish primarily in electric only reservoirs around Baltimore MD and yes that 46 will push you but VERY slow.  The rental boats that are available are LOWE 1448 with a 36 lb Minn Kota.  The reservoir is Loch Raven reservoir in Cockeysville, MD and it'spretty small.  The 36 lb will get you from the dock to either point (not both) in about 1 hour and 45 mins.  It's about 1.5 miles total distant from dock to point.  When I go out ad rent I go with a buddy (about 245 lbs) and I am about 190 lb. Two or three rods each with normal amount of tackle.  We need two batteies and can only go to one side.  Using the other battery to get back.

Last time I went I used my buddies 76 lb and rolled.  I could keep up with most 60 volt Ray Electrics on the lake although they are much bigger boats (18 - 20 foot).

So I would recommend going higher on thrust and buying 4 batteries for a 24 voltmotor.  2 to go and 2 to come back.  If the lake you fish on is the biggerside you will spend most of your time getting to where you are going.  The higher thrust is more $$ but well worth it.

I fish in electric onlyreservoirs 3-4 times a week and rent 2 of those times where I am using that 36 lber.

Just my two cents but I would go bigger and go 24 volt with 4 batts.

I fish out of an electric kayak and have a 40 lb thrust 12v motor. My boat will go the same speed with a 28 or 50 lb thrust motor. The reason has to do with how the motors are made. All trolling motors are permanent magnet motors and their speed (revs/min) is only a function of voltage applied. Thus the motor will run at the same rpm with the prop in or out of the water. In a light boat (mine is 250 with me in it) the 28 lb motor will get it up to hull speed (4.2 mph) with the motor drawing 28 amps. The 50 lb motor on the same boat also has a max speed or 4.2 mph and also draws 28 amps. This is because both motors have a prop with a 4 inch pitch ( prop moves 4 inches thru the water with each revolution) and both are spinning at the same RPM. Thus both are doing the same ammount of work. The battery current draw was the same for each motor at hull speed (4.2 mph ). I use a 40 lb motor because at full throttle it is operating at about half of its rated power and it will last longer than the 28 lb motor.

A heavy boat may not reach hull speed with a smaller motor due to prop slippage in the water, and the bigger prop of a 40-50 lb thrust motor will help. Of course the bigger motor will draw more battery current at the higher boat speed.

Hull speed is determined by the length of the waterline of the boat. It can be calculated (in MPH) and is 1.54 times the sq root of the water line length (in feet). To push the boat at twice the hull speed requires about 6-8 times the power needed to get it up to hull speed. Thus going faster consumes a huge ammount of power and depletes your batteries quickley. I think your boat will move along at 4-5 mph with one passenger and 3-4 with your partner aboard. going faster will consume more power than it is worth.

When choosing a motor you can help a lot by finding one with a continuously variable (c/v)throttle. Some call it a 'digital throttle' and others have another name. The motors with a 5 speed forward/3 speed in reverse scheme, control the speed by inserting a resistor in the power lead to slow the motor. A lot of energy is wasted in these resistors. For example at half speed, the C/V motor will use half the power the 5/3 motor is using. And at slower speeds the advantage of the c/v motor is even greater. Both motors will use the same ammount of power at full throttle. Unfortunatley the incrimental cost of the C/V motor is almost $200..

The advantage of a 24 v system is that you get the same power a 12 v system offers with half of the battery current. Of course you need 2 batteries. Not much help there. However motors are available with increased static thrust in 24 v versions and the voltage drop across the boat wiring is reduced due to the lower current. It will help a heavy boat, and make little or no differenct to a light boat.

Keep in mind that it takes about 750 watts to equal one HP, and a 50 lb motor will consume 11v x 50A = 550 W at full throttle, or about .75 HP. This estimate is based on a motor that draws 1 amp per lb of thrust, which is typical of 12 v motors, and a 1v drop in the boat wiring. So there is not a lot of power to work with, and you will have to adjust to life in the 'slow lane'. One way around this is to use a gas motor to get you to your fishing hole and an electric to fish, but you indicated you fish in an electric only environment.

So what to do? A 24 volt system will require 4 batteries if you want to go out on one set and return on the other. Batterys are about 50 lbs ea. Thus a minimal 24 v system will have 200 lbs of battery, where as a 12v system will be 100 lbs, but will go half as long.

Batteries are rated in ampere/hours (A/H) . A 100 ah battery will deliver 100 amps for 1 hour, 50 amps for 2 hrs, 25 amps for 4 hrs and so on. It sounds like your boat will use 40-50 amps at full throttle, so you might last 2 hours at full throttle and travel 2 x 4.5mph or 9 miles before you start rowing. With a c/v motor you could reduce your power to 1/2 and run for 4 hours, and your boat would slow to about 3.5 mph(not 2.25 mph). Your range would increase to 3.5 x 4 =14 miles. So operating at full throttle will save you a little time, but cost you a lot of range.

Well this is my experience in operating an electric boat. My little kayak has a range of about 20 miles and I have not yet used up a full battery charge in a day. If I run at 3.5 mph and paddle assist, I can almost double that range. Keeping the boat light is the best way to go further. I hope this has been helpful to you. :-/Good luck and carry your PFDs with you.

Nice write up sneaker.  I learned a few things right there.  Have you considered getting a higher pitch prop for your trolling motor or are you already at hull speed.  

Fish MD,

Something sounds wrong with your distances and times.  I cover a mile in 15 minutes with a #35 in a 10 ft jon about 50 lbs lighter load than you.  Measured it with Google Earth.

Hi surfer

Well 15 mins per mile is 4 MPH so we are not different by much. I do run a higher pitch prop. I took one of the 3 bladed 7 inch pitch props from a Tohastu 3 hp motor and machined and bushed it to fit the MK40 electric. The MK40 with the 3 blade prop is about is about 25% more effecient than the same motor with a 2 blade prop on my boat when running at 3.5 mph. It also provided far better boat control when in reverse than the 2 blade prop. It is worth doing if you have a light boat. For speed I use a GPS which gives the mph to +- 1/10 mph. But you have to run it at a constant speed for a min or so to allow the gps to average out its calculations. I get the effeciency by comparing the motor current between the 2 props. A bit of work but worth it.

Measuring motor current is not difficult. Turns out that the resistance of a 12 inch piece of #14 gau wire is .001 ohms. I insert (solder) it into the negative lead of the motor and monitor the voltage drop across the 12 inch wire segment with a digital voltmeter. The dvm is set to the 3v scale and indicates the motor current at 1 millivolt /amp. With this set up you can learn a lot about how well you motor /prop is matched to your boat. You can get an inexpensive dvm at radio shack for about 25 bucks.

Most trolling motors use a larger diameter (10+inch diameter) 4 inch pitch prop to provide more static thrust. So if your boat is tied to a dock, the MK40 will generate 40 lbs of thrust. The 7 inch pitch prop generates only 28 lbs of thrust on the same motor because its diameter is only 7.5 inches. But when the boat is moving, the forward

motion of the boat reduces the remaining thrust from the motor.

Imagine being towed by another boat at 5.6 mph and your electric is running at full speed (1500 rpm). The thrust of the 4 inch pitch prop turning 1500 rpm would be 0, because the water flowing thru the prop is already moving at the same speed as the pitch x rpm of the prop and the prop is not accelerating the water at all. If the prop had a pitch of 7 inches, It would accelerate the 5.6 mph water to  9.9 mph generating about 10 lbs of thrust.

If the hull speed of the boat is 4.5 mph, the additional 10 lbs of thrust will add only a few 10ths of an mph to the boat because it takes a lot of power to get a boat over its hull speed. However at low speeds where the drag of the boat is low (3 mph) the motor with the 7 in pitch prop can turn slower and thus use less power. This scenario only works on a light boat with relatively low drag. On a heavy boat thrust requirements are much higher and the 2 blade prop with lower pitch will be more effective. Since trolling motors are often used on heavy boats (bass boats ect) the 2 blade prop is a good compromise.

Calculating the drag/thrust/pitch/diameter effects on the motor and boat is beyond my abilities, so I have to do the work of changing the prop and make the measurements. There is no ideal prop for all boats, so I have to tinker around looking for the best solution for my boat/load situation. When the fishing is slow it gives me something to do.....