In short, you probably want a 60″ (152.4 centimeter) shaft for your trolling motor if you plan to mount your trolling motor on the bow of your pontoon boat, but there are certainly many things to be considered before applying that general rule. Most pontoon boats could really even get away with a 48″ shaft, but it is certainly better to go a little longer than you need. 55″ and 60″ trolling motor shafts are the most common for pontoon boats.
General Rule for Selecting Shaft Length
The rule that I usually go by is to take the distance from where the motor will be mounted (usually the top of the deck) down to the water. Then add 18 to 22 inches (46 to 56 centimeters).
When deciding what shaft length of trolling motor you need for your pontoon boat, the first thing to decide is where you’ll place the motor. You could place it on the bow, which is most common. Another option would be in the rear. Last, you could mount your trolling motor right on the main motor.
There isn’t a right or wrong in making this decision, but there are a few factors to consider.
If you place the trolling motor on the bow of the pontoon boat, you will likely need a slightly longer shaft length, as the bow is almost always higher than the rest of the boat, even with attention paid to balancing.
Some pontoon boats leave a generous space in front of the fencing on the bow for walking around, and mounting a trolling motor. Other pontoons don’t have any space on the bow between the fencing and the front edge. Depending on what style you have, you may need to make significant changes to your boat before doing a bow mount.
If you want to bow mount your trolling motor (after all, it’s easier to drag a rope than it is to push it) then you may need to cut and reshape the front gate on the bow of your boat. This can be done without looking ugly or involving too much work, but it is a project that needs to be done.
If you do not want to pay to have alterations to your front gate (which are quite common and inexpensive), you’ll probably want to place your trolling motor on the rear of the boat, which is lower and would use a lower shaft length on the motor.
3. Water conditions
If you’ll mostly be on lakes or rivers that do not have excessive waves, then you can usually get away with a slightly shorter shaft length. On larger bodies of water where chop in the water can sometimes be extreme, then a longer shaft length will be required.
Err on the Side of Too Long
The great majority of fishermen wish they had gotten a little longer shaft length on their trolling motor. It’s pretty common to go too short. Without question, it is worse to get too short of a shaft than too long of a shaft, but also keep in mind that if you get too long of a shaft, it can be cumbersome to have it stick up too high on the deck.
How to Measure Shaft Length
The trolling motor shaft length is measured from the bottom of the head, down to the top of the propeller housing. If you measure this incorrectly, you’ll get the wrong size, so be careful. Fortunately, any decent trolling motor will advertise the shaft length right on the package, so you shouldn’t have to worry about this, but knowing the distance will give you a better visual of how far down the shaft sticks from the bottom of the boat.