Tag Archive: 8 HP

How much HP for my S4 skiff’s outboard motor?

This article summarizes research performed by Captain Larry Jarboe, as well as inputs from Wavewalk dealers and S4 clients. Its purpose is to answer a frequently asked question (FAQ) from prospecting clients, which is “What outboard motor should I choose for my S4?”

The answer is that the outboard motor you should choose for your S4 depends on two factors, which are

  1. How much power you need
  2. How important is the motor’s weight for you

And there is a trade-off between power and weight, namely that the more powerful the motor, the heavier it is, and the harder it could be to carry it.
In any case, the motor should be a 20″ log shaft (L) model, and not a 15″ short shaft (S) model.

2 HP outboards

Outboard motors in this class weigh around 30 lbs, which makes them fully portable even for a user who’s not very strong. A 2 HP motor can propel an S4 skiff with one person on board at speeds up 8 mph, even in choppy water. This speed would decrease as the boat is required to carry more passengers on board. S4 owners who tested such motors with their S4 skiff reported that the boat felt under powered, which means that they felt like going faster, but the motor lacked the powered required for this. For this reason 2 HP motors are not popular with S4 users. Another reason for their lack of popularity is the fact that being air cooled makes them noisier than water cooled motors.

3.5 HP outboards

Outboard motors in this class weigh around 40 lbs, which makes them still portable, but less so than 2 HP motors. A 3.5 HP motor can propel an S4 skiff with one person on board at speeds up 14 mph, even in choppy water, and it can propel the boat at 12 mph with three passengers on board in  moving water. This size motor is the most popular among S4 and W700 users, as it offers a good trade-off between power and weight for people who must lift the motor or carry it by hand over long distances.These motors are also less expensive than bigger ones.

6 HP outboards

Outboard motors in this class weigh around 60 lbs, which makes them portable only for very short distances, and not for everyone. A 6 HP motor can propel an S4 skiff with one person on board at speeds up 18 mph, and it can propel the boat at 14 mph with three passengers on board. 6 HP motors are the second most popular motors among S4 users.

8 HP outboards

Outboard motors in this class weigh around 80 lbs. At such weight, these motors can no longer be considered as portable, and the only reason to use them is the fact that they are offered with electric ignition, which eliminates the need to start them by pulling a cord. The S4 outfitted with an 8 HP motor performs well in choppy water, but it could feel over powered for an inexperienced driver, which should avoid using such motors with their S4. Heavy users may benefit from driving with a U-jointed tiller extension, in order to move some weight forward from the stern to the middle of the boat.

6.5 HP mud motors

Mud motors are bulkier and heavier than regular outboard motors. A 6.5 HP mud motor weighs around 80 lbs, and it’s not portable. The reasons you’d want to use such a motor instead of a regular outboard of similar power are if you need to go in very shallow water (skinny water) and mud, and if you fish or hunt in water with plenty of vegetation and underwater obstacles. The S4 performs very well with a such a mud motor. We do not recommend using less powerful mud motors because typically, these motors require more power than regular outboard motors do.

Electric outboard motors

Some electric trolling motors are described by their manufacturer as “outboard motors”, namely comparable in power to small outboard gas engines. If you consider such electric motors, we recommend remembering the laws of physics, and applying the formulae for Kilowatts to Horsepower conversion, which are:

  • 1 KW = 1.34 HP
  • 1 HP = 0.745 KW







Maiden voyage with my Wavewalk S4 and an 8 HP Mercury outboard motor

By Paul Partridge

Rhode Island

It has a 3.5 gallon tank that fits perfectly in the 9 inches wide gunnel, and a hand bilge pump.
The maiden voyage was extremely lot of fun. Took it out by myself.
The outboard had a 9 inch prop, and it went way too fast. I’m going to calm it down. I’ll put a smaller diameter propeller on it, so it doesn’t go as fast. I think it was going between 5 and 6 miles an hour at idle.
It was pretty choppy but the boat handled it really well. A little scary at first, then I fine tuned it and brought the trim down.
I just ordered a handle extension.


Wavewalk S4 with DIY mounting plate and an 8 HP Mercury outboard motor


8 HP Mercury outboard with a 9″ propeller