Another important trade-off that you should be aware of is related to propellers: High pitch propellers are designed to deliver more speed and less torque (thrust, push force), and they work best with lightweight boats such as the S4, while low pitch propellers are designed to move bigger and heavier boats at lower speeds, but they should not be used with lightweight boats such as the S4, since they might make the motor run at a too-high RPM.
Outboard motors manufacturers’ websites say that (quote) “UNDER NO CIRCUMSTANCES SHOULD YOU EVER USE A PROP WHICH WILL ALLOW YOUR OUTBOARD TO OPERATE ABOVE THE OUTBOARD’S RECOMMENDED MAXIMUM RPMs“. This means that you should avoid using propellers designed for use with very heavy boats, namely propellers in the low-pitch range.
Note that 20″ long (L) propeller shaft motors typically ship with propellers that are not necessarily optimal for very lightweight boats such as the S4. For example, the 6 HP 20” long (L) outboard from Tohatsu often comes with a medium range 8 pitch propeller, which is fine, but mounted on the S4, such a motor could drive the S4 12% faster if outfitted with a 9 pitch propeller.
Propeller pitch information is available on outboard manufacturers’ websites.
Since the S4 is a very lightweight boat, you should preferably outfit the outboard motor for it with the highest pitch propeller available for it.
Diameter – Don’t try to use a propeller from a small outboard with a bigger outboard, or vice versa.
SMALL PORTABLE OUTBOARD MOTORS
For the S4, small size means a highly portable but under-powered outboard motor.
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 power 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 these small motors noisier than bigger, water cooled motors.
Propeller pitch – The Honda 2.3 HP comes with a 4.75 pitch propeller
MEDIUM SIZE PORTABLE OUTBOARD MOTORS
For the S4, a medium size outboard motor means powerful enough but still portable. Motors in this 3.5 HP to 6 HP range are the ones we recommend for most users.
3.5 HP outboards
Outboard motors in this range 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 to 11 mph, even in choppy water, and it can propel the boat at 8 mph with three passengers on board in moving water. This size motor is 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.
Propeller pitch – For their 3.5 HP motor, Tohatsu recommends either the 7 pitch (Plastic) or 6 pitch (aluminum) propellers, for lightweight boats such as the S4 (under 500 lbs). We say get the 7 pitch propeller, unless you think that you need the more durable aluminum propeller.
6 HP outboards
Outboard motors in this range weigh around 60 lbs, which makes them portable only over short distances, and not for everyone. A 6 HP motor can propel an S4 skiff with one person on board at 17 mph, and it can propel the boat at 12 mph with three passengers on board. 6 HP is the second most popular motor size among S4 users.
Propeller pitch For their 6 HP outboard used with lightweight boats up to 500 lbs (such as the S4), Tohatsu recommends their 9 pitch propeller. The 8 pitch propeller would work too, especially if you intend to have the boat fully loaded, so that it would weigh over 500 lbs in total.
BIGGER OUTBOARD MOTORS
8 HP to 10 HP outboard motors are too heavy to be carried by hand, and they may be too powerful for inexperienced drivers to use safely. However, some of them come with electric start instead on manual start, which is a nice feature. They also come with an alternator that can serve to power small electric devices on board.
8 HP outboards
Outboard motors in this class weigh between 65 and 80 lbs. At such weight, these motors can no longer be considered as portable, and the main reason to use them is the fact that are offered with electric ignition, which eliminates the need to start them by pulling a cord. People who like driving at high speed may prefer these motors to less powerful ones. 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 towards the middle of the boat.
Note that these bigger motors don’t come with an integrated fuel tank, but this isn’t necessarily a problem, since external fuel tanks can fit inside the S4’s hulls.
9.8 HP and 9.9 HP outboards
We tested the S4 with a 9.8 HP Tohatsu and a 9.9 HP Yamaha outboard, and it worked well. Practically, this class of heavier and more powerful motors offers no advantage over smaller motors unless you’re a speed fan, and you’re also capable of driving small boats safely at such speeds. To those who want to take the risk of overpowering their S4 with such big motors, we recommend reinforcing the mounting plate.
This video shows an S4 powered by a 9.8 HP Tohatsu motor filmed from the deck of an S4 powered by a 5 HP Tohatsu motor:
Currently, the S4 is the world’s fastest designated kayak. The 17 mph kayak speed record was achieved by Captain Larry Jarboe, of Key Largo, Florida, in his S4 outfitted with a 9.8 HP Tohatsu outboard motor.
We recommend that inexperienced drivers avoid using high power motors with their S4. Instead, they should pick a motor within the 3.5 HP to 6 HP range.
OUTBOARD MOTOR BRANDS
After years of testing motors and getting input from our clients, we can recommend all Japanese brands, namely Honda, Suzuky, Tohatsu and Yamaha. Mercury is a Tohatsu brand, and the small, portable motors offered by Evinrude are made by Tohatsu. Motors from all these brands are good, and your decision about which motor to use with your S4 should be based on factors such as price, weight, features, availability, warranty, etc.
A kicker motor is a name given to any outboard gas motor used on a big boat for trolling, or as a spare motor, and for positioning and driving sailboats over short distances when sailing them is not possible. Being used on bigger boats, kickers often feature a 20″ long (L) shaft, which is the right size for the S4, but the propellers used with them are typically low-pitch models that are not optimal for lightweight boats such as the S4. If you buy a kicker, check its propeller, and if it’s not a model with the highest pitch that the manufacturer recommends for lightweight boats, replace it with such a propeller.
Mud motors feature a surface drive, and they offer a huge advantage to people who want to drive in very shallow water, mud, water with many underwater obstacles, and water with plenty of vegetation.
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
Typically, electric trolling motors are not powerful, and they are designed to propel heavier boats than the S4 (e.g. bass boat, skiff, Jon boat) at a very low speed, namely trolling speed. This type of application requires high thrust (small pitch) propellers, and it’s also the reason why trolling motors are rated in thrust units (lbs) and not in horsepower (HP or KW) – When you buy such a motor, your primary interest is how big (heavy) a boat it can move, and not at what speed.
Some electric trolling motors are described by their manufacturers as “outboard motors”, namely comparable in performance to small outboard gas engines. If you’re interested in such electric motors, we recommend comparing apples to apples namely power units to power units, and not power to thrust, which is meaningless. Remember the laws of physics, and apply the formulae for Kilowatts to Horsepower conversion, which are:
I’ve had many fishing boats, including a center console catamaran, a 17 ft [pedal drive fishing kayak], and even a W300. I still use my center console boat, but I fish mainly out of my S4 now. The 17 ft [pedal kayak] was stable but just too big and heavy, and I could hardly move it on land and in the water, even with my father helping me. The W300 was too small and it didn’t work for me. I wanted to see the S4 before buying, but once I saw it I knew that was it. I love my S4! This boat is so stable that I stood in one of its hulls as soon as I put in in the water for the first time, like you [Yoav] did in that video. This is not a kayak, it’s a boat.
I used it once with a 2 HP motor together with a fishing buddy, but it was under powered, so I bought a 6 HP Suzuki long shaft, and it’s perfect. It goes fast!
I took two of my friends in the boat, with the new motor, and we went fishing in a pond. Each one of us weighs about two hundred pounds. Two of us stood in the boat and fished, and the third guy stood on the front deck. I told him to get down from there, because I was afraid he’d capsize the boat, but he said that he feels okay, and he stayed there. We ended up standing, all three if us, and fishing. I couldn’t believe it. This boat is unbelievable.
I’m planning to take it to North Carolina, and fish the shallow water next to the intercoastal. It will work better there than my big boat. I’m working on a cart for it.
Took off from work early to get my S4 on the water the first time. Arrived at boat launch and five minutes later was in the water. That’s at first! And without getting wet! 🙂 Easy to paddle seated or standing. Only minor issue was tracking in straight line up-river while coasting. Not an issue going down-river. Shouldn’t be a problem with two people. Can’t wait to motorize. Woo Hoo!!!!!
Oh, love the storage. Can pack it at home and then straight in the water. Same when coming out of water. Not like a SOT kayak where you loading/unloading your gear to transport. That’s a huge plus for me.
Spent 3 1/2 hours on Lake Dunlap this morning. Beautiful day. Got lots of stares. Almost constant paddling, seated and standing. So comfortable! Could have gone much longer.
Had a blast on the water on Sunday. Just need to get used to steering behind me. S4 handled perfectly, even over the wakes from other boats and jet skis. Got a few stares and thumbs up. Plenty of power from the 6hp Tohatsu to get to my fishing spots quickly. Then, I can tilt the motor up and paddle/pole around the skinny water.
Got my S4 up to 13 mph, but it runs consistently at 11 mph at open throttle. Just me and light gear on board. Wonder if others are experiencing the same, or better. Love to jump the wakes of jet skis and other boats. But, normally not at top speed. It could easily handle a larger motor.
We launched the Wavewalk® Series 4 dubbed S4 in May of 2017. So far, it has been acclaimed by its users as a very comfortable and easy to paddle kayak, and a high performance motorboat in terms of fishability, versatility, comfort, load capacity, stability, and seaworthiness. We publish a Wavewalk review only if it features its author’s full name and state, and pictures (or videos). We publish reviews contributed by Wavewalk dealers as long as they use our kayaks and boats themselves for paddling, fishing, touring, hunting etc. We listen attentively to what they have to tell us because we think such people know what they’re talking about. We also recommend that our clients consult with them.