Tag Archive: Honda outboard motor

Testing the Wavewalk S4 in our maiden offshore voyage

By Magnus Chung

San Francisco Bay Area, California

I finally got a chance to take the S4 out and test it on the water. It’s working beautifully with the Honda 2.3 engine. We actually have 3 people seat in it comfortably and both paddling and using the motor works quite well.

We launched the S4 at a rocky beach, and dragging the S4 over the sharp rocks caused some scratches on the bottom of the S4. This is a minor issue, and I’ve decided not to worry about it 🙂

Overall, I am very satisfied with the S4. Great Kayak and I can’t wait to show it off to my friends on the next fishing trip!

I was too busy with the S4. There aren’t any pics while the S4 is cruising in the water since all three of us were in the S4 and didn’t have anyone to take pictures from the shore.
Here are some of the pics my friend took on the beach –

 

 

Developments in Motorized Kayaks

This article examines the latest developments in motor kayaks, and what these developments mean for anglers.

Origins of the motor kayak

As kayaks became increasingly popular among anglers, some of them started ‘rigging’ (outfitting) their kayaks with electric trolling motors. The need for doing so arose from the fact that paddling alone was insufficient in many ways – Monohull (common) sit-in and SOT kayaks are excessively wide, heavy and sluggish to their very inefficient design [¹], and paddling them to longer distances in not a possibility that’s offered to most people, especially in adverse conditions such as wind and current.

Typically, the motors used for this purpose were weak (30 lbs to 50 lbs thrust) trolling motors, powered by a 12 Volt lead-acid, deep-cycle marine battery. To this day, this is still a popular setup, and it stayed so thanks mainly to its low cost.

In this sense, kayak fishing, which started as a human powered sport, joined other forms of fishing from small craft, namely canoes, dinghies, etc.

More power and less weight: Lithium-Ion batteries

The advent of Lithium-Ion (Li-On) batteries [²] with their more effective power to weight ratio has added to the appeal of the electric motorized fishing kayak, and as these batteries became more affordable, they contributed to the spreading of motorized kayaks as yet another fishing platform in the market for portable vessels. However, besides their high price, these new batteries still present a problem to the user, and it is the fact that the amount of energy they store is still no match for the energy stored in gasoline, which powers internal combustion engines, namely outboard gas motors, or simply “outboards”.

As much as manufacturers of both kayaks and electric motors taut solutions based on the new Lithium-Ion batteries as the eco-friendly and quiet equivalent to motorboats, the fact of the matter is that they don’t compete well, at least when power and range of travel are concerned. Simply, the numbers are not there.

SOT Fishing kayaks with integrated electric motors – “Motor Kayaks”

In recent years, a growing number of kayak manufacturers has been offering fishing kayaks designed especially to work in a motorized mode, with an integrated electric power drive. Typically, the electric motor is inserted in a special compartment in the middle of the kayak, under the area where the user sits, and the propeller rotates under the hull. This design is not effective in more than one way, starting from the fact that it exposes the propeller to unwanted encounters with vegetation that can make it stall, and hard underwater objects and structures that can damage it. This makes such motor kayaks rather useless in shallow water and/or in water where vegetation abounds. To say that this defeats the purpose of kayak fishing may not be an overstatement. On top of this acute mobility problem, the location on the propeller under the kayak’s midsection makes it ineffective for steering, and forces the user to steer with a paddle and/or with a rudder system that adds unwanted complexity and clutter to a small vessel whose deck is already characterized by much clutter and too little workplace and comfort.
No wonder these big ticket and rather lame motor kayaks haven’t become popular.

A few words on the basic problems of matching motors and kayaks

Typically, common kayaks feature an elongated hull that’s pointy on both ends, and a cockpit that allows their user to sit in the middle of the deck. However, when small motors are concerned, having the user, namely the driver operate the motor from a close distance presents a major advantage in terms of safety, comfort, convenience and steering. For example, canoes, which feature hulls that are similar in shape to kayaks, are offered as paddling canoes with pointy front and rear ends, and square-end canoes where the transom is straight rather than pointy, and allows for mounting an outboard motor and for the driver to sit close to it.

Having the driver of a motorized kayak sit in the middle of the boat and operate a motor that’s several feet behind them doesn’t work well, and in case of an outboard (gas motor), it doesn’t work at all, despite attempts from a few kayak manufacturers to create demo videos that would give the impression that it does….

‘Hybrid’ fishing kayaks designed for motorizing

A couple of manufacturers of extra-wide hybrid fishing kayaks have tried to offer models designed especially for effective motorizing. The special thing about these models is that similarly to square end canoes, they feature a straight transom instead of a pointy rear end. The width of the transom varies, and in the models that feature a very wide transom, it makes the kayak fall outside the designation of kayak, per US Coast Guard regulations.
In any case, even hybrid kayaks (namely hybrid kayak / canoe) with an extremely wide transom don’t work as well as square end canoes, because unlike canoes, kayaks do not offer much in terms of free board, and as soon as the kayak’s rear is loaded with a motor and a driver, and it starts moving in the water with its front end pointing upward, its rear end sinks considerably and becomes too exposed to flooding for safe driving. And this happens even while driving on flat water, let alone in choppy water and waves.
Which is why these days the manufacturers of these kayaks are more low-key about them…

Pedaling anyone? (Just a side note)

In their eternal quest to differentiate themselves from the competition and stay relevant, kayak manufacturers end up offering new designs and solutions that are highly similar to each other. This happens not just in motorized kayaks, but in the market for pedal driven kayaks as well. And while pedal drives for kayaks are not within the scope of this article, it’s worthwhile to mention them since some vendors promote the fallacious notion that pedal kayaks could be an alternative to motorizing, although they certainly cannot, and they don’t even come close, at least when the real world and real people are concerned.
To simplify the ergonomics that apply to pedal drives and to human power in general, an average adult kayaker who is neither old nor impaired can produce around 75 Watts, namely 0.1 Horsepower (HP) at a sustained mode, and only for a few hours. In comparison, the smallest outboard gas engine available today, which is the Honda 2.3, can deliver over twenty times more power, and 6 HP outboard motors that some Wavewalk S4 owners use can deliver up to sixty times more power… and all outboards can run as long as there is fuel in their tank.
Are more words on this subject necessary?

Kayaks with jet drives

These specialty kayaks have been around for two decades, and they have not become popular although their performance in speed terms is impressive. The reason for this lack of market success is not just their price. It is the combination of the fact that they are still just SOT and sit-in kayaks, and this is not a good reference in terms of comfort and load capacity. Besides, jet drives don’t work that well in shallow water, where they can get clogged rather easily. In addition, unlike outboard motors that can be conveniently and inexpensively serviced by professionals at thousands of locations nationwide, proprietary jet drives are hard to fix, and fixing them requires support from the manufacturer, which is expensive and inconvenient.

“Kayak on steroids”

A heavy motorized board described by its manufacturer as a “kayak on steroids” and offered by them as a skiff for a solitary passenger is worth mentioning too, if only due to the fact that it relates to fishing kayaks, despite the fact that paddling it is harder than paddling most barge kayaks out there, namely the very big ones that are excessively wide and heavier than some dinghies. As this craft’s own owner’s manual states, it doesn’t work very well in choppy waters, and it shouldn’t be manned by more than one person. At 150 lbs without a motor, it is not a car-top boat, and it’s not a solution for anyone who doesn’t like to get wet while they engage in fishing or boating.
Enough said.

Fishing kayaks with outboard motors

What is the advantage of outboard gas motors?
As previously mentioned in this article, an outboard gas engine is the only type of propulsion that delivers sufficient power to allow for a kayak to go fast in all kinds of water, to run all day, and to travel for long distances. In other words, it’s powerful and reliable, and therefore safer and more fun.

YouTube features some videos of SOT kayaks outfitted with outboard gas motors. Some of these kayaks are outfitted with an outrigger, because unlike in YouTube, in the real world, SOT kayaks, including big ones, are not stable enough to be driven with outboard motors. Either way, the result is rather pathetic, and makes the viewer wonder about whether our species really deserves to be called Homo Sapiens, namely wise man… The drivers of such kayaks are noticeably uncomfortable, and in most cases wet as well. Not a pretty sight.

Practically speaking, Wavewalk kayaks are the only kayaks that offer full functionality and high performance when powered with outboard gas motors. This is why the company labeled its two bigger models skiff and portable boat. Indeed, they perform perfectly as such, and even better, be it in terms of stability, ease of use, comfort in driving, comfort to the passengers, dryness, load capacity, mobility, speed and seaworthiness.

 

The Wavewalk is a patented invention, and it can be described as a compacted catamaran that features the saddle-seat of a personal watercraft (PWC) also known as jet-ski. This unique combination creates the most stable hull while offering the driver and passengers to balance themselves intuitively and effortlessly, in the most effective way possible.
The result is a boat that punches way above its weight in terms of performance, to a point that it rivals much bigger boats.
And indeed, some anglers and other fishers use their S4 instead of much bigger boats that they used to have before.
For example, this crew of two shrimpers used an 18 ft skiff before they switched to the S4:

 

Motorizing options for Wavewalk kayaks are not limited to conventional outboard motors. In fact, it is possible to outfit the S4 with powerful surface-drive motors (a.k.a. mud motors), and by doing so, enhance their mobility and enable their users to go through very shallow water (“skinny water”), rocky streams, and water with abundant vegetation, such as lily pads, grass, and seaweeds.

And let us not forget paddling, because the ability to propel a motor kayak with paddles as an alternative or complementary mode of propulsion is very important, to a point where it may be critical in certain situations, such as launching and beaching in tough spots, going in very shallow water where a boat could get stranded, especially at low tide, going through weeds, and in case something else prevents the motor from working.


[¹] See articles about kayak design for speed: The Secrets of the SOT Kayak’s Underside , and Kayak Design for Speed

[²] See article Smarter electric motors and Lithium-Ion batteries – A winning combination for kayak fishing, by Gary Thorberg

Related articles

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

Motorized Kayaks

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

Updated February 3rd, 2018

The purpose of this article to answer a frequently asked question (FAQ) from prospecting clients, which is “What outboard motor should I choose for my S4 skiff?”

The answer is that the outboard motor and propeller you should choose for your S4 depend mainly on two factors, which are –

Power

  1. How much power you need: How fast you want to go, in what kind of water, and how many passengers you’ll have on board
  2. How important to you is the motor’s weight.

There is a trade-off between power and weight, namely that the more powerful the motor, the heavier it is, and the harder it is to carry it.

In any case, the motor should be a 20″ log shaft (L) model, and not a 15″ short shaft (S).

Recommended reading: How to measure an outboard motor’s propeller shaft length? »

Propeller Pitch

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.

 

KICKER MOTORS

 

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

 

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 OUTBOARDS

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:

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

No amount of words can overcome this reality.

Electric motors are discussed in the Electric Trolling Motor or Outboard Gas Engine section of this article »

 

Wavewalk S4 with 2 HP Honda outboard in strong wind, lake Simcoe, Ontario, Canada

By Pyt Rotary

Ontario, Canada

Lake Simcoe is a 280 square mile lake in Ontario.

12km/h [7 mph] with Honda 2Hp against wind of 24km/h [15 mph]

Lots of fun except my rocky mistake to not have enough gas with me.
I got excited and let the boat run for 15km straight into the lake and realize I am out of gas.
I paddled back half the distance and got gas from shore.
Now I know… From now on I will carry enough gas with me.
Luckily I paid with just one blister on my hand.

I did come back at night and feel SUPER SAFE in it.
It is a great, fantastic boat.

 

(added comment) –

The S4 is SUPER, SUPER, SUPER stable. It does not sway at all.
I have been in bigger boats with V shape hulls.
Those boats don’t have the same stability on the water as the S4. The waves hammer them straight in the teeth.
The catamaran design cut the waves like a knife cuts through butter.
Definitely there is room for more HP on the S4.

It was my fist ever trip with a gas motor, I do use W500 with an electric motor but never played with gas before. Lots of fun. Now I can reach easily lots of my fishing spots.
Regards from Ontario, Canada.


(added later) –

After 7 years of tests I think I found the best way to store the rods on Wavewalk, at least for me.

The challenge was in S4 where drilling on the back side where the gas engine reside is not much appealing to me.
So what I did was to buy 2 Homer Tool boxes from Home depot $10 each and use the box to store dry different items at the tip of the S4.
The end of the fishing rod where the reel is, rests on the box and the tip is secured on the upper side of the kayak with sticking Velcro (same Home Depot).

I had some exist on water testing and I can carry easily 4,5 fishing rods in S4.
Since I like the concept I start to think how I can fit that in W500.

I got 2 plastic rings from dollar stores (shower curtains rings) and secure them with a round screw inside the tips on back side under the transom. The handle of the rods rest inside the rings, the tip of the rods is secured by same sticking Velcro in front of W500. 2 rods can be stored easily inside a W500 this way.

Now I am still in doubt to install the same rings in S4 as well since the setup is so successful for me in W500. I will still used the Tool boxes as storage (2L of gas, gloves, tackle, ropes, anchor).

More kayak fishing with Pyt in Canada  »

Testing 15″ short (S) shaft outboard motor performance with Wavewalk kayaks and boats

This article summarizes the research that Captain Larry Jarboe, of Florida Fishing Kayaks and Boats in Key Largo, Florida did on this subject, and we are very grateful to him for this exceptional contribution.

Background –

 

Larry’s main goal in conducting this series of experiments that lasted for several weeks was to find the “sweet spot” for 15″ (S) outboards, namely a setup that would enable him to successfully outfit W500 and W700 boats with such motors, which are typically cheaper and easier to come by than 20″ (L) motors.
His secondary goal in running these extensive tests was to check the performance of Wavewalk’s TMM 700 HD motor mount, and see if we could improve it.

Larry is a passionate fisherman, mechanic, and seaman. He works as a commercial fisherman and fishing guide, and he is Wavewalk’s distributor in Southern Florida.
For the past fifty years, Larry has been involved in using, building, refurbishing and testing motors in various land and water vehicles, including electric racing cars, regular cars and trucks, a wide range of small watercraft, and big diesel engines in stern-drive commercial fishing boats, such as he still operates in Key Largo.

Means and Method –

 

In his tests Larry used five portable outboard gas motors that he had refurbished and tuned himself. Some of the motors had 15″ short shafts, and the others had 20″ long ones, and their horsepower rating ranged from 2 HP to 5 HP. He also tested a couple of electric trolling motors.

Larry conducted his experiments systematically – Being a handyman as well as a mechanic, he built a series of transom motors mounts that enabled him to mount outboard motors of both sizes in various places at the boats’ stern.
In his tests, he changed the height of the mounting plate, and/or its distance from the cockpit’s rear end.

Results –

 

There is no “sweet spot” for mounting a 15″ short (S) shaft motor on a Wavewalk, and any configuration involving the use of such size motor would inevitably result in sub-optimal performance compared to the use of a 20″ long (L) shaft outboard motor of the same power.

The main problems that Larry found with 15″ short (S) shaft outboard were the following:

Ventilation

 

Outboard manufacturers recommend mounting outboard motors with their anti ventilation plate (sometimes called “anti-cavitation” plate) immersed a couple of inches below the boat’s lowest point, which by definition is always immersed. This inevitably means that the anti ventilation plate is several inches below the surface. If the propeller rotates with its blades too close to the surface, it sucks air from the surface, and instead of rotating in water it rotates in a mixture of water and air bubbles. As a result, the propeller loses efficiency and power.

  1. At higher speed – Larry found that with 15″ short (S) motors, ventilation started to occur at about 5 mph, when the boat was transitioning from a displacement mode into a semi-planing mode, and its hulls were slightly raised, thus pulling the propeller upward and too close to the surface. The higher the speed the more extensive the ventilation and power loss. No ventilation occurs with 20″ long (L) shafts, even at speeds higher than 12 knots (13 mph), when the boat is in a full planing mode.
  2. When making sharp turns – Larry found that the 15″ short (S) motors’ propellers sucked air from the surface while he was making sharp turns. This happened since the boats tilted on their side, and the propellers got too close to the surface. In this case, ventilation resulted in loss of power as well as loss of control, to some extent, which made turning more difficult. Such problem did not occur with 20″ long (L) shaft motor, which performed flawlessly in sharp turns at high speed.

Splashing and discomfort

Splashing – In order to avoid ventilation, it is possible to mount 15″ short (S) shaft outboards at a lower level, with its propeller immersed more deeply. This can be done when a specially designed motor mount is placed several inches behind the cockpit’s rear end. However, at such position, the lower part of the motor mount’s vertical mounting plate is too low and too close to the surface of the water, and it will come in contact with the water. In such cases, the result is spray splashing over the motor’s head and into the cockpit’s rear end. No such problems occur with 20″ long (L) shaft outboard motors when mounted correctly on a standard Wavewalk motor mount.

Discomfort – When the 15″ short (S) outboard is mounted several inches behind the cockpit’s rear end, it is harder for the user to reach the motor and its controls (e.g. choke knob, starter grip), and it is harder for them to steer. This is not the case with 20″ long (L) motors that are mounted at the rear of the cockpit.

Bottom line

 

There is no “sweet spot” setup that allows for mounting a 15″ short (S) shaft outboard on a Wavewalk (500 or 700) without it incurring serious drop in performance. The way to motorize a Wavewalk is to follow the recommendations of outboard manufacturers about mounting their motors, as well as Wavewalk’s recommendations that fully coincide with them, namely to use only 20″ long (L) outboard motors with Wavewalk’s kayaks and boats.

 

A sweet spot, sort of…

 

When Larry checked 15″ short shaft, weak electric motors, he found that the ventilation problem at higher speed didn’t occur, because such motors lack the power to propel a kayak at speeds that are high enough to make it reach a semi-planing mode, or have the propeller suck in air from the surface. Knowing about such a sub-optimal performance envelope, the user already expects sub-optimal performance. This said, this rule is not ironclad, and ventilation may still occur in case the boat makes a sharp turn.even when it is propelled by such weak 15″ short electric motors, and while going at low speeds.

This is to say that Wavewalk recommends not to use short shaft motors even in the case of weak electric trolling motors.

In sum, the only propeller shaft size that we recommend for all types of motors is 20″ long (L)

 

More reading:  How to measure an outboard motor’s propeller shaft length? »