Wavewalk 700 DIY motor mount for short shaft outboard motor

By Steve Lucas

Florida

This modification to Wavewalk’s [discontinued] 15″ motor mount works.
No ventilation, no cavitation. Steering is fine.

All you need is a 1 inch square dowel added to the top of the short shaft motor mount. Then shim in the space under the spray deflector’s rim.
No holes were drilled through the hull but I did use the existing holes where the original pad eyes were.

I used a piece of the dowel and Sintra board for the shims.
Not fancy but effective. You just clamp the motor on the mount and over the hull.

 

 

Wavewalk 700 skiff outfitted with DIY motor mount for short shaft 3.5 HP outboard motor

DIY-motor-mount-for-short-shaft-outboard-motor

DIY-motor-mount-for-short-shaft-15"-outboard-motor

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Wavewalk 700 skiff with 5 HP Tohatsu outboard motor and electric trolling motor

By Captain Larry Jarboe

 

I think the yakkers I passed yesterday weren’t very happy to see me…

Here’s a couple quick pics of my DIY motor bracket and 5 hp long shaft 2 stroke Nissan (really a Tohatsu) outboard motor. I got the refurbished motor from Brandon Kurz at BMK Enterprises near Deerfield Beach. Brandon runs an outboard and small boat repair shop near I-95. He is a great source for affordable long shaft motors for our Wavewalk adventures.

The motor bracket is mostly HDPE decking material with some Azek board. It is glued and screwed with PVC cement and Torx head self tapping stainless screws.

This rock solid bracket is relatively removable with only four thru bolts passing through the upper rear deck. I really don’t like drilling holes in my Wavewalks but I don’t want my Nissan passing my W700.

I estimate that this rig planes at 12 knots. It is a blast to go fast in a USCG designated kayak.

Obviously, a lot more sea trials have to occur. The kayak and stand-up board purists may have a hard time identifying with a cracker yakker zipping past to parts far beyond the reach of paddlers, pole pushers, and pedalers. But, although it may defy convention, having the fastest yak in South Florida does rate bragging rights.

And, I have not yet begun to flout and tout my magic boat!

W700 skiff with 5HP outboard and electric trolling motor

13 ft skiff with 5HP outboard and electric trolling motor

Portable skiff with 5HP outboard and electric trolling motor, FL

 

Video added a few days later:

More fishing adventures with Capn’ Larry »

 

Choosing an outboard motor for your Wavewalk® 700 skiff

This article is an attempt to answer some questions that Wavewalk skiff owners ask in the process of choosing an outboard motor for it –

Short shaft oR long shaft?

We definitely recommend using outboards that feature a long (20″) propeller shaft, and for multiple reasons, which are discussed in this article entitled Outboard motor propeller shaft length for Wavewalk fishing kayaks and boats »
We recommend not to be tempted by the availability and lower price of 15″ short shaft outboard motors, because such motors don’t fit the W700, and using one would never produce optimal results, even for a highly skilled individual with a lot of experience in boat outfitting.

Here is a list of long (L) 20″ shaft outboard motors currently available in the 2 to 6 horsepower range, and their HP rating:

  • Honda 2.3 HP (air cooled), 5 HP
  • Suzuki 6 HP
  • Evinrude 6 HP
  • Tohatsu 3.5 HP, 4 HP, 5 HP, 6 HP
  • Yamaha 2.5 HP, 4 HP, 6 HP
  • Mercury 3.5 HP, 4 HP, 5 HP, 6 HP
  • Mariner 3.5 HP, 4 HP, 5 HP, 6 HP

Air cooled or water cooled?

Water cooled motors are quieter but heavier than comparable air cooled motors.
The only motor featuring on the above list that’s not water cooled is the Honda 2.3 HP. It is very lightweight, and works very well, but being air cooled makes it considerably noisier.

Note: Outboard motor manufacturers recommend flushing the motor’s cooling system with fresh water after every trip in saltwater. It’s possible to flush an outboard with a garden hose outfitted with a special adapter.

4-Cycle or 2-Cycle engine?

Nearly all new small motors on the market are 4-Cycle (4-stroke) and not 2-Cycle (2-stroke).
The advantage of the 4-Cycle system is twofold –

  1. The motor runs on regular fuel, and there is no need to mix it with oil.
  2. A 4-Cycle motor is cleaner, namely it emits far less stinky fumes than 2-cycle motors do.

Some experts argue that for the same displacement of its combustion chamber (cc, volume, size), a 2-Cycle engine in more powerful than 4-Cycle one, but we think that convenience and fresh air are more important.

electric or gas?

Many Wavewalk owners outfit their W500 and W700 with electric motors in the 30 to 50 lbs thrust range, and some go as far as 70 lbs thrust. They use their electric kayaks and skiffs for assisted paddling, recreation, touring, trolling, fishing, snorkeling, etc., but we prefer not to include electric motors in our list of “real” outboard motors for two reasons, which are:

  1. Power – Although some small electric motors are offered as “outboard motors”, just looking at their basic, objective power rating makes us think that they are too weak. Kilowatts to Horsepower conversion: 1 KW = 1.34 HP, and 1 HP = 0.745 KW. Consequently, an electric motor can work well on flat water and at a moderate speed, but not necessarily in adverse conditions, namely strong current, strong wind, etc.
  2. Range of travel – A gallon (3.8 liter) of fuel costs a few dollars, and it’s enough for a typical small outboard motor to run for 4 hours at a high RPM, or an entire day at a lower RPM. You can refuel a small outboard’s built-in fuel tank when you’re on board your Wavewalk®. You can take several gallons of fuel with you on a long camping trip, and you can buy more fuel almost everywhere, while recharging an electric motor’s battery can take half a day. Therefore, gas outboard motors offer a reliable and convenient solution whose price / performance ratio is unbeatable by any electric motor available today.

Weight

All small outboard motors listed above are considered to be Portable. However, between the 29 lbs of the 2.3 HP Honda and the 59 lbs of the 6 HP motors there is a considerable difference, if you need to carry the motor by hand over a distance.

The shallow water position

Most of the small outboard motors listed here offer to lock their propeller shaft in an intermediary position between the vertical (down) and horizontal (up) positions. In this intermediary, slanted position, the propeller drafts less than in the vertical position, and this allows for driving the boat at a moderate speed in very shallow (‘skinny’) water. Therefore, if you’re looking to fish in skinny water, we recommend that you look for this feature.

gear shift lever

Most outboard motors on our list feature a gear shift level, and this is a good thing, because the alternative is a centrifugal clutch that lacks an absolute neutral position. The absence of a full neutral gear can make starting the motor a little tricky, if you’re a beginner.
Our preference goes to the outboard motors that feature the gear shift lever at the front, rather than on their side. The frontal position makes it easier for the driver to access the lever whether the motors points left or right, and even if the driver is facing forward.

built-in fuel tank

All the above listed outboard motors come with a built-in (integrated) fuel tank, and this is a convenient feature considering the alternative is to have a fuel line run from a separate tank to the engine. When you operate such a small craft as a Wavewalk, simplicity becomes increasingly important.

propeller

The propellers that come standard with these outboard motors fit Wavewalk’s kayaks and portable skiffs. Typically, these motors propel much heavier boats, which is why the propeller’s diameter and pitch which determine output in terms of speed and torque are of no real consequence to the owner of a Wavewalk under normal conditions.

price and brand

All the brands listed above are known to produce quality motors, and in fact some of them produce motors for others. For example, Mercury is a Tohatsu brand. This is to say that we see no reason to pay more for a particular name brand, and we recommend to consider only the motor’s technical attributes, and its price.

HP rating – can i overpower my skiff?

6 HP is the absolute maximum for which the W700 is rated, and this is only for its RIB model. Overpowering your Wavewalk can be hazardous, and if you use the wrong motor mount you’d be calling for trouble. This said, if you happen to own a 20″ shaft 5 HP motor and your W700 is rated for a 4.5 HP motor, you can keep your motor, and you won’t necessarily have to get a new one. Similarly, if your W700 is rated for up to 4.5 HP and you found a nice 4 HP that you like, you’d be fine with it.

motor mount

If you choose to make a DIY mount for an electric trolling motor, chances are that you’ll succeed, since these motors are so weak that they’re not likely to cause trouble. But this is not the case with the gas outboard motors in the range that features on the above list.
There are several issues to overcome with motor mounts, and the motor’s weight is the least of them. The main problem is that operating at the end of a 20″ lever, the motor’s propeller generates a great amount of torque, especially at high speed, in rough water and when making sharp turns at high speed. This torque can twist and crack a 4×2 timber, and pull out nails and screws from their place. After having seen motor mounts get broken by outboard motors ranging from 6 to 3.5 HP that were mounted on them, we strongly recommend not to build a DIY motor mount for these motors, and to use only the motor mounts that Wavewalk recommends.

alternator

Some of the more powerful outboard motors listed here can be outfitted with an alternator and an AC to DC converter. Note that such accessories cost hundreds of dollars.
The electric current produced by this system can be used to power lights on board, or to charge a trolling motor’s battery. Such setups are common in bigger boats (e.g. bass boats) that feature much more powerful motors. Although some Wavewalk owners have outfitted their W700 with two motors (a powerful one for driving and a small one for trolling), we don’t know of anyone who’s outfitted their outboard motor with an electric current generation system.

Why an outboard motor?

Skiffs, Jon boats and other small boats sometime come with other motors, among which are air drives or air motors (large diameter propellers) for running marshes and flats, jet drives (similar to personal watercraft, a.k.a. jet-ski), long shaft mud motors for going in shallow water and over obstacles, and outboard motors that run on propane.

While each of these motors offers certain special advantages, and we’d love to see the W700 outfitted with any of them, as well as with other propulsion systems ranging from sails to oars, and even pedal drives… we think the common small outboards such as we listed here offer the optimal mix of price, performance, reliability, versatility, ease of use, and ease of maintenance – Just think how common are boat dealerships and repair shops that service these motors… And if you know how to use your outboard motor and you take care of it, it’s truly a wonderful thing that you’d enjoy for years, and possibly even decades.

Outboard motor propeller shaft length for Wavewalk fishing kayaks and boats

November 12, 2016

Wavewalk will no longer support the installation of any outboard motor whose propeller shaft is shorter than the standard 20″ long (L) on its W500 fishing kayaks and W700 portable boats.

How to measure an outboard motor shaft’s length?

An outboard motor’s propeller’s shaft length is measured from the top inner side of the motor’s clamp bracket to the horizontal anti-ventilation plate located above its propeller.

The outboard motor industry has determined four standard lengths for outboard motor shafts, which are:

  1. 15″ (S) “Short”
  2. 20″ (L) “Long”
  3. 25″ (XL) Extra Long
  4. 30″ (XXL) Extra Extra Long

For both the Wavewalk 500 and 700 series, the length we recommend is 20″ (L).

What’s wrong with short shaft outboard motors?

Depending on the type and quality of the motor mount’s installation, the use of shorter shaft motor (electric or gas) can result in any of the following problems:

  1. Motor mount’s mounting plate too high – Strong vibrations and loss of power due to ventilation that occurs when the propeller rotates at high speed too close to the surface, and its top part goes through a mixture of water and air bubbles coming from the surface.
  2. Motor mount’s mounting plate is too low – The motor mount’s mounting plate’s lower side scoops water and generates excessive spray, some of which can find its way to the back of the cockpit, and some to the top part of the motor.
  3. Motor mount too far behind the cockpit – Access to the motor’s controls is not easy, including for starting it, shifting gears, using the choke button, and refilling gas. Driving is harder too. The driver is forced to drive from the cockpits rear end, instead of driving from the middle of the cockpit.
  4. Motor mount’s mounting plate too low, and mounting plate too close to the cockpit – The motor’s top part is prevented from tilting downward in case the lower part of the propeller hits bottom or a submerged object and gets pushed upward automatically, in order to avoid damage. If this basic safety function is disabled, the propeller is exposed to severe damage, and so is the propeller shaft.

For the above stated reasons, Wavewalk does not recommend using any motor, electric or gas powered, whose propeller shaft is shorter than the 20″ (L) standard length.

Why does Wavewalk restrict its support now?

In the past, Wavewalk supported owners’ efforts to outfit their W500 kayaks with short-shaft motors. This policy stemmed from the fact that long-shaft motors in the 2-3 HP range are harder to find than short shaft ones, and we don’t recommend more powerful motors for the W500 series.
Installations of short shaft motors on Wavewalk kayaks and boats worked, but they were sub-optimal, since there is practically no way for a 15″ setup to match the performance and convenience that a 20″ outboard offers when properly mounted on a Wavewalk.

Last year we came out with the W700 series that’s compatible with several 20″ (L) outboard motors up to 6 HP, which is to say that since then, Wavewalk owners benefit from a much wider choice of outboard motor models.

Currently, the only outboard motor under 3 HP that we recommend is the lightweight, air-cooled 2.3 HP 20″ (L) 4-Cycle Honda.
Several outboard brands offer water-cooled, long shaft (L) motors in the 3.5-6 HP range, and our preference goes to Tohatsu, since these outboards (also sold under the Mercury brand) feature a gear shift lever in the front side of the motor, where it faces the user, which makes them easier to use.
Other 20″ (L) quality portable motors in the 3.5-6 HP range are offered by Yamaha, Honda, Suzuki, Evinrude (6HP only), etc.

Short Shaft Outboard Thoughts

By Captain Larry Jarboe

Yesterday, the sun came out and the wind died down enough to try the 2 cycle 2.5 Mercury short shaft outboard (an old rebranded Tohatsu) that I picked up for a hundred bucks. It now has a new carb and an aluminum prop. Essentially, with some minor changes, it is souped up to become the 3.3 hp Merc motor that is still marketed around the world where 2 cycle outboards are not discriminated against.

Notice, I mounted it on my vessel using the smartly designed W700 transom bracket that allows for long or short shaft outboards. Also, I put a concrete block in the bow to help balance the load.

Turning the bracket upside down for the short shaft also means the motor is another 6 inches aft. This is necessary to tighten the motor clamp bolts which are down between the two hulls.

That extra distance aft requires a level of dexterity to reach. After some personally challenging contortions to face astern, I started the motor. Then there were equally challenging physical maneuvers to spin around while underway. That nice lightweight motor (28 lbs.) has no neutral, only forward.

The motor does turn up sufficient torque to make the boat plane smoothly. But, the lowered transom digs into the water during the transition thus throwing water into the face of the engine. That is not good, at all.

Putt putting around was fine. Planing the W700 with the short shaft motor is presently unacceptable. Maybe, a joystick option or more weight in the bow might alleviate the lowered transom grabbing water. Or, a spray shield installed in front of and under the transom bracket. I, personally, want a daily driver with minimal maintenance issues. And, easier reach to start and service the motor.

Yoav, has consistently been recommending the log shaft outboards. I thoroughly concur. The short shaft Mercury would make a good display engine for sales but it runs so well I am putting it up for sale and looking for a 3.5 hp long shaft as the most ideal power source for my application.

Also, Yoav’s recommendation for Tohatsu small outboards is right on. The Tohatsu engines are probably the most affordable and dependable small outboards on the marine market, today. Mercury, Nissan, and Mariner use the Tohatsu power head and drive that they rebrand with their own logos. If you remember to 1) always use non-ethanol fuel and 2) after each use, flush with freshwater, while 3) running the carburetor dry, and 4) store upright, your engine will last a lifetime.

However, until my short shaft outboard sells, a transom well will not be too difficult to construct. And, some yoga exercises prior to getting underway might not be too terrible. Easier than a Zumba class…

Larry J.

Read much more and see pictures and video in the comments below ⇓

Wavewalk 700 bow with DIY motor mount for an electric trolling motor and a cinder block  …
Old 15″ shaft Mercury outboard motor attached to W700 HD motor mount that’s mounted on upside-down

Read much more and see pictures and video in the comments below ⇓

More fishing adventures and outfitting tips with Capn’ Larry »