Motor mount for a 15 inch outboard motor for the S4 microskiff

Captain Larry Jarboe, Wavewalk’s distributor in southern Florida, is a prolific innovator, who has come up with many interesting projects.
His latest success is a fully functional motor mount for a 15 inch outboard motor for the S4. This is not a small feat, considering the fact that the S4 was designed specifically for 20 inch outboard motors, and it does not work properly with  motors that feature a different size propeller shaft.

In a few words, the problem that Larry faced was to mount the motor several inches lower than the standard height, while effectively preventing spray from the “rooster tail” generated by the propeller to reach the motor’s powerhead, namely its engine.

Don’t try this at home

Before we go on describing Larry’s design, we must warn anyone who’s reading this article: DO NOT TRY THIS AT HOME. The reason for this warning is that this project requires extreme modifications that would be very hard for a person who does not possess Larry’s experience and skills to succeed in with their own S4.
Explanation: Being a Wavewalk distributor, Larry had access to non-assembled S4 parts, namely a hull and a saddle, and he was able to attach the saddle in this S4 all the way to the front of the cockpit, and thus create enough room at the rear for the 15 inch motor’s mounting screws.
This was absolutely necessary, since in order to accommodate a motor with a shorter propeller shaft, Larry’s mounting plate is several inches lower than the standard S4 mounting plate. Without the extra space in the back, the saddle’s rear would have been in the way of the motor’s mounting screws, and mounting the motor would have been impossible.
If you already bought an S4 whose saddle is not attached in a forward position, detaching it from its location and re-attaching it in a new forward location would be a complex project that requires skills and experience that few people have. An imperfect job could make the saddle non-watertight, and thus deprive the boat from its built-in flotation chamber.
Again, if you already have a 15 inch outboard, sell it or keep it, but get a 20 inch outboard for your S4, and don’t mess with the boat’s saddle.

The Solution – Details

Mounting Plate – As seen in the picture above, the vertical mounting plate is several inches shorter than the standard one, and its top reaches only the top of the S4’s cockpit rim (coaming).  This mounting plate is attached to the molded-in motor mount similarly to the way that the standard plate is attached, namely while taking advantage of the presence of a standard, wooden, structural element named “saddle bracket” attached to the back of the cockpit. This wooden bracket is not seen in the above picture, and it looks like this –

S4 wooden saddle bracket
A wooden saddle bracket attached to the rear side of the S4 cockpit, standard

Spray Guard – This elongated horizontal plate protects the motor’s upper unit, namely its power head, from the “rooster tail” generated by the propeller. A rooster tail is the name given to the powerful stream of spray that a propeller generates. In order to keep this powerful jet of spray under control, and prevent it from reaching the motor’s top unit named “powerhead”, Larry reinforced the PVC plate with metal profiles, and he cut a bay in the plate’s rear part that would fit around the propeller shaft, while letting it rise out of the water when needed. Without these metal reinforcements, the rooster tail would have bent the horizontal PVC plate.

Spray guard plate for 15" motor mount for the S4 microskiff
Bottom view of the horizontal plate that prevents rooster tail spray from reaching the motor’s head
Reinforced spray guard plate for 15" motor for the S4 microskiff
Bottom view of the horizontal plate that prevents rooster tail spray from reaching the motor’s head. Note the metal profiles that reinforce the plate, and prevent it from bending upward under the pressure from the rooster tail’s spray
Mounting plate and spray gurd for a 15" outboard motor mounted on a Wavewalk S4 microskiff
Overturned S4: Bottom view of the horizontal spray guard and vertical mounting plate

More S4 rigging projects

Terry Pritchard

North Carolina / Florida

Driving my S4 microskiff

I have upgraded my s4 from the first pics I sent. I’m using it exclusively in the intercoastal waters in Florida catching snook, tarpon, and red fish. I have done a lot of modifications to make all this work.

Note the front mounted electric trolling motor

I added a seat and I made a U-jinted tiller extension for the motor.
I also reinforced the transom, because this motor is heavier and more powerful than the max 6 HP that Wavewalk recommends.
Seat, articulated tiller extension, and reinforced transom on S4 micoskiff
The leaning bar and platform – Leaning bar unlocks and swings away for access to the bow. The platform is 17 inches by 34 and standing that high in the boat is very stable, so stable I can stand on the edge, with my tes stick out.
Casting platform on top of S4 cockpit
Leaning bar for casting platform - Wavewalk S4 microskiff
Standing platform and leaning bar for Wavewalk S4 microskiff
I made a battery compartment  by cutting a section out of the floatation seat and plastic welded an end back in. I also installed another saddle bracket that the modification eliminated.
Electric batteries compartment in the S4 microskiff
And this is a storage compartment on the side of the hull –
Storage compartment on the side of the S4 microskiff hull
This is the transom saver for transporting the boat. The 9.8 is a heavy  motor and the vibration and stress in transport is another factor for reinforcing the transom –
9.8 HP Tohatsu outboard mounted on Wavewalk S4 microskiff
The propeller pitch is 7 which came with the motor. I also have a 9 pitch and only gained 2 tenths and the rpms dropped about 475 rpms. As you can see from the pictures I have added a lot of weight to this boat.
9.8 HP Tohatsu outboard motor on S4 microskiff
The speed I get is 16-17 mph using GPS. Conditions have to be really good to  hit 17, and I once did 18 mph for a brief period of time.
Tohatsu 9.8 HP outboard motpr mounted on Wavewalk S4 microskiff
This motor weighs 84 lbs, which is over 20 lbs more than a 6 HP, so I had to trim it very aggressively, and add a trim tab to keep the bow low and the stern high –
Trim tab for outboard motor mounted on S4 microskiff

Wheel cart for portable boat, kayak-skiff, and cartop microskiff

This article offers instructions for making a wheel cart for a kayak, canoe, portable boat and microskiff.

This article offers recommendations, guidelines and hands-on instructions for making a wheel cart for your kayak, portable boat, kayak-skiff and  cartop microskiff from the W700 and S4 series.

Sadly, we haven’t found a commercially available canoe or kayak cart that we like.

There is no perfect wheel cart for a portable boat, or a cartop  microskiff, because the requirements from such a device can vary greatly, depending on the weight of the boat (motorized or non-motorized), the terrain on which it needs to be carried, and whether there is a need to transport the wheel cart on board the vessel.

All terrain wheels for an S4 portable boat
Chris Henderson and the Northern Tribe Outdoors team with their S4 and a pair of XL inflatable wheels, Puget Sound, WA

General guidelines

These recommendations are valid for all types and sizes of wheel cart, regardless of boat model, and of the weight it carries. Whether you need to carry an empty W700 that weighs just 80 lbs, or a 100 lbs S4 outfitted with a 60 lbs 6 HP outboard motor, which brings the total weight of the boat to 160 lbs even before you load it with your fishing gear, you want your wheel cart to be sturdy and stable, and make it as easy as possible for you to go on whatever terrain you need to travel on.

Simple is Best

The wheel cart design we recommend is robust as well as easy to make, even if you’re not an expert carpenter. It’s also inexpensive and durable. This design consists of a 2×4 or 2×6 lumber, a steel axle, a pair of wheels, and two latches. The axle is attached directly to the underside of the lumber “body” on which the boat rests. The wheels are mounted on both sides. The boat is attached to the wheel cart body by means of two latches.

  • Length of the lumber body: 35″ for the W700 and W720, and 42″ for the S4. This means a 2″ clearance on each side.
  • Lumber size: 2×4 for a non-motorized W700, W720 and S4. 2×6 for a motorized W700, W720, and S4. This means you upgrade from 2×4 to 2×6 if the total weight of the boat plus its motor is equal to or exceeds 100 lbs.
  • Waterproofing: Wood rots and steel rusts, so we recommend coating all parts of the wheel cart with 2 coats of urethane.
  • Wheel diameter: Minimum 12″, even for flat and even terrain. This requirement has to do with the size of the boat, and the clearance from the ground. For very rugged terrain, such as trails in the woods, don’t hesitate to use 20″ diameter wheels.
  • Wheel width: Minimum 2″, even for flat and even terrain, and pavement. Minimum 6″ for sand.
  • Type of tires: Flat free. The last thing you want when you’re out there is a flat tire, and not having a spare tire…
  • Wheel material: Plastic is lighter than steel, and it doesn’t rust.
  • Steel axle: Minimum diameter 5/8 for lite duty wheel cart, and minimum 3/4 for heavy duty one. Stainless lasts forever but it’s more expensive. Remember to make the axle long enough!
  • Attaching the axle under the wooden body: Anything goes, from plumbing brackets to simple nails bent with a hammer, pieces of wood, etc. Build strong!
  • Attachment points for the latches: You can drill a pair of narrow holes on each side of the lumber body, or outfit it with O screws fore and aft. Preferably, keep the biggest distance between the two attachment points, in order to minimize torsional movement when you’re pulling the boat.
  • Latches: Preferably wider than 1″. Ratcheting latches are overkill.
  • Where to attach the wheel cart to the boat: The optimal spot for the wheel cart is right below the boat’s vertical mounting plate, because this location provides means to secure the latches more effectively, and prevent slipping. If this spot is not convenient (e.g. due to weight distribution), any spot between the middle of the boat and the rear end of the cockpit is fine.
  • Carrying the wheel cart on board: The two pictures in this article show the preferred way to do it. For the S4, adding a transversal piece of wood in the middle of the cart can help keeping it in place if rough waters, by inserting this element into one of the vertical slots in the boat’s front deck.
No wheels, sled style

If your W700 or S4 are non-motorized, and you don’t carry heavy gear on board, and the surface on which you’re carrying the boat isn’t abrasive (e.g. grass, sand, pebbles), consider dragging the boat sled-style, with no wheels. It can make things simpler and easier, and it won’t necessarily damage the boat.

Central beam, if you can leave the wheel cart on shore

A central beam is attached to the middle of the wheel cart, and it stretches forward along the center line of the boat. The front tip of the beam is attached to the tip of the boat’s bow (S4) or bows (W700).
Pulling a boat that’s attached to such enhanced wheel cart is easier, because the beam helps keep the wheels going straight forward, and not sideways, as they might tend to do if they’re not attached properly. This full fledged cart is too big to take on board your vessel, so this solution works only for users who can leave their cart on shore after they’ve reached the water.

Please email or text us if you have comments or questions about this article. We love helping our clients!

Toggle Bolts for attaching items to your boat and kayak

Kayaks and ultra lightweight boats such as the S4 are molded from Polyethylene (PE), which is a relatively soft but very strong material. In order to reduce both weight and cost, the walls of these small craft are made thin, which presents a challenge as far as permanently attaching objects to them. Such object can be carry handles, rod holders, seats, etc. Screws don’t work in such cases due to the thinness of the walls, and bolts don’t work if there is no access to the other side of the wall, in order to apply the nut in its place on the tip of the bolt.

The typical solution, which works in most cases, is to use special rivets that were developed for soft walls. These rivets split into three arms that fold back into the surface of the other side of the wall, and they are the standard rivets used in kayaks and small craft.
See article on watertight riveting »

But these rivets are relatively small, and sometimes they’re not enough. In such cases, Toggle Bolts provide a sturdy and easy to apply solution – Toggle Bolts were initially developed for hollow gypsum drywall. Gypsum boards are thick, but gypsum is a very soft, brittle and weak material, too weak to resist pull from screws. The problem of softness and lack of access to the other side of the wall required an ingenious solution, and toggle bolts are without any doubt a most ingenious invention.

Toggle Bolts for kayaks and small boats
A toggle bolt is a two-piece, steel fastener. Its two parts are a bolt and a spring-loaded pair of steel wings that fit on it –
You just drill a hole in the wall in the diameter indicated by the toggle bolt manufacturer, and push the bolt in with its wings folded. After the wings are forced all the way through the hole, they will open up by the action of the spring. Rotating the bolt will cause the wings to get drawn back towards the bolt’s head, and against the wall. Once the wings are pressed tightly against the other side of the wall, they will provide enough support to the equipment that you want to attach to the boat’s wall.
Waterproofing the hole in your boat or kayak can be done by using a generous amount of Goop, which is a watertight adhesive that adheres sufficiently well to Polyethylene walls, enough for such a light duty application. This said, we recommend not to drill holes below waterline, or even close to it. Any hole in the boat should be only drilled only at a safe location.