Tag Archive: kayak design

Wavewalk S4 pattern pretty much done

This morning the mold makers sent us a batch of new photos. This time it’s the top part of the S4 wooden pattern.

Some of the areas that have fine details in them were done with a plastic material, in order to achieve the highest precision.

As seen here, this wooden pattern is almost ready to serve as a mold for making the S4 in fiber-reinforced plastic (FRP), such as fiberglass, carbon fiber, Kevlar, etc. But in order to produce a cast aluminum rotational mold for the actual product, the mold-makers first need to use this wooden pattern to produce a set of two second generation molds called ‘sand mold’.

 

In the actual Polyethylene boat, the flat surface on top of the cockpit is cut away with a computerized router, thus enabling access inside through the opening, and attaching the two MDO saddle brackets and the saddle itself.

Stand up casting platform with integrated anti-skid surface. The slots are vertical structures that support the platform’s center.

Front tip and integrated carry handles. Good view of the slanted sides of the cockpit, designed to offer passengers comfortable paddling.

Front view.

Rear view with integrated carry handles and integrated stand for mounting plate for motor, rod rack, etc.

Side view.

Close-up on the slide-in mount for a vertical plate that can serve either to attach a motor, or to install a rod rack. If it serves to mount a motor, the vertical plate should be bolted to the cockpit’s rear end.

Inside the Wavewalk® S4

The Wavewalk® Series 4 incorporates a number of design innovations, including the way its bow is bridged by a structure that can serve as a stand up casting platform.

The S4 bow structure features a pair of molded-in carry handles in its front tip, and four molded-in vertical walls that support the platform on which the angler stands.

This video offers an external view of this bow structure from the top, as well as from below:

But what would we see if we looked inside the bow? –
The following image shows the space that’s inside the bow, between the top ‘ceiling’ and the bottom ‘floor’ – The angle of view is that of a person who’s inside the cockpit, and sticks their head in the entrance to the right hull at the bow –

At the right end of the image, we can perceive the inside of the tip of the bow, with one of the molded-in carry handles.

From there and looking to the left, we can see the four vertical walls that support the top of the stand-up casting platform. When standing next to the boat and looking over the bow, these walls’ top parts look like elongated pits (as seen in the video).
The vertical wall that’s the closest to the cockpit’s front end serves as support to a wooden (MDO) wall that’s not seen here. This wooden wall is the top part of a structural element whose lower part is a front saddle bracket. The wooden wall’s top end is inserted into the coaming (spray deflector), and it is attached to the molded-in wall by means of extra-long aluminum rivets. Thus, the wooden wall adds its own support to the stand-up casting platform.

The top surface of the bow’s standing platform features grooves, and the above image shows these grooves as they would look to someone who was in the front end of the cockpit and peeked inside the right hull at the bow.

Readers who are familiar with the W700 saddle’s round ‘holes’, which are molded-in support columns for the saddle’s top, will recognize this function in the elongated ‘walls’ at the bow of the S4.

More about the S4 »

 

 

Aluminum rivets in fishing kayaks and boats

You may have an outfitting project in mind, such as attaching a rod holder to your kayak, or you may just wonder how strong are Wavewalk kayaks and boats built.
More generally, how well do aluminum rivets work when used in kayaks?

Before going further, we need to explain that nearly all modern kayaks are made from Polyethylene, a polymer (plastic resin) softer than steel and aluminum, and even softer than fiberglass, which is why it requires the use of special rivets that split in three and provide a better grip over a broader surface.
These rivets go under commercial names such as Tri-Fold, Tribex, etc.

Alumium rivets are used for attaching kayak parts together, such as the 14 rivets that attach the W700 Saddle part to the Twinhull part.
They are also used for attaching accessories such as handles, pad-eyes (eyelets), etc.

Here is a little experiment we did –

We riveted together two pieces of Polyethylene that we cut from a part of a Wavewalk kayak. We used just one rivet for this.
We hung one end of the joint pieces of plastic from a basketball pole, and on the other end we hung a fish scale.
We hung a travel bag from the fish scale, and filled the bag with bricks.
We stopped after ten bricks, because the dial on the fish scale had ran full circle, and stopped at 50 lbs.
At this point, neither the plastic pieces nor the rivet showed any sign of stress.

testing-the-strength-of-riveting

50-lbs-pulling-on-a-rivet

fish-scale-at-51-lbs

Needless to say that the effectiveness of a rivet depends on more than just the force applied on it in lbs, and additional factors are very important, such as the angle of the force (vector), leverage (a critical factor), the temperature of the plastic (hot plastic is softer), etc.
If we had attached the parts in this experiment differently, we would have seen different results.

Personal Catamaran

What is a Catamaran?

Typically, a Catamaran, a.k.a. ‘Cat’ is a twin hulled watercraft that features two slender, parallel hulls of equal size, and a wide structure that’s connected to the upper sides of these hulls, holding them together at a big distance from each other.
This structure makes the typical catamaran a geometry-stabilized craft, deriving its lateral stability from its wide beam and the distribution of its buoyancy along its sides, rather than from a ballasted hull, which lowers the boat’s center of gravity (CG), as a typical monohull (single hull) boat does.
The catamaran’s two hulls combined often have a smaller hydrodynamic resistance than monohulls of comparable size, and therefore require less propulsive power.
Catamarans range in size from small sailing boats and motorboats to large ships and ferries. The structure connecting a catamaran’s twin hulls can vary from a simple, lightweight frame to a bridging superstructure, namely deck from which the catamaran is operated, and can be used for carrying freight and passengers.

Is the Wavewalk a Catamaran?

The Wavewalk resembles a catamaran, but it is not a one in the full sense. The Wavewalk design is based on a proprietary (patented) invention – a new type of small watercraft. This patent is entitled “Twin Hull Personal Watercraft”, which is revealing of the fact that a Wavewalk is meant to serve one person, or a small number of persons, and closely interact with them. A Wavewalk is designed around the person and for that person, and it offers them the optimal means to balance themselves. Wavewalk and user are an integrated system that can achieve the most stability in a watercraft of similar size and even bigger ones.
Unlike a typical catamaran, a Wavewalk is narrow – It is slightly wider than its operator, similarly to typical monohull paddle craft such as kayaks and canoes.
The user of a Wavewalk operates the boat neither from one of its hulls nor from the top of a deck-like structure that bridges the hulls. Instead, the Wavewalk user operates it from within, with a leg in each of the boat’s two hulls. The user’s feet rest firmly on the bottom of the hulls, below waterline, namely as low as possible.
And this is the main difference between a Wavewalk and a typical, wide catamaran – The Wavewalk is a smaller and narrower watercraft whose design offers a hull for each of its user’s legs, and the means for them to balance themselves effortlessly, intuitively, and with the maximum effect.
In sum, the Wavewalk is different from a typical catamaran in that it is not a pure form-stabilized boat, but one that combines more than one feature and approach in order to maximize stability*

Another difference between the Wavewalk and a typical catamaran is the form of the structure that connects its twin hulls. This structure is called the Saddle, because it resembles the type of seat found in personal watercraft (PWC) a.k.a. ‘Jet-Ski’, snowmobiles, and all-terrain vehicles (ATV), all of which are high-performance personal vehicles.

If not a catamaran, is the Wavewalk a kayak, a boat, a PWC?

Thanks to its overall size, dimensions, and primary propulsion by means of a dual blade paddle, the authorities, namely the US Coast Guard, officially classify the Wavewalk as a kayak.
Motorizing a Wavewalk with an electric or gas outboard motor does not change this basic classification, and when its owner registers it at the local DMV, they register it as a kayak with a motor, and not as a full fledged motorboat, and this is a good thing both for all parties involved, namely the manufacturer, dealer and owner of the Wavewalk.

The Wavewalk is considerably more stable than kayaks are, including the wide fishing kayaks. It tracks better than kayaks, and paddles infinitely better in strong wind, which is why it does not require a rudder. The Wavewalk also offers much more storage space.
But most importantly, unlike monohull kayaks that force their users to paddle seated in the notoriously uncomfortable L posture, the Wavewalk is back pain free, since it offers it users to comfortably ride its ergonomic saddle, with a leg on each side of their body.

The unique combination of maximal stability and better ergonomics makes the Wavewalk such a perfect match for a motor.

A personal watercraft (PWC)?

Riding the saddle of a motorized Wavewalk® 700 at over 10 mph is an exhilarating sensation that may remind the driver of driving a PWC, but the latter type of watercraft feature much more powerful engines, and can go much faster than a Wavewalk. Additionally, PWC are designed for instant full recovery in case they capsize, which is not the case with a motorized Wavewalk, although outfitting a Wavewalk with inflatable side flotation greatly reduces the probability of it capsizing.

A boat?

Even a small boat is still much wider than a kayak, or canoe, which is why it’s practically impossible to paddle a boat to any meaningful distance. This extra width gives a boat a significant stability advantage over kayaks and canoes, and typically, a normal size person can stand on one side of a boat without tipping over.
But a normal size person can do this in a Wavewalk® 700 too, and this unique fact places the Wavewalk® 700 in a class of its own – a kayak that offers the stability of a small boat.
Motorized, a Wavewalk® 700 offers the performance of a small boat, on top of its unique and unrivaled performance in terms of mobility, comfort, storage space, etc.

What about A canoe?

Canoes can be very big, and transport dozens of passengers. The popular North American recreational canoes that measure up to 17 ft in length can take 3 to 4 adult passengers on board.
While Wavewalks work perfectly with single-blade (canoe) paddles, both solo and in tandem, they can carry less payload than large size canoes do. However, a Wavewalk tracks better than a canoe does, and unlike canoes, it is easy to paddle in strong wind.

… and a motorized canoe?

A motorized square-stern canoe performs much like a lightweight dinghy, and as such it doesn’t work very well as a dedicated paddle craft, namely a canoe…. In addition, it is usually less stable than a typical dinghy, which is wider.
Thanks to its slender, parallel twin hulls, the Wavewalk® 700 tracks better than a motorized canoe, it’s more stable, and being narrower it paddles better as well.
Driving a Wavewalk® 700 is easier too, thanks to the ergonomics of its saddle, and the fact that the motor is located closer to the middle of the boat, away from its stern, which improves balance.

Skiff?

In the sense that it works well as a skiff, namely a small, flat bottomed boat used for fishing in flats, estuaries and protected bays, yes, a motorized Wavewalk® 700 is an ultra lightweight, trailer-free micro skiff, and it can even be outfitted with a bow mounted electric trolling motor powered by a battery fed by the alternator in a small stern mounted outboard motor. This said, its form is very different.

Wavewalk vs Other fishing boats

When it comes to discussing various types of small fishing boats, Michael Chesloff is an expert, and his encyclopedic comparative Wavewalk review entitled “All My Other Boats”  is eye opening »


* Interestingly, the crew of competition sailing catamarans has to relocate from one side of their boat to the other in order to help stabilize it.