Tag Archive: twin hull kayak

Steering A Motorized Fishing Kayak With Cables

John Zoltner, an engineer and kayak fisherman from upstate New York, outfitted his W500 fishing kayak with an electric trolling motor system (Read More >)

Electric_trolling_motor_and_steering_on_fishing_kayak_JZ

Using his knowledge of prior art in this field, he created a remote steering system using cables. And finally, he improved upon it:

-“I’ve also been fine-tuning my trolling motor concept: I crossed the cables between the TM cross shaft and where it enters the yak. What this does is give me steering that responds directly to the direction I push the control handle. I no longer have to reverse my direction logic when I choose to turn in either direction. I also wasn’t satisfied with my TM crank pulley, so I ripped it out and now have a horizontal reel crank that works much better. .. I also want to try adding a rudder directly to the body of the trolling motor…”

This is a great example that shows how design processes are never final – There is always something new to learn, something new to test, and something that you don’t like  🙂
It’s possible to find many examples for this in reviews of fishing kayaks contributed by anglers.

What Is The Meaning of Aesthetics In Fishing Kayak Design?

To some people, Aesthetics and Design are almost synonyms, and whether this notion is true is debatable, but when boats and outdoor products are concerned, aesthetics is key. But what does it mean, really, when we say that a fishing kayak “looks good”?
This article published on the Wavewalk fishing kayaks blog tries to decode the notion of aesthetics in fishing kayaks (excerpt):

The Good, the Bad, and the Ugly – Aesthetics and Performance in Fishing Kayak Design

What is beautiful?

According to the dictionary, we perceive something as being beautiful if it is attractive to us (e.g. a beautiful woman) or pleasant (e.g. a beautiful day), or pleasant to look at (e.g. a beautiful dress), or if it’s done or made very well (e.g. a beautiful goal in the second half), or with a lot of skill (e.g. a beautiful roast).
Beauty can be associated directly with sensory pleasure, or with indirect, social value related to monetary value, or prestige (e.g. a beautiful diamond), or with both.
In case of a product such as a kayak, the beauty we see in it is a measure of how much we appreciate its performance in terms of what’s important to us, subjectively, whether as something we’ve already experienced with this kayak, or something we believe we would experience, if we used it.

In this sense, the saying ‘beauty is in the eyes of the beholder’ is perfectly true.

What’s important?

What’s important in a product varies according to what different people are interested in. For example, if you’re into kayak racing, you’d be interested in kayaks that are as fast as possible, and very fast kayaks would seem beautiful to you, but if you’re into kayak fishing, you’d be interested a number of things, including stability, comfort, storage, etc. offered to you by that kayak. In other words, for a kayak angler, the beauty of a kayaks depends first and foremost on its fishability,…. (read the full article about aesthetics in fishing kayaks >>)

Stability: The Key Factor In Fishing Kayak Design

Abstract

This article describes the challenges facing the designer of a stable fishing kayak, the factors contributing to kayak stability, and the optimal solution achieved by applying both classic naval design and Micronautics in the design of W fishing kayaks.

Background

Stability is a key factor in kayak design, judged by the number of kayaks designed to offer more stability compared to kayaks designed with little or no regard to stability. The latter types are kayaks designed for rolling, and they sacrifice stability for maneuvering capability in the case of whitewater kayaks, and for speed, in the case of racing kayaks and sea kayaks. These applications are practiced by a relatively small number of kayakers, and they do not show a tendency to gain in popularity. It’s possible to argue that in a broad perspective, the unstable kayak is a failed experiment, or an evolutionary dead end.
All other kayaks are not designed for rolling, and their main safety attribute is the stability they offer, to variable extents. This stability is what helps the kayaker and kayak angler prevent their kayak from flipping in case they lose balance.

The kayak market opted for stability in the recreational, day touring, and fishing applications. Together, these three segments constitute the bulk of the kayak market in terms of sales and participation.
The attempts to paddle kayaks and boards in the standing position (SUP), as well as talks about stand up kayak fishing reflect a need for stabler kayaks.
As for fishing kayak propelled by pedal drives, since this method of propulsion results in the kayaker losing some control over their kayak, including over lateral its stability (balance) to a certain degree, it demands kayaks that are stabler, by definition.
Needless to say that as motorized kayaking and kayak fishing gain in popularity, so will the need for stable kayak designs increase, whether it’s for recreation, touring, or fishing.

Initial (Primary) and Secondary Stability

This article avoids discussing the difference between Initial (primary) Stability, defined as what the kayaker feels in normal circumstances, on flat water, and Secondary Stability, which is what they feel once the kayak has been destabilized, and it’s tilting on its side. The reason for this being that we think of stability as one quality in various conditions, and we maintain that under normal conditions, the kayaker should not be required to make any effort to stabilize their kayaks, or even pay attention to their being in a kayak. This approach is different from the traditional kayak design approach that’s applied mainly to the design of very unstable kayaks such as whitewater and ‘sea’ kayaks. This approach assumes that passenger would roll the kayak if they got destabilized, rather than simply right it.

How To Design A Stable Fishing Kayak?

Regardless of hull type, a kayak is a small boat that features certain universal characteristics, and therefore challenges, including:

1. Kayak Are Narrower Than Other Small Boats

Compared to other small boats, such as canoes and dinghies, kayaks are narrow, by definition, because they are mostly solo boats that are paddled from their middle section, by means of a dual blade paddle. Kayaks that are too wide become too hard to paddle, not just as a result of the paddle strokes becoming less efficient, and therefore less effective, but also because such kayaks are slow due to poor hydrodynamics, they track poorly, and they require the use of a rudder, which further slows them down, as well as makes operating them more complicated.

2. Kayaks Are Lightweight, And For A Reason

Making a heavy and cumbersome boat and labeling it ‘kayak’, or ‘hybrid kayak’, may be a good marketing tactic for some manufacturers who want to address the kayak fishing market, but it makes no sense in plain, technical terms, and from a user’s perspective. At some point, it becomes too hard and complicated to paddle such ‘barges’, or car top them, and that’s when they lose the right to be called kayaks, and earn the right to belong to another category of small boats.

3. Kayak Propulsion Is Weak, In Most Cases

Kayaks are mostly human powered, which means they suffer from a severe power deficiency, which restricts their hull design to forms that are sufficiently efficient in a displacement mode – No planing and no hydrofoils for the common kayak used in the real world for everyday applications, by people who are not kayaking champions… This power restriction also limits the use of outriggers as stabilizers, since outriggers generate much unwanted additional drag, thereby making it to hard for the common paddler, or angler, to paddle kayaks outfitted with such devices.

4. Fishing Kayaks Need To Be Stabler Than Other Kayaks

Fishing out of a kayak involves performing hard physical tasks on the sides of the kayak, such as casting, and landing fish. While doing so, the angler cannot use their paddle in order to balance their kayak, and they have to rely entirely on the kayak’s basic stability.

The Meaning Of These Physical Limitations For Kayak Stability

Being limited in its width, overall size, and hull form, the kayak can offer limited stability. This is not good news for kayak anglers, since fishing out any boat requires it to be stable.
The limits of the kayak’s stability are defined by its volume, and its width.
The volume corresponds to the kayak’s Buoyancy, or its ability to float and support additional weight without sinking.
As the kayak loses its balance, weight gets quickly shifted away from its center to one side, and this extra weight pushes this side downward. If the kayak side is supported by a sufficient amount of buoyancy, it will sink just by a small amount, and offer the kayaker sufficient time and support to regain their balance and right their kayak. If the kayak’s side is not supported by enough buoyancy, it will tip too fast and too low, and thus make the kayaker lose their balance, and capsize their kayak.

How Distributing The Kayak’s Buoyancy’s Relatively To Its Center Line Affects Its Stability

The further away from the kayak’s center line, the more effective the kayak’s buoyancy becomes in supporting its sides, I.E. for stabilizing it.
In other words, for every cubic inch of the kayak’s volume, the distance from the kayak’s center line works to increase the leverage and stabilizing effect: A cubic inch of the kayak’s buoyant volume located along the kayak’s center line has zero stabilizing effect, while a cubic inch of buoyant volume situated at the very far side of the kayak provides a maximal stabilizing effect, for a given kayak width.

For example: For a kayak that’s 28 inches wide, one cubic inch of buoyancy located at its far side, at a 14 inch distance from its center line, provides 14 times more lateral support than a cubic inch located 1 inch from the center line. This is means it’s 14 times more effective in terms of stability.

In other words, if we look at a given kayak volume in cubic inches as an asset that we need to allocate in a way that would maximize the kayak’s stability, we should avoid placing any units of buoyancy (e.g. cubic inches) along the kayak’s center line, or close to it, and allocate as much buoyancy to areas located as far as possible from the kayak’s center line, namely  along the kayak’s two sides. Practically, this means the kayak’s center line should not be in contact with the water at all.
In other words, we need to give the perfectly stable fishing kayak two hulls – one on each side, thus making it a twin hull.

Location Of The Center Of Gravity (CG) And Its Effect On The Kayak’s Stability

A kayak going in water has a total mass, which includes its own mass, and the bigger mass of its operator. This is a classic case in which traditional naval engineering should be complemented by Micronautics.
For the purpose of keeping this article simple, we’ll treat mass and weight as the same thing, and describe the kayak’s center of mass as its center of gravity (CG). The kaya’s CG is located above its center line, and because the kayaker is heavy and sitting upright, the kayak’s overall CG is situated quite high above waterline.  When the kayak gets destabilized, it means that its CG shifts to one side, sometimes rapidly, and in some cases to a great extent. The higher the kayaker is seated, the more leverage its own CG has on the mass combined of themselves and their kayak. This means that a kayaker sitting on top of a kayak, such as when paddling a sit-on-top (SOT) kayak, or fishing from it, is less stable than a kayaker seated at the bottom of a sit-in kayak.

Twin Hull Fishing Kayak Vs. Catamaran Kayak

Going back to our ideal stable kayak form, which is a twin hull – A traditional catamaran design would imply that we connect the two hulls by a platform, and let the kayaker operate their kayak while seated on top of this platform, as well as fish from it while being seated in the traditional L position, similarly to a SOT kayaker. This has been tried in the past, and similarly to the SOT result,  it was sub-optimal due to the fact that the kayaker’s CG was too high, and the L position offered no advantage when it comes to reacting to lateral forces, whether while paddling or when fishing.

The Traditional L Kayaking Position Vs. The Riding Position

The combined stability and ergonomic problem described above was solved in the W kayak by designing deep, hollow hulls for the ideal stable kayak, and enabling each of the operator’s legs go in its own hull, all the way down, with feet firmly resting on the bottom – that is below waterline, as low as possible.  This took some of the kayaker’s weight and redistributed it lower than it would have been if the kayaker was seated in the L position. By that, the kayak’s CG was lowered as well.
In addition, placing the kayaker’s legs in the hulls offered the kayaker better leverage on the kayak, by enabling them to use their legs intuitively and effectively for balancing and stabilizing the kayak, and doing so by applying their weight on the bottom of the hulls, instead of on the top of the deck. This advantage can be described as ‘active ballasting’. It is comparable to the advantage achieved by ATV, snowmobile and PWC drivers, who operate their vehicles from similar riding positions.

Some Fishing Kayak Stability Facts

Fishing kayaks are wider than the average kayak, but although it’s one of the narrowest fishing kayaks (just 28.5″ wide), the W500 is the world’s stablest fishing kayak. In fact, it’s even stabler than fishing kayaks outfitted with outriggers.
Due to its narrowness, narrow hulls, and improved ergonomics, the w500 is faster than most fishing kayaks, including some that are considerably longer, and many touring kayaks as well.

The W Kayak invention is protected by US patent number 6871608