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Design & Illustration

Jack 14

Images | Particulars | Background and history

Jack 14

Plans, Jack 14 - 96 EUR Purchase

Jack 14

Jack is a handy mini sea kayak, that is doing quite well in a lot of different environments and conditions. It is short and handy on land and on water, more stable than most of my other kayaks, but not excessively so – it moves smoothly and predictably in waves.

In overall shape and function, it is a development of the Discovery 14 I designed for Seabird some years ago. Now, a few years later and on my own, there is potential for improvements. As usual, it is about fine-tuning the hull hydrodynamically and visually. The hydrodynamics follow my usual agenda: low friction and reasonably low wave-building for a healthy touring pace with minimum effort (for a short kayak), trackability and maneuverability balanced for ease of handling in all conditions, and a stability curve that lets beginner trust the kayak but leaves the competent paddler in command. Aesthetics is about finding harmonious relationships between lines and surfaces, so the visual qualities come from the designed function, not superficial styling.

Some things come free when building a wooden kayak: low weight – often 3-4 kg lighter than laminate and 6-7 kg lighter than plastic – and stiffness. The latter means less energy wasted on deformation in waves (it is like comparing the energy transfer on an old ladies bike with a bendy frame with a modern competitive bike) resulting in better paddling efficiency.

Compared to commercial kayaks, the home builder can fine-tune the seating and cockpit configuration – a DIY kayak has the potential of superior comfort and control.

Even if Discovery was clearly outside my comfort zone (far from Black Pearl and Njord ;-) I was very satisfied with the result – better than I had anticipated when accepting the assignment. Comments from retailers, press and users were very positive. The new Jack 14 is an improved Discovery: light, efficient and fun.

This is what Playak.com had to say about Discovery when it was introduced:

"Get out onto the water with ease: the Discovery provides it all in one neat little package! The kayak is responsive and stable, plus it features a distinctly shaped hull great for bridging a wide choice of day trips. The Discovery is light and very easy to handle, additionally providing extra fine-tuning options for meeting your personal preferences. This mini sea kayak is exactly what you need for exploring open, choppy waters on the sea; the lull of lazy rivers and wild beauty of lakes.

The Discovery is fantastic for fishing excursions. A high level of stability allows you to feel assured while turning your attention to reeling in a catch; the specialized hull is likewise very conducive for extra-kayaking activities."

 

Images

Jack 14 – Karl VesterdahlJack 14 – Karl VesterdahlJack 14 – Bjørn Arild HauglinJack 14 – Bjørn Arild HauglinJack 14 – Bjørn Arild HauglinJack 14 – Bjørn Arild HauglinJack 14 – Bjørn Arild Hauglin

Particulars

Jack 14 – linjeritning

A flattened bottom combined with considerable rocker places the paddler slightly deeper for more initial stability and a more comfortable paddling stroke, giving superb control over the very easily maneuvered hull. The ends are fairly full to prevent the kayak to dive when surfing steep waves in speed and, with a rounded bottom profile to move smoothly and predictably. The keel is drawn out aft to improve direction control in speed. Together with an adjustable skeg, it covers a wide performance range. The deck and cockpit configuration are almost the same as those recommended for Njord and Frej, but with a couple of centimeters extra room for knees, feet and gear.

Length¹ 420/396 cm (overall/WL)
Beam 63/60 cm (overall/WL)
Draft 11 cm
Cockpit¹ 80x42 cm
Height¹ 32/22 cm (in front of/behind the cockpit)
Load capacity 130 kg/412 litre
Prismatic coefficient 0.52
Wetted surface 1.84 m²
Intended use Det mesta – fors, sjö, hav; dagtur, fiske, långfärd...

* These dimensions can be adapted to suit personal needs or wishes.
** Depending on type of wood, equipment, care with epoxy usage, sanding etc. etc.
*** The speed numbers are based on mathematical standard formulas (175 lb paddler + 30 lb carco weight) and corrected from the kayaks actual performance om trials, on tours and in races.
⁴ Calculated resistance in 4 and 5 knots (at nominal load capacity).
⁵ Initial stability and secondary stability on a subjective scale, where 1 is very tippy and 5 is very stable.

Plans

To build Jack you will need approx 260 meters strips (20x5 mm) including a little extra for waste and a mistake or two, 13 meters fiberglass. Epoxy usage differs a lot among builders, but for most, 6 kg will be enough. If you change any of the dimensions on the plans, you must of course recalculate.

The easy lines of Jack 14 make it relatively easy to build. Just remember: don't even think of using full-length strips on the deck! Cut all strips that fall over the cockpit.

Minimum window dimensions to get your kayak out from the workshop: 63x37 cm

Beskrivning ritningsblad

The illustrated step-by-step building manual is in Swedish only, but it is available online in English: it covers all steps in detail and will guide first-time builders through the project.

Plans, Jack 14 - 96 EUR Purchase

Background and history

An assignment always comes with compromises. You give and you take in discussions with the client. Discovery was my first design assignment outside my comfort zone (long, low, narrow and fast kayaks) – a short and wide recreational kayak. But developing the hull we slowly pushed the envelope, and out came a very competent and versatile little kayak. Transcending the limits of what is commonly understood by "recreational", it proved to be more controllable, faster and more fun to paddle than I expected.

Seabird Discovery
Seabird Discovery 14, designed 2009

My concessions with the Discovery project were a little more waterline beam midships, and a higher deck than I would have wanted – and a rudder (that on a highly maneuverable kayak actually decreases the maneuverability by limiting the stern's ability to skid at slow speeds)!

With Jack I have optimized the hulls performance with a skeg, lowered the deck a couple of centimeter for more comfort and better kayak control and shaved an ounce off the wave resistance – altogether resulting in a slightly increased touring speed for the same effort, more comfort, and better control in different conditions than a rudder would have allowed.

Jack 14The name, Jack 14, alludes to "jack of all trades, master of none", as someone who is competent with many skills but is not necessarily outstanding in any particular one. That is the way I regard Jack: maneuverable enough for surf or whitewater but with skeg down tracking nicely on long distances, touring speed to accompany full-length sea kayaks on tour but winning no races, load capacity for touring but performing nicely unloaded, initial stability enough for beginners but a balanced stability curve to suit competent paddlers in waves, ideal for summer vacations as well as demanding fishing trips on sea or lakes etc.

The number 14, of course, is the approx LOA in feet, a figure rarely used in Scandinavia where we are all metric, but common in the industry and among paddler in many parts of the world. From contacts with builders around the world I have noted that the metric system is widely accepted, with the exception of the US – I still get quite a few emails with questions of what fx 64 mm will be in US customary units? (conversion apps on the internet, someone?). But I have always wondered how England could have been a major shipbuilding nation through centuries with the handicap of having to communicate a simple number like 645 mm as something like 2 feet + 1 inch + 3/8 of another inch + another plus sign to indicate that the actual number is actually a little more than the number itself indicates ;-) 

There are no universal kayaks, best for all paddlers and all conditions – but if pressed, I would suggest Jack 14 as a promising candidate...

Comments

Dear Björn,

Having recently retired I am looking to doing that travelling that many of us elder's do.

Beside the cross country road trips, I have in mind to do some kayak fishing as well as single and multi-day water bound trips.

I have spent the day drooling over the fluid pen strokes of your designs, and at last managed to narrowed it down to three, the Jack, the Frej and the Panthera... ok the last just because of it's looks.

I have read through most of the posts and comments (at least the english ones) in those design with regards to weight but found little a for a guy like me. I am one of those skinny guys that just can eat and never gain weight, so for 172 I only weigh 52kg and even though I don't have the strength from my rock climbing day I still have stamina to resell. I don't plan sea trips, it would be more for lakes, but you never know.

I like the Jack for it's JOAT functionality and car top practicality, but am worried the multi-day trips could "suffer" from to much spaghetti per mile. Should I switch to the faster Frej or maybe just narrow down the Jack?

Just wished they had that plumb bow of the pantera into them, what a nice design!

Cheers

Daniel,

All my kayaks are basically designed around my own 185/85 (of course adjusted up or down depending on use and user) and will be unnecessary big for you. Thus they will float high in the water, being more exposed to the wind and less to the water.

Frej and Jack 14 (and Njord) are basically versions of the same hull, just different proportions. And since length is the easy parameter to change I would suggest a Frej, shortened to Jack-length.

That will reduce the load capacity to achieve a better float level, while the reduced width will increase speed and paddling comfort, and the reduced height will achieve better kayak control and handling.

You will also get a more plumb stem this way (but I am not quite comfortable with plumb stems on short and wide kayaks – makes them look a bit chubby... )

You can of course also shorten the Panthera, but with the surfski-inspired hull it lacks much of the directional stability of sea kayaks, and will probably be dependant on a rudder even shortened – a rudder that will be unnecessary on such a short and maneuverable kayak in all other respects.

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