Updated Friday, August 15, 2008 10:41 PM
Plans kayak - Jehu, €89
images | information | lines | particulars | history | comments
Jehu is a very fast kayak for exercise and competition. The hull form is close to a competition K1 with high PC and minimal wetted surface. When competing it measures as a "turkajak" (exercise/touring kayak, as defined in the Danish competition rules).
The tradeoff is of course low stability. It takes a skilled paddler and some practice to keep Jehu right side up. The secondary stability is on the high side for the type though - in capable hands Jehu can be a swift touring kayak, provided you travel light.
Jehu can be used with a stern rudder for touring or a standard through-the-hull competition kayak rudder – faster but more vulnerable. More exciting but also more complex to build is an integral rudder (an under water section of the stern turns 20° to either side), a virtually friction free steering system with extremely low turbulence. The speed advantage is surprising.
Even apart from the rudder Jehu is a more demanding project than the other kayaks. With thinner strips and a severe bending in the ends, this should probably not be your first attempt at boat building. But if you try your hand at it, the reward is a kayak with a great potential to be first over the line.
Images - Jehu
Lines - Jehu
Particulars - Jehu
| Length: | total/lwl: 520/516 cm* |
| Beam: | total/lwl: 51/42 cm |
| Draft: | 11 cm |
| Cockpit: | 90 x 40 cm* |
| Height: | in front of/behind the cockpit 25,5/20 cm |
| Weight: | 12 kg |
| Load capacity: | 110 kg - 280 liter |
| Calculated speed: | 9,6 - 14.4 km/t** |
| PC: | 0,63 |
| Wetted surface: | 1,89 m² |
| Calculated drag: | (4 knop) 3,21 kp - (5 knop) 5,85 kp |
| Stability: | low |
| Intended use: | Exercise, competition, and day tours. |
* These dimensions can be adapted to suit personal needs or wishes.
** The speed numbers are based on mathematical standard formulas (175 lb paddler + 30 lb cargo weight) and corrected from the kayaks actual performance om trials, on tours and in races.
I can also offer complete kits and professionally built and finished canoes. Please contact me for prices and terms.
The plans
Two sheets contains the nescessary information to build the kayak.
The hull shape change
When Jehu was designed in 1997 it was as a very fast kayak for comptetition, training and light touring, without any regards for rules and classes. Lately I have had a number of requests to draw a version that conforms to the Danish touring class of kayaks, that has a similar agenda, but demands a wider hull for more stability. Some have also asked about the American touring class and the coming european rules for kayaks used in multisport events.
These three rules systems, though not identical, have enough specifications in common to allow designing a version of Jehu to suit them all. The difference is mainly the length, but this is easily customized when building, by just altering the distance between molds.
So a new Jehu was born. The main dimensions are the same, but the waterline beam is increased from 40 to 44 cm and the draft adjusted from 11 to 8,5 cm (to maintain the displacement). The deck in front of the cockpit is raised 1,5 cm (requested by those used to competition paddling) and to keep the visual balance the stem was raised the same. The volume in the stems are reduced slightly and the sheer is a little narrower in front of the cockpit to allow for a closer stroke.
Much to my surprice I managed to tweak the wider hull to almost the same speed potential as the older (the hydrodynamical calculations indicate a loss of just 0,5% at approx 6 knots), and is of course more stable, which means that a lot more paddlers will be able to use the speed potential.
Left: the new Jehu with a wider underbody – right: the old Jehu plans, that will be available for those who may prefer the more classic look.
