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Spindrift

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Spindrift 2 – surfski in wood

Plans, Spindrift - 108 EUR Purchase

My wood strip surfski has been brewing for a very long time. It started with the Sea Racer. As the name implies, it was designed as a very fast sea racer with long distance touring capacity. I found the inspiration in Alaska and the plans were finalized during spring 2006. 

But before I had my own Sea Racer launched I was asked to design surfskis: first out was Nordic Kayaks Fusion, the first in a long line of top skis. Then came Seabird Designs, for which I designed the Wave line of skis, followed by a new company, Axis, with a line of surfskis and surfski hybrids (which due to issues with the company structure is discontinued). 

Now realizing the potential of surfskis I initialized a project of my own: a wooden surfski. The idea was to, that with the inherent advantages of wood (lighter and stiffer) would almost match the top elite skis while still be within reach of intermediate paddlers. The result is Spindrift.

What a fabulous boat! I have done 5 races and have had 2 first place wins, a second and a fourth. Surprisingly have been able to come out in front of a number of paddlers that are 1/3 my age. [...] I can't take all of the credit for my success and have to thank you for a design that has exceeded my expectations. I am truly amazed at the speed/stability ratio. I know that given the dimensions of this surfski, it can't possibly be as fast as many of the elite level boats on the market. The fact that it is fast for its length and beam can partially be attributed to its linear stability curve. I am able to apply full power in this boat and that is not always the case for me in "faster", tippier boats. [...] I have been in some reasonable sized "bumps" and have occasionally had the bow dip under, but not too far. [...] The boat has attracted more attention than I ever imagined. The lines that you drew create a beautiful sight when they come to life in wood.

Ken Katz

It can be built with an under-the-hull rudder (the most efficient version) for racing/exercise or an aft-mounted rudder and hatches for touring. The dimensions are 608x48 cm and the length can be adjusted as usual during setup, with advice on the plans for hulls between 576 and 640 cm. The surfski hull is easy to build due to clean, harmonious lines. The cockpit structure may seem complicated, but three different methods are indicated on the plans: stripfoam or carbon/fiberglass and a general shape is drawn as a good starting point for individual adjustments.

  

Spindrift 2 – surfski in wood

A shorter and wider version will be available later – in about six years... (just joking ;-)

I do not plan to include a top level elite ski. Very few amateur builders would be able to match a professionally built elite ski tipping the scale at approx 10-11 kg – and those who would, won't need my plans anyway. If you want to compete in the surfski top worldwide circus, I suggest you buy a Nordic Kayaks Nitro, or one of the other top skis.

Images

Ken Katz – SpindriftKen Katz – SpindriftKen Katz – SpindriftKen Katz – SpindriftKen Katz – SpindriftKen Katz – SpindriftKen Katz – SpindriftRoderlösningSpindrift – Ken katzSpindrift – Robert RusselTwo New Zealand Spindrifts and a Spray on the water. Photo: Lockie Russel.Two Spindrifts and a Spray in New Zealand, built by Robert Russel.The Russels with their Spindrifts and Spray. Photo: Warwick Russel.

Particulars

Spindrift 2 – lines

Length¹ 608/603 cm (overall/WL)
Beam 48/44 cm (overall/WL)
Draft 10 cm
Weight² 16-19 kg
Load capacity 110 kg/381 litre
Prismatic coefficient 0.55
Wetted surface 2.05 m²
Intended use Racing, excercise and touring on open sea, lakes or rivers

* 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

The plan sheets contain the information needed to build the kayak/canoe. Station molds, stems and construction details are full scale. For kayaks the recommended cockpit size is shown half scale with offsets for a full scale drawing and advice on altering the size. On the plans you will also find advice on how to shorten or lengthen the craft. Lines and construction drawings are in metric scale 1:10.

Spindrift 2 – plans

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, Spindrift - 108 EUR Purchase

Minimum window dimensions to get your kayak out from the workshop:
49x34cm

Why a surfski instead of a sea kayak?

There are of course good reasons for both. They do the same job and there is not much that cannot be done in both. But I guess that surfskis will take over some of the sea kayaks home waters (perhaps we will declare rudder-dependant sea kayaks, multisport kayaks, and training kayaks endangered species in a few years). Surfskis are in a way a step forward in the kayak concept. The rationale may go like this:

Safety

The safety routines in a ski are easier to master than comparable routines in a sea kayak.

  • Reentering the cockpit from the sea is a straightforward and quite simple procedure (at least in surfskis with some level of stability) that takes a couple of seconds and is done the same way in all conditions. Since it is very quick there is less risk of getting cold or tired, and there is no water to pump out – it drains as soon as you start paddling (but, of course, a well-designed sea kayak and a bomb-proof roll is even better!).
  • A surfski is basically a simpler craft with fewer components that can break or malfunction, and the few needed are within reach in the cockpit (the pedal setup and the drain).
  • A surfski is an efficient craft; faster and lighter – but it is not just about speed. Just as important is conserving energy on long distances, touring or racing, about having the strength to deal with a headwind or current at the end of the day.
  • A surfski is controllable in conditions where a sea kayak is hard to control. The reason is efficient steering: solid pedals and big efficient rudders (never thought I would actually say that ;-). But an elliptical rudder two or three feet from the stern on a highly maneuverable hull is far more efficient than an aft-mounted rudder on a sea kayak and the solid and precise pedal control with no flex is much better than on most sea kayaks – and the direction stability needed in a sea kayak will compromise maneuverability to a degree.

Fun to paddle

A surfski is exciting on the water. In addition to all what most sea kayaks can do, the surfski offers downwind runs in rough seas with amazing surf under full control and at speeds well above what even a very fast kayak can achieve - or to play in the breaking waves in the same way board surfers do.

Simple to use

The surfski invites a minimalistic approach: fewer gadgets to buy, pack and unpack during trips, and less upkeep. That means less weight, better performance, and quicker launchings. Of course, those paddlers used to filling up their sea kayaks for trips will perhaps not like roughing it out in a surfski.

Excercise

A surfski is a formidable exercise and training craft. A trip in a sea kayak is of course as efficient as a workout (provided you do not lean against the backband and use your arms only) but the simplicity is a bonus: a light surfski on the shoulder, paddle and PFD in the hand, launch and away you go...

Sea racer vs surfski?

What is the real difference between the Sea Racer and the Spindrift? Or in general – what separates surfskis from sea kayaks or multisport kayaks?

Well, it turns out the only sure sign is the cockpit configuration. In everything else there are lots of crossover crafts floating around, defying categorization: sea kayaks with surfski maneuverability and surfski with the calm movements of sea kayaks and all kinds of hull configurations.

Modern Surfskis were from the start developed to run off the wind on large swell reaching extreme speeds, and to surf the wavefronts in control. To keep the position and direction on those waves, extreme maneuverability was needed. To control the craft, precise steering and a large rudder were necessary. The stem was high to avoid diving in the gigantic waves of the native waters in Hawaii, South Africa, California, Australia – while the stern often became little more than a long tail with a rudder. The fore part was deep and narrow moving the lateral center forward to balance the large rudder, while the aft part was wide and shallow to prevent the stern from submerging in speeds close to or above hull speed. Surfskis became elite tools for tough oceans races. But eventually, the market evolved to include also crafts more suited to "normal" paddlers with touring ambitions.

Sea kayaks, on the other hand, evolved towards strong tracking, rather than maneuverability. The designers sacrificed some maneuverability for comfort on long passages – in automotive terms, they have the soft somewhat imprecise steering with a healthy margin for errors of a family car, rather than the precise and attention-demanding direct steering of a race car. Of course, some of the control is lost in the process. Have you tried to surf a steep wave diagonally in a sea kayak, you will know what I am talking about. But lately, we have seen a lot of sea kayaks with almost surfski-like maneuverability and control.

A look at the lines of the Sea Racer and Spindrift reveals these differences. The Sea Racer hull is more symmetric, with LCB, LCF and CLA quite close to the center, indicating a hull that moves smoothly and predictably in the water (LCB = Longitudinal Center of Buoyancy = the centroid of the underwater volume of the boat expressed as a longitudinal location. LCF = Longitudinal Center of Flotation = center of the waterplane, the "seesaw" pivot of the craft. CLA = the geometric center of the lateral plane). The seat is located slightly aft of the center, providing controllability without being overly dependent on the rudder (mildly understeering in automotive terms). The rocker is not very accentuated, which improves tracking. The kayak deck with cockpit rim/spraydeck keeps water out, allowing for a lower and less wind sensitive profile. For the same reason, the freeboard amidships can be lower, to allow a lower and less tiring paddle stroke on touring.

Sea Racer and Spindrift – lines

In the surfski, the CLA is moved forward to balance the large rudder. The seat position slightly forward of the LCB is the key to the efficient and precise steering on wavefronts – in automotive terms, the ski is slightly oversteered in low speeds, but becomes neutral in higher speeds since the longitudinal position of the hull's center of turning is related to speed.

Sea Racer and Spindrift – lines

Note that the Sea Racer is not a typical sea kayak – it was influenced by surfskis from the start.

The station drawings show that the surfski is wider and higher than the Sea Racer. But the difference in volume and load capacity is not as large as it might seem – the higher Cp of the Sea Racer means that the volume is more evenly distributed along the hull, while the surfski has more volume concentrated midships. This suggests that the Sea Racer should be slightly faster on flat water, but the surfski should win in waves.

Sea Racer and Spindrift – stations

The shape of the sections looks quite different. In the Sea Racer, I wanted to optimize the initial stability in what is a very narrow craft (43 cm), with the chines also enhancing steering control when the hull is leaned (a way to keep rudder turbulence to a minimum). For the wider surfski, I chose to minimize friction with elliptical sections below the waterline.

Software and the design process

The sectional shape is also to a degree influenced by different calculation algorithms. The Sea Racer was developed using Bearboat by Robert Livingstone for the hydrodynamic calculations. The main advantage of this is that the underbody defining vectors hang from the waterline and the keel, which makes it possible for the software to minimize the wetted surface for every set of design parameters chosen. It saves a lot of time fine-tuning the hull to low friction but also means that the bottom and freeboard are two independent sets of curves, meeting at the waterline. On certain kinds of hulls, this complicates getting a smooth natural curve from the sheer to the keel.

For the surfski, I used Ross Leidy's KayakFoundry, forked from Bearboat, but with one important difference: the vectors hang from the sheer and the keel. That means better overall control of the lines (including deck shape and stem and stern) compared to Bearboat, but the disadvantage that you have to work the wetted surface manually based on experience and through repeated iterations followed by checking the calculations. One further disadvantage is that KayakFoundry is just for Windows. I have to run it virtualized in Parallels on my iMac – it works, but a bit slower than native Mac applications (it takes a lot of memory to run two separate OS).

Both applications are easy to use and do an excellent job at their level, but the downside of the simplicity is the many limitations in what can be achieved (not a problem for the amateur builder, who would solve those issues in the construction phase rather than on the computer anyway). Therefore I use them for a quick zooming in on the hull shape I want, along with all the hydrodynamical data I need – getting within 95% of the final design in surprisingly short time and with adequate accuracy. From there I transfer the lines to Illustrator for the final manual fine-tuning, including both functional tweaking and the visual layout of lines and surfaces – which always takes a lot more time than the first 95% in the design software!

That may seem a tedious way to design a kayak, but the alternative – professional ship CAD design systems are very expensive and bloated with features of which I would use a small percentage (I do not need to know what happens to the ship's stability when 600 tons of crude oil sloshes around in a half empty tank, nor at which parameters the risk of propeller cavitation becomes an issue ;-) and would take hundreds of hours training for me to master.

Spindrift

The surfski is named Spindrift – an apt name for a craft with an appetite for wind and waves.

Spindrift – logo

Surfski history

The surfski history is linked with surfboards rather than with kayaks. One common starting point is two brothers in Australia, Harry och Jack McLaren, using a kind of paddleboard hundred years ago in the breakers around the oyster beds the family owned at Port Macquarie, New South Wales. From the descriptions, these were ancestors of today's surfboards and SUPs rather than what we now mean with surfski. But surfski was the common name then.

Sometimes mid-century the rescue organizations in Australia found out that these “surfskis” were more efficient than the rowboats with a crew of 5 that were used to save swimmers swept out to sea by the currents. They were simpler, cheaper and faster, and 1946 surfskis were officially accepted as rescue crafts – then flat surfboards, far from the surfskis of today.

What now is known as surfskis developed in competitions between rescue teams on different beaches during the 50s. The early paddle boards were heavy skin-on-frame designs, but they soon evolved to longer and narrower hulls – still paddled standing up as SUP:s.

At the Melbourne Olympics 1956, athletes from other countries saw the surfboards and were impressed. In the US and South Africa, the next step in the development of a modern surfski was taken.

In South Africa, the skin-on-frame was exchanged for foam-filled fiberglass hulls with a cockpit and the main focus was distance competitions. In Australia, the sport came to focus on sprint in strictly regulated fiberglass surfskis.

On Hawaii, this evolution took off a little later and, very interestingly without any rules regarding the hulls. The developing environment was the toughest possible:  formidable Pacific swell and fast-moving currents around the islands. Molokai Race became the most important event to evaluate new designs and ideas. Also very interesting is that the fastest time ever on Molokai is from 1997 with an older, shorter and heavier Hawaiian ski and a standard flat paddle (Dean Gardiner). That is just one indication that today's surfskis at 6,5 meters may be longer than necessary – and the reason may be that a couple of very big and strong competitors dominated the sport for some time, tricking the manufacturers to increase the length. They could make good use of the long hulls in spite of the increased friction. But can we?

I believe that the top surfskis of tomorrow will be perhaps 5% shorter.

Comments

Hi Björn,

you write "This suggests that the Sea Racer should be slightly faster on flat water, but the surfski should win in waves…"

Can you explain a little further what lead to your suggestion? I believe what you write is true but I don't understand the physics behind it. How does the surfski profit from the more centered volume in waves?

It is a complex equation and I am not sure about the outcome until tested IRL. But the rationale goes something like this: the Sea Racer has a flatter run, less rocker resulting in a slightly higher Cp, which in turn means better top speed. The surfski on the other hand has more rocker and lower Cp, meaning lower top speed. But the superior maneuverability, neutral steering and seat in the center of the hull means a softer, drier run and less speed loss in waves. Since the Sea racer is a slightly "surfski-ified" sea kayak the differences may be small – but the surfski has a definitive edge off the wind, where the maneuverability and control will make a huge difference.

It is a bit annoying to see my article copied and modified as if it is your own. I am talking about all the points about the difference between surfski and sea kayaks. The same goes a guess with the design that is claimed to be so revolutional and exists from another brand for over 2 years.

Boyan, certain things are indisputable true about surfskis vs sea kayaks, and I can't omit them just because you have mentioned them (Cadillac once referred to this as "the penalty of leadership").

Revolutional is your word, not mine, never mine. I believe in evolution rather than revolution, in incremental improvements rather than innovations.

In the above I have shared my process of reaching the functional and visual design that is represented in Spindrift and in Spray. Nothing less, nothing more...

Hi Bjorn. I have built a few kayaks before, so I am familiar with the strip process. But; the seat bucket and rudder pedals looks complicated. How can I get a good result?

Peter, this is the text on the drawing;

"The cockpit shown is a generic cockpit that fits most paddlers – long enough for tall paddlers, plus a sliding pedal set-up and similar to the ones used on commercial surfskis.

When changing the cockpit configuration to suit, remember that the position of the seat part is crucial to the performance of the craft – you adjust the forward bulkhead and footwell to your own length.

The cockpit can be built in many ways: it can be stripped like the hull and deck, keeping the overall shape and volume approximately as on the plan.

It kan be built from foam insulating boards between two solid wood bulkheads, again keeping the overall shape and volume (glue 4” foam boards together vertically to fill the cockpit and cut and sand to shape). This is an adaptive process, where you can work the shape in incremental steps by cutting, sanding and filling, until the cockpit is comfortable and efficient.

An even better way (light and beautiful if executed with care) is to use the foam cockpit as a mold for a glasfiber/carbon cockpit structure. Cover the mold in packing tape and release wax, laminate the entire structure – 4-5 layers fiberglass, 1 layer carbon and on top 1 layer fiberglass (to protect the carbon when sanding). Remove the structure from the mold and glue it in the deck cutout."

In the links to builders project above you will find photos and description of possible ways.

Then of course some builders, with experience of surfskis, just made a mold from the cockpit on their favorite commercial surfski and and built their own copy from that.

Ji Björn,

I really love your Spindrift design, both as a sea kayak and ocean ski paddler, and as an ex boatbuilder. I've been looking for a convincing long ski design for some years and am delighted with the lines you've drawn up.

Thank you

Thank you Benjamin!

Du kan mycket Björn och det är alltid lika intressant att titta in på din sida. I följande så tror jag dock faktiskt att du har fel:

"Någon riktigt vässad elitski kommer däremot inte som byggritning. Mycket få hemmabyggare kan matcha en professionellt byggd toppsurfski kring 10 kg – och de få som verkligen skulle kunna behöver inte mina ritingar."

Har man paddlat lite kajak innan så tar det bara några veckor att lära sig att behärska en surfski med Spindrifts mått, -även i stökiga förhållanden. Därefter så känner man sen att man vill ha något ännu snabbare (/smalare).

Visst är det kanske svårt att med ett hemmabygge matcha vikten på en kolfiber-surfski men alla har ju knappast råd att lägga ut 27' - 35 tusen på en sådan heller. Personligen så tror jag att omkring 44-45 cm är det perfekta breddmåttet på en surfski. Då kan man bygga den snabb men den är fortfarande tillräckligt bred för att man ska kunna bygga in tillräckligt med stabilitet så att en glad amatör kan paddla den utan större svårigheter. Så mitt tips är att du tar och designar ytterligare en surfski-modell som du gör smalare och snabbare. ;-) Är helt övertygad om att det skulle bli många sålda ritningar! Och om man kan bygga och paddla en 43 cm bred Havsracer så kan man väl bygga och paddla en 44/45 cm bred surfski... Eller? ;-)

Tack för en bra sida!

Javisst skulle de flesta kajakbyggare kunna bygga en smal surfski, och några få kan kanske även komma ner i konkurrenskraftig vikt. Men de kajaker jag har på sajten är inte avsedda för tävling på hög nivå: varken racing, maraton, surfski eller fors. Det finns flera skäl till det; dels har jag aldrig tävlat på elitnivå och har därför för lite erfarenhet, och dels är jag involverad i utvecklingen av Nordic Kayaks elitsurfskis och har ingen anledning att sälja ritningar till en konkurrerande surfski.

Det jag menade var inte att den skulle vara avsedd för tävling, utan snarare tvärtom; för glada amatörer som vill ha en snabb surfski att paddla utan att för den sakens skull behöva lägga ut en förmögenhet på en ski i något avancerat material... Men jag hör vad du säger och din ståndpunkt gällande att ej vilja konkurrera med Nordic Kayaks köper jag helt och fullt!

Hej Björn,

Jag överväger att bygga någon av dina surfskis - verkligen fina! Jag undrar dock om och i så fall hur de utrustas med självläns?

Med vänlig hälsning,

Fredde

En läns är närmast en nödvändighet på en surfski, i alla förhållanden där du skulle haft ett kapell på en motionkajak – annars kan det bli en hel del jobb med en länspump under paddlelturerna.

Du ser länsen som en svart rektangen bakomm fotstödet i bilderna ovan. Den monteras genom skrovet från in- eller utsidan i sittbrunnens djupaste del, och kan manövreras med foten eller handen. Vissa länsar har en klaff som automatiskt stänger när man stannar eller backar.

Hi Björn, thanks a lot for your tips and shapes. I saw black pearl and hunter and was inspired to build a strip kayak this year with a hull like surfskis(I read about it now) I used the kfoundry. I can confirm that a round belly is very stable in waves. This autumn I surfed first time a bit in the waves of north sea. And it was great, although I´m beginner in this. The kayak is very maneuverable, smooth-running and save in the wave. Jump through the waves and be pushed by them is great. Next summer I do it again!! On the contrary the knight heron s& g with a less round belly is much more tippy and less manoeuverable. To turn is more difficult and to go straght on also. Edging is better but I hardly need it. And top speed I don´t need neither. And my kayak looks at least as good:) https://imageshack.com/a/SZ64/1

Greetings from Hanover

Looks nice, Joachim. But there is a lot more to performance in waves than the shape of the bottom. The kayak in which I feel most safe, secure and relaxed in different conditions on open sea is my Njord – in spite of its trapezoidal sections. It is also fast (touring speed) and highly maneuverable.

Normally a round bottom has less initial but more secondary stability compared to a hard chine hull. But since this difference is rather small, tweaking other data (loa, beam, Cp, sheer height, rocker etc), can change this to whatever you want.

Eller spindrift

Hei Björn.

Jeg har bygget 4 strip kajakker tidligere og vurderer å bygge en surfski.

Går det an å tenke enklere angående sittebrønnen i strip? Jeg tenker at dobbelt bunn både øker kompleksiteten og vekten. Kunne det være en ide å montere bulkhead foran og bak for så å montere sideplater og ikke lage dobbelt bunn. Så kunne man montere et sete på bunnen og sitte tørrere. Ulempen blir et større gulvareal og noe tregere vanntømming tenker jeg. Styrken kan ivaretaes med forsterkninger rundt toppen av sittebrønnen.

Hilsen Bjørn

Ett av mina förslag på sittbrunn är just att sätta skott framför och bakom och använda mellanrummet som sittbrunn. En sits är egentligen allt som behövs därutövet. Dubbel botten är onödigt – det är bara en följd av att sittbrunnen är en gjuten balja. Men det är samtidigt viktigt att minimera den fria volymen, annars blir kajaken rank efter en vattenfyllning och tar lång tid att tömma via länsen (som inte är gjort för att hantera stora mängder vatten). Din idé med sidoväggar bör fungera utmärkt för detta. En annan idé är att fylla mellanrummet med vertikala skivor expanderat skum med slutna porer (polyester-, vinyl- eller PVC- skum), utskurna till att bli en komfortabel sits och ett lagom stort benutrymme (allt format som en vanlig surfskisittbrunn). Lite slipning och ett lager väv eller liggunderlag där man sitter kompletterar.

Denne vinteren bygger jeg en stripbyggekopi av en Disko Bay 1931 modell. Side 308 og 338 i "Kayaks of Greenland". Inkludert S-formet kjøllinje..

Jeg har også bestilt planene til en Spindrift, men det blir til neste vinter. Tanker rundt denne surrer rundt i hodet hele tiden. Har fått tak i en skadet Wave 5,5 som blir mal for sittebrønnen.

Spørsmål 1: Hvis jeg sager formene etter strekene uten å trekke fra listtykkelsen på 5 mm (4 mm etter pussing), blir bredden 48,8 mm med litt økende stabilitet og motstand. Vil dette ha noen andre negative konsekvenser jeg ikke tenker på?

Spørsmål 2: Hvis jeg senere ønsker å bygge en slankere versjon ved å skalere ned planene med 5%, slik at bredden blir (48 x 0,95) + 0,8 =46,4 cm, er dette lite smart?

Jeg har lest du ikke anbefaler å skalere planer, men er veldig interessert hva du tenker rundt dette.

Sågar du spanten efter ritningen blir skrovet 48 cm – spantlinjerna är till insidan av bordläggningen. Att öka eller minska bredden någon cm har inga andra konsekvenser än att stabiliteten och motståndet ökar resp minskar en aning.

Gör du ändringen i ett ritprogram brukar det blir tämligen exakt. Gör du det i en kopiator med justerbar längd-breddskala blir det ibland småfel, men inte värre än att de försvinner vid slipningen.

Hei Björn,

Grunnen til at jeg stilte spørsmål 1 over, er notatet på tegningen jeg har mottatt.

"Note!

The lines are to the outside of the hull, and the hull thickness must be deducted from the moulds when building.!

Tegningen er datert 2013-05-10.

Jeg målte det bredeste formspantet i går kveld til 47,6 cm. Dette gir vel en bredde på 48,5 cm på surfskien og er helt greit for meg.

Tenker likevel at beslutningen om å trekke fra eller ikke trekke fra er av en viss betydning, da endringen er relativt større på smale formspant enn brede formspant. Det vil gjøre en liten endring på Cp. Dette er trolig mer av akademisk interesse en praktisk betydning.

Hilsen Bjørn

Ja,du har rätt. Jag missade det i mitt förra svar. En del byggare har valt att bygga just Spindrift med tunnare strips för att minska vikten och åtminstone en har experimenterat med honeycombkärna och lite tjockare skrov. För att ge möjlighet till varierande byggmetoder ändrade jag Spindrifts spantlinjer till att visa utsidan av skrovet (till skillnad från övriga kajaker).

Största bredden hamnar mellan spant 9 och 10 – du får alltså förmodligen (beroende på hur du slipar) ytterligare någon millimeter totalbredd.

Att använda utsidans mått som insida innebär främst att volymen (och därmed lastkapaciteten) ökar en aning, vilket innebär att skrovet flyter en aning högre i vattnet (4-5 mm). Påverkan på skrovformen och Cp bör däremot vara knappt märkbar. Formändringen är procentuellt större i ändskeppen, men eftersom volym och våt yta där bara är en liten del av den totala volymen/ytan tror jag inte att det kommer att ha någon praktisk betydelse.

Hello,

I have built my last kayak and am now looking for a surfski style and really like the look of your spindrift. Are the plans still available and how do we go about buying them ? Is the boat suitable for myself at 1828 height and 180-185 kg ?

Thanks

Mirko

Mirko, I am a bit confused about your questions. First; of course the plans are available. They are after all in the catalog with a prominently displayed purchase button.

And I guess you mean 1828 mm, right?

But 180-185 kg is not recommended in a kayak with a load capacity of 110 kg – unless you want to study submarine life forms (but why not?). Or is it lbs instead of kg you mean (corresponding to 82-84 kg), in which case you are a perfect match.

Hi Bjorn,

I'm just at the planking of the hull stage of my spindrift using paulownia as red cedar is pricey in Australia.

Looking ahead, do you have any more info on the rudder system? The surfski seems to favour its own style of pedals and internal rudder. Is there a supplier that you recommend?

Best

Tom

Hi Tom

That depends on your intended use: for training, racing, surfing etc an under-the-hull rudder is recommended, and my experience of commercial surskis is not enough to be able to recommend one brand over the other.

If you plan to use the surfski more as a touring kayak or exercise kayak, an add-on stern rudder makes more sense – not as vulnerable in shallow waters, but not as efficient as the racing rudder (it may hang in the air when surfing a steep short wave). Of these, the VanDusen kick-up rudder and the SmartTrack Sea Kayak rudder are the best I have seen and tried.

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