I’m a novic when it comes to understanding kayak design, specifically on the topic of speed. I realize that longer length and shorter beam width boats generally are faster. But what else determines speed? Deck height?
The engine
is the most important aspect.
Paddle retaining nut.
speed
It is how the hull parts the water and allows the water to return with out any resistance to slow the hull down. A hull that is blemish free and proper powerful strokes applied at a constance pace. The paddler need nitrous injection at times
what they said
that’s like asking the same question about cars.
If you have a 1000hp engine there’s a limit to the top speed according to aerodynamics (the hull)
If you have a 100hp engine there’s a limit to the top speed (engine and hull)
So the question then becomes do you know what the hp of the engine is (it really does matter) then design the hull accordingly. It really doesn’t make sense to design a hull for a 900watt engine if your engine is a 600watt one.
Then of course the next parameter is the conditions. A 1000hp dragster wouldn’t be the right design for a Nascar race and the most efficient hull for flat water probably isn’t the best hull for 3’ waves.
Paddling with the wind and current…
Ok, so it has nothing to do with kayak design. But some smart trip planning and conditions that actually perform as predicted can make a trip really pleasant and fast.
Interesting
how the racer types totally get all this, and a lot of sea kayakers never will…They just believe the brochures, or mentors who also never got it… Refreshing thread…thanks all!
More length/reduced yawing?
I wonder if one advantage of length is reduced yawing. That is, better tracking means more effort is directed at going forward rather than side-to-side.
Other factors
– Last Updated: Feb-04-08 12:08 PM EST –
Deck height? Not directly -- pure aerodynamic drag at normal kayaking speeds is minimal. But too much freeboard can make a boat more vulnerable to crosswinds, and too little can make a boat submarine. A deck shape that makes it easy to plant the paddle next to the boat helps, as does one that sheds water quickly.
Cockpit fit/size: racers and fitness paddlers often prefer cockpits that let them sit with their legs together, allowing them to "pump" for more powerful torso rotation. This is especially important when using a wing paddle.
Stability: The fastest hull shapes tend to be less stable, but there's a tradeoff -- if you have to spend time bracing you won't be as fast. That's why no single design is fastest in all conditions. A paddler who feels confident in a slower boat may be faster over a course than someone who's nervous in a faster boat. The big advances in surfski design recently have been in making the speed more useable for a greater range of conditions and skill levels.
Rudders: Rudders should have an aerodynamic cross-section instead of being a flat plate, and should not vibrate or wobble. A rudder doesn't make a boat faster, but may allow a paddler to focus on propulsive strokes instead of corrective ones. A rudder also allows a designer more options when making the tradeoffs between speed, tracking, and maneuverability.
Weight & hull stiffness: Light, stiff hulls are considered faster than heavy, flexible ones by the racing community.
A few "fast" kayaks:
http://www.qcckayaks.com/kayaks/model.asp?model=q700x
http://www.valleyseakayaks.com/rapier20.htm
http://www.huki.com/store/index.php?main_page=s1xs
http://www.kayakpro.com/kp/nelokayaksusa/wwwhtml/contents/compt_int_k1m.htm
The importance of matching the hull to the "engine" can't be overstated. There have been many posts here from smaller/less powerful paddlers who achived their best efficiency by moving to a smaller boat.
not always
length does not get you tracking. ever paddle a Nimbus Lootas? 18+ feet and loose as a goose with diarrhea. ever paddle a 10’ pungo? straight as an arrow. length DOES NOT get you tracking.
V, skeg and forefoot get you tracking and can add to the wetted surface (makes it slower)
race boats are thin, long and fairly rockered and run with rudders for directional control.
steve
All depends
on how hard you depress the gas peddle while the boat is tied to your roof rack…
Oh wait you meant while it is in the water! 
Rocker?
– Last Updated: Feb-04-08 2:21 PM EST –
The longer Futuras don't appear to have any appreciable rocker.
http://www.surfskis.com/database/pages/models.php
How easy is a 21 foot going to be to turn?
Rocker in K-1
– Last Updated: Feb-04-08 2:48 PM EST –
http://www.kayakpro.com/kp/nelokayaksusa/wwwhtml/contents/compt_int_k1m.htm
http://www.simonriversports.ca/english/images/products/kayaks/vector_side.jpg
Looks like lots of rocker aft of the cockpit.
How easy to turn?
– Last Updated: Feb-04-08 3:48 PM EST –
How easy are these boats to turn?
The first one, at 15.2m, is a bit shorter than 21 feet.
====================
The Lootas isn't a racing boat:
http://www.nimbuskayaks.com/lootas.htm
There's a lot of overhang. Thus, the waterline is significantly shorter than 18 feet.
Also, the length of the waterline is going to vary with the amount of load in such a boat. Thus, what is "loosie goosie" for one person might be significantly less so for someone carrying more weight.
So, as much as this boat "proves" that length doesn't yield tracking, it also "proves" that length isn't faster. Thus, it's a poor example. Silly racers for not using 10 ft Pungos.
====================
http://en.wikipedia.org/wiki/Surf_skis
"Surf skis are very long and narrow for kayaks, typically about 20 feet (6 meters) long and 16-20" (40-50cm) wide. As such, they excel at going fast and tracking well, but at the expense of maneuverability and stability."
??
put a straight edge on the screen under each design.
no rocker?
look again.
steve
well now
"The Lootas isn’t a racing boat"
never said it was. my point was JUST length does not always get you tracking, a common misconception amoungst yakers.
steve
Didn’t say that
– Last Updated: Feb-04-08 5:00 PM EST –
"no rocker"
I didn't say that.
Also, the pictures exaggerate the relative rocker because the 21 foot boat is being displayed (roughly) at the same size a 16 foot boat would be displayed at.
Racing
– Last Updated: Feb-04-08 5:06 PM EST –
I was talking about kayaks designed for racing (that wasn't clear) since kayaks designed for racing have some reputation for being "speedy".
The other posts (the non-joke ones) were talking about racing kayaks.
"never said it was. my point was JUST length does not always get you tracking, a common misconception amoungst yakers."
If it ain't in the water, it ain't "length". There are some here who think that "overhang" (ala "Brit" boats) serves no real purpose.
A great thread
– Last Updated: Feb-04-08 7:31 PM EST –
It's very apparent that the race crowd is way ahead of the touring crown in terms of general understanding of hydrodynamics.
I guess that's not suprising, but am I the only one who feels like the touring market as a rule is misinformed? It seems that tourers have been taught oversimplified thinking such as long is "fast" and "more seaworthy" etc, Or that a tracky long boat is easier to handle in a big sea.
This thread has had me saying yep yep yep to myself as I read through the posts...something kinda rare.
I wonder if designers and tech folk wrote the brochures we'd have a more informed marketplace?
Folk intuitively get it with paddles, but not so much with boats. At events etc., you see 110 lb. 5' 3" women in Explorers or the like cuz someone told them they'd go faster and be more seaworthy.