When selecting a kayak, new kayaker are often advised that a specific length is important, but the reason is typically vague. Basically, the longer the boat, the better it will be able to bridge the trough related to the hull speed principle. Other factors influence how fast your boat will accelerate, how long it glides, or whether it cuts through waves or flies and dives. However, the primary feature that limits paddling speed is length; all other features only influence potential speed by plus or minus 10 percent.
The easy to use chart shows the relationship between boat length and the speed cap. You can expect actual speeds to vary but all 14 ft kayaks will hit a wall around 5.8 mph, which is where it becomes exponentially harder to increase the average speed by even a few tenths of a mph. It doesnt mean the boat won’t go faster, just that it will eventually become ten times harder to go. 1 mph faster, and if you press harder, the boat will become unstable and get squirrelly.
Longer doesn’t necessarily mean faster. If you have problems maintaining an average speed of 3.5 mph over 10 miles, you won’t really benefit by going up to a 17 ft boat, and you may actually find the long boat to be slower. Some will argue longer boats have greater wetted surface and all of that, but typically a plastic 145 model and the same model in 175 will be end up with the longer boat being 12 lbs heavier. So it displaces my 255 lbs of lard, as well as nearly an addition 1 1/2 gallons of water, which accounts for the additional wetted surface. One way to understand that is to compare a 175 ft plastic boat @ 69 lbs with a 175 composite boat @ 49 lbs, which is nearly 10 lbs lighter than the 145 plastic @57 lbs and 20 lbs lighter than the 175 plastic. Now, which boat has more wetted surface? The real question is whether you want durability, lightness, speed, control, and so on, and how much are you willing to spend for it. There are few perfect boats. Only you can find thr perfect boat for you. My 140 lb sister couldn’t stand paddling my 14.5 ft long by 24.5 inch wide Tsunami, but she lives her 14.0 ft by 24 inch wide Tsunami. Based on her comments, she would dislike the new 140 Tsunami at 25.5 inches wide (I still don’t understand the logic of WS adding what amounts to 1 inch to the width of a 145 and then reducing the length by 6 inches. My sister didn’t like the width of my 145 at 24.5 inches. Great corporate decision).
All I can tell you is the features I like, and how ot performs. I upgraded to a 12 ft kayak, ghen a 14 ft kayak, the a 17 ft kayak because each upgrade allowed me to handle more severe conditions, but that doesn’t mean you need the same thing. My 9 ft 6 in rec boat was fine near shore in a protected cove, but in open water, the wind resistance, current from an outgoing tide and wave height reduced my forward speed to about .5 mph, while the 145 kayak coukd manage 4.75 mph and the 175 could manage 5.0 mph. If you’re ability is limited to 3.5 mpg, a 125 kayak would perform adequately. Its all relative to what you intend to face. If you paddle on a 3 mile long by 1/2 mile wide lake, you don’t need the same boat that a person needs in more taxing conditions, such as the San Francisco Bay which has incredible tidal currents, being a basin with a narrow entrance. Similarly, the Great Lakes or the conditions @szihn describes where he paddles in Wyoming require very different boats. You need to understand that speed is relative. At two miles from the launch, .5 mph means four hours. Fine if you have all day, butbif a storm is approaching and estimated at 30 minutes away. You better be making 5 mph of progress.
My first kayak was lots of fun. 9 ft 6 in by 30 inches wide. Since I’m a strong paddler (who displaces a lot of water which was then 255 lbs), it was easy for me to paddle to speeds that buried the stern as the kayak tried to climb the growing bow wave. I didn’t understand the concept of hull speed and eventually reached an impass.
I went out on a fair day. After a few hours, the moderate wind changed to 10 to 15 mph and changed to West so I got caught in the .5 mph trap. Speed is no big deal if you stay close to home, but as you explore further and veture into open water, understand the limitations of your kayak. Sometimes speed isn’t about physical prowess or bragging rights. It can be critical to your survival when facing unexpected conditions.
Its important to realize that safe load capacity depends on displacement, which depends on width, length and draft. You need to fit the safe load limit of the kayak so it floats at the designed load-water-line. That enhances the performance parameters of the design. Overloading the boat can make the handling more difficult and decrease the freeboard beyween the water and the coaming. Edge an overloaded boat could make the manuever less effective, and not having enough weight could make it more susceptible to the influence of wind.
