When I first saw this thread, I thought it was a joke or a trap question.
Then I realized that not all know the maxim of most naval architects. Give the same other parameters, a longer boat is faster.
My 19 foot Westside Wave Exceed is the fastest boat on the Hillsborough River 364 days of the year. That other day is a race on that river.
However, if you can’t get comfortable in a long, skinny boat, the boat you are most comfortable in will be the fastest for you.
Apples to apples longer is faster. Just look at what is raced. Yes you can throw in a million variables.
Fast is determined by the biointegrated propulsion/navigation system.
Peace J
In computer engineering (a long long time ago) that was call “wetware” as opposed to hardware and software.
Seems like an appropriate term for kayakers…
I think a lot of you are missing the point I originally raised, actually Brian raised, then Nick raised.
Yes, I think we all agree that a longer boat is fast if the paddler can supply the power. That’s why races are won by long boats. The athletes paddling them can provide the power.
But what if you can’t supply power. If you can never reach hull speed, might not the increased drag by more wetted surface actually make more resistance? Nick’s graphs seemed to suggest that.
Maybe a desk jockey can paddle 3.5mph for an hour in their 14 foot boat, but only 3.4mph in their 18 foot boat?
Faulty logic.
For any one paddler, a shorter boat of the same waterline width will sit lower in the water, increasing drag. I suspect that a bow plowing through the water at a greater depth encounters more resistance than a greater wetted surface area skimming closer to the surface.
There are likely multiple factors involved, but in all the years i have been paddling I’ve never heard anyone claim that they were faster in a shorter boat over a reasonable distance. If the shorter boat is much lighter they may accelerate faster but their average cruising speed will be slower for the same effort.
My Nomad / Extreme 18’9" x 21" glides easy at any speed. Few strokes I’m going fast. I see no disadvantage of it’s length at any speed.
Everything has a limit to the gains when adding length.
There comes a point when adding length without also adding width the boat becomes increasingly unstable to the point of being unusable. Not to mention extremely difficult to turn.
We should separate skin area friction from streamlining, and streamlining from hull speed.
Skin friction is the dominant factor only at very low speeds. There is a horsepower where a spherical kayak hull would move faster than a streamlined hull of the same weight, but that horsepower is well below what a weak paddler can do.
Hull speed (and wave friction) rears its ugly head at higher efforts than most casual paddlers perform at, so in most cases streamlining, including length/width aspect ratio, is dominant. Not sure what the aspect ratio is for a waveski, but rowing shells are over 30 and so their Froude numbers are twice what a typical kayak has. The fast ones are so narrow that blades have to be in the water for bracing.
I would add: ‘or do not supply power’ to your comment
I’m a ‘comfort’ paddler, not fast, not (necessarly) slow
So, just the numbers:
Of current boats:
(by order of decreasing avg speed)
[note: surf/roll sessions and club trips filtered out]
other factors not shown, eg: on windy days, I would typically pick the Petrel Play or Ice Kap over the 18X
This chart is funny…those lengths are NOT what the water sees. The 18x was designed to fit the needs for racing and fitting into kayak length class but with the most waterline length. Many of the listed kayaks only use the portions of their length in waves. {leading the way thru and over turbulent waters} This chart has absolutely nothing to do with actual water displacement
i have two kayaks:
17 ft tempest
15 ft perception expression
I checked the speed several times with my gps and found I paddled the expression slightly faster at my so-called cruising speed. All test were done on flat water with no breeze at all. One course was 0.8 miles and the other 2.7 miles. The difference was minimal ie 4.4 mph vs 4.2 mph. However the max speed for the tempest I could muster was 5.7 mph whereas for the tempest 6.0 mph.
One thing I noticed that probably influences my cruising speed was I averaged 59-60 strokes/min. for the expression vs 57-58 for the tempest.
I’m not at the experience level of many here, but I agree that hull speed is the upper limit, not an indication of how fast a boat will go. My recall is that the hull speed for a displacement hull of 12 ft = 5.3 mph; 14 ft = 5.8 mph; 17 ft = 6.4 mph. (using 1.34 factor). Hull shapes like fish form, pointed bow and stern, round, or V-shape are about efficiency - distance traveled with X propulsion. Efficiency also benefits glide, but not max potential.
I visualize a plane approaching the speed of sound. The body begins to buffet as the sound waves builds. Breaking through is like a boat designed with a planing hull. The boat experiences the same trap as it gets caught in a trough and tries to climb out. It’s no suprise that you can see incrementally greater deceleration as the boat approaches the hull speed.
Many of you are no stranger to pain or physical exertion. You can tell how much energy you are expending through HR monitors or by staying in an aerobic state. You know instinctively that you’re at 66% output. Its reached more quickly and you work harder to maintain 4.6 in a 12 ft boat. I’ve hit 4.9 mph avgs on long trips in the 145 Tsunami, but I haven’t recorded faster avgs in the 175 Tsunami. It surely has more potential, but it’s also a few pounds heavier, which means it displaces more water. It tells me I wasted $1 500 on a boat that I’m not strong enough to take advantage of that three additional feet. Even though the potential is there to theoretically go .6 mph faster. So I drive a 145 boat because I don’t gain a dang thing dragging that big hoss around and fighting the higher rate of weather cocking.
I had to test this because the last time I added, I counted a big toe twice. I checked this and will stand by my numbers, but at the risk of compromising my argument, my logs show the 145 will go higher than the 5.8 peak hull speed. It can spike 6.2 in relative neutral water and has hit 7.7 and 8 mph on 30 inch waves, then dies down to 2.9 in the trough. Part of the reason is that I use a 250 cm touring paddle and maintain a 70 strokes per minute paddle rate. Data provided using a Garmin Colorado deck mounted GPS.
How can you measure any hull speeds in waves and or currents for any useful data?
I haven’t paddled a Tsunami 145 in quite a few years but I don’t recall it being a particularly fast boat. A 4.9 mph average in that boat is remarkable over a long trip, especially since you stated that you use a 250 cm paddle. Color me impressed.
Longer is faster.
Paddle Dog52, I was hoping you could answer that. Don’t know how. I view hull speed as a static water measurement. When I look at my log. I exclude trips with another paddler. Tide H/L times and start/stop tells me if with/against the current. Paddling with tidal flow adds speed/against reduces speed (ex: a plane cruising at 100 mph into a 25 mph headwind covers 75 miles ground in a hour, unless I trivialize the concept). Paddling 5 mph with a 1 mph current at a given effort, would theoretically drop to 4 mph if you reverse, which I do to judge current impact (ex: launching an aircraft from a carrier into the wind). You may ask, how do you know paddling into current is the same effort as exerted with current - I don’t know for sure.
I believe head first into a 30 inch wave is so disruptive to the standing wave . . . Does a standing wave even exist. Some contributer have really spun me up talking about wave forms. Intervals, peaks, I welcome details, because I want to go there. Some kayak for solitude, to enjoy exploration or drink coffee and see wildlife. I feel you. If you want action, you need a better boat
To ride a wave, I “think,” a large sq in blade is best. You just gave me an idea - stow a 2nd paddle with a bigger blade). All waves aren’t created equal. A surfer might know. Space between the peaks, height and speed of the wave makes a difference. The depth of the bottom shapes the wave, whether Iit tends to break or roll on. They may progress from left or right and when a big one passes to a side, it may have missed, but your wave is coming with each miss. Im curious whether a shorter/longer boat responds more effectively.
What does happen is you have to start paddling in a trough with a forward speed of maybe 2.9 mph, because you are climbing a hill. The balance changes as the nose drops and you see the speed spiking. The fastest speed I ever reached was 8 mph, then you fall off and speed drops to 2.9 again. Any insight or correction on my observations is welcome.
You can float a marginal boat all day long in sheltered water. I believe fear protects the average rec boater from danger. The problem happens when they venture out and the weather conditions don’t telegraph a change, but the change happens and you’re stuck going into a headwind. I’ve seen claims of driving a 10 ft boat into 35 mph wind, with 24 inch waves. I don’t believe it. I couldn’t make more than .5 mph headway in 15 mph. Body English helps easy the plunge, but when you stop to bail, you lose more than you can gain. I won’t try.
Agree pine. But do agree with others who say they can’t extract the speed advantage due to lack of power. I feel that with comparing multiple entries comparing 145 and 175 Tsunamis. I regret that I can’t get that advantage. For that, I need a 17 ft boat thst is shaped more like a destroyer than a battleship. That doesn’t mean I can’t push to and beyond the hull speed, just thst I can’t do it over distance. Next questiin is have you tried different techniques paddles, blade size, cadence, length. Everything but GP.
