Are longer kayaks slower?

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.

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Apples to apples longer is faster. Just look at what is raced. Yes you can throw in a million variables.

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Fast is determined by the biointegrated propulsion/navigation system.
Peace J

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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?

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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.

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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.

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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)
SNAG-0001

[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

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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

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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.