When is a wave not a swell or vise versa?

I’m all :ear: ears. Thanks.

Depends on how you handle it.
My definition is a swell doesn’t break on you.


My understanding at least applied to the ocean, a wave is the result of locally generated wind energy. A swell is residual energy from some distance away. If you look at an app like Windy, most times it gives vectors for waves, swell 1 and swell 2 which can all be different directions and heights.


You’ll know it when you see it. A swell is a wave that is dissipating, no longer driven by the wind. They tend to sort themselves out into longer wavelengths. They will definitely break on you in shallow water.

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I was reading definitions I googled which I knew but checked anyway.

Guy posted a video in kayak claiming 3’ waves. They weren’t even remotely 3’ swells. I didn’t want someone to watch video and say 3’ waves I can do that. Then go out if 3’ waves were real and get in trouble. He did change his claim after I shared my thoughts which was good. That got me on this tangent of thoughts. Also told him about wave period of the waves having a big effect also.

I was in my 19’ Boston Whaler Montauk coming out of NYC harbor. My friend left in his 45’ I guess cabin cruiser you’d say. He left ahead of me by 5-10 minutes. Later we spoke he was in 10’ waves he claimed. I was in 4-5’ waves in ocean which has tons of white caps. Checking weather reports the waves were 4-5’ as I told my partner. We got hammered fairly well. Just showed me once again how some people gauge waves. When I raced offshore boats most tended to add 50% or more to wave heights in discussions later. Again not what weather reports we’re saying.

not a definition, just experience.

I’ve been paddling in large swells, 10feet plus. You can arrange to take pictures at certain angles to make them look quite large, though very safe paddling in.
The problem comes when you want to land.
Large swells turn into monster surf, so, when paddling on days with large swells, make sure you know where you’ll be finishing at the end of the day - into a safe harbor, around a headland - out of the swell direction, or, you are just prepared to get trashed coming in.


Had a guy join us once on a calm lake. A boat wake rolled past and he started talking 3’ wave. Perception.

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Wave measured peak to trough.

Hey anything over my head (sitting in my kayak) is big! call it what you want, measure it however you want. Some waves are swell and some not so swell!


A wave can be a swell when long range winds drive them. There are other types of waves, too, depending on the energy that drives them; such as tides, currents, and geological events.


Swells are usually deep water waves that originate a long way away.
Waves are usually wind driven locally produced waves. They can be augmented by tides and, river currents.

RE wave height- even among my highly experienced surfski friends from the Midwest, they got in 2-2.5 foot waves on the Columbia River and said “that was 4 foot!”.

I reminded them if you can see the horizon the wave is under 3 feet (I’m over 6’ and my butt to eyes is about 32")

A 10 foot wave is triple-quad overhead. Also I have never seen a boat wake over 3 feet and that includes the 80 foot ferry by me. The ferry wake is close to 3, but not more.

Also, the main difference between swell and wave is the wave interval. 1-5 second waves are short and possibly steep (depending on height).
Longer period swell contains much more water volume, moves faster, and the wave is much less steep.
When waves hit shore they build and break in a short distance.
Swell builds much more slowly because the wave starts “feeling” the ocean floor much sooner and starts to slow down and build up over a much longer distance.

The power of a wave must grow exponentially with interval, because a 1 foot 20 second ocean swell can easily build to 6 foot+ with a thick wedge when breaking. A 1 foot 4 secon
d wave will only build to like 1.2 ft at break.

Read up on Bathemtry if this interests you (the science of waves. It’s really interesting)

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I think generally the word “swell” is used to describe one of a series of waves arriving from across the sea (as others have mentioned traveling from the place where the waves were generated often a significant distance). Swells can be multiple series of waves that combine into a single series and, due to interference, may have some waves that are larger and some that are smaller and generally repeat that pattern or might be a single irregular set. Whether you’re talking about waves or swells the height is the vertical distance from trough to peak.

If you have wind in your area, it can generate waves. If there are swells, too, then you can get some really fun paddling conditions! For the Salish Sea where I am, we sometimes get swells in the bigger channels. But usually weather waves and currents are the primary conditions that combine to make things interesting here.

confusion abounds. perception of height above the still water line (waterline if there were no waves present) is the crest of the wave. the other half is submerged. this is the national weather system definition. so if a mariner with a radio hears a forecast of three foot waves how they interpret it is or could be misleading. and then repeated. so everyone could be correct.

Waves are swell when you’re surfing otherwise you want a swell. :stuck_out_tongue_winking_eye::crazy_face:


I liked waves and swell better when sailing. Generally we considered swells “rounded” and comfortable. Then waves have two sides. One steep and breaking and one rounded and swell like.

Swells about always have some fetch behind them. Waves as in a breaking top can happen due to changes closer to shore in depth. As well as by open water conditions that tend to shorten the period between swells or cause the tops to white cap.

I have definitely seen 4’ boat wakes. Let a 55’ sport fish stop when he’s upon you then punch it when he’s two feet past you. They figure they did you a big favor. In reality they couldn’t make it any bigger. Better they just kept up full throttle.

Just be in the St John’s River at Maypoet when the pilot boat passes by.

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Or in the Cooper River at Charleston when a destroyer goes by, if they still do.