Whats the difference between SEA and SWELL

[Volitan]

Hi. Can someone please explain to me the difference between SEA and SWELL. I don't mean the dictionary definition - I've done plenty of Googling on the subject and I have seen lots of standard definitions for both - but I haven't seen anyone explain what the difference means when you are actually out on the water ?

See, when I see a weather forecast like this :

Wednesday 16 April

Winds Southerly 15 to 25 knots.

Seas 1 to 1.5 metres, increasing to 1.5 metres during the afternoon or evening.

Swell Southeasterly 1.5 to 2 metres.

Weather The chance of thunderstorms.

then I expect to see two different types of wave - maybe some long slow rather glassy ones which are swell, and some shorter sharper ones which are sea. But I don't - I just see one type of wave, which naturally varies a bit in height and pointiness - but all look pretty much the same.

So what is the difference between sea and swell from a boaters point of view.

If swells are long slow waves which raise a boat but don't really rock the boat around, then If my main concern is avoiding days that will make me seasick do I need to worry about swell at all ?

cheers

Arron

Edited April 13, 2014 by Volitan

[oz_brett]

seas = sloppy, choppy & crappy 1.5m seas is really rough.

swell = rolling motion that eventually becomes a wave at the beach, when watching swell also pay attention to ho far apart the waves are further apart is better 1.5m swell 10 seconds apart I class a not too bad of a day offshore but keep in mind that a lot of the time its that rolling motion that causes sea sick to those with a sensitive stomach..

Brett

[Croydon]

Sea - waves generated by local wind conditions, the size being determined by the length in time a particular wind has been blowing, the distance wind has travelled across the sea, and the depth of water.

Swell - are regular longer period waves generated by distant weather systems.

For a more in depth description of sea/swell have a look at the BOM marine weather definitions. Also helps explain how it relates to boaties and may answer your question about comfort. A combination of both will effect how comfortable a day is at sea.

Hope that helps..........

Dave

Edited April 13, 2014 by Croydon

[Nolongeramember]

then I expect to see two different types of wave - maybe some long slow rather glassy ones which are swell, and some shorter sharper ones which are sea. But I don't - I just see one type of wave, which naturally varies a bit in height and pointiness - but all look pretty much the same.

This kind of sounds like you are not seeing any swells. Are you going outside the heads on the open ocean? Swells occur in the open ocean but may come into bays somewhat if it is travelling in those directions through the heads. You don't generally get swell in bays, rivers or lakes.

A simple way to explain it is,

Swell is a VERY long raised unbroken wave. It keeps travelling along and come one after another in the same direction. You cant miss it on the ocean unless its small, under 1m maybe.

Sea is all the choppy water.

[Nolongeramember]

If swells are long slow waves which raise a boat but don't really rock the boat around, then If my main concern is avoiding days that will make me seasick do I need to worry about swell at all ?

Yes you do... Swell, even small makes you sick. Constantly going up then down over and over. Seas can make you sick too but not as much. The larger of any the more likely you will get sick.