What causes sweep

[fish2eat]

I'm trying to find out what causes sweep along a beach, so that I can sort of predict what it might be before going beach fishing. It isn't tide, cause I have been fishing a beach for 48hours, with the sweep running in the same direction all the while. Tide causes rips....but what is sweep caused by?? any oceanographers out there??

Stu

[Heath]

Sweep is the general movement of water along a gutter, the rip is where the water from the gutter is rushing out through a bank into deeper water.

When beach fishing I like fishing where the rip is ;)

[seatime]

Was there a bit of swell running at the time. The accompanying energy with the swell may cause small inshore currents/sweep as the energy moves around headlands and bays etc. just a theory, cheers

[teach]

Sweep is also called longshore current. Longshore currents are caused by wave action. Waves mostly do not hit the beach in a parallel fashion, but in an oblique fashion. The water from the waves washes up the beach on the angle the waves hit the beach, but then the water rushes back to the sea perpendicularly to the beach due to gravity. This sets up a zig-zig motion of the water moving along the beach, called longshore currents. These longshore currents may flow in one direction along the shore between the breakers and the shore. These currents may form circulatory patterns, leaving the shore in narrow rip currents and returning to shore as dispersed flow with the breaking waves. The longshore current is strongest when the waves are high and approaching at a greater angle from the perpendicular to shore. If you are standing on the beach, facing the water, and the waves are approaching at an angle to the shore from the right, the longshore current is probably moving in one direction towards your left. The highest velocities in a longshore current are typically near the water surface and nearer the breakers than the shore.

Longshore currents are what made the Southport Spit, Moreton & Stradbroke Islands and Fingal.

See these links for more info
http://www.bergen.org/AAST/Projects/ES/BS/def/currents.html
http://faculty.gvsu.edu/videticp/longshore.htm
http://www.uwsp.edu/geo/faculty/ritter/glossary/l_n/longshore_current.html
http://www.answers.com/topic/longshore-drift

[fish2eat]

Thanks teach......I went to a lecture on beach fishing regularly and the "guru" conducting it claimed that sweep was caused by tidal flow. If this were true it would be reversed on the tide change, which does not happen. Very annoying when it is really strong. I'll check out all those articles.

Ta very much

[dasher]

Geez I'm glad I read your post first. :o I was about to post that the daddy sweep takes the mummy sweep to the bedroom and...... oh well we know the rest. ::) ;D

[seabug]

Good one dasher ;D ;D ;D ;D

[spindles]

Sweep is caused from the waves breaking over a sand bank filling the gutter, so then it has to go somewhere and flows to the nearest exit which is a break in the sandbank for it to flow out. you will probibly find that the flow is in that direction. Spindles

[fish2eat]

No, sorry spindles, that is NOT correct.

I checked out 45km of beach last week and the sweep was all in the one direction. in your theory, the "nearest exit" would different parts of a coastline flowing in different directions. You should read the material teach put up......

[CHRIS_aka_GWH]

"sweep" broad scale motion of water, usually coincides with isobars & wind direction & wave/swell direction - is enhanced by tides.

"rip" localised motion of water usually perpendiular (or angled) to the beach. As heath said usually from waves coming over an outerbank & surging back out through a gap in the bank.

they are terms though - sweep = parrallel to beach, rip = perpendicular (angled) to beach

I sort of agree with spindles that a sweep can be produced from a long outer bank - like north straddie had at easter - a rip occurs at its drain.

either can your good mates on a beach.

Some blokes put on a big lead to fish the outer bank - find the drain from a rip take the lead off & you'll be out the back before you know it & your bait will sit in the eddy outside.

Whiting sit in melon holes on a sweeping beach waiting for food to come to them. If you carry very little gear in a wading bag you can fish kms of beach by walking with the sweep. This is a very natural way to present bait. Heavy sweeps produce eddies in holes and around sand spits etc.

Fish use current to travel as the documentary film Finding Nemo demonstarted. Tailor usually hit in the direction of the water flow. You can also use sweep to beach a bigger fish by walking with it as you slowly bring it in.


Beach fishing lessons begin May 01 - come and see me teach the Wolf a lesson.

and Spindles - you are welcome again on the Blackmoon taxi if ya want.

[spindles]

I have read the input by teach and now if I could I would retract my input.
sorry if put anyone in the wrong direction.spindles :-?

[spindles]

Chris I'd like to see that. Spindles.

[farky]

Thanks for that info Teach,
Farky

[fish2eat]

"

Beach fishing lessons begin May 01 - come and see me teach the Wolf a lesson.

and Spindles - you are welcome again on the Blackmoon taxi if ya want.


Thanks Chris, you don't know how much I'd love to come and see you and the wolf in mortal beach combat.......sent the wolf a Pm but I think he's disappeared :(

[CHRIS_aka_GWH]

i think he had some offshore plans today if the winds suited