Question about tidal force [Archive] - Fly Fishing Forum

: Question about tidal force


Sean Juan
05-22-2008, 06:57 PM
This is just something I've noticed a few times - actually very few times - so I figured I'd ask.

Has any one else noticed that sometimes the tides are wimpy?

I don't mean in terms of height or the volume of water moving, or even the speed of the water. Its more like torque. Most tides you can really feel the water pull around your legs, pull on your fly line, but every so often there is a tide that doesn't seem to have the same strength even though the same volume of water moves. Its not a moon thing since this can happen on the same day.

It makes me wonder about mung, which can be around for a few days and then one tide later its gone.

Adrian
05-22-2008, 08:52 PM
My experience is that the big factor is the moon and associated volume/flow.

But, depending upon location, the "rules" can become distorted by local structure. Bristol Narrows in Rhode Island comes to mind. The incoming tide here comes in series of incoming and outgoing waves over the six hour flood. Seeing that much water apparently defy gravity can be a bit disconcerting. :Eyecrazy:

A couple of years back I also learned how much difference a single day can make in terms of tide strength. I had fished the South Monomoy Rip from shore with Greg and Mike Estey one Saturday and the fishing was great. The next day was the "official" Rip Trip and it just didn't happen. We stood on the beach and waited, and waited and waited but all we got was a whimpy flow with a ton of mung.

Wind is another variable that can be a big factor in determining tidal strength. The effect on the flood tide over on Brewster flats is a good example of how the prevailing wind can affect the timing of the tide by as much as two hours.

Warren
05-22-2008, 09:18 PM
Sean, Adrian brings up a good point. The wind was blowing in the right direction to influence many things that afternoon, including the velocity of the outgoing tide. It could be that wind was the deciding factor of why the current did not sweep our lines down stream as we thought it should. Who knows?

striblue
05-23-2008, 12:15 AM
Changes in off shore structure can have this effect as Adrian states. You might be on the inside of South beach with strong moon tide(during the days when the southway was open)... and on the repeat it can get wimpy or stronger...you look around and the flat is the same, and you see no noticable difference in the channels, etc. The boat bouys are the same.... and the channels will not change....but if there is odd shoaling ...even 1 to 5 to 10 miles off shore this can have an effect on water back up or slowing down where you are.

FishHawk
05-23-2008, 06:10 AM
Get a copy of Dr David A Ross's book a Fisherman's Ocean. Or check out
midcurrent.com where there is an article about tides by Dr. Ross. It's under the science section of the newsletter. He a scientits and flyfisherman who works for Woodshole . FishHawk

juro
05-23-2008, 07:09 AM
Just look up the "swing" (difference between lowest and highest levels) and you can expect strong current when the gap is wide - especially where equalization is channeled by structure.

Google 'tbone tide' and use the Graphical plot option for an easy read. I don't bother with any other tide sites anymore, IMHO this is the best resource.

Tide swing is governed by the proximity and/or distance of the moon and sun. We get big tides when the moon is close to the other side of the earth as well as when it's close to our hemisphere.

Monomoy Pt, Race Pt, the Canal, river mouths, etc - are confluences of two different tide systems and have the additional time offset as well as temperature and height differences playing into it.

Wind plays a role on extensive flats relative to tide size (i.e. the tropics) where small tides can be virtually erased by wind - however Bayside Cape Cod tides can have well over 10ft in swing over flats that are barely one mile perpendicular to shore thus wind only delays the inevitable, I would never hang out on a flood tide because there is an offshore wind up here but I would in the Bahamas.

Stripers love fast currents for a simple reason - bait can't swim against it but they can slice right through it.

In such currents I seek out the cleanest sand bottom possible with the most sculpting and present the fly right on the sand where only a high-density sinking line is worth a damn except for the 1% or so of the time they are up in the column - Monomoy Point and Big Girl being prime examples.

Tide current is your friend, just don't put much between you and the shore :)