Ultimate bobbin

[lutra]

Pretty easy really, large lake, fairly deep, good breeze blowing the top water into one end. Lower water being pushed back = strong current.

 

Happens every time the wind blows

 

Den

The trouble is i don't think it is that simple as the warmer top water will be very reluctant to sink/stay down. Depending on a number of things like angle of the wind is hitting the bank, shape of the bottom, shape of lake, temp, strength of wind and probably a few more the returning water will do different things and may be in the same day.

 

Like Anderoo says it can make your head hurt. The best Ive ever been able to come up with is try to fish into the prevailing wind and fish at the bottom of a drop off if you can find one.

Edited April 1, 2009 by lutra

[phil hackett]

The trouble is i don't think it is that simple as the warmer top water will be very reluctant to sink/stay down. Depending on a number of things like angle of the wind is hitting the bank, shape of the bottom, shape of lake, temp, strength of wind and probably a few more the returning water will do different things and may be in the same day.

 

Like Anderoo says it can make your head hurt. The best Ive ever been able to come up with is try to fish into the prevailing wind and fish at the bottom of a drop off if you can find one.

I'd agree with you it isn't as simple as that, most of the energy from the wave orbitals is dissipated as they hits the shallow water and the bank. The swash (rebound backwards) is minimal and as I pointed out earlier only reach a max of 20 yards backwards travel.

 

I've never seen Wingham but, have seen many other pits, and wouldn't disagree with the comments made about bars, troughs, baffling and so.

Perhaps the best way to view these pits are as landlocked rivers when the wind is blowing strong. The wind driving the flow direction and orbitals, the bars, etc acting as obstacles in the river channel. Throwing that flow in several directions at once.

If you can work out where the lee of the flow is at any given time for an obstacle, it will deposit debris there, including natural food and light bait that has been introduced.

[Kappa]

If you can tell me what wind strength, roughly, there was on the day when it was shot, how deep the water was and how far from the bank it was shot. I may be able to give an explanation why the flow was so strong.

 

The wind was not more than 20mph but probably significantly less. I don't know about the time of day. The water in this swim is 8 or 10 feet deep straight off the bank. My understanding of wave orbitals is that the strength decreases exponentially with depth of water, and is less than 5% of the value at the surface at half the wavelength of the wave. As such if we assume a wave length of less than 4 foot there will be essentially no movement much below 2 foot due to the wave orbitals. In the case of the swim in question, the wavelength of the waves would need to be greater than 16 foot to have movement of much more than 1 mile an hour (assuming all above accurate). More info on waves caused by wind http://en.wikipedia.org/wiki/Ocean_surface_wave

 

Rich

[poledark]

Where is this heading? For all my fishing life i have watched the wind and undertows. Yes bars and weed can divert/slow/even stop the tow in places. But if water moves in one place, then it must move somewhere else. Water is not compressible. You usually end up with several diferent areas circulating at different speeds according to the direction and shape and depth.

 

No way can you plan unless you get to see and read these effects on your own particular water.

 

An example from today....I know the lake I intended to fish and after 6 years I know the effects of the wind. I also know the water temp up to yesterday at 7pm (49F) Night was warm stayed above 47F so not likely to chill the water much. I headed for the western end into which the strong wind was blowing, stuck the TM in the water (10.30 ) and it was already showing the effects of the sun and wind, and had risen to a fraction under 50F. By 3pm it had gone up to just over 52F and I caught 2 nice fish of 18lbs and 20lb 2oz

 

No one else caught, some saying they fished the other end/side to where the lake was more sheltered and warmer :)

 

I chucked a weighted reed in and watched it sail merrily back up the lake against the wind until it dissapeared from sight.

 

Richard, I have seen the clip from Wingham, but would not know the speed of the 'tow, except to say it looked pretty strong to me, and what I would class as strong 'tow

 

 

Den

[Dick Dastardly]

This is interesting and Ive certainly learned something new from it.Im not convinced that "orbitals" could produce the strength of "current" the underweater video showed in the wind strength on that day.However its imaterial if they did or not.As a simple guy what I take from all this is that the "current" was a lot stronger/had more affect on the fish and feed than I would have thought.

 

What I now feel I need to work out is how this newly gained apreciation of the strength will affect my fishing.

 

It will certainly affect how I position my free offerings and rigs in relation to features.But do the fish like or dislike it? I suppose if they find food in a calmer area where they dont have to swim against a current to feed that would be their prefference but if the current is causing the food to be in one place and therefore easier to oibtain?

 

Im not going to get to bogged down with it other than taking it in to consideration when working out where the food is/will end up same as Ive always done,just "re calculate" the distances due to the strength.

 

My only real question though is why I never noticed the strength when I had dived? possibly because even though it looks strong in the video in actual fact its strength is only relative? i.e. looks strong when its effects are on the maggotts/feed and the tench's "swimming" against it really just the fish holding station....but in reality not strong enough for a human diver to notice?That said its the effects on the food and fish that are really relevant.

 

I seem to understand most of the theory and agree with the accepted conclussions re undertow,current,back wash etc affects on the fishs food (and therefore probable location) but still unsure exactly how (if at all I need to) use this! information!

[Kappa]

This is interesting and Ive certainly learned something new from it.Im not convinced that "orbitals" could produce the strength of "current" the underweater video showed in the wind strength on that day.However its imaterial if they did or not.As a simple guy what I take from all this is that the "current" was a lot stronger/had more affect on the fish and feed than I would have thought.

 

What I now feel I need to work out is how this newly gained apreciation of the strength will affect my fishing.

 

It will certainly affect how I position my free offerings and rigs in relation to features.But do the fish like or dislike it? I suppose if they find food in a calmer area where they dont have to swim against a current to feed that would be their prefference but if the current is causing the food to be in one place and therefore easier to oibtain?

 

Im not going to get to bogged down with it other than taking it in to consideration when working out where the food is/will end up same as Ive always done,just "re calculate" the distances due to the strength.

 

My only real question though is why I never noticed the strength when I had dived? possibly because even though it looks strong in the video in actual fact its strength is only relative? i.e. looks strong when its effects are on the maggotts/feed and the tench's "swimming" against it really just the fish holding station....but in reality not strong enough for a human diver to notice?That said its the effects on the food and fish that are really relevant.

 

I seem to understand most of the theory and agree with the accepted conclussions re undertow,current,back wash etc affects on the fishs food (and therefore probable location) but still unsure exactly how (if at all I need to) use this! information!

 

 

Budgie,

 

I have a theory about the tow, I reckon the swim shown in the video is perhaps one of the very worst for undertow if the wind is in the right direction. I'll talk to you about it next time I see you.

 

One thing to think about, I was under the impression that the surface water in deep margins actually moves along the bank rather than sinking and moving back in the opposite direction. This flow may explain why few of the Wingham bars actually make it as far as the bank, particularly those on the NE bank. Clearly, as Den says, some water has to move back to where the original surface water came from but I don't think it has to be from directly where the wind is blowing but rather where the flow of water in the opposite direction is easiest, e.g. in deep straight gulleys running the width or length of the lake.

 

All theories but you never know . I actually know a marine engineer, I'll ask him if he has any insights.

 

Den,

 

I think I (we) want to better understand what the flow is doing in a very complex lake like Wingham so that for a given day or conditions location within a given arean of the lake/swim becomes a little more informed/easier.

 

Rich

[Dick Dastardly]

Thanks mate.

[Phone]

Without reading ALL 37 pages can a Yank jump into the middle of this one?

 

The water at the bottom of the lake (any lake of size) will always be 39 degrees f. That is the heaviest water. Below the thermocline (if there is one) the seperation of warm water from cold water will be quite different. The cold water will be near motionless if the lake is a closed impoundment. The warmer water can move about freely on top of the colder water like dust on land. In large lakes it really takes a gale wind to breakup the seperation line (thermocline). Wind rarely has an impact on the bottom temperature. When the bottom does get affected/effected the entire water column changes place.

 

So the water goes like this from the bottom (heavy/cold) - (light weight/warm) - (extremely light weight/frozen).

 

The light weight/warm is usually 100% the area of water motion.

 

Is this what this thread is about?

 

Phone

[poledark]

I took my temps on the bottom, about 6ft deep. This is the average depth of the lake. . Nearly 35 years of taking temps and watching 'tows tells me that even with depths of 18 ft the effect reaches to the bottom. Best example I can quote is No2 Larkfield, 5 parrallel bars running the length of the lake,stopping about 20yds from the end. About 13ft deep. Stiff breeze along the bars and discoloured water returning up between the centre bars. Usually took about an hour to really pick up, but it happened every time the wind blew in that direction.

 

Richard, at this time of year, knowing the likely effects on your particular water can be really useful. Think cold water. sluggish fish. Add in warm wind and sun and 'tow. Water moves, temp rises, fish react. Believe me mate, it happens every year. No theories, no charts and data, just simple observation/deduction.

 

Once the water has warmed up to the low 50's and the fish are actively feeding then the benefit of that knowledge is no longer of much use, so by the end of this month different thinking is needed.

 

Now I don't mean this in any nasty way, but more time on the bank is needed, you can't catch in front of a computer

 

Speed? I doubt if a strong 'tow even reaches slow walking pace on the sort of waters we are discussing. Chuck some maggots in and watch the sinking rate and angle of descent (something match anglers do as second nature). My reed moved slowly and steadily against the wind yesterday, maybe a yard a minute, it could be seen to be moving, but as for the actual speed I couldn't say.

 

Den

Edited April 2, 2009 by poledark

[Anderoo]

Where is this heading?

 

It's heading towards - hopefully - understanding how undertow affects how and where you fish for big bream in gravel pits. Not just to do with temperature but also how and where to bait up, and also, most importantly, whether big bream will tolerate feeding in it or not.

 

Suss all that out and the biggest problem - swim selection and where in that swim to bait up - becomes smaller.

 

As far as I know, no-one has been seriously considering undertow when choosing where to fish for big bream in gravel pits. Now we're thinking about it, patterns may emerge.

 

(It was originally about Richard building some bobbins!)