Any mathematicians out there?. Re. Deeper, distance, swingback.

[wellyphant]

I'm wondering if there is a simple mathematical formula for the following problem.

 

Using my Deeper fish finder, I find a likely looking underwater feature in eg. 30 ft of water where I'd like to cast a bait to.

Using my spool clip and distance sticks, I measure the distance of this feature from my casting point at eg. 10 rod lengths out.

 

As I prefer to feel my lead and bait down on a tight line, what would I need to add on to the distance to allow for swing back?

 

 

 

[Ken L]

"eg. 10 rod lengths out."

That's the problem. The maths is easy but how far exactly is "10 rod lengths out" and how far above the horizontal will your rod tip be?

Much easier to drop on a slack line and tighten up.

[wellyphant]

"eg. 10 rod lengths out."

That's the problem. The maths is easy but how far exactly is "10 rod lengths out" and how far above the horizontal will your rod tip be?

Much easier to drop on a slack line and tighten up.

It's easy to measure eg. 10 rod lengths out by using distance sticks, eg. ten wraps around two distance sticks set a rod length apart.

Rod tip would typically be close to water's surface, no more than 3ft.

I agree that to drop on a slack line would be better for accuracy, the problems there however are, having to release the line form line clip immediately after cast and dropping on a slack like increases the chance of tangles.

[Phone]

welly,

 

use a trigonometry calculator you want your bait 30 ft from a base point. 10 ten foot rods = 100ft plus 30 ft deep plus the height of the cast =10 feet (10+30=40 How far beyond X is

 

It won't take you long to be able to guesstimate. It will never be better than a reasonable estimate.

 

Think of a protractor in degrees with the bottom as the bottom of the pond. The highest point of the cast as one point.

 

The bottom of the protractor represents the base of one line - you 30 ft above X on one end and the "plop" on the other.

 

between you, the plop and the highest point in the cast is a triangle. You need to calculate to find "Y" on the base line (the distance you will have to overcast).

 

SOooo the height of the cast is 10 feet plus the 30 feet down. How far (or high) do I have to cast.

 

The resistance of the water, I should think, is minimal. It's the height of the cast that will be suspect.

 

I've tried to make this so simple it appears complicated. It isn't - - skill required to achieve a given height and arrive at a given distance beyond (the plop) is the tough part.

 

Phone

[Steve Walker]

Pythagoras.

 

The length of line to your clip forms the long side of a right angled triangle. The depth forms the short side. The distance along the surface is the third side which you can calculate as the square root of the square of the length of line to the clip minus the square of the depth.

 

 

So if you clip the line at 120 feet and the water is 30 feet deep, the horizontal distance will be sqrt(120*120-30*30) - which is 116.2 feet.

 

Possibly more usefully, if you know the distance you want to cast, and you know the depth, the distance to clip up at is the square root of the sum of the squares of the distance and the depth. So if you want it to land on the bottom below a point 120 feet away on the surface in 30 feet of water you want to clip up at sqrt(120*120+30*30) - which is 123.7ft.

 

So the maths is easy. In practice, though, leads don't fall on a precise circular arc, because the line is subject to surface tension and water resistance, which will tend to cause them to fall short with a bit of slack once everything has settled. Your lead will not land on the surface the exact clipped distance from your tip, even if you dip your rod tip to the water's surface so that the line is straight and horizontal when it hits the stop. There will be some degree of elastic bounce in the line. You can feather it if you're skilful and maybe minimise that, but still...

 

Maybe worth doing the calculation if the water is deep, but keep in mind that it's still pretty approximate!

[ayjay]

As Steve says , the maths is easy, but the practical side doesn't work exactly as you want.

 

Once you have your set up worked out, try using an open ended feeder filled with small polystyrene balls cast to the spot and see where they arrive on the surface.

 

There may be some sort of current/undertow to allow for, (you can check the extent of that with a float set-up) but it should help put you closer to where you want to be.

[Steve Walker]

More environmentally friendly alternative to polystyrene balls - you can get brightly coloured blown foam made of PVA. Will dissolve in a little while.

[Martin56]

More environmentally friendly alternative to polystyrene balls - you can get brightly coloured blown foam made of PVA. Will dissolve in a little while.

I wonder?????

 

Could you attach a sliding Float above the Lead/Feeder?? the float would then act as a marker when it comes to the surface.

 

An adjustable Stop Knot so you can play around with the depth - The float will be directly vertically in line above the terminal tackle.

[Ken L]

Still no distances but having thought about it, no matter how accurately you calculate the geometry, a much bigger factor is going to be the drag on your mainline as if falls through the water column. This will pull your line into a curve and cause the lead to land much closer to you than the geometry might suggest.

It's rule of thumb time.

Seems that unless it's deep water close in, most people add 3 feet of extra line for every 3 feet of depth where they are fishing.

[Vagabond]

 

, leads don't fall on a precise circular arc, because the line is subject to surface tension and water resistance, which will tend to cause them to fall short with a bit of slack once everything has settled.

I remember Dick Walker being asked to solve a similar problem. His correspondent had deduced something like the above and described it as follows "As the weight sinks, the line goes round the bend in the water " Very unscientific, but Dick knew instantly what the guy meant,

 

A bit like the instructions on the first Japanese fixed spool reel marketed here "Wind handle, bale arm go flip-flop, all go happy fish"

Priceless !