Ideal kayak rod for big fish

Easier to figure out the torque numbers by field trial, then.

That wouldn't be too hard with a spring scale, a lever arm, and a little winch.

But you math wizards can run your game however you like!

If you can calculate the torque it takes to roll a kayak I would love to see it. Hull shape alone is way to big of a variable for me to try and assign a value to. Then you get to look at the length of the lever, the distance from the side of the boat, the center of gravity for a boat with a paddler. Whew! 

I'm not interested in the absolute number so much as I'm interested in the difference in approaches.

I think one can make reasonable assumptions on most variables and come up with a valid comparison, much like you did with the comparison of 5' to 7'.

I would never have started down this road if you hadn't opened the door.  Gee, thanks!!!   

-Allen

I think that in order to come up with some assumptions that would let you write an equation, you would need some known values. In the rod length you can absolutely know where your hands are, the length of the rod, and your drag setting, leaving only one calculation to be able to set a benchmark for force. I don't know what known variables you could use for rolling a yak.

Easier to figure out the torque numbers by field trial, then.

That wouldn't be too hard with a spring scale, a lever arm, and a little winch.

But you math wizards can run your game however you like!

That could be fun! Max out your drag, attach a scale, and have a diver pull you over while you experiment with different techniques to stay stable. 

Good discussion and good math Jay. 

It's worth noting that a key benefit of a slower action rod, is that as the rod is loaded, the lever arm is effectively shortened (Fi approaches Fe).  Your leverage on the fish is increased in proportion to the force applied up until Fi equals Fe, at which point you are "locked up". 

Jay... do this math (if you are inclined).  How much could the drag setting in your scenario be increased if the distance between the Fi and Fe approaches zero... or say 12 inches to replicate a slow action rod fully bent 90 degrees to the grips?

Clearly this is a very dynamic situation and you're right Allen, there is no free lunch.  Everything is a give and take.

As for roller guides, they would be advisable for rods of this class for fish that smoke out the line as you are discussing.  Tip and stripper at a minimum, with high quality ceramics (SiC or SiNII) in between.  You can also do an Acid roller guide setup to provide not only low guide friction, but also eliminate torque on the rod as heavy load is applied... just another option to throw out there and confound you further.

Like this:

To simply increase the force it take to roll a yak simply gain weight and lean your torso off the opposing side.

If the the fish on a 7 foot rod with 10 pounds of drag is exerting 47 pounds of force and the handle then simple wear a dive belt over your shoulder and lean off the other side of the yak. A big guy with a 30 pound belt should be able to max out most reels. Even Avets only go to 20#s or so on most models.

Are we getting to the point of talking about taking out a Penn International 50 with 30 pounds of drag?

Now this whole concoction will raise your center of gravity and we are right back at how bad ass of a paddler are you?
=)

BTW that full rollered Seeker build is pretty F-ing Sweet.

Jay,

Scenario #1.  Rod butt at my hip, 7' long rod, 45 degree up angle, line is pointing straight down.  For simplicity, measure the torque at the point where my rod but is at my hip.

Scenario #2.  Rod butt 1.5 feet higher, 5' foot long rod, 20 degree down angle, line is pointing straight down.  Measure the torque at the same point as #1.

-Allen

Jay... do this math (if you are inclined).  How much could the drag setting in your scenario be increased if the distance between the Fi and Fe approaches zero... or say 12 inches to replicate a slow action rod fully bent 90 degrees to the grips?

To get this number I had to go back and benchmark it against the original assumption of a 7' rod set at 10lb drag, but with the 7' rod bending as much as the 5.5' rod. In each case I calculated the rod being 18% shorter due to the bend.

So, with a 5.5' rod that's 12" shorter due to the bend you could put on approximately 12.75 lbs of drag and have it feel the same as a 7' rod with 10lbs of drag. It didn't change much because if you compare bent rod numbers to bent rod numbers you're just changing proportions, so the value you get for drag settings will remain constant. If anything, calculating bent rods just gives you a better idea of the real "force applied to the angler" numbers (F_e).

However, a rod that bends further gets shorter, puts less pressure on the angler, and allows you to apply more drag. For example:

Let's assume that your maximum comfort level fishing from your kayak is 10 lbs of drag on a stiff 7' rod that only becomes 6" shorter as it bends.
At 10lbs drag the angler gets 38.9 lbs of pressure applied to him. Therefore the maximum force you are comfortable handling is
38.9 lbs and if you can change the other variables you can increase drag.

So let's change up to a 5.5' rod that shortens by 12" when it bends, and use the same maximum force value. in this case the same angle with a shorter rod that has a softer action could apply 14.4 lbs of pressure.

Right, so how about a 5.5 foot rod that shortens by 2.5 feet when bent (slow action rod bending pretty much up to grips).  How much drag could be applied to stay at the same 38.9 lbs of force on the angler.

Jay,

Scenario #1.  Rod butt at my hip, 7' long rod, 45 degree up angle, line is pointing straight down.  For simplicity, measure the torque at the point where my rod but is at my hip.

To calculate "torque" you simply take the force and multiply it by the length. 10lbs of force at the tip multiplied by a 7' long rod gives you 70 ft/lbs of torque. But I don't think you want to know torque. You have the butt of the rod jammed someplace acting as a fulcrum with your hands forward of the fulcrum pulling against the weight at the tip of the rod. The force acting against you is at your hands, not the butt of the rod.

Scenario #2.  Rod butt 1.5 feet higher, 5' foot long rod, 20 degree down angle, line is pointing straight down.  Measure the torque at the same point as #1.

-Allen

Similarly you probably don't want torque. As you point the rod at the fish (ie. the rod moves below horizontal) you're taking the rod out of the fight and putting more of the pressure on the reel. You'll feel less pressure at your hands because your drag is releasing easier due to reduced friction from the rod bend. So, once you go below horizontal, the equation I've been using is no longer valid.

Right, so how about a 5.5 foot rod that shortens by 2.5 feet when bent (slow action rod bending pretty much up to grips).  How much drag could be applied to stay at the same 38.9 lbs of force on the angler.

That comes out to a whopping 21.6 lbs of drag!

As you approach zero length (you're just holding a reel in your hands) you could get the drag setting all the way up to your maximum comfort level of 38.9 lbs. But as you get shorter and shorter, the shock absorbtion of a rod is lost little by little. A 7' rod with a slow action might have several feet of travel at the tip to help with shock absorbtion, while a 3' stubby has almost no shock absorbtion. Somewhere in there you gotta find the sweet spot! Shock absorbtion vs. drag.

Jay,

Torque for this isn't that simple in these examples, right?  The 10 pounds of force is at an angle.  You need to calculate the perpendicular force, don't you?

And in scenario #1, the radius is from the butt end.  In scenario #2, I keep the same point and move the butt end.  It's all in the angles, and in scenario #2, my body becomes another lever point.

-Allen

Jay,

Torque for this isn't that simple in these examples, right?  The 10 pounds of force is at an angle.  You need to calculate the perpendicular force, don't you?

And in scenario #1, the radius is from the butt end.  In scenario #2, I keep the same point and move the butt end.  It's all in the angles, and in scenario #2, my body becomes another lever point.

-Allen

If you are putting the butt against something so it can't move, or putting the rod under your arm, the point the rod rotates around as you pump is the fulcrum, and the force needed to hold the weight up comes from your hands. Think what would happen if you let go with your hands, the rod would drop right? Your hands are where the force is applied to you as you pull against the weight and the butt of the rod is the fulcrum point for pumping.

In example #1, you are right about perpendicular force, but it has less effect on a fishing rod at lower angles. As you increase the angle of the rod the 70ft/lbs of torque at horizontal reduces until you have 0ft/lbs of torque at vertical. However, the reduction is not steady, it decreases faster as you approach vertical (and you also risk breaking your rod as you high stick it). We could try to work this in, but the fact is, it doesn't matter beause you aren't fighting torque when you fight the fish. You are simply using leverage to try to put pressure on a fish. Torque does not play into this. Leverage does.

In scenario #2, unless you're fishing with a hinged fishing rod, there is only one lever point. Again, the torque on the lever is not where force is applied to the angler. Force is applied at the point where you are holding the rod. If you really want to feel torque, let the butt of the rod sit free and fight the weight with your wrists like you're using a fly rod without a fighting butt. That force that rotates the rod is torque. The way you prevent torque from taking over is by wedging the butt of the rod against something.

Also in scenario #2, if you start pointing the rod at the fish, you're taking the rod out of the fight. At that point your reel is more important than the rod. And leverage matters less and less.

Again, I'm not worried about the force applied to me, the angler.  I'm worried about how that translates into instability of the kayak.  Never mind that I have horrible balance.  If I was a rigid structure on the kayak, the force applied in the different scenarios would have an impact (I have no idea how much) on the stability of the kayak.

Or maybe let me try to phrase this another way.  Does me holding the rod in a different fashion affect my ability to put more force on the rod (assuming the rod was the same length) while still maintaining the stability of the kayak?  The answer has to be yes because obviously holding the rod at different heights extends the overall distance from the kayak.  But if I change the anglers from positive to negative the kayak becomes more stable.  Look at the extremes ...

Baseline) 7 foot rod, perpedicular to the kayak with the butt zero feet off the floor.

Alternative #1) 7 foot rod, perpendicular to the kayak with the butt 7 feet off the floor.  Hugely unstable.

Alternative #2) 7 foot rod, at -90 degrees (straight down) with the butt 7 feet off the floor.  Most stable.

-Allen

Ah ... it just hit me after I posted.  The stability is proportional to the distance of the tip of the rod to the point that I'm interested in measuring the torque.

Shorter rod ... good.
Hold butt higher, but point rod down ... good.

-Allen

And ... if I hold the rod butt on my right side with the tip on the opposite side, that's also good since we have some forces balancing each other out.

-Allen