Marlin Lure Hydrodynamics

Discussion in 'Hydrodynamics and Aerodynamics' started by johnnythefish, Jun 27, 2022.

  1. johnnythefish
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    johnnythefish Junior Member

    Please forgive this somewhat off topic thread - but I couldn’t think of a better place to ask about hydrodynamics.

    Marlin lures are traditionally weighted with lead on the “keel” side so that they run in a vertical position consistently.

    Aside from attracting a marlin, a good lure must be stable enough that it acts as a “vehicle” for the hook it pulls in order to ensure a good hook up ratio to the number of strikes.

    Most single hook rigs will “lock” a hook into an upright position thus helping ensure a good hook up in the topside of a marlin’s jaw.

    A marlin lure must also go through a cycle as it is pulled behind a boat at around 9 kts where is comes up to “breath” and then goes down for 3-5 seconds before surfacing again. For whatever reason this action over the years has formed the basis of why marlin lures are successful.

    Typically marlin lures are typically some sort of cylinder with a round cross section.

    I am looking for some ideas as to how to make a marlin lure that is stable vertically (always runs one side up), follows a nice breathing cycle and does not require keel weighting with lead.

    One idea is to have one half of the lure face (the bottom half) have holes in it allow water to pass through and the top half some sort of “air chamber” to make it lighter.

    I am also not against a shape that isn’t cylindrical.

    If anyone has any ideas I would love to hear them!
     
  2. philSweet
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    philSweet Senior Member

  3. kapnD
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    kapnD Senior Member

  4. kapnD
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    kapnD Senior Member

    I have this lure from the 70s that looks like it was designed to run flat side up. I haven’t used it for a long time, but your question inspired me to dig it out of the archives.
    It did produce some strikes, but that could have been because it was the anomaly in the spread, certainly an offbeat lure.
    Locking the hook to the lure helps stabilize any lure, the hook acts as a rudder, stiff rigging the hook helps as it prevents the hook from rotating at point of attachment.
    Most lures rotate from side to side a bit when towed, especially at faster speeds.
    4DD49963-E262-43E5-A819-3D1377E99286.jpeg 8A76C7CC-C924-403D-A970-A4E34E398269.jpeg
    Edit: just hung the lure on a wire, the flat side is weighted, and now I’m really curious as to which side is actually the top.
     
    Last edited: Jun 30, 2022
  5. johnnythefish
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    johnnythefish Junior Member

    Interesting looking lure. I am sure there isn’t a lot that hasn’t been tried somewhere in the world - but underwater cameras have probably helped understand what’s really happening.

    Interesting what you say about the stiff rig - lots of opinions on that. I know some lure makers (Pakula) and I think Bonze prefer a free or semi free swinging single hook rig.
     
  6. fallguy
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    fallguy Senior Member

    I really love the idea about discussing it here. Of course, I'm not the one in charge.

    But am moving to the GoM and have a chance to bw fish for marlin.

    Can you explain the reasons you want to go leadless? How do the current baits cycle and surface?

    I envision a bait that is tunable. Is that the goal?
     
    Last edited: Jul 6, 2022
  7. kapnD
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    kapnD Senior Member

    I mentioned stiff rigging because you referenced Marlin lures, which are the only lures I stiff rig.
    This being a result of studying Kevin Nakamaru’s great videos of Marlin striking lures.
    Hook placement definitely matters in Marlin fishing.
    Fallguy, leadless lures will tend to skip and flip clear out in rough water, resulting in fouled lures and tangles.
    Well, maybe not all leadless lures, but a discussion of Marlin lures, in my mind, means extra big bubblers.
     
  8. johnnythefish
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    johnnythefish Junior Member

    Do you have any experience/ thoughts on the new Pakula Air Heads/ 3D printed lures?

    @ Fallguy He explains his rationale for no lead here …

    Fish Print Lures https://www.pakula.com/2014-09-03-22-45-9/fish-print-lures.html

    I guess I am simply curious in the same vein and had never really thought about it like this before.

    I am sort of trying to understand what is happening to keep those lure heads stable - do the vent holes bite the bottom side into the water - a bit like “water ballast” in a boat - or does the lure have an air chamber on the top side.

    I would quite like to try turn a few wooden lures based on this idea - just for fun.

    It also got me wondering if a marlin lure is supposed to ride one way up then why is it a cylinder and not say a rectangle/ triangle cross section ….

    There are of course many lures that have no orientation and they do just fine as well in many conditions but part of the reason a keeled lure is good is to control the hook angles
     

  9. fallguy
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    fallguy Senior Member

    My guess is that the lures have two separate functions.

    One would be fixed air chambers that keep the bait from flipping over. So, bladders on upper portions, perhaps kidney bean cross section.

    Then the other is the smoke makers which he refers to as venturis. I must admit some confusion on the how. The smoke is a stream of bubbles, right? So the bait would fill with air on surfacing, then as the bait plunges back into the water, the water pressure forces the air out the back of the bait via what is probably a tinier hole to get the stream to last a bit. My guess and that is all it is...there is a separate air chamber for smoke behind the two inlet holes on each side.

    What 3D printing affords is the ability to size the chambers for both the top buoyancy bladder and the smoke bladder(s).

    The part I don't quite get is how the water exits the bait on surfacing. Because water would not always exit real well..

    The one fellow on the forum who is an expert is baeckmo . But I feel a bit guilty calling him because there is no drawing and you have to watch the video and make quite a few assumptions here, so I did not.
     
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