Posts by seaweed

  • 10/09/09 Surprise Surprise

    Good day today, no current, and enough vis to make out where a wreck ends and sand begins to 80ft.


    Our first time out of Stuart were surprised to how much fish there are. Tons of mangos, sheepshead, monster snook and Jewfish on every dive, hardly a tropical in sight.


    I was lucky enough to land these 2 gags, the smaller one bent my shaft and after a cubera tore off the flopper to my backup shaft I had to straighten it and shot the second Gag. Harry landed a nice cobia and all of the snappers.


    These Pargo Russos were about half the size of some that we saw. I know for sure that there can be a new WR for the pargo russo in Stuart waters.





    Size 13 Crocs for size reference



  • 10/09/09 Surprise Surprise

    Harry and I headed out today to a new location to find lots of surprises. Best fishing I've seen so far, majority of fish were shootable on all dives, except snook and Jewfish of course. Hardly any tropicals and good vis in this area.


    Also had one fish do this to me, conservative estimate at 50lbs, too bad he tore the flopper off.


  • Speargun Dynamics

    In water the spear vibrating has drastic effects. If the gun kicks up 6 inches drag increases minimum 20 times and this doesn't include effects of dragging water in the vortices created.

  • Speargun Dynamics

    Quote from Tin Man


    If you follow Davie's analysis a little further, it may even reach the theoretical conclusion that you could reduce muzzle jump by LOWERING the band slot, to put it inline with the grip?


    It seems to me that if the Band Slot, grip, and Center of Mass of the gun were all in line, then you should have no muzzle jump. I have wondered if the way the bands jump around at the end of their contraction could somehow cause the muzzle to move. But I don't know how this would be different for inline versus normal bands.



    Wow you nailed it!!! I thought my writing was pretty sloppy since it was done quick but you are right.


    Pretty much it all surmises to distance between handle and band hole.


    Also something I didn't talk about is how surface area comes in for reducing muzzle jump.

  • Speargun Dynamics

    4



    Now the muzzle flip is a rotation of the gun about point P. This rotation is equal to I* (alpha), I being the moment of inertia and alpha being the rotational acceleration. This is equal to the sum of moments (torques) caused by all of the forces acting at their respective distance such as the driving force at a distance o| from point P, the moment caused by the mass of the spear traveling forward, moment of mass of gun, moment of buoyancy force. Surface area also comes into play which causes drag. Some of these forces are negligible but actual calculations have to be made to gauge their impact.


    I think I is the most important since we have much control over it in balancing the gun. If no balancing is needed the surface area dominates.

  • Speargun Dynamics

    3



    This is the forces acting at point H.


    The normal force, vertical force, is negligible because the band angle is so small also it's counteracted by the wood.

  • Speargun Dynamics

    2



    This explains how the vertical force exerted by the bands causes no muzzle flip.


    This came out kind of slopy but Point B is the notch drawing 1 is the applied forces and drawing 2 is the effective forces.


    Drawing 1


    The force of the band can be split into 2 components. The one that drives the spear FBx and the one that pushes the spear into the track due to band not being horizontal, FBy[/SIZE].



    Drawing 2


    The force driving the band causes reaction force which is what we feel, FBx=msas. It is equal and oppistite in direction.


    The vertical force is counteracted by the wood. Therefore it does nothing except cause friction between the wood and spear. It's like squeezing the wood and spear together. The friction force is equal to ud*N. N is small, around 5 lbs,and u[size=8]d is even smaller, around .02-.1 so the friction force is negligible, .1-.5 lb, compared to the driving force 200lb.

  • Speargun Dynamics

    I think this will be useful for gun builders. Seeing the whole picture of what's going on will help.


    This might not be %100 of what's going on but it is pretty close. Any mistakes seen will be gladly appreciated.


    I will put a couple of hand drawings up trying to make sense of everything going on.



    I'll add descriptions later on.



    Point P is the point around which a gun can pivot. Somewhere in the wrist depending on how you hold the gun. The W's are the weights of the gun and spear and the By is the buoyancy force. Bouyancy force is the weight of the water displaced minus the weight of the wood gun.


    b is the band lenght and d is the distance from band hole to notch and B is a point on the notch.


    Also the mass of the person is much greater than the mass of the gun and spear which I have asssumed makes point P stationary. That is, a force exerted by the gun cannot move the person due to their mass and surface area.

  • Finger safe table saw

    Dan approximately equal to.


    His fingers didn't look wet, I bet the ice was to keep his hand from burning under those strong lights.


    They are so intense he had to wear a welders helmet.

  • good reel needed

    If you can get one a Maorisub Dentex is really good. It actually floats so it wont affect bouyancy and is not as easy to lock on you like other reels.