went for a swim today!

[kickin' bass ass]

well i actually didnt get in the water but my new plugs did however.man these came out awesome!!!!!!!!!!the three 40s swam excellent,the danny im made from scratch swam ok,i think i need to move the weight alittle more close to the nose to give a little more wiggle?the new 1.5 oz tatto was incredible that swims REAL nice and casted well,well what would you expect from tatto.cant wait to build some more will post pics after painted.

[merch]

I've never made plugs before, but I know a little about hydrodynamics. I'd make a guess that you should take the unweighted Danny's and design it so the unweighted version will balance on your finger at the widest part of the plug (design so the center of gravity is at the belly). Once you locate the CG on the plug, you should insert the weight right at this point. The idea is that it will allow the plug to move about freely and easily, centered at this point with equal mass in either direction (balance), effectively bringing down the minimum speed at which you need to move the plug to get it to wiggle. The slower a retrieve it takes to get a danny to start rolling is one of the methods I use to measure the effectiveness when tuning a particular model.

I could be wrong, but I'm sure some of the more experienced plug builders could give you some recommendations. It just seems counter-intuitive to me to bring the weight forward to help the plug roll. Also, plugs shouldn't necessarily be designed to cast well, they should be built to perform once they are in the water. Sometimes people get so fixed on getting maximum distance they forget that performance is much more important than castability (most of the time striper fishing anyway).

[kickin' bass ass]

im not really designing for castability,i totally agree with what you are saying,action of the plug is far more important to me than castability.the reason i said to move the weight foward a touch is because when tattoos danny is just sitting in the water the tail tends to be a little higher than the nose i then thought if the fulcrum was a little foward of center the tail might wiggle a little more?im not sure thou,ill make two more and try dead center and foward of center and see what happens.thanks for the imput merch ill let ya know

[merch]

I don't have a tattoo's dannys but the CG location is not the only thing effecting the way it floats.

There are two major things to consider when designing a submerged body. The center of gravity (CG), or fulcrum point as you described it, and the center of buoyancy (CB). You determine the center of gravity out of the water but you typically can only determine the location of the center of buoyancy once the object is in the water.

The two have a very important relationship with one another and both should be considered when designing. The center of buoyancy is the place where if you held the plug underwater with you finger the sum of the buoyant forces acting on that plug would be located at this point. It's like the opposite of the CG test. Hold the plug underwater, with your finger on top, and where it balances is the CB. Designing the plug with these two points to be coincident with one another will give you the most freely moving version of a plug. Playing games with the separation of these two points along the length of the plug is what helps to give different designs different personalities in the water.

Sorry if that was a little confusing, but I was just trying to find a simple way to explain it. You said the tatto's floats with the tail up a little which means the CB is toward the tail but does not necessarily mean the CG has been brought forward.

Was that helpful? Again, I'm talking about submerged bodies in general and not necessarily the art of making plugs which I really know little about.

Good luck!

[kickin' bass ass]

could i do this test with freshwater?i know fresh and salt have different density but would that afect the results that much ?i guess i could go get some salt water but was wondering if its neccesary iyo?

[merch]

You can do it in fresh as long as the l plug is very buoyant (floats in salt and fresh). I asked about this on another site and was told that the dannys in particular has a lot too it when it comes down to different shapes, sizes and weight placement. This little experinent should help you understand all of the factors affecting buoyancy though. Make sure the hooks are on the plug when you dest it. They will affect the final CG. take led wire and wrap it around the body and float it to see what the different weight placements do to the trim without cutting your plug up. That's a good method to change a plugs behavior in a pinch for us non plug making people. (i.e. make a floater a sinker).

Good luck and post some pics. Id love to see what you did.

[scottw]

ok.......soooooo...you've had my brain reeling for 12 hours or so...which would be the better point to place a weight the CG or the CB? I would think that the CG has the greater infuence on the vertical orientation(front back/up-down) (I'm trying to think in three dimensions and picture this...not easy for me) and the CB a greater influence on the horizontal(front back/left-right) movement... which point would you weight or focus on or is it some combination of the two.. or use to determine weight placement to get the greatest effect or does that simply depend on desired effect? a lot of builders "float" or "hydro-orient" their plugs to determine up and down based on the graining of the wood...so you can determine the "up" mark it, then with a simple jig also find the CB...next determine the CG with a finger or simple jig...if you know these two (which will be different on every piece of wood) and how each relates to the action that you desire and to each other on a given piece of wood you can theoretically adapt to each type of plug and affect the motion depending on what you are looking for...keep a lot of notes and have "dummies" for reference , whether you are using lips which will change everything once the plug is in motion ...I read another plug forum recently where a plug builder remarked "it's not rocket science, it's plug building"...he obviously hadn't talked to Merch yet...I think I've succeeded in really confusing myself...please keep us up to date Kickin'...Monday is a holiday and it's supposed to be warm...

[merch]

Don’t mind me, I tend to overcomplicate things sometimes. Your friend was right, it’s not rocket science but I find if you take the time to understand the fundamentals of what makes certain things act the way they do, it will help you know what to do if you want to recreate a certain characteristic or put you in the right direction when you want to try something a little different. It helps to make things a little more predictable. I'm talking more about engineering here rather than the art of plug building. Plug building is an art and I don't presume to know what makes the best the best, but understanding some physics can't hurt when trying to figure things out.

Different wood grains and densities through the wood will change each plug. The CB/CG Separation in the plug from the top to bottom is what will cause an object to find it's static roll position. The CB will always float to a position directly above the CG in the water. The hooks of a plug will help force it into the orientation you are looking for most of the time. I was trying to avoid talking in 3D because it gets hard to visualize sometimes.

As far as a weight at the CG or CB goes, I’d determine it’s placement relative to the CG. Just an easier reference point because it’s easier to find. A plug should have it’s most unstable or “liveliest” behavior if the CB and CG are located in the same place in the center. Adding weight at different locations on the plug should effectively dampen some of the motion by requiring more force to get the plug to wiggle. Putting the weight further toward the bottom, or the belly, should help to dampen the roll of a plug at slow speeds. In the case of a metal lip plug this force is generated by water flowing by the lip creating an unstable flow at the nose. Back and forth, like a flag in the wind. The faster it goes, the quicker the flow goes to one side, followed by the force of drag on the side of the plug over coming this force on the nose, and the plug is pushed back the other way. Back and forth, back and forth… For instance, adding weight to the tail of a plug would be likely to slow the action of the plug and require it to be moving faster through the water in order to get it wiggling. Just a guess. A larger separation from the lip and the CG would need more speed to generate more force to get things rolling.

Like I said before, I’m basing my thoughts on physics and I’m probably missing about a thousand variables. It’s probably more effective to try something out and see what happens, maybe take notes, rather than to try to plan what’s going to happen from the start.

I’m surprised one of the professional plug builders here hasn’t chimed in yet to shut me up.

[scottw]

that is incredibly helpful....if you are weighting you plug with the intention of trying to line up the CG and CB then you actually have a defined goal rather than trial and error on each and every plug....I think if you are building commercially you just let any added weight nullify most of what we discussed and produce a product that does the , swims well and that people like to fish with, if you have the time to work on each by hand this is really interesting stuff and could save time in the long run, it would be pretty simple to determine the two points that you talk about and the axis between and adjust that with weight depending on the characteristics that you want to impart, like you said, if you want the most action with the least "work" it makes sense to consider CG/CB

[scottw]

I should probably add that there was absolutely no slight there to any commercial plug builders, I know nothing compared to those guys and I am also in a business where I need to get as much finished work out the door while maintaining the highest quality... but it was a high profile commercial guy that commented in a "hydro-orientation" discussion that I read where he insisted that the addition of properly placed weight nullifies a lot the issues that guys try to correct with H-O and other things, but who knows...if these factors are considered you might be able to weight a plug quicker with better results and without drilling so many holes....I'm always trying to reinvent the wheel...been sketching out hand carved eel needles today?!?! Can you impart a little side to side action in a needle(you wouldn't need much with a big siwash behind ...WOW) by placing a weight at the point discussed rather than several weights spread across the bottom? I'd love to have a simple formula to get the most from given piece of wood with as little thought and effort and time...I am however fascinated by all of this which means I'm likely nuts....can't wait to fish!