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!  |