Let Me See If I've Got This Right
34 replies to this topic
Posted 30 October 2010 - 05:20 PM
As always Dave/Ben, fascinating stuff, I’m still struggling with a formula where you can weigh a blank and calculate the precise ballast weight to make it neutral when finished, sooooo many variables.
Something I think much neglected, is the vertical rather then horizontal ‘fight’ between buoyancy and ballast. One of the all time greatest lures ‘Rapala Original/CD’ (IMHO), and one which has been accounting for large numbers of Trout around here lately, uses this to get that enticingly subtle action that many makers have copied, these lures exploit the buoyancy of balsa with a slight taper on the sides, relatively little ballast (wire, hooks and rings), and a tiny bib to get that irresistible sway that fish can’t seem to resist. If this lure was made of a heavier timber and ballasted the same it would probably be useless and in all likelihood roll over.
Just some food for thought??
Dave how is the dust collector going??- got mine near to acceptable------
Posted 30 October 2010 - 06:07 PM
You've gone and let me down. I never figured you for a quitter.
Posted 30 October 2010 - 06:16 PM
It's funny that you should post that about Rapala's lures when you did. I just finished an "autopsy" on an old Rapala a few minutes ago and made note of the very things you described in your post. Not sure what they seal their lures with, but it seemed to be a pretty substantial type of plastic shell. White in color and seemingly about as thick as a piece of printer paper. I was surprised at how thin (around .030") and soft the through wire was. I would have thought it would have been much stiffer.
By the way, how have you been and did you have any luck on your last fishing trip?
Posted 01 November 2010 - 12:15 AM
In the example of the balsa, if you think about it, you need a whole bunch of weight to offset all that light wood. You end up with a fight between the weight wanting to control and sink the lure and the very light wood wanting to make the lure float. This wrestling match is what creates the lively lure.
In the case of the heavy wood, you need far less weight to make it sink so there isn't such a struggle between the more dense wood and smaller volume lead needed to make it sink and so you lose some of the action.
Nevertheless, it has been my experience that you can't assume this will always hold true. Find a lure shape and size you like then build the lure out of several woods and see what you like the best. You should also experiment with the placement of the lead, a small change in the location of the lead can make a huge difference in lure action.
You can put all the math you want into lure building and in the end you will still find it necessary to experiment.
Posted 01 November 2010 - 02:02 AM
This is so true. Fortunately, this experimenting and prototyping, is my favorite part of lure design. I am just off to my friends pool, to test a handful this afternoon.
Edited by Vodkaman, 01 November 2010 - 02:02 AM.
Posted 01 November 2010 - 02:46 AM
No way! I am staying home tonight and read some technical manuals.
I thought vodka and reading technical manuals had the same effect on brain cells
Now let's see what we can all learn from this thread.
Riverman is perfectly right when he says there no substitution for experimenting. But at the same time you have to know how to experiment, and the knowledge to experiment comes mainly from theory. I think we are lucky to have Vodkaman here, to guide us with his knowledge. I, for myself, have always taken into consideration his theories about a lure's action, and found out they are useful.
Posted 01 November 2010 - 02:48 AM
Didn't know how to cancel a double post
Edited by rofish, 01 November 2010 - 02:53 AM.
Posted 01 November 2010 - 07:53 AM
Rofish, I use all the theory too, I find that it helps, in fact I cannot stop thinking theory all the time. Theory is what I do, but I would not want anyone to think that theory is anywhere near essential to lure design, it is just another way of going about things and you still have to test the theory.
We have already established that lures are way too complicated to put numbers on, I already tried that several years ago. Even the fancy fluid dynamic programs cannot help with lure design, because they can only handle static objects in a flow. A lure is a dynamic object, continually moving in the flow, The software cannot cope when the goal posts keep moving.
Lure theory is just understanding a few basic principles, understanding vortices around the lip, understanding buoyancy and weight distribution. It can help explain why a lure doesn't swim and guide you towards a solution without having to aimlessly try everything. Lure building experience gives you the exact same knowledge without the fancy words.
In my early days of lure design, I did not have the experience to fall back on and wanted to understand how things worked. This was a good plan and it helped me find/predict some different movements/actions, which is something that only blind experimenting can do. But after about four years of building, I find that I have a 'feel' for the lure and can get a new design to swim how I want it by instinct and experience. It is hard to build a lure that doesn't swim now, which was not my experience at the start.
I had a point to make when I started typing, but have lost it, so will probably have to post again, probably those damaged brain cells playing up. Many members get irritated about my theorizing and I can understand that, each to his own. I find the theory side interesting and rewarding, especially on the rare occasion that it gives me something new. I believe their is a lot left to be discovered in the sea of lure design. Discover it with theory or blind luck? I'll stick to theory thanks.
Posted 01 November 2010 - 09:33 AM
Thanks for all the help everyone. I wasn't necessarily looking to make a choice of building a lure from the two woods originally mentioned. I used those examples because of the great difference in their buoyancy. One of the questions I was looking for answers to was if the greater amount of weight added to the balsa lure to make it the same weight as the heavier wood would cancel out the livelier action of the lighter wood. I realize it would be much harder to find a place to put all that weight in the lighter lure, but since we were talking about a theoretical problem I didn't let that concern me. One thing that stands out in this thread is that there is no replacement for experimentation, but I like to have at least some idea of the reaction to the actions taken. And thanks to all of you I feel like I now have a place to start.
Posted 01 November 2010 - 08:58 PM
No Ben, I am thinking of taking up sailing as I spend most of my time bobbing around doing nothing, might as well use the boat for something.
Posted 02 November 2010 - 11:12 AM
Ben, in my experience so far, adding lots of ballast to a balsa bait makes for similar in-water performance to the same bait made from a heavier substance and ballasted to the same total weight. Similar but not identical due to the difference in weight distribution. Similar enough that it seems fruitless to me to use labor-intensive build techniques just to get a deep diver made from balsa - if one design criteria is that it must weigh the same as a similar hardwood or plastic bait. I've made balsa deep divers that were DOA due to excessive ballasting. I've also seen deep divers from balsa that had livelier action than "normal" but I think their action resulted from a good balance of body and ballast weight (just like any other bait), not that the baits were built from balsa per se. Balsa allows you to experiment with ballast amount and placement more than you can with a heavier material. But in the practical world, if you get a bait "just right" in balsa, changing to another wood means starting from scratch. Why do some manufacturers build deep divers with balsa (Rapala DT16 and Sisson P20 come to mind)? Maybe for performance but also because their design, manufacturing, and raw material processes are set up to build balsa baits. That's no criticism of building balsa deep divers. If you're dedicated to balsa, you can design and build some great deep baits with it. Whether they will catch more fish than a hardwood or plastic deep diver is another question. Not only does a great bait have to swim well, it also has to cast efficiently and be durable. JMHO
Posted 02 November 2010 - 03:06 PM
Thanks Bob. What you say makes a lot of sense. I'm a long way from tackling the more complicated deep divers. Will try "getting my feet wet" with some shallow running, flat sided cranks to start with. As it stands right now I'm using nothing but hand tools to carve out a few blanks and then playing around with different lip sizes, lip angles, weight sizes and placement. If and when I can get a few of them to work properly I will most likely invest in some power tools that will make it much easier to duplicate multiple baits. As close as wood can be "duplicated" anyway. I've already been looking at some bench top models of band saws, drill presses and disc/belt sanders. I guess you can count me as being thoroughly addicted to this "hobby". Pretty sure there's no pulling back now. Thanks again for all the help.
Posted 05 November 2010 - 12:31 PM
I think you're right about why Rapala uses balsa for their deep divers. They're set up for balsa, so it makes sense.
Due to another broken Rapala bill I had a chance to investigate the ballast of a D16. The entire bottom section of the lure from the front hook hanger to the bill is some kind of lead alloy.
That's a lot of ballast to try and add by hand, and still have it in the right place.
I fish my deep divers slowly, with them digging into and bouncing off the bottom, so they really don't need to be as lively as a shallow running crank that's deflecting off shallow cover like wood.
Posted 05 November 2010 - 03:34 PM
So sorry Pete, somehow I totally missed your post No21.
It is possible to predict the ballast to get close to neutral buoyancy. You can accurately predict the density of your body by measuring the length, breadth and depth of your stock (centimeters) and weigh the stock on a digital gram scale. Divide the weight (grams) by the volume of the stock (cm3) gives the density. You then weigh the body after carving is complete. Divide the weight of the body by the density that you calculated, this gives you the volume of the body.
Knowing the volume of the body tells you how much weight that body must weigh for neutral buoyancy, eg, if the volume is 21cm3, then for neutral buoyancy, the body must weigh 21 grams. Simple huh!
But from here on in, it gets messy. You are going to add a lip, harness or screw eyes, hooks split rings, paint, top coat and ballast. The hardware is easy to deal with, because you can weigh it. Even the paint and the top coat can be measured on the first build, by weighing before and after and making notes.
Here are the problems or the things that you probably did not take into account:
1. cutting holes and slots for ballast, eye hardware and lips. You are removing light body material and replacing the volume with the denser material. This has to be taken into account.
2. everything that sits outside the original carved body (paint, top coat, hooks, split rings, lip protrusion, eye protrusion), is increasing the volume of the final lure and thus increasing the final weight of the lure to achieve neutral buoyancy. So your original estimation of 21 grams goes up to say 22.5 grams, so the ballast has to be re-calculated. The main offender is the volume increase from the epoxy top coat, this is very significant.
3. consistency when applying top coat.
There are solutions to all the above, but it doesn’t really work unless you are building a series of lures, so that the relevant information can be collected on the first build, mainly the weight of the paint and epoxy application. On the second build, weigh out the exact amount of epoxy plus a tad to allow for the waste left in the cup. This is about as accurate as you can get. You have all the information on the lip material, hooks, split rings etc, so with the use of a spread sheet to do the sums for you, it is possible to get very close. This will get you to a slow sinker or floater. If you want something that actually hovers or suspends, you will usually have to fine tune after the build.
This is basically how I build the first two lures of a run. On the first build I collect the information, the second build I apply the information and check that I am close. All subsequent builds all I have to do is weigh the carved body and can calculate the ballast straight away, even if the wood is denser or lighter. I can control the amount of ‘float’ of the final lure. I like about 10% to 15% lighter than neutral buoyancy. For just building floaters, I do not get involved with the finer details of the above, but the epoxy volume, I do.
Question now is, “do I press the post button”? Well, the question was asked, this is my answer.
Pete, haven’t built the Thien separator yet. But when I do, I will be going with the side mounted inlet and mounting the shop vac in a bucket int the lid, so the entire unit is self contained. Here is a link to my design: http://www.cgallery....php?topic=375.0
Posted 06 November 2010 - 11:13 AM
If you've built enough lures, all types for enough years out of enough materials, the specifics of this discussion become quite intuitive. While I build numbers of certain lures, I'm also constantly building "one-off" baits. And while I never calculate anything on paper, and never have, I'm very much using the parameters being discussed here. When I decide to build a new design, I build a lure, complete with topcoat, and take it to the water to evaluate its total performance according to my particular expectations of its performance. For example, a particularly important parameter for my lures is their running attitude combined with hook placement, which is a primary factor in how well the lure will come through woody and rocky cover; which equals how efficient the lure will fish for me.
A working knowledge of this discussion,whether "guesstimated", or digitally calculated, is definitely an advantage in achieving the desired results for your lures.