# Ballast calculator

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I have done a lot of work on ballast calculators in the past. I have never offered them up for use by TU members because I considered them complicated and clumsy. This one however, I consider to be very slick and versatile.

You can enter data from a first prototype and it will calculate how much ballast you need to add or subtract to achieve the buoyancy that you desire, be it slow sink, neutral or float.

Boxes 1 and 2 are merely to collect data on the body material in order to obtain the material density.

Boxes 3 and 4 are measured from a completed lure with hardware, hooks and topcoat.

Box 5 is your desired buoyancy, 100% = neutral buoyancy.

Box 6 is the density of the ballast. This can be changed if not using lead.

The calculation takes into account the body material removed or added to make room for the ballast.

PM your email to me if you would like to try this spreadsheet.

Dave

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Here are three examples of the application, aiming for neutral buoyancy. In each case the ballast adjustment is shown in the green box. It looks like the ballast adjustment values don’t add up, but this is because the material removed for the ballast hole(s) is taken into consideration.

I measured and weighed a block of the body material:
1.5cm x 1.5cm x 4xm = 9cm³
Weight = 2.39g.

EX1 – a completed lure with 10g ballast installed.
volume (Archimedes) = 21.2 cm³.
weight = 18.79g.

EX2 – a completed lure with no ballast installed.
volume (Archimedes) = 21.2 cm³.
weight = 8.79g.

EX3 – a completed lure with 16g ballast installed.
volume (Archimedes) = 21.2 cm³.
weight = 24.79g.

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I would appreciate it if all those that requested copies of the ballast calculator brought feedback and suggestions of improvements to the table, either by PM or posted here.

Many thanks for the encouraging response.

Dave

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Vodkaman,

i was able to use your calculator on my first ever pours this morning. I got a sinking, very slow sinking, and floating flat sided crankbait with only adding a very small amount of lead to stabilize it! Super awesome and easy to use! Seriously one of the most helpful tools I’ve come across since i started making baits!

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Thanks NoMi baits

Dave

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Dave,

that is amazing!!..Thank you!!...Nathan

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Dave I would love to have a copy of the calculator. Thanks for your generosity.

capt_mike_herrmann@yahoo.com

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Hi Dave,

Me too  I would like to try, could you please share calculator on my following email id.

sudanraghu2210@hotmail.com

Thanks  & Regards, Raghubir

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Capt Mike and RSS - files sent.

Dave

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Hi Dave

Thanks for sharing the excel, will start working on same.

I have some lure blanks to finish, will try to use the excel.

Regards, Raghubir

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I would love to try this out and provide feedback. Thank you for sharing this.

I make allot of one off baits and this could prove very helpful with the design and speed up my tank testing. Currently i fill the baits with more lead than i need and drill out. Float test. Drill Out Float test...... repeat........ Until i get the result i want. Thus the baits tend to have the weight higher up in the belly and require more filler.

mmanolis2001@gmail.com

Thanks

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mmanolis2001 - file sent.

Dave

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3 hours ago, Vodkaman said:

mmanolis2001 - file sent.

Dave

Got it. Thanks

Working on a small glide bait now. This will prove helpful im sure..

Ok now for my first dumb question,

How are you determining your wood density? I see you are using Body Material volume (L x W x H) X (0.265)

How are you  determining the Density value of 0.265? I see charts on the web listing wood density as cubic kg/m or lb/ft

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You have to use Archimedes to do this. It sounds difficult and highly technical, but it is really very easy. Actually easier than measuring the length breadth and width of a block of wood. The method is explained in the post Archimedes Dunk Test.

Dave

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Do NOT rely on published data to determine material density for the chart, it is simply not accurate enough, there are too many variations between samples even from the same tree.

You will need to use Archimedes for the shaped body as there is no other way of obtaining the data that comes close in accuracy. If you are hoping to get anywhere near a neutral buoyancy (suspender) then accuracy is everything.

Also, do not even think about working in inches and ounces. If you want to use engineering to help you, then get used to centimeters and grams. Believe me, it is a lot easier.

Dave

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Dave, would love to have a copy of your calculator. Thanks for sharing. desmondowen@yahoo.com

Edited by Saffie

Sent.

Dave

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Hey Dave,

could you send a copy to me?

techknuckle@gmail.com

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Old1ncal - sent. Sorry for delay, my internet was down.

Dave

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6 hours ago, Vodkaman said:

Old1ncal - sent. Sorry for delay, my internet was down.

Dave

dave how much weight to sink a 120mm+10mm wood lure blank?

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Posted (edited)

If you have a digital scale, you will be able to measure this by using Archimedes. This link will show you the method.

Water weighs 1 gram per cm cube.
if the volume of your blank is 20cm3 and the weight of the blank is 8gm then it will require more than 12gm to sink.

Dave

Edited by Vodkaman

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troutbum24@gmail.com

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And can you explain how to come up with Archimedes assy volume of completed lure? Not sure I understand that one. (assy volume cm^3)

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Sent.

1 - Place a container of water on the gram scale and zero the display.

2 - Insert the lure assembly using long nose pliers or tweezers so that the lure is completely submerged and not touching sides or bottom.

3 - Write down the weight in grams.

4 – Weigh the dry lure assembly in grams, write down the weight.

The weight (3) represents the volume of the lure cm³.
Density is measured in grams per centimeter cubed (gm/cm³).
To calculate the lure assembly density:
density = weight(4) ÷ weight(3)

Dave

Edited by Vodkaman

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