How to Calculate How Much Ballast You Need

Save

Ballasting your vessel correctly is more than simply shifting water between ballast tanks. When well and properly ballasted, your vessel will handle properly in all seas. If your vessel is ballasted poorly, the end result can be devastating. The formula for determining how much ballast to take on without hampering performance, based on the vessel's static condition (not underway), depends on knowing the vessel's metacentric height, the current state of her ballasting and her list when in that static condition, if any.

Things You'll Need

  • The vessel's metacentric height
  • Calculator
  • Measure the amount of ballast water you have on board. Convert the number of gallons to pounds; if you have 100 gal. of fresh water aboard, 1 gal. of fresh water weighs 8.43 lbs., so multiply 100 by 8.43.

  • Multiply the weight of the water by the metacentric height of your boat. If your boat's metacentric height (the distance between the center of gravity and the metacenter, the point at which a vertical line from the center of buoyancy during heel intersects a line from the keel through the original center of buoyancy when the vessel was upright) is 7 feet, so multiply 843 by 7.

  • Multiply the result by 0.1746. The answer, 1030.3 is how much ballast you will need to have aboard.

  • Subtract 843 from 1030.3. The answer, 187.7, is how many pounds of ballast must be added to correct a 1 degree list. If the list is greater than 1 degree -- say, 8 degrees -- then multiply the answer by the number of degrees. Thus 187.7 multiplied by 8 equals 1,498.5 lbs. of additional water that would be needed to correct an 8 degree list.

Tips & Warnings

  • This formula does not account for live loads (weight not permanently attached to the vessel, like cargo or people) aboard the vessel.
  • Caution should be exercised during ballasting to ensure that the vessel's hull is not placed under an undue stress because of weight, lest the vessel break or be overballasted. Your vessel's ballasting software, if equipped, provides the necessary information.
  • If your vessel is not equipped with ballasting software, your boat's owner's manual will contain basic loading information.
  • Overballasting can result in a stiff vessel that handles poorly because of excessive draft; underballasting can result in a tender vessel, which rolls excessively in seas.

References

Promoted By Zergnet

Comments

Resources

You May Also Like

  • How to Calculate Volume

    You can calculate volume with an easy to use formula. The standard shapes such as a square or rectangle all use the...

  • How to Lay HO Scale Track

    There is nothing more attractive on a model train table than well-laid trackwork, with sweeping curves and properly positioned switches. Laying good...

  • How to Calculate Ballast Weight Displacement

    Calculating your boat's displacement related to ballast weight may surprise you in two respects. The first is that your boat's displacement is...

  • How to Calculate How Much Landscape Rock You Need

    Calculating exactly how much landscape rock you need for your project beforehand will save you time and money. You will be able...

  • How to Calculate Dead Weight

    Dead weight (often referred to as Dead Weight Tonnage or DWT) is a term used to measure the carrying capacity of a...

  • How to Calculate a Freeboard

    Freeboard is a design characteristic of a vessel. For small boats, it is the minimum distance from the top edge of the...

Related Searches

Check It Out

3 Day-to-Night Outfits for the Work Week

M
Is DIY in your DNA? Become part of our maker community.
Submit Your Work!