Positive Buoyancy exists when a spar floats on the surface and remains afloat for an indefinite length of time. Spars made from a material, such as wood, that is lighter than water will float and have positive buoyancy. Other spars made from metal or reinforced plastic resin can attain positive buoyancy if enough air is trapped inside sealed chambers within the spar to cause the spar to be lighter than water.
- Negative buoyancy exists when a spar sinks below the water surface and remains underwater. In this case, the spar is heavier than water.
- Testing for positive buoyancy is conducted in seawater. Buoyancy testing is easily accomplished from a low dock.
- Tie a teather securely to the spar to prevent loss, and to provide for easy retrieval.
- Place the spar in the water. Check for emerging bubbles. Non-wooden spars will easily bubble at first; then, if the spar has positive buoyancy, the bubble stream will cease.
- If the bubble stream continues, wait to see if the spar sinks. It is permissible to hold the spar underwater to make sure all air escapes. A spar that sinks below the surface has negative buoyancy and may not be used in competition until its buoyancy is made positive.
- A spar with positive buoyancy should float with its length parallel and slightly above the surface, and when submerged will return to the surface.
- A boom that floats for a period of time, then sinks, does not have positive buoyancy.
- It is assumed that a spar with positive buoyancy will float indefinitely; however, the tester’s time is limited and signing off that spar as buoyant is at the tester’s discretion.