Measurement Corner

Proceedure for Checking Spars for Positive Bouyancy

Positive Bouyancy exists when a spar floats on the surface and remains afloat for an indefinate length of time.  Spars made from a material, such as wood, that is lighter than water will float and have positive bouyancy.  Other spars made from metal or reinforced plastic resin can attain positive bouyancy if enough air is trapped inside sealed chambers within the spar to cause the spar to be lighter than water.

1. Negative bouyancy exists when a spar sinks below the water surgace and remains underwater.  In this case the spar is heavier than water.
2. Testing for positive bouyancy is conducted in seawater.  Bouyancy testing is easily accomplished from a low dock.
3. Tie a teather securely to the spar to prevent loss, and to provide for easy retrieval.
4. Place the spar in the water.  Check for emerging bubbles.  Non-wooden spars will easily bubble at first; then, if the spar has positive bouyancy, the bubble stream will cease.
5. 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 bouyancy and may not be used in competition until its bouyancy is made positive.
6. A spar with positive bouyancy should float with its length parallel and slightly above the surface, and when submerged will return to the surface.
7. A boom that floats for a period of time, then sinks, does not have positive bouyancy.
8. It is assumed that a spar with positive bouyancy will float indefinitely; however, the tester's time is limited and signing off that spar as bouyant is at the tester's discretion.