ABOUT SURFACE MARKER BUOYS
Our Advice: For normal use orange, closed bottom, short tape loop attachment point, stainless steel low pressure nipple, dump valve, and reflective tape sewed onto the top.
Orange vs yellow SMB
Red or orange means "I am under here", yellow means "I am under here and have a problem" (emergency), half orange-half yellow means "I don't know what SMB colours signal to the boat".
Open vs closed bottom
SMBs may have an open or closed bottom. An open bottomed SMB is deployed either by catching gas exhaled from your regulator, or purging a regulator into the open bottom. A closed bottom SMB is deployed by attaching a low pressure inflator hose (from your stage cylinders, wing, or drysuit) to the SMB's low pressure nipple. Closed bottom SMBs are easier to deploy one handed (remember you will also be managing a finger spool) and waste less gas. Open circuit divers may choose either closed bottom or open bottom, but CCR divers will usually choose a closed bottom.
The low pressure nipple used on a closed bottom SMB will be entirely smooth, without the usual locking ridge, so that when the SMB shoots to the surface the low pressure hose will slight right off. For a closed bottom SMB make sure the low pressure nipple is stainless steel or Delrin, not plastic which will break.
All SMBs should have these features:
- Overpressure/dump valve,
- Reflective tape towards the top, and
- Short tape loop to thread line through.