Decompression Diving Prerequisites

Below are the requirements for any diver conducting any decompression dive from Southern Image or with Image Dive. They are for your own safety and the safety of others. They are not negotiable, so please check that you meet the conditions and have the equipment before the day, as it is upsetting for everyone if we have to refuse to allow you to dive.

Divers Must:

  • Be certified to do the dive. This includes depth, gases used and equipment specific qualification eg rebreathers.
  • All divers must carry all items on the safety list and have all items for the dive master on request. 
  • We require you to have boots on your 80/95 stage cylinders  to stop the vessel getting damaged

Prior to a 60m dive:

  • Have at least one dive to 30+ metres in the last 6 weeks and three in the last 6 months.

Prior to a 85m dive:

  • Have at least one dive to 60 metres in the last 3 months  and three dives past 40 metres in the last 6 months

Prior to a 100m+ dive:

  • Completed at least one dive to 80 metres on "The Southern Image" in a competent organised fashion


1. If you are a decompression trained diver all cylinders need to be marked according to the format in the TDI Blog here
- This applied whether you are doing a deco dive or not. If you have the training you mark your cylinders appropriately.
- This includes Side Mount Divers because it is both good practice, and it is hard for a Deck Hand to know which cylinder with rigging on it is a side mount diver and which is a stage for a CCR Diver.
- So if it slings on the side of your body it needs to be marked.
2. If you are a non-decompression diver your cylinders need to be marked with appropriate international standards (Nitrox Wrap) or otherwise clearly marked to show the O2 Percentage if they contain anything other than AIR.

To simplify  this is

A) 15cm (preferably 20cm) wide, 1.5m tall Orange/Red SMB WITH YOUR NAME ON IT (for normal use)
B) 15cm (preferably 20cm) wide, 1.5m tall Yellow SMB WITH YOUR NAME ON IT (for emergency)
C) Pre written slate for emergency with the following on it “Lost Buddy” “Lost Gas” “Bailed Out” “Send Diver” (this is separate to a slate you use for general communication)
D) 1 Reel equivalent to depth plus 1 other.
D) Whistle and one of the following
Signal Mirror (can be a factory silver CDROM, in a bag to stop it getting scratched)
Dye Marker
Nautilus rescue gps
4. Dive Planning
If you are doing a decompression dive you are
a) expected to file a dive plan at the start of the day, reach the surface not more than 3 minutes after your plan
b) expected to submit your contingency time (Bailout on CCR or Lost Gas on OC)
c) bailout gas calculations need to be according to your training organisation (e.g. TDI CCR bailout states to use 45.3L/minute bottom gas and 30L/min if another gas is also carried)
5. You are expected to keep within your 2 tank allocated space. If this means that you need to bring a bag instead of a tub so you can put your scooter under the seat with your bag squeezed beside, then this is what you need to do.
If you think you can’t fit in this space, you need to discuss with the boat the day before.