Dive gear is a complex system which can be fine tuned on a quarterly basis. You need to keep a diary of your previous dives and make adjustments as required before the water tells you that you need to make some changes. Really, really simple.
Build around two suits, not four
For temperate locations two thicknesses are generally required, to be worn singly or in combination depending upon water temperature, and ‘added’ as required. A 3mm wetsuit plus liner will get you through the warmest months of the year as well as the early/late season warm periods. For the colder winter months, and very deep dives, a 5mm or 7mm wetsuit is required.
The difference in thickness of neoprene found in wetsuits is less important than how well the wetsuit fits, especially around the neck, wrists and ankles. A well fitting 5mm wetsuit is likely to perform better than a poorly fitting 7mm wetsuit. Also, most wetsuits are made with open cell interiors which provide better insulation due to them compressing less against the skin than a comparable thickness of lined neoprene. However, wetsuits with open cell interiors require lubricated entry as opposed to lined shrugged shoulders.
Thickness against water temperature and dive profile
Of course, the duration of your dive can play a much larger role in cooling off than the water temperature itself. A 90 minute dive from the shore in 18 degree water will often require a thicker wetsuit than a 40 minute dive off a bommie in similar temperature water.
| Water temperature | Short session under 60 min | Long session over 90 min | Key accessories |
| 24 degrees and above | 1.5mm or rash top | 3mm | Thin gloves, low profile socks |
| 19 to 23 degrees | 3mm | 3mm plus vest | 2mm gloves, 3mm socks |
| 15 to 18 degrees | 5mm | 5mm plus vest or hood | 3mm gloves, 5mm socks |
| Below 15 degrees | 7mm | 7mm with attached hood | 5mm gloves, 7mm socks, face seal |
Extremities decide how long you stay in
This problem tends to arise towards the end of the dive when cold hands no longer have sufficient dexterity to secure a stringer or release a caught fish. The reasons for this are caused by blood flow ceasing first to the extremities of the body and then the head, which is where the problems are felt.
Gloves give the worst ‘trade off’ in their insulation and ‘feel’ via their triggers, lines, knives and stringer clips. The more you insulate then the less sensitive your hands become to touch and feel.
- Warm water, 1.5 to 2mm with a textured palm for grip on wet float line
- Mid range, 3mm with a pre curved cut so the hand rests closed rather than fighting the neoprene
- Cold, 5mm, accepting reduced feel and adjusting gun handling to compensate
- Rocky entries or heavy reef work, prioritise abrasion resistant palms over thickness
Socks, hoods and the fin fit problem
Moreover, when choosing fin socks, one must also consider the change in sock thickness during the different seasons. Therefore, if one uses 3mm socks in summer and 7mm in winter, one will either need to have two pairs of foot pockets or to choose foot pockets of the largest size for which he also has a heel wedge for the warmer periods. Sticking 3mm thick socks into 7mm thick wetsuit socks would only increase the restriction on the foot as much as regular socks would.
Necks get less attention than they deserve. Attached hoods score big time for dive depths below 15m and stop heat flushing in the neck area. A separate hood covers a greater temperature range but you can pull it back for the surface interval.
Weighting changes with every layer
2mm neoprene is buoyancy material. Often divers forget to re-weight themselves for the season and then suffer at the end of the dive. Even in summer divers often put excessive winter weighting in their wetsuit to be able to get down to depth. For a short time this makes them negatively buoyant very quickly.
- Reweight in a pool or shallow water each time you change suit thickness
- Target neutral buoyancy at around 10 metres for shallow reef work, deeper if you dive deep consistently
- Record the belt weight for each suit combination and write it inside the gear bag
- Recheck after a suit has been used for a season, since compressed neoprene floats less
Reading conditions beyond temperature
How bad is the visibility, are you constantly fighting against strong currents or being splashed by rough surface chop. All of these factors can affect the choice of your spear gun and/or floating device.
Camouflage and seasonal water colour
Most underwater wetsuits have designs that will fade out quickly in certain types of underwater environments. For instance a green kelp pattern wetsuit will often disappear in the Spring as the kelp grows back out to recover from winter. Since wetsuits for spearfishing are worn across a whole season, choose a design that will dominate the other design for the greater part of the diving season. Mid-tone colour suits that are neutral in design are best as they will never disappear but will also never be noticed by other creatures.
It’s very easy to fine-tune your dive gear on a quarterly basis to be sure that you have the best gear to complete a job at the end of the day. After each dive, note down as much as possible from your previous dive and adjust accordingly before the water shows you that you need to make some changes.
