Which Suit and Options?
Suits are one of those essentially personal bits of equipment and can either be bought "off the shelf" or "made to measure". There are a number of choices:
These are rarely used for UK diving and are not recommended because their insulating qualities are inadequate. They are regularly used in overseas environments, where the insulating qualities need to be matched to the local conditions.
They can come in thicknesses which are generally between 3-8mm and be of different types. ie shorties (torso/shorts sized), one piece (torso, legs and arms) or two piece (torso legs and arms, normally with a double layer on th torso. The picture on the right is a two-piece suit consisting of a Long-John and Jacket with integrated hood.
These are effectively wet suits with improved seals and insulating qualities. Semi-dry suits are frequently bought as a "disposable" item by trainees until they can either afford something better or until they know better due to the general cold & discomfort whilst waiting on a boat for a second dive.
Most UK diving is done in dry suits, which use neck and cuff seals to trap a layer of air between the suit and the divers body; the diver can then use layers of warm dry clothes to insulate himself from the outside water. These are a little more complicated to use than semi-dry suits but the skills can be easily mastered, and ensure you'll get a warm, dry dive. Dry suits can be an expensive piece of equipment so make sure that you get it right first time and don't rush into something!
If you buy a made-to-measure suit then you can normally specify which options you can have fitted. Ideally these should include:
1. A shoulder gas dump. (Newer, low profile shoulder dumps unfortunately seem to be less resilient; less reliable; more prone to allowing water ingress and less efficient at dumping air, particularly when being pressed. You may therefore wish to ask for a traditional high profile design)
2. Reflective Patches.
3. Cargo pockets on the left and right sides of the thigh for open water diving, NOT on the front of the legs. This will reduce the in-water drag, give you easy access to the contents and won't catch when climbing back into a boat. Cargo bockets should be sealed with velcro for ease of access (zips may jam, when you least want them to, preventing access to that vital piece of equipment). There should also be some method of attaching things such as a loop of bungee, to prevent everything from falling out.
Cave divers frequently use a lower profile pocket on the right-hand thigh, not needing to carry as much equipment.
The placement should be such that the bottom of the pockets are in line with the bottom of your fingertips, with the arms fully extended downwards, This should be sufficiently above the knees that it won't interfere with your finning technique.
4. Other options worth considering are front entry zips; knee or elbow pads; warm neck collars; double cuff seals and making sure that the suit inflation valve uses the same fitting as your buoyancy compensator (see below).
Neoprene dry suits use the thickness of the suit material to insulate the body. They are used with a thin underlayer. Unfortunately they can cause problems:
i. As you dive deeper the suit will compress, reducing the insulation and buoyancy it offers. (By 30 metres, the bubbles in the material will have compressed to ¼ the size.)
ii. These Suits have to be a close fit, which reduces your flexibility. Neoprene also becomes less flexible as it ages, worsening the problem.
iii. You need more lead at the surface to sink, than at the bottom, due to the loss of buoyancy.
iv. It isn't as easy to increase the layers of warm under-clothing as the alternative dry suits, due to it's tighter fit.
v. As the neoprene ages it loses insulation, the close fit makes it hard to add insulating layers under the suit.
vi. As the neoprene ages, the bubbles in the material start to break down and can lead to leaks. These leaks are very difficult to find as they can travel within the neoprene. Beware of old second hand suits.
These are better alternatives to the previous option and vary between 2 and 5 mm thick.
2. Crushed/Compressed Neoprene Dry SuitsThe thinnest compressed or crushed suits should be considered as membrane suits.
They are made from standard thickness neoprene, which is compressed or crushed, resulting in a far thinner suit. This reduces or even removes the problems of suit compression. In the case of 2mm suits they are virtually non-existent and this is certainly the better of the two options.
Crushed / compressed neoprene suits tend to be heavy and slow to dry, although they are also 'bullet-proof' in terms of material strength. They also tend to be the most expensive suits you can buy.
Due to the nature of the material used it can be almost impossible finding leaks if you are unfortunate enough to hole your suit.
Membrane dry suits are typically made out of a thin skin of nylon-butyl-trilaminate or rubber. They allow you to vary the layers of underclothing according to the ambient water/air temperature.
Membrane suits are generally more "baggy" than neoprene suits to allow for the undersuit, which can result in greater drag in the water. Since many membrane suit materials (excepting rubber/neoprene-materials) have very little inherent stretch, they have to be an even more "generous cut" to allow the diver a full range of movement. If you buy a membrane suit ensure you check your full range of movements with the thickest undersuit you will ever use. Also be aware of the material's inherent strength and puncture resistance. Some can be extremely 'lightweight'.
Membrane materials tend to be lightweight and dry quickly.
Under suits are frequently provided with a new dry suit as standard and include "fleece", "thinsulates" or "pirtek". They come in various grades from 100gm to 400gm, depending on the level of insulation you require under your dry suit; 100gm may be sufficient for summer sport diving, with a 200gm for winter, although those undertaking technical diving or even just dives involving moderate or longer exposures generally use a 400gm all year around. The choice of undersuit to a certain extent can depend on personal physiology.
There is a common misconception that adding air to a drysuit will help to keep you warmer, this is only partially true since any gas added will naturally migrate to the uppermost part of the suit so that whilst you are horizontal, it will pool around your back, leaving the lower part of your chest/body/limbs with no added insulation. This can also result in buoyancy/trim problems due to excess gas migration around the suit. If you find yourself getting cold the best option is to buy a thicker/newer thinsulate.
Some undersuits compress substantially (85-95% in some instances) and are able to offer little insulation whilst under pressure (3 psi or 0.2 bar), except to those who seem intent on doing "Michelin Man" impersonations underwater; if one of the features of an undersuit is that it packs down into a small bag, you would be best to avoid it. 3M's type B 400gm only compresses by some 40-60% in similar circumstances, the B stands for "Boot" and has been made specifically to resist compression, the dense fibre also resists saturation if flooded.
Try to avoid washing thinsulate materials if possible, the washing/spinning cycles age these far faster than you might suspect. Detergents also encourage the retention of moisture by the fibres, substantially reducing the efficiency of the insulating materials. Treat these garments with respect and you will considerably extend their working lives.
Ideally you want at least three layers, consisting of two separate garments:
- The first would be a set of wicking thermals to carry and keep sweat and other moisture away from your body.
- The second would be a thinsulate material in insulate you from the elements.
- The third would be a shell material, which is normally part of the thinsulate garment. This keeps spray/rain from being absorbed by the under layer and also acts as a barrier to the condensation which may form on the interior of the drysuit.
Argon systems can also be used to improve the thermal protection offerred by your suit, however you would be best served by ensuring that you have the best undersuit and layers you can get before adding additional clutter, afterall you may not need it...it is like making sure that the foundations are there first before adding the first floor. Argon systems are only essential when using breathing gases which include helium. See Which Argon System?
The head and neck are the areas through which people lose most of their heat and so it is important that this area is properly insulated. Hoods are generally supplied free of charge with the first suit you buy, but can be sub-standard, so you may still need to consider buying a separate hood.
Hoods used for UK diving are generally 5mm thick, with a softer seal which goes around the face.
The area that may not be properly catered for is around the neck, it is quite common for the hood to sit proud from the neck, leaving a space through which water may flush, conducting heat away from the skin surface. You should ensure that the hood properly protects this area. Some hoods can be bought to fit a warm neck collar, if one is provided with your suit. Basically the hood comes with an extra long skirt which fits beneath a collar attached to the suit, reducing the flow of water.
The problem with warm neck collars is that it can be very difficult to get to the neck seal in an emergency, if for example you need to vent the suit to avoid a torpedo ascent if your dump valve should fail. Gloves come in 5mm and 3mm neoprene versions, and can either be bought as with five fingers or as three finger mitts (Thumb, fore finger and others). 3mm five finger gloves are suitable for UK summer use with 5mm three-finger mitts for winter. 5mm five finger gloves can be a little uncomfortable but are suitable if this is all that is available. Dry gloves are available but can result in an excessive loss of dexterity.
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If you buy a made to measure suit, make sure that they have a no fault return guarantee in case it doesn't fit properly and you measured yourself - They aren't one of the cheapest of items. When buying a suit off the shelf, there are a number of exercises to try to make sure it fits properly. Before you go to buy a suit, please ask someone for some advice. Dry Suits Good dry suits are made by a number of manufacturers including O3, and Otter Watersports; both these manufacturers have a reputation for quality service. DUI dry suits are easily the most expensive and the least well supported, their reputation varying widely, depending on who you talk to. It is best to buy either a membrane or a 2mm crushed or compressed neoprene suit, this will give you greater dexterity and flexibility in varying the thickness of undersuit, but make sure that it will fit the heaviest duty of undersuit that you may wear. The better suits have their seams double stitched, glued and taped. David Ainsley is the UK's leading agent for Otter Watersports and can normally give a very competitive price. Under Suits DUI's C4 undersuits were the standard against which others were measured, being of 400gm Type B thinsulate and the warmest you could get. Unfortunately there is no "made to measure" service available and the girth could easily contain two medium sized people leading to more gas than necessary being retained within the suit Polar Bears has recently launched it's version using 400gm Type B thinsulate, the P400, which is available made to measure. It has only been recently launched, so the author cannot yet attest to it's performance over time. Diving Concepts' undersuits are gaining popularity and have "stretch" panels to assist mobility and may be an alternative worth considering but only appear to be available in a thinner 200gm thinsulate. Fourth Element have their Xerotherm wicking thermals for use beneath an under suit. These are comfortable and stretch with the body, although top quality hiking thermals would probably be just as good. Hoods Reasonable quality "short" hoods are made by Typhoon. |
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Diving can be a hazardous sport and the information contained within this site is not intended to replace formal training.
Furthermore no responsibility will be accepted for any accidents, injuries or financial disadvantage, howsoever caused.
Copyright © H Beasley 01 August 2001 All Rights Reserved
