Jack Ingle is the BSACs Technical Diving Adviser. He is a BSAC National Instructor, an IANTD Technical Instructor, a TDI Tri-mix instructor and co-author of NSAC nitrox courses.
I am planning to carry out deeper dives in the future. I realise the extra time in water requires a better diving suit, so can you give me any advice on what I should be looking for
Stuart James

Your options are endless. It all depends on the conditions and temperature of the water in which you plan to dive. For example, I have recently been diving in the South China Seas, where the water temperature is 29ÂC. Although dives were in excess of four hours, we were able to use 3mm wetsuits.
In northern European waters, drysuits are a must. The choice is subjective and opinions endless. I choose to use a DUI thin neoprene suit which allows for great flexibility but also helps with thermal insulation. An effective undersuit is vital, and Weezle produces a good range of these in various weights. They work very well.
What I want most from a drysuit is ease of movement and, of course, to stay dry, and unfortunately not all drysuits achieve this (see the Diver Test Special on 20 drysuits, October 1998).
Depending on how deep you plan to go and how much money you want to spend, you could always opt for the Phil Nuytton one atmosphere Newt suit. Advantages No decompression and you definitely wont get wet!
Never mind the length
Someone told me recently that it is not recommended to use a full-length hose on a contents gauge for nitrox. They said I should use a gauge directly on the first stage or a shortened hose. Is this true, and why

The prime consideration with any equipment being used with nitrox is to ensure that it is in oxygen service, which means it is oxygen-clean and the parts are compatible. The length of your hose is not important, so dont believe people who tell you that size matters in this context!
Your options are various. You can use a button gauge directly into the first stage without a hose. This is very neat and compact but, on the downside, the cylinder contents reading is inevitably imprecise because of the very small increments on the gauge.
You can use a standard contents gauge with a short hose (normally 15cm), which ensures that the gauge can be stowed neatly. This and the button gauge are normally used on stage cylinders when they are side-mounted.
The final option is to use a standard-length hose, which is necessary if the cylinder is back-mounted. One recommendation I would make is to use air-filled gauges rather than those with oil in them. These usually leak, and oil does not go well with oxygen-enriched gases.
Starting on trimix
What is the minimum qualification that you need before you can start training for an entry-level trimix course

Moran Brown

All training agencies require a certain amount of knowledge and level of skill to allow students to commence training in trimix. You will need to know about nitrox and also need the skills required to use stage cylinders, which are necessary for travel and decompression gases when diving trimix.
To achieve these requirements you should have completed advanced nitrox and extended range diver courses. The various training agencies have different terminologies for these courses, but entry-level requirements are very similar among them.
As an Instructor who has been teaching trimix for many years, I not only want to see these qualifications but also want to talk to the students to find out what sort of divers they are and what type of diving experience they already have, and to discuss the pros and cons of trimix-diving to find out if it is right for them.
As a student deciding on whether or not to learn about trimix, pick your instructor carefully - insist on a very experienced one.
Wing for twins and singles
Im thinking about buying a wing system with a stainless-steel backplate for my twinset configuration. I dont dive twin cylinders all the time, so is there a way in which the backplate system can be adapted for single cylinders as well
Phil Simpson

Not a problem. One of the main reasons I dive a wing and backplate system is that it can be very modular. When using twin cylinders they are connected together with cylinder bands (stainless) and the backplate is attached via wing nuts onto the studding that clamps the bands to the cylinders.
If you wish to use a single cylinder on another occasion, many manufacturers make a single cylinder adapter. OMS, Dive Rite, Custom Diver and SDS all sell them in various materials, normally stainless or plastic.
The adapter consists of a single plate with two stainless threaded studs 275mm apart with a camband at each end. The adapter is slipped over the single cylinder and the cambands are then tightened.
Once this is on the cylinder, you simply put the wing and backplate over the studs and tighten it down in the normal way with wingnuts.
One other system I have seen consists of two individual cambands with stainless studs attached to the webbing. This system tends to allow the cylinder to flop from side to side when it is on your back, so it needs the solid plate between the two cambands to hold the whole thing firmly.
Getting into rebreathers How many dives should I have under my belt before going for a rebreather course, and should I go straight to closed circuit
Mike Small

A difficult one to answer. I have heard people say you could learn to dive on closed circuit without ever going through open-circuit training, and it is true that closed-circuit diving is completely different from standard scuba and an experienced diver will not necessarily find rebreather diving
a simple switch.
However, there are skills and qualifications you require before you can start down the rebreather road.
The main one is nitrox, as it is the gas most rebreathers use. For this reason you will need to be an experienced open-circuit diver and have quite a few dives already logged before you start learning about rebreathers.
Answering the second part of your question depends on the type of diving you plan to do. If you want to dive in the recreational shallower depths, semi-closed rebreathers are perfect and have proved very successful. The best-known name is Draeger, but there are other options. If you plan to carry out more technical dives, a fully closed-circuit rebreather could be preferable, and it would be able to cope with recreational dives as well. Options in this field include the Cis-Lunar Mark 5 and the Buddy Inspiration.
A friend recently told me that training for and use of the semi-closed system had prepared her well for diving with the CCR system. She was more comfortable with the whole concept of rebreather diving and found the closed-circuit unit different and more complex, but the learning curve was less steep than it would otherwise have been.
Please remember that all rebreather diving requires discipline to ensure that everything is working correctly before, during and post-dive. It is vital not to become complacent.