In the next picture we can see the four types of bolt snaps that are necessary for a typical dive configuration, either for recreational or technical diving. This doesn’t mean that other types of bolt snaps can’t be used for some specific diving activity. From left to right the types of bolt snaps we see in the picture are:
- Double-eye small bolt snap
- Double-eye large bolt snap
- Swivel-eye medium bolt snap
- Swivel-eye small bolt snap
Double-eye bolt snap
Double eye bolt snaps are ideal for use with spools of all sizes and to clip off the head of a canister light to our harness when the lamp is not being used.
In the previous picture we can see two double eyes, the largest is the most common double eye bolt snap, the smallest is very useful with canister lights and finger spools.
Worth mentioning that somebody might think that when using the double eye bolt snap we might have the so called metal to metal connection and in case of entanglement or jamming of the bolt snap we cannot cut the connection, the connection can be opened using the other end of the bolt snap that works independently. In other words if one end gets jammed the other one is not compromised and can be handled without problems.
Swivel-eye medium bolt snap
This bolt snap is the ideal for clipping off pressure gauges, stage tanks and surface markers. Unlike double eye bolt snaps, this bolt snap has a swivel eye where is placed the loop that hold the bolt snap to the element that we want to clip off to our harness. The swivel eye allow us to introduce a finger, it can be the middle or ring finger depending on the technique, which give us more control over the bolt snap and at the same time allowing us to lift an element of some weight.
It can be seen in the previous picture the size difference between the middle and large swivel-eye bolt snap. The problem with large swivel-eye bolt snap is that the ring only increases slightly in size but the head of the bolt snap is enlarged considerably, this creates several problems:
- Significant increase in the weight of the bolt snap.
- If we have several large bolt snaps clipped off to the same D-ring, the bolt snaps take too much space the handling gets difficult.
- The head of the large bolt snap is in fact more difficult to clip off to a D-ring of the harness than the medium bolt snaps.
It’s common to think that with thick gloves or too cold hands is better to have the biggest possible bolt snap, but the truth is that with a good technique and an adequate thermal protection, the swivel-eye medium bolt snap can be used more effectively even with dry gloves.
Swivel-eye small bolt snap
This bolt snap is the smallest of all we use in our diving equipment, its smaller size does not add much weight which makes it ideal for use with the primary second stage and is also ideal for use with handheld lights that will be clipped off in the chest D-rings or stored in pockets. Like other bolt snaps, the correct technique is essential.
This bigger bolt snap doesn’t present any advantage over its smaller sibling and the only thing you get is the increasing of weight, for example when it’s used with the primary second stage it adds unnecessary weight.