#AskMark: Dive Computer Test Logs, Leaving Transmitters on First Stages & Knife Hose Mounting

@MrElvisr27

#AskMark: My new computer came with a 275ft dive already recorded. Is that normal or used? Can I delete the logs if I want?

It is not unusual for new dive computers to have a test dive in their logbook from new. Every dive computer manufactured should undergo a test dive in a pressurised container to ensure it is working properly. Some manufacturers will clear the test dive while others will leave it so that you can see it has been tested. If you look at the dive profile, a test dive will have very straight lines as if done by a machine.

I would only be worried if the dive profile is wavy and looks like a human took the computer for a dive and there were obvious signs that the box had been opened before. It’s very hard to repackage computers like new. Some computers will allow you to delete individual dive logs either on the computer or on an app. And some computers can be formatted completely, which can remove all logs.

@jadurkin1

#AskMark: Is it bad practice to leave the transmitter on your first stage?

It’s fine to leave your transmitter on your first stage during storage. Transmitters will go to sleep a few minutes after you depressurise your regulators to save battery and reawaken when you pressurise them again for your next dive. If the transmitter is attached directly to the first stage, then a good knock can damage the transmitter or your first stage.

Many divers use a short high-pressure hose between the first stage and the transmitter to add flexibility to the transmitter. While you could remove the transmitter between uses, you increase the risk of damaging the threads or forgetting the transmitter or the swivel pin if you’re using a hose. It’s best to leave your transmitter in place.

@giacmon85

#AskMark: Would you recommend mounting a small dive knife on a regulator pressure hose? There are pros and cons to mounting a cutting tool to a hose. The main benefit is that they’re easy to find and reach, and if the knife is attached to your regulator, then you can’t leave it behind for a dive. There are several downsides, however. The largest risk is the potential for damaging the hose. Whenever you need to use the cutting device, it starts very close to a hose and when you go to put it away, it’s close to the hose again and there is the chance of you cutting the hose. And because the sheath is attached to the hose, any small nicks will be in the same place along the hose. The knife will add some weight and a snag hazard to that hose, so knife placement should be a careful consideration.