A diving knife can be a lifesaver if you find yourself caught in an emergency situation while diving, such as being caught in a drifting net or seaweed.
If you can cut free from the net that is holding you and escape, you will be safe.
However, if you use it improperly and it loses its sharpness, it is useless if you cannot use it in an emergency.
This time, we will explain how to use a diving knife so that it does not lose its sharpness.
■ Use a diving knife
What are the main situations in which you would use a diving knife when diving?
Let's take a look at it along with its uses.
・Remove restraints
It is used when your feet or body are restrained by drifting nets or seaweed, and you need to cut the nets or seaweed to free yourself from the restraints.
-Cutting food into pieces
It is used to cut up bait to feed to fish while diving.
・Communication with divers
They use the handle or spit of their knife to hit fellow divers' tanks or rocks.
This can be used to call attention or to notify of an emergency.
・Assistance for moving forward, retreating, and stopping
If you are on sandy ground and the tide is strong, you can move forward by holding the knife in your reverse hand, stabbing it into the sand, and pulling it along.
Conversely, if you push forward, you can retreat.
By grabbing onto the stabbing knife, you can stay still safely, which consumes less energy than staying still by swimming.
・Measure distance
The distance to the target is measured by how many times the player pulls the knife towards them from the ground.
To do this, you need to know in advance how far you can go in one go.
This is most likely to occur when using a diving knife.
When hitting a diver's tank, hitting the blade instead of the handle can cause the blade to chip and lose its sharpness.
Also, stabbing the knife into the ground can damage the blade, which can also cause it to lose its sharpness.
■ To prevent loss of sharpness
In a sudden emergency, you may panic and hit the diver's tank with your blade to signal, or the tide may be so strong that you are forced to stab yourself into the ground to maintain your position.
In addition to these situations, if you neglect regular maintenance, even if the material is rust-resistant, it may rust and lose its sharpness.
If you take good care of your knife on a regular basis, it will be less likely to lose its sharpness.
・Care after diving
After use, if you leave the knife as it is, it will get stained with salt, so wash the knife and sheath with water.
After that, dry it in the shade.
Putting it back into the sheath without drying it will cause rust.
・Care after returning home
Fill a basin or similar container with water and place the knife and thief in it. Once all the salt has been removed, rinse with a wet towel.
If you don't have much time to dry it, you can use a hair dryer or similar to dry just the knife itself.
Once it has dried, apply some rust-preventive oil to the blade and wipe it off lightly.
There may be salt remaining in the thief, so if you are not going to use it for a while, cover the blade with aluminum foil or something similar and store it separately from the thief.
If it has rusted
If the rust is only slight, you can remove it by polishing it with a metal abrasive or cleanser.
Even if the rust is severe, you can remove it easily with sandpaper.
Removing rust too much can damage the blade, so be sure to sharpen it when you're done.
If your knife can be disassembled, take it apart further and clean each part.
We explained how to use a diving knife to keep it sharp.
The rust-proneness of a knife is related to the material it is made from, and diving knives are generally made from rust-resistant materials.
However, this does not mean that rust will be completely prevented.
Proper care will extend the life of your knife.
Regular maintenance is the best way to keep your blade sharp.
Totty — BIGHOLIDAY Owner's Guide
I've lived in Miyako Island for 21 years (since 2005). I specialize in fun diving. I select Miyako Island's three major dive sites more than 150 times a year, and I've done about 20,000 dives in Miyako Island. YouTube "Totty / scuba diving" shares Miyakojima diving information with more than twelve thousand subscribers.
Since 2023, we have been among the top-ranked Marine Diving Award winners for three consecutive years.
2023 Japan Coast Guard Director-General's Award (for meritorious service in maritime rescue)
Discoverer of Miyako Island's first manta ray station in 2025
