Sep 15, 2019
Guest Author

Tips for underwater metal detecting for treasure hunting and archaeology

Tips for underwater metal detecting

Metal detecting is an amazing hobby. It helps us unearth many relics and know more about the history of our ancestors. Many want to take it to the next level and hunt underwater treasures. In this article, I will give a few tips that will help in your next diving adventure.

Do your homework

Before going for a hunt, you need to do some research and look for promising locations to increase your chances of finding something precious. This is especially important for shipwreck diving.

You have to gather as much information as you can about the ship. This includes the departure and arrival ports, the cargo and its trajectory. This type of diving is very difficult, needs experienced divers and a lot of expensive equipment. However, if you were lucky and found a Spanish shipwreck full of gold, you are going to be rich, very rich!

Pick the right metal detector

To pick the right metal detector you have to take into consideration the depth you want to dive to and whether the water is salt or fresh. There are two types of metal detectors: VLF and PI. Each one of them has its pros and cons.

Technology type

VLF (very low frequency): the crashing majority of the devices on the market are VLF. Their operational frequency ranges from 4 to 30 kHz. They are very good at distinguishing between different metal types; this will save the diver a lot of time. He will know what type of metal is buried under the sand before even digging it.

If the machine indicates that the buried item is, for example, gold, he will (obviously) dig it. If not, he keeps looking for other interesting targets.

The problem is that this type of detectors isn’t suitable for saltwater. The mineralization will hinder its performance and it will emit many false signals making it useless. So it is recommended to use them only in freshwater.

The PI (pulse induction): is suitable for scuba diving in saltwater and can perform well when used with salt wet sand. The minerals don’t affect its depth range. Their downside is that they can’t discriminate; they will beep whenever they detect a metal. In this case, the diver has to dig in order to find out what is buried underneath the sand.

Operational depth

If you want to hunt shallow creeks and ponds, any metal detector (even cheap entry-level ones) can do the job. They can be submerged up to the control box.

If you want to go a little deeper (snorkeling), then you need a waterproof metal detector. You can get a reasonably priced device that can run up to 10 feet underwater. They are usually VLF machines. So they are suitable for freshwater.

If you are a professional scuba diver, then you need an underwater detector that can operate up to 200 feet. These are very expensive and meant for professional use.

Use the right accessories

In addition to the appropriate scuba diving equipment and to the metal detector, there are some tools that can make your hunt easier.

You can dig many targets with your hands but a sand scoop will make things easier and faster. It is recommended you choose a scoop with a wooden handle to reduce the weight.

You also need a pinpointer, which is a mini handheld detector with a limited range.

Metal detectors have onboard speakers. If you want more comfort, you can use waterproof headphones.

Maintain them in a good shape

Before going for a dive make sure there are no cracks in your devices. Check the O-rings frequently. Ensure they are in good shape and sand-free. Then lubricate them with silicone grease.

Use the right technique

It depends on the detector type. VLFs are motion detectors, you need to swing the coil from side to side in order to detect something. PIs are static detectors, they can detect metals even if they are motionless.

If you’re hunting shallow waters, relax and let the currents move you back and forth. Focus on low spots and around the rocks and scan them multiple times with your detector. The goodies are usually there.

Practice and practice more

Treasure hunting underwater is a lot more difficult than on land. Being a professional detectorist isn’t enough. You need to get sufficient training from professional divers. You can find many schools where you can get your diving certificate.

The same applies to divers who never used a metal detector. You need to learn how to use your device before going for a dive. This includes doing some air testing. This means passing some metal object in front of the search coil back and forth to get used the audio signals emitted by your machine. You need to read the user’s manual carefully and play with the settings to get used to them. I highly recommend that divers collaborate with detectorists to exchange skills.

About the Author

Rob Green is passionate about metal detecting, history, and archeology. He is also interested in shipwreck diving. You can follow him on his blog MetalDetectorPlanet.com where you can find many tips and tricks about this hobby.

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