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Sep 15, 2019
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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.

Apr 27, 2014

Dive Sites

Went out for a jaunt today looking at possible dive sites, knew there were a couple of small quarries near by and had to start somewhere.

Quarry Dive Site Exploration Map

Can’t reveal its exact location yet but the first place I found was down a few windy lanes and I didn’t take a photo of the gate which could give it away.

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The site looks large enough for a reasonable dive but it is obviously the depth, especially as there is a good layer of dead Algae and other particulate matter like most quarries. There was a lot of life at the edge of the water, tadpoles, larvae and newts but what isn’t clear is the layer of white on the bottom 18 or so inches of the overhanging trees round it but we are in Imerys country and it is most likely just dust from the china clay.

There is an easy entry point after squeezing through the gap in the hedge, could possibly be some cars in there as the ramp leads down from the road, there wasn’t any defined path around it and I didn’t try making a way through as to the left of the photo is a near vertical eroded earth bank face, and to the right more overgrown trees and scrub than any sane person would try and get through, especially with dive gear.

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As can be seen on the map there is another site a short distance away between the paths to the SW, so after a jolly ramble down the hidden footpath and chatting to a local over his garden gate, where I was mauled by his 3 dogs, my hands were lucky to be intact after all the licking they did, I came across an ominous sign. This is a public footpath though so I found a way over the hedge to the right of the photo.

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The state of the entrance gave a clear indication as to the state of the ‘public’ footpath that had been closed off, and to the level of pollution that will occur over time as will be seen in a moment.

I jumped over the hedge and turned to give my friend a hand up but he was raring to get up the bank so I just went through the gap to find a beautiful woodland only a few years old.

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I started clambering through the thicket only to hear from behind ‘It’s this way, a path’, to which I replied ‘Maybe but my way is more fun’ and I promptly kept fighting my way through only to find the path he was walking on.

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We walked into an area that looked more like a dump than a public footpath, this is where I should name the land I was on but living where I do is only one company that owns all the land round here, Imerys and the fact they have done what you are about to see is shocking.

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This was probably the part that angered me the most, rusting oil drums full of… oil and they were breaking open as you can see.

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Now this may have taken a long time to get like this but it is clearly something that should now be cleaned up before it gets any worse.

It didn’t end there though, heavy duty plastic pipes may take thousands of years to break down, but at the base of a watershed with all the other things lying around this is just a disgusting excuse for a company to dump things for later on their land.

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The area these pipes are is where it shows a fairly large water body on the map, but it was clearly more of a pond and I couldn’t get through the hedge but could see plastic sheeting and all sorts in it.

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I just hope the other oil drums around the area haven’t already leaked because Imerys need to be shamed into making sure any area they own is kept clean of rubbish, not only to stop pollution but to stop locals from thinking it is OK to dump their waste their as well.

waste_dumped_07sound_proofing

The last one is rubber sound proofing, just thrown over the hedge and going to take an extremely long time to break down, when it does it will get carried away as small particles and will get in the food chain from the bottom feeders in the stream and further down in the river.

There were more oil drums in an old tin shed, couldn’t tell if they had anything in them and didn’t want to rock any of the drums just in case.

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There was also what looked like an old oil container for a house or business

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I am going to be contacting Cornwall Council over this as it is disgusting that not only no one has noticed they have closed a public right of way but also the state of it with rubbish piled everywhere. I am not going to turn my blog into a clean up your pollution and waste page, but every time I go exploring for possible dive sites if I find anything I will name and shame Imerys or who ever the land owner is because these things are just taking the piss when they are meant to be a lot more stringent on protecting the environment.

As for the first quarry as a dive site, when I get the chance to re-visit it with friends will post an update if it is worthy of looking for to get wet.