UNDERWATER METAL DETECTING – THE ULTIMATE GUIDE
Underwater Metal Detectors
Historically, underwater metal detectors are responsible for some of the biggest and most famous treasures ever found. The Atocha Spanish ship wreck for example had 24 tons of silver and 125 gold bars on board when it sank in 1622. The Atocha was found by a guy named Mel Fisher more than 300 years later in 1985 with his underwater metal detector. That treasure today would be worth about US$1Billion and there are even bigger treasures still out there!
You’ll be glad to know that modern beach and underwater detectors have come a long way since 1985. They are now deeper seeking, light weight, powerful and affordable all at the same time meaning treasure hunting has become possible for everyone!
Today, underwater metal detectors are used by everyday people and professionals to search for lost coins, jewelry, artefacts, phones, cameras, watches and of course treasure troves in creeks, rivers, oceans and old swimming holes to name a few.
In this article, we’ve compiled a few things you need to know about underwater metal detectors!
Forget what you might have heard in the past, and read on to find out about detectors that will help you find treasures below the waterline!
Waterproof VS Underwater Metal Detectors
Many people think that any ‘waterproof metal detector’ would make a suitable ‘underwater metal detector’ however, this isn’t the case and we’ll explain why now. In some cases these ‘waterproof’ detectors are simply rain proof, can be washed down, or handle the occasional dunking… but these are not the kind of detectors we are here to talk about today. A dedicated underwater metal detector is one that will give you a serious shot at finding coins, rings and treasure in a variety of underwater conditions and will stand the test of time.
There are actually a few very unique characteristics that set underwater metal detectors apart from everyday waterproof detectors! These special attributes are why true underwater detectors work well in both saltwater and freshwater environments, from depths of just a few feet to a few hundred feet. It’s also why they are responsible for finding more treasure than any other type of metal detector in the world.
Types of Underwater Metal Detectors
Undeniably, the most important characteristic of a good beach or underwater metal detector is its ability to see through salt water as if it wasn’t there. To the surprise of many new detectorists, salt water at the beach is one of the most difficult obstacles to overcome when beach and underwater detecting. Why? Because saltwater, just like metal, is electrically conductive with the result being that many metal detectors will actually start reacting when in or even near salt water. This is because they’re detecting the conductive salt water just like they detect conductive metal of all kinds!
The amount of stories you read about people discovering that their brand new detector won’t work at the beach is incredible! Therefore we recommend you pay close attention when looking for a beach and underwater metal detector. If your detector is randomly beeping (falsing) and making a host of other unpredictable noises in saltwater, it’s a sure sign that it’s either; not set up optimally for saltwater detecting or isn’t well suited for it.
The best underwater metal detectors employ one of two types of specialised circuitry that ignores the signals given off by salt water, they do this whilst still giving great detection depth on coins and rings and providing sensitivity to smaller targets like earrings and gold chains.
Underwater metal detectors generally do this without the user having to tweak many settings making them very easy to use. It is worth noting however that even the best saltwater metal detectors will lose some depth and sensitivity over wet salty sand and then lose a bit more when fully submerged in saltwater.
The two best underwater metal detector types:
- “Pulse Induction” (PulseDive, Seahunter and high end gold detectors)
- “Multi-Frequency VLF” (Excalibur, Equinox etc)
Both Pulse Induction and Multi-Frequency metal detectors can completely cancel out the noises from salt signals and make underwater metal detecting a lot easier.
How Waterproof should Underwater Metal Detectors be?
If you want to find underwater treasure like the pros, you will need a true underwater metal detector with a deep waterproof rating. Underwater metal detectors like the PulseDive, Seahunter or Excalibur for example have waterproof ratings to 60m deep (or 200ft). This 200ft rating certainly sounds like overkill considering most of us aren’t going any deeper than 3m with our detectors, but the reality of underwater metal detecting is that the higher the depth rating, the higher level of reliability you’ll enjoy in an underwater environment, over a long period of time.
A depth of 60m underwater is a lot further than most professionals are likely to go, especially when you think that most people swimming at beaches only swim out to an area with about 3m in depth tops. Now, of course the detector manufacturers are very aware of this fact, but the reason they make detectors with these excessive ratings is a very good one. Underwater metal detecting – due to its nature – puts a lot of more stress on all the components compared to other waterproof devices like watches or cameras, making water ingress more likely.
It is possible to use waterproof metal detectors with a lesser rating of 3m+ for some underwater detecting, however the real intention for this type of waterproofing is for the occasional dunk and so that rogue waves aren’t liable to drown your metal detector!
For long use underwater, we do recommend a metal detector with a higher waterproof rating like 60m (200ft), in the end it’ll last you a lot longer, be much more reliable and you won’t get caught out without a working detector on your next day out treasure hunting.
How do you hear an Underwater Metal Detector?
Extremely important for underwater metal detecting or detecting in general is the ability to hear the detector when it detects a target! Most metal detectors have a loudspeaker built in with the option of wired or wireless headphones for when you don’t need the rest of the world to hear. Underwater metal detectors have special ways of doing this, which we’ll explain below.
Most run of the mill waterproof metal detectors have a waterproof speaker built in, these waterproof speakers are simply to stop water getting in and to the surprise of many they are not suitable for operation underwater! Those types of waterproof detectors require you to buy separate waterproof headphones for them if you want to use them underwater, however most dedicated underwater metal detectors include specialised headphones or have other ways of alerting the user when it finds a target.
For example, underwater metal detectors such as the Excalibur and Seahunter have wired, fully waterproof headphones which use ‘piezo transducers’ instead of normal speakers in the ear cups, these types of headphones are not affected by the effects of deep water and will not be crushed by water pressure at depth. The volume from these types of underwater headphones is good underwater and aren’t negatively affected by the higher pressures experienced underwater.
Other underwater metal detectors such as the PulseDive use a couple of different methods to alert the operator to a metal object! The PulseDive uses a mixture of beeping and vibration in the handle to alert the user to a metal object, it does this with a small in-built piezo speaker for the beeping sounds and a rumble motor for vibration. The PulseDive’s audio can be heard underwater from up to 20m away but can be used silently with just vibration for extra stealth or just audio to save on battery.
The advantage to these types of audio/vibration alerts is that it provides freedom from cables by eliminating the need to wear headphones. This also means you won’t be obviously noticeable when walking to the beach, snorkeling or scuba diving. In fact the PulseDive is so subtle that most people won’t notice it at all!
Small Underwater Metal Detectors
If you’ve done your research on the most popular diving and underwater metal detectors you’ll find that all of them come with some type of short shaft or diving shaft option. These shafts serve one purpose and one purpose only. To reduce drag from the water!
Unlike air, water is a lot harder to move through so it’s very common to make underwater metal detectors as short and streamlined as possible to reduce the drag from the water.
Underwater metal detectors like the Seahunter and Excalibur come with an optional short/diving shaft whilst hand-held versions like the Pulse dive are already very short and slice through the water very easily.
Reducing drag on your underwater metal detector is possibly the most neglected aspect of underwater metal detecting, Reducing drag increases swinging and detecting speed. Faster swing speed means more ground covered, more covered ground covered equals more targets found, which equals more treasure!
To sum it up, if you can swing 20% faster and cover 20% more ground, then you are going to average 20% more finds and 20% more treasure!
An example of the kinds of finds that can be uncovered underwater!
Underwater Metal Detector controls
Underwater metal detectors have to deal with extremely harsh conditions. The high pressure salt environment means that these detectors use specialised highly waterproof sealed controls that are very reliable and robust.
Knob type controls are the most commonly found controls on underwater metal detectors and offer a very simple to understand, very waterproof option for tuning your metal detector. Knob type controls however are susceptible to breaking off if bumped hard enough and require that the o-rings are inspected and replaced every few years. The only current alternative controls for underwater detectors are stiffer membrane buttons which are harder to push in and therefore less easily pressed and are pushed in by deeper water pressures.
The Pulsedive underwater detector uses these stiffer membrane style buttons which will not be pressed in unless further than 10m underwater. The PulseDive however is waterproof to 60m so the manufacturer chose to incorporate a clever feature called “Dive Mode” into the detector. Dive mode allows deep diving users to lock the buttons so that they do not operate at all. The user can then control the detector by changing the orientation. For example, if the detector is upside down it will be off and if it’s right side up it will turn it on again.
Buying an Underwater Metal Detector
Like with any product, warranty is an important consideration especially if that product comes at a high cost and underwater metal detectors are no exception!
Even more important than salt water functionality or waterproof rating is overall functioning reliability! To ensure you have a reliable metal detector, choose from the well known brands with trusted warranty programs like Nokta Makro, Garrett and Minelab. Warranty on detectors being used underwater is especially important because water ingress and other forms of damage are not uncommon due to the harsh environments we throw at these underwater metal detectors.
Make sure that there is a service/repair centre in your country for the brand you are looking to buy and ensure that you buy from a trusted dealer within your own country. Buying within your own country will ensure that the detector is covered by warranty. Please note that many manufacturers will not warranty/service detectors outside of the country they were purchased meaning you may have to send your metal detector overseas to be repaired which can be extremely costly and time consuming!
UNDERWATER METAL DETECTORS
Underwater Metal Detecting is fast becoming one of the more popular metal detecting styles and it’s easy to see why. With an underwater metal detector you can find some very interesting, as well as highly valuable, targets.
Most people when thinking about metal detecting, they picture someone using a detector on dry land, be it in gold fields, parks or on the beach. But getting below the water is where some very unusual and lucrative finds can often be recovered.
Whether it is in the ocean or freshwater, there are so many places where you can go can take an underwater metal detector to find some hidden treasure.
In this guide we will talk about the different types of detectors used for underwater metal detecting, their uses and applications, and also great locations for detecting underwater.
TYPES OF UNDERWATER METAL DETECTORS
1. HAND HELD, PURPOSE MADE SCUBA/SNORKELING DETECTORS
Hand held metal detectors, as mentioned above, are purpose built for finding targets underwater. They operate on a Pulse Induction operating system and can handle the high mineralization of salt water extremely well.
These types of underwater metal detectors have a simple and robust design, so can handle deep water pressure and can go to depths of up to 60 metres.
Being a small hand held detector they are very easy to maneuver underwater and can go between tight spots such as rocks and sea plants with ease.
Who are scuba detectors best suited to?
They are best suited for people who enjoy snorkeling and scuba diving and generally being in and underwater. While they are designed for being used underwater, one model, the Quest Scuba Pro, has an extension handle attachment included in the box. This allows you to add a pole to the detector so it can be used on the sand or river banks while remaining in an upright walking position.
ADVANTAGES AND DISADVANTAGES
Advantages of hand held scuba detectors:
- Pulse Induction Technology, so they are very stable in salt water
- Small and compact and easy to maneuver
- Can be taken to extreme depths, up to 60m
- Very affordable option for underwater detecting.
Disadvantages of hand held scuba detectors:
- Smaller search coil compared to full sized detectors, so less ground is covered with each pass
- Less target search depth due to the smaller coil size
- No extra features of full sized detectors such as target identification or discrimination
- Not suited for detecting in parks, bush and gold fields.
2. FULL SIZED MULTI PURPOSE UNDERWATER METAL DETECTORS
Full sized multi purpose land and underwater metal detectors are an excellent choice for people who would like to search underwater but also search on land for coins, relics, treasure and even gold nuggets.
As these detectors are full size, you get the added bonus of having all the features that come with modern detectors such as:
- Large display with numerical target identification.
- Discrimination to identify or reject unwanted targets
- Automatic or manually adjusted settings
- Larger coils for more depth and ground cover
- Built in speaker for sound as well as headphone capabilities.
WHO ARE FULL SIZED UNDERWATER METAL DETECTORS BEST SUITED FOR?
These detectors are suited for anyone who enjoys detecting in parks, beaches and gold fields but who also enjoys detecting in and underwater. Their advanced technology and features make adjusting the detector to handle salt water and the mineralisation associated with it very easy.
They come with pre-set settings for beach and salt water but can also be manually adjusted to get more out of the detector and ground conditions.
While they are not designed to go as deep as their hand held counterparts, they can still get some impressive depths and can be taken down to 5 metres in any body of water.
ADVANTAGES AND DISADVANTAGES
Advantages of full sized underwater metal detectors:
- They have all the features of modern metal detectors
- Can run in auto settings or can be manually adjusted to suit ground/water conditions
- Deeper target depth recovery
- Cover more ground due to their larger search coil
- Can be used for all types of metal detecting, including gold detecting in most models.
Disadvantages of full sized underwater metal detectors.
- Cannot be used as deep underwater as hand held underwater metal detectors, with a maximum depth of 5m
- Larger in size, they are not as maneuverable as their smaller counterparts
- Higher cost compared to hand held models.
WHERE TO GO UNDERWATER METAL DETECTING
Underwater metal detecting can be a very lucrative hobby and is also a lot of fun. Where you go detecting depends on what you are looking for.
If you are looking for old coins, relics, jewellery and the like, then you have a great deal of choices.
Beaches: Search in the shallows at low tide as many lost items are pulled in by the waves and buried in and around the low tide water line. Detect around piers and jetties as many valuables are dropped off them. Detect in shallow water in between life guard flags as most people will swim and gather in these areas.
Lakes and swimming holes: These bodies of water are another great place to detect underwater. Research public swimming spots in your area and particularly places that have been used historically. People have been using these types of places to cool down in summer for generations, so they are an excellent location to find old relics, jewellery and coins.
Rivers and Creeks: In gold bearing ground, rivers and creeks are a great place to search for gold nuggets. Gold often gets lodged into the cracks and nooks of bedrock at the bottom of rivers and creeks. Having a waterproof metal detector means you can snorkel or dive these waterways and find the nuggets that others can’t get to.
LOOKING AFTER YOUR UNDERWATER METAL DETECTOR
Caring for your underwater metal detector will ensure it will last you for years to come. Here are some tips to help keep your detector good as new.
- Check all plugs, caps and seals have been fastened tightly before entering the water.
- Always wash your detector in fresh water after use in muddy or saltwater.
- Check O’Rings and seals on your underwater detector regularly. With time, salt water can degrade these. Keeping them lubricated with a suitable lubricant can keep them from drying out. For Silicone O’Rings, use a silicone lubricant, for rubber O’Rings, use a suitable non petroleum based lubricant.
- Avoid going deeper than the manufacturer’s recommended maximum depth. Water pressure gets stronger the deeper underwater you go. Going past these depths may put too much stain on the detectors housing and cause damage.
- Make sure your detector is dried thoroughly before charging or unscrewing caps and fitting.
Whether you are just starting out or already have some detecting experience, owning an underwater metal detector adds an extra layer to your metal detecting adventures.
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