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You and I are not stabbing anyone underwater. That’s a fact. In scuba diving, a dive knife is considered a tool used to cut a line especially when you are entangled or pound an object like a scuba tank to get your buddy’s attention. If we try to compare it with a kitchen knife, dive knife has several designs, type of material and accessories that performs a specific function. With this and before buying a dive knife, we highly suggest you should be aware of the different characteristics of a dive knife that will fit your preference.
Note: Please don’t entertain the fact that the bigger the dive knife the better. Or perhaps consider a sword rather than a knife?
Blade length: 4 inches (10.2 cm) Pros: easy to grip, comfortable handle, blunt and pointed version available Cons: slim blade
The Atomic Aquatics Titanium Ti6 Diving Knife is made from lightweight titanium steel that is corrosion resistant. It features a 4-inch blade that has a sharpened curve on one side and a straightened serrated edge on the other end. It has an ergonomic handle grip that has a low profile and comfortable to handle. This is brought to you by its plastic handle grip with grooves that naturally fits to each of your fingers when handled. At the end of the knife handle is a lanyard hole where you can place a short string which can add to your hand’s dexterity even if you are wearing gloves.
Blade length: 5 inches (12.7 cm) Pros: has a deep line cutter, quick release sheath mechanism Cons: large size may be difficult for others to handle
The Cressi Borg Stainless Steel Divers Knife is a large modern dive knife with a futuristic design that is both strong and functional. The blade is made from 304 Japanese Stainless Steel with a 5-inch long blade that is sharpened on one side and serrated on the other. The sharpened blade is very sharp that it can easily cut through any fishing lines and thin ropes. At the edge of this knife is the ergonomic handle grip that has a soft and comfortable grip. The knife is encased in a plastic sheath that has an easy single-touch release mechanism and rubber straps for attachment. Due to the size (total knife length at 10 inches or 25.4 cm) and length of the rubber straps, this dive knife is ideal to be attached on your leg portion and not within any part of your scuba equipment.
Blade length: 4.3 inches (11 cm) Pros: low price tag, good steel quality, blunt and pointed version available Cons: needs regular maintenance
The Cressi Skorpion Dive Knife is a new generation dive knife that has a medium dimension with blade length at 4.3 inches (11cm) long and a total knife length at 9.1 inches (23.2cm). Its resistant tempered blade is made from AISI 304 steel that has a smooth and curved sharpened blade on one side and a serrated edge with cutting hook that acts as a wire cutter on the other side. The handle grip is made from polymer that has a soft and gentle feel. The whole knife is encased in a knife sheath that has a single press locking mechanism. WIth regards to blade tip design, this dive knife comes in two version where you can either choose the blunt or pointed tip.
Blade length: 4.5 inches (11 cm) Pros: comfortable handle grip, midpoint price tag Cons: releasing mechanism can sometimes be hard to press, no blunt version
The Tusa Xpert II Titanium Dive Knife is made from an anti-corrosive titanium metal Ti-6AI-4V. From the 10 inch (25cm) total knife length, it features a 4.5 inch (11cm) long blade that is sharply pointed on one side and serrated on the other side with a ring hook just inches before the handle. The handle has an ergonomic shape and a built-in counterweight which gives this dive knife an overall balanced feel when handled. The knife has a sheath cover with a quick release lock and an easy to adjust rubber straps. Take note that this dive knife can be disassembled for cleaning and maintenance purposes.
Blade length: 5 inches (12.7 cm) Pros: sharp and pointy edge, blunt version available Cons: large handle grip
The Promate Barracuda Titanium Diving Knife is designed for professional divers who intends to use it for an extended period of time. It is made from titanium alloy that is rust-resistant and able to withstand most of the physical parameters in scuba diving. It has a 5-inch long knife blade that is very sharp on one side and smoothly serrated on the other end. The blade tip is very sharp and is designed for piercing hard objects. Just take note that the handle grip is larger and thicker than the actual blade which makes this an easy to handle knife even if you intend to use this in cold water environments while wearing a pair of gloves.
Blade length: 3 inch (7.6 cm) Pros: unique release mechanism, low price tag Cons: requires frequent maintenance, no pointed version
The Aqua Lung Squeeze Lock SS Blunt Tip Dive Knife is made from a high grade 304-series stainless steel. It only has a 3-inch blade that is sharpened on one end, serrated with fine ridges on one side and a blunt tip. But what really stands out with this dive knife is its patented squeeze lock sheath where the release of the locking mechanism is not located in the case, but in the knife itself. All you need to do is squeeze the colored tabs located at the base of the handle, and the knife will release from the case. And lastly, this small dive knife is ideal for women’s use or attachment to your BCD.
Blade length: 4.19 inches (10.6 cm) Pros: small, foldable, can be stored in BCD pocket Cons: requires frequent maintenance
The Spyderco Atlantic Serrated Edge Dive Knife is a new innovation dive knife. Instead of having a separate sheath cover, this dive knife is foldable and easily opens with the use of a single hand. It is made from a corrosion resistant H-1 steel that is known for its edge retention properties. Instead of having a sharp and pointed blade, this dive knife is totally smooth on one side and highly serrated on the other end. Its handle grip is incorporated within the outer edges of the knife courtesy from its fiberglass reinforced nylon handle bar.
Blade length: 4.8 inch (12.2 cm) Pros: highly resistant to corrosion, rugged and robust Cons: no dedicated line cutter, high price tag
The Aqua Lung Argonaut Titanium Diving Knife is a long and thick dive knife that measures 9.6 inch (24.4 cm) long and 4mm thick. It is made from titanium that is embedded with an EDP coat making it highly resistant to corrosion. A unique characteristic of this dive knife is its handle. Instead of the typical ergonomic plastic, it is wrapped with a 5mm paracord that is 7 feet in length and reeled in a neat fashion. Instead of plastic, the cover sheath of this dive knife is made from 2mm thick kydex with grommets measuring ⅛ of an inch.
Blade length: 3.3 inches (8.5cm) Pros: easy to use, multi-functional, versatile blade tip design Cons: requires frequent maintenance
The Scubapro Mako Titanium Dive Knife is a multi-functional dive knife with several features embedded within this cutting tool. With a total knife length measuring 7.5 inches (19cm), this dive knife has a short blade measuring only 3.3 inches (8.5 cm), a sharp blade, a serrated side and a conventional blade tip that is both point and angularly blunt. It has a ring notch at the end of the sharpened blade designed to cut fishing lines and small ropes. Aside from the embedded plastic at the tip of the knife that acts as a handle grip, it has a bottle opener which you can use in opening your drinks during surface interval.
Blade length: 2.83 inch (7.2 cm) Pros: compact, sharp blade point Cons: very small blade, no blunt version, needs frequent maintenance
The Mares Argo Titanium Knife is a compact dive knife designed to be worn on the arm or at the legs particularly in the calf. This dive knife features a 2.88 inch (7.2cm) blade that is angularly pointed going towards the blade tip. One side of the knife blade is sharply honed while the other side is finely serrated which makes cutting small ropes very easy. The handle grip is made from plastic with an ergonomic shape making it easy to handle while the cover sheath is made out from impact resistant plastic.
Type of Metal – there are 2 types of metal material commonly used in manufacturing a dive knife: stainless steel and titanium. There are 2 main difference between the two metals. First is the price where titanium dive knife is expensive when compared to the units made from stainless steel. Second is its resistance to corrosion. Titanium dive knife will never corrode while stainless steel dive knife will rust over time especially if you maintain it poorly. However, there is a trick for a stainless steel dive knife to last long: you need to soak and rinse in freshwater after use, dry it and coat the blade with a thin layer of silicone.
Blade Design – a simple dive knife has a straight design where one side of the blade is sharpened while the other side is not and can only do one function: cutting. This is the reason why manufacturers have added more design and features to allow the dive knife to perform other functions. Most of this added features are located on the blade tip or at the non-sharpened side of the blade. New designs include a serrated blade that is designed to cut through thick lines such as polyethylene rope and high-rated nylons. Some dive knife has a hook-like depression that is intended to cut through monofilament and other types of fishing line.
Pointed vs. Blunt tip: most blade tip of a dive knife has two designs: either blunt or the traditional pointed. Functioning like a screwdriver, a blunt-tipped dive knife is effective in pounding and prying while its pointed counterpart is designed for piercing. But you have to take note if you choose the pointed version since there are regulations (laws may vary per country) in carrying a pointed knife especially when it comes to the length of the blade.
The bottom line in choosing the right dive knife for you is that the more cutting function it serves, the better.
Where to place your dive knife?
Do not place your dive knife inside your pocket. They are not designed to be inserted. Instead, a dive knife has it own housing called a sheath and a rubber strap that allows you to place it securely in a safe but accessible location within your body.
There are 3 recommended areas within your body for a dive knife to be placed: on the low pressure inflator hose, on your BCD’s waist harness or in your legs particularly on your calf. And not just anywhere in your calf, but a dive knife should be mounted on the internal side of your calf. In this way, the knife handle which is the part exposed out of the housing, will not get entangled and is naturally protected by both of your legs since it will now be located in between.
The Benefits of Owning a Dive Knife
While the possibility of not having a dive knife and solving a potential underwater entanglement problem can be solved with the help of your buddy who has a knife, we still highly recommend that you have your own cutting tools. Further, despite some dive shops that rents out a dive knife, it is highly possible that you will be using a dive knife that is not suited to your needs and preferences.
Having your own dive knife allows you to passively prepare yourself for any untoward incident by equipping with the right cutting tools. But just in case you cannot bring your own dive knife because of the restrictions set by the country you are visiting, make sure to select a rental dive knife that has the features closest to the one you are using.
Advice: If you are bringing your dive knife for a dive travel, make sure to check first the regulation of the country you are visiting particularly on the blade length restrictions.
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