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Underwater Welding Equipment: Power Tools

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Photo Property of NZSCDT

When you imagine an underwater welder, you probably see a careful, precise, analytical suit with a keen eye for minuscule details – even the smallest crack. But there’s another side to most welder-divers; a side that enjoys sending shockwaves and blasts of air through the water (not just electricity).

In fact, demolition, cutting, and securing go hand-in-hand with the other responsibilities of a specialist in underwater construction. Underwater welders should train in the use of all manner of power tools that function in a similar manner to their topside counterparts, albeit with a few more bubbles.

It’s unfair to group all of these tools into one category, as they have two different operating systems for power and function. Most use either hydraulic or pneumatic systems. Let’s define these ahead of time:

Hydraulic: Powered by a pistons that apply force to one another with an incompressible fluid in between them. This makes use of the power of force multiplication.

Pneumatic: Powered through a compressible gas, such as air or nitrogen.

Underwater Hydraulic & Pneumatic Equipment

1. Jackhammer

Down deep, the jackhammer or “breaker” has a different tune. Commercial divers use these to dig in and clear away unwanted rock or debris around a construction site. They can take a bigger beating than just about any other power tool out there.


Your movement in the water is already limited due to wave current and other unpredictable factors. Find a jackhammer with thick grips and a good balance of weight across its length. And speaking of length, look for a jackhammer that allows you to comfortably extend your arms without strain. The machine length will vary according to the bit on the end, though most will measure around 2 – 3 feet without a bit.

In regards to operation, your underwater jackhammer’s recoil is the elephant in the room. If you’re able, take your jackhammer for a test run or watch a video of it in action to determine how much recoil it has. Take account your jackhammer’s size, weight and blow energy.

You’ll want your equipment to have as much downward focus as possible; outward, surrounding pushback reduces the efficiency and increases your jackhammer’s recoil. This wasted energy takes a huge toll on your muscles and limbs during a lengthy underwater demolition project.

Power & Bit Capacity

We all have our limits. Underwater jackhammers can only take so much abuse, and they need to be powerful enough to break through the cement, rock or another material you’re digging through. The performance is measured in blows per minute (bpm), which may range from less than 1,000 or greater than 2,000. The heavier the jackhammer, the more punch it packs – usually.

Your jackhammer should also have capability for multiple bits. You want as much versatility as possible so you can get the most for your money.

Sidenote: Make sure your jackhammer allows you to use it in any position. The underwater construction world isn’t a respecter of persons – or direction. You don’t know how you’ll be using it until you’ve inspected your area of focus.

2. Chipping Hammer

Image credit: Stanley Infrastructure

If you can’t bash it, then chip away. Underwater welders clear out rock, cement and even plant life with an underwater chipping hammer. It also works well for masonry work, such as carving out measurements into hard spots. Most chipping hammers are hydraulic-powered.

Versatility with Bits

The chipping hammer works similarly to an underwater jackhammer – almost like its younger brother. And like a jackhammer, you’ll want multiple bit capability, whether you’re using square, round or oval bit shapes. Bit size difference have an impact on versatility as well.

Safety First

Safety comes first in all underwater welding work, including with power tools. Search for a chipping hammer built-in precautions like an oval handle to prevent unintended operation. The handles should be thick and solid to allow for a vice grip when its powered up. Soft coatings like rubber or malleable plastic on the hammer’s body provide more comfort and ease, so you can look for this feature as well.

3. Chainsaw

Image credit: Stanley Infrastructure

Joining the team of marine lumberjacks with a fast, sharp underwater chainsaw. Surface chainsaws are powered through gas or electric means, but underwater application requires a pneumatic process. Underwater welders use chainsaws to cut through plastic and wood materials, such as plant growth or beams attached to wreckage. With water restricting movements, divers must carefully lock on to their targets of cutting and apply precise vertical or horizontal force.


Most underwater chainsaws have a trigger-controlled mechanism. Find one that allows speed adjustability when squeezing the trigger, as you won’t always want full power.

Cutting Capacity & Power

Divers measure the cutting capabilities of their chainsaws by the length of the cut (inches or centimeters). Similar to underwater jackhammers, greater capacity usually translates to heavier equipment weight. Standard underwater chainsaws usually weigh around 20 – 30+ pounds, a burden that wears on the strongest of divers. The actual power supply is measured in horsepower (HP), but this number doesn’t change much between various models. Your main concern should lie on the weight and cutting length of your chainsaw.


Heavy power tools do the hard work for us, but that also means their moving parts need plenty of maintenance. This responsibility is amplified in an underwater environment where fluid can penetrate joints, slides and rotators. Find out how much work and expense will go into maintaining your chainsaw.

Some underwater chainsaws possess a self-lubricating system of oils when the chain moves past them. This sounds good, but make sure these lubrication process are simple and effective – you don’t want to spend your time maintaining the maintenance system.

Saw Chain Adaptability

Your chainsaw can work with several different saw chains for various types of cutting, whether for ripping or slicing. The saw chain that comes with your equipment may not be the best fit for the job, so look for a higher quality (carbide-tipped) saw chain if necessary. These cut through hard plastics and woods.

4. Circular Saw

Image credit: Stanley Infrastructure

With higher precision than the chainsaw, the circular saw works great for close-quarter cutting. You can use it to cut through coral, metal and even cement. Like other underwater equipment, it should be built for use in a variety of positions.

Performance Spectrum

You probably won’t find many size and power differences between underwater circular saw models. Look at the optimum psi and gpm during your research, and make sure your power sources and hoses can handle this. The higher the torque on the motor, the more cutting power you can apply. The tradeoff? Less control – unless you have adjustable settings on the trigger.

Adjustable Blade Types

You may be able to use your saw blade topside as well as underwater. Along with this bonus, determine what types and widths of blades can be attached on your equipment. Common saw blades include materials like diamond, carbide and metal alloys.

5. Grinder

Image credit: Stanley Infrastructure

Sometimes a diving knife isn’t enough. If you’re preparing a site for an underwater welding or cutting job, you’ll want to start your preparation with a grinder. These tools take out all of the grime, rust and growth around your work site. They also act as a heavy-duty cleaning device.

Mobile & Ergonomic

You probably won’t be the only one using this thing, in which case you’ll want a tool that works for righties or lefties. The underwater grinder should also have a solid grip around the handle areas, with enough length for larger hands. Trigger-activated grinders should extend out to equal the length of the handle (or close to it). You don’t want to loosen your entire grip to power it up.

Alterable Parts – Maintenance

Grinders make use of many different attachments (wire brushes, metal wheels), and you’ll need to keep an eye on your equipment’s upkeep on a regular basis. It should have a removable eye (top section) and easily detachable process on the bottom section for attachments. Also, the wheel guard should be able to move a full 360 degrees around the grinder for any position of operation.

6. Impact Wrench

Image credit: Stanley Infrastructure

Underwater welders use impact wrenches for smaller projects requiring bolting or unbolting. Pipes, hull doors and other metal lining have bolts and nuts that require power beyond human capability. It makes use of a swing-hammer mechanism to apply back-and-forth motion, like a ram on a castle gate.

Power Adjustment

Your impact torque will directly affect the performance of your underwater equipment. You may need a range of torque anywhere from 300 – 3000+ Newton meters (Nm). If your impact wrench only has one power setting, I wouldn’t even consider purchasing it.

Removable Parts

Again, maintenance is key to a long-lasting, healthy tool life. Look for adjustable and removable parts as a standard part of your product purchase. Ask the manufacturer for the manual ahead of time if you’re not certain of this characteristic.

See also: 

Power Purchase: A Serious Endeavor

As you can see, underwater power tools aren’t just a “category” in an underwater welder’s arsenal. They truly make the difference between a dive project completed quickly…or not completed at all. They come with more power, weight and size, along with extra destructive power than other underwater welding equipment. This means greater safety precautions and responsibility. Take it seriously – the research, purchase and use of your hydraulic and pneumatic underwater tools.

Cameron Dekker

Cameron grew up in Allentown, Pennsylvania, a once-proud steel town on the Lehigh River, where he got a taste of TIG welding in his high school shop class. He holds certificates for Certified WeldingEducator (CWE) and Certified Resistance Welding Technician (CRWT) from the American Welding Institute. His interests include scuba diving, sculpture, and kayaking.