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Building A Marine Mechanic's Toolkit

by Binnie Smith

a tool boxPhoto courtesy Jensen Tools/Techni-Tool

As your experience in working on marine engines grows, naturally it follows, so too will your toolbox. Here then follows some suggestions of what to add to your inventory of tools.


Wrenches are the number one category of hand tools required. Optimally, a marine mechanic's tool kit will have:

A set of 12-point combination wrenches

A set of flare nut wrenches for snugging hydraulic lines on the lower unit's trim/tilt without buggering up the fittings.

A trio of ratchet wrenches: Quarter inch, Three-eighths inch,and Half inch supplemented by both metric and SAE sockets ranging (8 mm through 19 mm and 3/8ths to 1-inch, bolstered by set of deep well sockets.

When using air tools, only use hardened sockets specifically made for air tool use. Regular hand tool sockets, fitted to an air tools, are prone to break and are dangerous.

A torque Wrench

A Strap Wrench: Handy for removing spent oil filters and holding an outboard motor's flywheel when removing it.


An marine tech’s second most important must-have tool collection includes a variety of screwdrivers that go beyond just flat and Phillips head. Mis-matched drives burr screw tops and are shoddy worksmanship. Get the right tool for the job, which means drivers that match the fasteners in a range of shapes and sizes such as:

Stubbed or pocket screwdrivers.

Hex screwdriver, featuring a five-sided head and used for hex or cap screws.

Torx screwdrivers featuring their six-point star-shaped head. With their more substantial grip on the work piece, one can apply greater torque as necessary.

A long-handled slot-edge screwdriver, with its extra leverage, needed for removing stubborn gearcase drain plugs


For gripping, pulling, turning when a wrench won’t cut the mustard

Slip joint: Versatile, multi talented grippers. This plier type features fine teeth for gripping smaller items and coarse teeth for larger bolts.

Vise grips, commonly known as locking pliers, provide strong clamping power adjusted by a screw at the end of the handle to tighten whatever you’re gripping like a vise.

Needle nose, with the thinnest of plier levers, are helpful for bending or steadying wires or intricate pieces.

Diagonal wire cutters

Hammers and Mallets

Sometimes a job requires the added force of a hammer or mallet to get the job done. Ball pein hammers feature a flat hammer side surface for smacking and a round side (a ball) for peening, or marking metal, to keep things in place. Rubber mallets are used to hammer surfaces that might otherwise be damaged by the brute force of a ball pein. Doubtless you've heard the tongue in cheek bromide that advises, “Never use force. Just get a bigger hammer.


A marine technician’s toolkit should include the following for obvious reasons:

Safety glasses

A small flashlight or headlamp.

Sturdy, slip-resistant shoes, optimally with steel toes.

Must-Have Tools for a Marine Mechanic

Here's a list of the top ten tools needed and an explanation of how to use them.


1. QUALITY WIRE STRIPPERS As simple as the sea is salt, inexpensive, dime store wire strippers are a poor investment. They're downright clumsy because their skinny handles dig into the palm of your hand making them hard to use. Invariable they bend and the cutting edges go dull. A wise mechanic gets good ones from the start and the job will go smoothly thanks to sharper insulation cutters, smoother joint action and a better padded grip. Ancor, a brand name renowned for its wire and connectors make a number of possibilities.

Snap-On radiator  hose  pick

2. HOSE REMOVAL TOOL Heat renders cooling system hoses as hard as a rock. Even worse they seem to weld themselves in place. Removal with a screwdriver or awl can be frustrating. Don't fight it. Instead of fighting to remove a cooling hose, use a tool known as the radiator hose pick. Jam the tip under the hose, then work the shank around the inside circumference, making a big circle, freeing the hose for immediate removal. It also works on bilge pump and freshwater hoses.


Do-It-Yourself Boat Owners Appreciate The Way Special Tools Make A Job Easier

3. LINE WRENCHES Also called flare nut wrenches, these box end wrenches are designed to grip as much surface area of a fitting as possible to prevent rounding off the corners, an otherwise common result from using open-ended wrenches on a soft brass fuel line fitting. One of two sizes are all you'll need. Use them on the hydraulic trim cylinders of a lower unit.


4. MULTIMETER Use a digital multi-meter for troubleshooting electrical problems. Things like battery voltage (either high or low), alternator output and tracing circuits to find shorts and opens. On a boat cheap models work fine, but tend to die an early death. More expensive models are more robust and last longer.


5. LOCKING PLIERS Known worldwide under the trademark of Vise Grips, these pliers are a veritable third hand, good for holding a work piece firmly in place for drilling or fastening. You can use them to grip on stubborn, corroded bolts.


6. BUTANE SOLDERING TOOL Butane tools heat their tips red hot but without an exposed flame. There is no dangling electrical cord to tangle. But the main feature is the way they are superior for soldering or for heating heat shrink tubing.


7. OIL CHANGE PUMP Extracting crankcase lubricant with an oil change pump virtually eliminates the chance of errant oil droplets fouling the bilge. Or trickling from an outboard onto the water. The best of the best incorporate a reservoir for storing the oil until you reach an environmentally-friendly disposal site.

channel lock pliers

8. CHANNEL LOCK PLIERS Channel locks, or sliding jaw pliers, are first-rate for removing or installing cotter pins. The long handle lends leverage; the serrated jaw grips a work part tighter than ought to be legal. Jaws adjust to open wide or narrow, making it a universal tool.


9. PROPELLER WRENCH Obviously a propeller wrench of some sort is a must have item that you could use to swap a propeller with a damaged blade. Or to extract fishing line that's wrapped around the prop shaft between the propeller hub and housing. Get a wrench that floats, or be sure to use a wrench fitted with a hole for a tether.


10. DIAGONAL CUTTERS, commonly abbreviated as dikes, are essential to working on propellers. Use Channel locks to straighten the bend in the cotter pin, or outright cut it off with dikes. Grasp the closed end of a cotter pin with the jaws of the dikes and pull it out of the castle nut.