“Have you ever grounded a ship?” asked the marine superintendant interviewing me for my first captain job. Little did I know this was a trick question. The superintendant later told me “yes” was the only correct answer. If I had answered “no,” he would have known I didn’t have enough experience navigating ships close to shore or I was lying. Either way, he would not have been interested in putting me in command of one of his ships.
While all experienced small boat sailors have, like their commercial counterparts, gotten stuck in the mud at least once, a related problem plagues the small boat skipper: a fouled propeller. We’re going to explore the best way to free your prop when its wrapped up in a line.
You probably already know enough to prevent a line from fouling your prop by stowing, or at least coiling, your mooring lines immediately after departing the dock, by giving lobster pots a wide berth, and by using polypropylene line, which floats, for anything intentionally put overboard, like a dinghy tow line.
Another option is to install marine spurs. The spurs consist of two knife blades that mount on the shaft just forward of the propeller. The knives spin along with the shaft. When a net, line or weed gets pulled into the prop, the spurs cut it. Spurs work 90 percent of the time, but are expensive. They also require professional installation and regular maintenance. At The Teak Rail, we recommend simple, cost-effective systems. Since spurs are neither, we suggest that, unless your cruising grounds are littered with crab pots AND bergy bits, it’s better to go unprotected.
However, sometimes, despite your best efforts, you just can’t avoid a fouled prop. In such cases, your first duty is to prevent the situation from getting worse. Don’t give the engine more throttle in the hope of breaking the line loose. You’ll only break something besides the line. And don’t put the engine in reverse; you’ll just turn a loose tangle of line into a knotted mess. Instead, shift the engine into neutral or, if sailing, drop your sails and calmly assess the situation.
Some custom products are available to help you cut the line from the shaft. A large hooked knife mounted on the end of a pole, which is called a hooknife, is one popular option that claims to let you cut a line loose without getting wet. While it can often free you from a mooring or a lobster pot attached to the seafloor, it’s nearly impossible to get the hooknife between coils of line that are tightly wrapped around a propeller. Also, since space is at a premium aboard small boats and few boaters have the luxury of storing more than one boat hook, let alone a pole-mounted knife.
The solution for most is to dive off the stern — equipped with the proper tools— and untangle the mess by hand.
First, get or use an anchor. If there is any current, the first snip of a tangled line will send your boat floating away, and even a trusted helmsman will not be able to use the engine to turn around and retrieve you. The anchor can also take much of the tension off the fouling line.
To properly deploy an anchor it’s best to lead the end of the anchor line through a stern chock, then put the anchor itself in a dinghy and drive it a few hundred yards astern. Once dropped, you can haul in on the anchor line, and take the strain off the fouled line. This will make detangling the line much easier. Also, don’t set the anchor directly astern. Setting it on your quarter will help pull you away from the obstruction, and help prevent the two lines from fouling each other.
With the anchor set, take a break and think through the situation. If you have a GoPro camera onboard, you can affix it to the end of a pole (Pro TIP: Most Good Fiberglass Spearfishing Poles can screw directly into the GoPro’s tripod mount) and drop it into the water to determine just how fouled the line is. If you’re short on time, skip this step because you’ll probably have to jump in the water anyway.
The most basic gear needed to untangle a prop is snorkeling equipment. You can get by with just a dive mask, but if there’s any current you’ll also need a good pair of dive fins. If the water’s cold, you’ll also need a wetsuit.
The second must-have is a good pair of heavy duty dive gloves. Props tend to have sharp edges and any line submerged for a length of time will be littered with barnacles and marine life that will slice open a palm if you pull on the line barehanded. Plus, if there are any waves, one hand will probably serve as a cushion between the top of your head and the boat’s bottom.
The Best Knife For Cutting Tangled Nets & Line
The next item is a good knife. Most people use a dive knife to clear a prop, but it’s less than ideal because most dive knives lack the serrated blade needed to cut the line fast. If a net’s fouling the prop, a smooth blade will do more slipping than cutting. Dive knives also tend to be relatively thick, making them difficult to get beneath a line or inside a wrapped net.
The best knife for quickly cutting through line is a serrated hawkbill. These knives have curved, sharply pointed tips that can burrow into a tightly wrapped net and dig between lines. Their curved blades also “catch” on a line or net and deliver more downward force than straight blades. Most sailors’ favorite hawkbill knife is the Spyderco Tasman Salt, about $63 at Amazon.
It’s easy to see why sailors like the Tasman Salt, as it’s an excellent knife. But we have a different recommendation. Spyderco equipped the Tasman Salt with state-of-the-art rustproof H1 steel. The H1 steel separates Spyderco’s Tasman and Atlantic Salt models from other knives. A precipitation-hardened steel alloy, H1 uses nitrogen, which does not rust, instead of carbon. As a result, the blade doesn’t require heat treatment and actually gets harder and tougher with use.
I haven’t had to put a drop of oil on the Spyderco Atlantic Salt, my own favorite H1-steel blade, in years and it’s still rust-free. In addition, all the other components in the Atlantic Salt’s steel have been specially treated to make them impervious to rust and pitting, making it a perfect knife for fresh and salt water use.
However, the Tasman Salt has one serious flaw that makes it less than ideal for freeing propellers. it’s a small knife. The blade is only seven-tenths of an inch longer than Spyderco’s diminutive Ladybug, which has a 1.687-inch cutting edge. The Tasman Salt rarely succeeded in cutting a 1-inch line in a single stroke in our tests, and multiple cuts can become a major problem when you’re trying to hold your breath underwater.
The best knife for freeing a propeller is the Spyderco Civilian. Designed for undercover FBI agents, this is the knife to bring during late-night excursions into dark, unfamiliar alleys. The Civilian has a patented reverse “S” blade intended to be used like an oversized claw by someone with little or no formal knife training to non-lethally lacerate and scare away attackers. The Civilian may be a good knife to fight pirates (if they’re not carrying guns), but it’s also the best knife for freeing fouled propellers.
The hooked blade, which is so good at reaching out and cutting someone, also makes quick work of slicing open lines and fishing nets. And the Civilian is a BIG knife. With a 4.125-inch blade and 3.75 inches of serrated teeth, the knife will cut anything short of a hawser with one stroke.
Good as it is, the Civilian, too, is not perfect. The knife is constructed of VG-10 cutlery-grade stainless steel, which holds a very sharp edge but, unlike the H1 steel in the Tasman Salt, will rust if left exposed in a marine environment. Since the knife comes with a nice felted pouch, the solution to keeping it rust-free is adding to the pouch a few desiccant packets from, say, an expired bottle of Tylenol. This should keep it rust-free during storage, but is not enough protection in and of itself. After diving below the boat with the Civilian, it’s imperative to thoroughly wash the knife with fresh water, dry it fully, and oil the blade before putting it back in the pouch.
Extending Time Underwater
With an anchor taking the strain from the fouled line, with snorkeling fins to fight the current, and an excellent knife to slice through rope and netting, you should be able to quickly free a prop. But these are only half the equation. The most effective way to free a prop fast is to stay clam and work slowly underwater, a nearly impossible task if you’re trying to hold your breath.
With the proper tools, you don’t need much time to free a prop but it certainly makes the job go faster and more pleasantly if you don’t need to stop every minute to surface and take a breath. That’s why we suggest keeping a canister of Spare Air aboard. Spare Air is a self-contained, refillable back-up air system designed to give SCUBA divers 3 cubic feet of air, enough to get them to the surface in the event of an emergency or if they run out of air in their primary tanks. The unit looks like a mini SCUBA tank with a bite plate, which is exactly what it is.
To operate, just pull the bottle out of its holster, gently bite down on the mouthpiece and start inhaling. Many SCUBA divers hate Spare Air, and you will find negative reviews online. But this is because the bottle provides less than 2 minutes extra air at depths below 50 feet, hardly enough time to solve whatever the problem is and decompress before rising to the surface.
The criticism is legitimate, but how deep is the propeller on your boat? Five, maybe 10, feet below the surface? This is not deep enough to require a safety stop and, since you use less air in shallower depths, the bottle should deliver the 10 or so minutes you’ll need to cut free the prop with your Spyderco Civilian.