Say the prop suddenly begins vibrating. First you checked the shaft coupling; they’ve been known to work loose, allowing the shaft to come clean out and leaving a good sized hole in the boat. The shaft appears straight and you didn’t feel an impact. Remote inspection reveals a rope around the prop, and you know in your heart it should be cleared before it does damage or jams further. You could call for a tow. Or you may just need to go for a swim.
At the Dock
- Lock-out the prop. The keys must be out of the ignition and in the control of a responsible person.
- Electrical Shock Drowning (ESD). Primarily a freshwater problem, even a tiny electrical field can paralyze swimming muscles and cause rapid drowning. In freshwater, do not dive at the dock; move at least 200 feet away from all power sources. In seawater it is probably sufficient to unplug your boat, and if possible, all neighboring boats (see “Preventing Electric Shock at the Dock,” Practical Sailor, August 2019.
Anchored and Underway
- Stop, obviously. Adjust heading to calm the waters in the dive zone by heaving to or streaming a sea anchor. Drifting is generally better than anchoring if there is sea room. Pitching can result in the boat slamming against the swimmer; a helmet may help, but most provide too much flotation and snagging is a risk.
- Strong swimmer. This is not just splashing at the pool. Even at the dock there will be a lot of treading water and breath holding involved. It is possible to become snagged. Underway there will be waves, so experience snorkeling and swimming in surf is mandatory.
- Dress for the water temperature. No amount of gritting you teeth is safe below about 68F. A wet suit is better for swimming, but a dry suit works well if you get alls of the air out. The final seal must be made in the water.
- Minimize snag potential. All clothing must be snug. Do not put tools on wrist lanyards if free diving; it is far better to drop a knife than to snag your wrist on the prop. Take tools you don’t like.
- Take your time. It is possible to pass out during extended breath holding underwater, and the combination of treading water and working hard can challenge the strongest swimmer. If you are out of breath, take a break. Dangling a flotation aid in the water for rest is a good idea.
- Don’t tie a line to the diver. It is far too easy for a “safety line” to become snagged.
- Do trail a safety line in the water. A Lifesling is very good for this. If the swimmer drifts away and the boat is disabled, recovery is no joke.
Like much of sailing, judgment is required. Consider all of the variables, the seriousness of the need, and know your limitations. I’ve dived on and even replaced props underway and off-shore, but always with care and planning. Well planned and with patience it can be safe and much is possible. Never rush.
Drew Frye is technical editor for Practical Sailor and author of the how-to book on anchoring, Rigging Modern Anchors. He also blogs at his website www.blogspot.sail-delmarva.com
