SEAL Training: Underwater Knot Tying

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Becket Bend (aka Sheet Bend)

Bowline

Clove hitch

Rolling Hitch (1) #1734

Square Knot (aka Reef Knot)

​WARNING: Do not try any of the activities described here on your own. Even with the supervision and guidance of active-duty SEAL instructors, serious injuries have resulted. Without this experienced supervision and guidance, permanent injuries and death can result.

Wearing only our UDT shorts, my class climbed the outside stairs to the top of the fifty-foot dive tower and entered. Inside, I lowered myself into the warm water. The depth was fifty feet. I would have to dive down about fifteen feet and tie five knots: becket bend (sheet bend), bowline, clove hitch, rolling hitch (1), and square knot. These included some of the knots we would have to use for demolitions. For example, the becket bend and square knot can be used for splicing the end of det (detonating) cord. I learned most of the knots in Boy Scouts, and we practiced these at BUD/S, so I had no problem doing them, but this was the first time tying them at 15 feet underwater.

We could tie one knot for each of five dives, but I thought that five dives would be too tiring. Or one dive with five knots—I didn’t think I had the lungs for that. Or any combination we wanted.

I greeted the instructor, who wore SCUBA gear. “Respectfully request to tie the becket bend, bowline, and clove hitch.” He gave me the thumb down. I mirrored his thumb down, showing him that I understood. He gave me the sign again, and I did my combat descent fifteen feet below, where I had to tie into a trunk line secured to the walls.

In Boy Scouts, I could tie the bowline with one hand in the dark, so I was able to tie it fast using both hands and my eyes open. Still underwater, I tied the other two. Then I gave the instructor the OK sign. He checked the knots and gave me the OK sign. I untied them and gave him the thumbs up. He acknowledged, pointing his thumb up—giving me permission to ascend.

On my second dive, I tied the last of the two knots and gave the instructor the OK sign. He didn’t even seem to look at the knots, staring into my eyes. I saw he was going to give me trouble. I gave him the thumb up sign to ascend, but he just kept staring. The depth put pressure on my chest, and my body craved air. I knew what the instructor was looking for, and I wouldn’t give him the satisfaction. The SEAL instructors had taught me well. I can ascend myself, or when I pass out you can drag my body to the surface. Either way. He smiled and gave me the up signal before I even came close to passing out. I wanted to shoot to the top, but I couldn’t show panic. And shooting to the top isn’t very tactical. I ascended as slow as I could. Pass. Not all of my classmates were as lucky, but they would get a second chance.

Note: Thanks to C. for taking time after Hell Week to update me on the knots. Any errors are my own.

(Photos of becket bend, bowline, and clove hitch courtesy of Markus Barlocher. Square knot photo courtesy of Ben Frantz Dale.)