Features December 2018 Issue

Leg Straps Put the Load on Fanny

Considering the short comings of existing leg loops for harnesses, we designed an add-on set of leg loops that can transform any ISO 12401 chest harness into a harness capable of safely distributing the force of a epic fall, without adding significant weight and without inhibiting wearer moment. Below is general guidance on construction, for more details on this project, see the in-depth report "Sailing Harness Leg Loops."

The force is better transferred to the legs by directing the main support straps directly to the D-ring. By changing the orientation, the weight is also borne by the buttocks instead of the vulnerable inner thigh.

We kept the harness light by using 25 mm webbing for most of the construction, but we increased the width to 70 mm under the thighs for comfort under load. Instead of attaching the loops to the sides of the harness, they are attached front and rear.

Two design features allow the leg loops to be fitted comfortably and still stay in place. First, the crossovers at the hips and upper back can slide and adjust with body movement, preventing the harness from binding and allowing all of the parts to remain in their proper positions through any twist or bend.

When weight is applied, the crossover points on the hips slide, snugging the loops on the thighs only when needed. This self-adjusting cross-over is the key to free movement, comfort, and security in a fall.

Second, there is a simple elastic inverted Y on the back that holds the leg loops up where they belong at all times. There is only one non-textile part, the lone adjusting buckle on the right hip. We did this intentionally, for simplicity, for ease of fitting, and to reduce snagging and scratching potential on deck.

Sizing is not universal, but a line of five sizes — small to extra-large— would suit most sailors. The front closure is a soft shackle. Two soft shackles would increase security.

The loops are removable, the harness does not require any modification, and it should fit any chest harness. Harnesses with a single back strap will require a non-structural loop to stabilize the crossover. The loop securing the elastic to the chest band on this prototype is Velcro, but it could be tied or connected with a small Fastek snap; it is not structural.

The stitching is in accordance with rules published in “Is Hand Stitched Webbing Strong Enough?,” Practical Sailor Magazine, April 2015. The self-adjusting junctions on the hips were created by adding second layer of webbing and leaving a 1 ˝-inch slot between the two.

1. A view of the front of the harness reveals the sliding crossovers on the hips. These are what allow free movement without binding and ensure that the leg loops to fit comfortably.

2. This is a close-up of the hip crossover section. This is an essential design feature. Without this detail, the leg loops will not work as designed.

3. One significant advantage of our redesigned harness with leg-loops is that they are ready-made for recovering a person in the water using a halyard or block and tackle. We were able to hang for periods of up to 20 minutes without any significant discomfort while wearing the new design.

Comments (9)

I am very interested in this subject. Since I have made it to 71 I am looking earnestly at jacklines & harnesses. For way too many decades this singlehander was foolishly cavalier about personal safety because i mistook luck for skill.
Please continue with this reporting and research on harnesses.

Posted by: charles@charlespeck.com | November 29, 2018 5:26 PM    Report this comment

An interesting demo for your yacht club meeting would be hanging from PFDs, with and without leg loops.

With leg loops, there is the anatomical problem. There is the problem with crotch straps getting behind your knee when you crouch, making standing up again difficult. Finally, all are connected with plastic buckles, rated for little more than body weight.

Without leg loops, both OSHA and UIAA (climbing) have cautioned that hanging for more than 30 seconds (if anyone can last that long--time them) can cause permanent nerve injury. Chest-only harnesses are strictly forbidden for every activity except sailing.

The obvious lesson is to clip to hard points and jacklines in such a manner that going over the lifeline is impossible. Use the short tether whenever practical. Even so, mistakes happen.

Posted by: Drew Frye | November 29, 2018 8:55 AM    Report this comment

The purpose of the article was to demonstrate what is possible, and to throw down the gauntlet for equipment designers to develop something that works. Several high profile accidents, involving tether and clip breakage, prove that a sailor restrained by a tether can generate impact forces of over 1000 pounds. Industry, climbing, military and sailing experience have established that that serious injuries accompany such forces when taken on a simple chest harness, and that these injuries are likely to contribute to drowning and death. In fact, even lifting with a chest harness is strictly forbidden by both industrial and climbing standards.

The current leg loop designs are not load rated and are intended only to keep PFDs in place in the water. This is insufficient for harnesses that may experience impacts. Current climbing and industrial harnesses are heavy, cumbersome, and generally incompatible with foul weather gear. The tether attachment locations are generally wrong for safe use on deck and in the water. Thus, we developed something that meets the requirements (light, comfortable, does not interfere with movement, correct balance point, and impact rated) to prove that it can be done. Ideally, the leg loops will be removable but integrated into the harness design.

The test model is a rough proof of concept, though it survived very tough testing; the climbing rope used was fatally damaged within 7 drops. The stitching at the leg loop cross over is not structural and can be a box pattern with heavy whipping twine. The stitching of the end loops at the harness attachment should be fully stitched, though reinforcement is not required because the load is spread across two loops. The buckle was from an equivalent location on a retired climbing harness, although the specific load rating is not known.

As I said, the intention was to throw down the gauntlet. To our knowledge, there is no current sailing harness design that can pass a hang time or drop test similar to falls that have happened in MOB events.

Posted by: Drew Frye | November 29, 2018 8:38 AM    Report this comment

Creative solution if the question is what to do about lifting with a chest harness. Here's my understanding, open to being corrected. Leg straps on a PFD are there to prevent the PFD from floating up on the wearer in the water and, as far as I know, not for lifting. Climbing seat harnesses are for, essentially, sitting in, supplemented by a separate climbing chest harness to better direct the support from the climbing rope. These two are not typically connected. The climbing seat harness can substitute for bosun's chairs and certainly your athletic bow person can do tricks wearing one (when they stop griping about the helm). You could wear the climbing harnesses with either an inflatable PFD or a foam one. Putting aside the unique needs of the bow person, for any crew wearing a harness, if the load bearing connection to the seat climbing harness is hidden, or a tether runs under a PFD being directed through a chest harness, you can't get to the quick release we want on a tether for sailing. A full body climbing harness (both seat and chest) puts the load bearing attachment on the chest, so could be tested for clearance past a foam PFD to release the quick release. There are also more elegant full body sailing harnesses. Commercial occupational safety harnesses, like for roofers, window washers, etc. are mostly for load bearing from the back, good for lifting a recovered MOB, but not where you want to attach your tether. The chest ("sternal") attachment on one commercial harness is rated for only a 2 foot drop, 1/3 of your tether, so that one's out. Back to the invention. It's not clear from the picture what's around the wearer's chest. It doesn't look like a usual offshore inflatable PFD. It might be, or it might be only a harness with a cover. In any event, it looks like it does the same job as a climbing seat harness, and the important feature is that the connection to the quick release has a load bearing connection to the seat harness. That's absent from the climbing, two - harness approach because climbers don't care about a quick release on the chest. Could I add it to a Mustang or Spinlock inflatable (two types I have, but I suspect they have the greatest market share)? It wouldn't seem so with just those carabiners, because of the way they attach. But it could substitute for the "no float over your head" leg straps only on the inflatable with a less demanding attachment for that function. I would think it would probably need attachments on either side of the PFD buckle, to be used to lift using an integral PFD harness. I'm looking forward to good solutions, as are most sailors i know. One of our local yacht clubs is hosting an afternoon seminar in a couple of weeks and the sole topic is PFDs.

Posted by: DaveChicago | November 28, 2018 10:39 AM    Report this comment

I think this is an interesting proposal and once which might solve another problem that I have. This is that after crouching down to adjust something on deck I often find the straps have dropped down my thighs and get caught behind m knees!

Posted by: bobgarrett | November 28, 2018 2:52 AM    Report this comment

Why reinvent the wheel? climbing harnesses are WAY better, and there's a wide range of choice. And they've been perfected for several decades. And the bigger market makes them cheaper.

Posted by: ozdigennaro | November 27, 2018 6:36 PM    Report this comment

I would suggest caution in trying to make leg straps do a job that is not the intended purpose of these devices.
Leg straps/crotch straps/thigh straps are used to improve performance of PFDs by keeping them closer to the wearer's body.
Many wearers of PFDs have experienced the feeling that the PFD was up around their head - or that an inflatable was too tight around their neck.
The PFD does it's job, the person inside the PFD did not properly fit the PFD or it needs to be held down at the bottom to keep the wearer closer to the vest. This is common with shorter-waist wearers.
Leg straps are effective with both inflatable and inherently buoyant vests.
Leg straps need to be adjustable as once in the water, the wearer will tighten the straps to keep the PFD closer to the waist and chest.
The leg straps were not designed as fall protection or lifting straps.
There is no USCG standard for the attachment of or design of leg straps as lifting straps or fall protection on USCG Approved PFDs.

Posted by: BB | November 27, 2018 4:06 PM    Report this comment

Very cool addition. I have 2 questions: A) Can you describe the adjusting buckle you used? No idea what sort of rating it would need, how to affix it or where to source one. B) The article refers to a previous article on hand stitching of webbing (optimum = 8 rows @ 1/8" apart with extra webbing sandwiched) but the photos do not show this construction. Photos look like a box of single stitches. Is that what you tested?

Posted by: Areddon | November 26, 2018 9:25 AM    Report this comment

Very cool addition. I have 2 questions: A) Can you describe the adjusting buckle you used? No idea what sort of rating it would need, to affix or where to source. B) The article refers to a previous article on hand stitching of webbing (optimum = 8 rows 1/8" apart with extra webbing sandwiched) but the photos do not show this construction. Photos look like a box of single stitches. Is that what you tested?

Posted by: Areddon | November 26, 2018 9:23 AM    Report this comment

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