Jack stays and tethers are used too often in calm weather

[Adios]

Gosh. Where to begin?

Well first of all, none of the stuff is ce marked as safety kit, so none of it is properly tested by an independent body. Maybe the safety harness is. In climbing no ce mark means it can't be sold as climbing equipment period. That goes for the bolt through the deck, the jack stay itself( if wire, then wire and swages), the clips on the lifeline and the tether itself. Having said that i don't think sailing is plagued with loss of of life from regular breakages of the listed items. But it is banged into climbers heads that the impact forces that can be generated by an 80kg body falling even a metre can be enormous, hence the 'joke' comment.

Watch this:

I think we forget how heavy we are. I had to lift a 50KG trolley jack into the back of my car the other day. Seemed like a massive chunk of steel. It hadn't occurred to me until now that I weigh nearly double that. Falling a meter to the end of the tether with a jerk just as your face hits the water. Got to be a bad thing.

 

[dunedin]

I'm certainly not the only one thinking the current usual way is poor. Here are some alternative layout for the jackstays. The ideal being a line from an arch, over the sprayhood to the mast up the center of the boat. Can clip on from either side and go up either side with the same length tether, could even jump across the cabin roof if have to I guess. How to stay on deck and avoid MOB - Yachting Monthly If no arch then from the cockpit around the coaming and to the mast rather than along the side decks. Lots of good discussion on it in that link

Again far too many generalisations to be relevant in different boats.
On ours a jackstay from cockpit arch to mast might get a Darwin award in the event of a gybe, as mainsheet passes on a track in front of the sprayhood.
And a route from sidedeck to mast would be more dangerous away from the secure route tucked along the coach roof sides.

To be honest I think I and others are far more likely to go overboard in modest conditions doing something simple and impulsive rather than in serious weather. Seen it happen on a boat with harness at all times in dark rule, minor incident and crew rush up from bunks, half asleep, and a have a go hero rushes on deck in dark to try to fix the problem with no deck shoes let alone harness.
Or putting out fenders, or rushing up to photograph the dolphins at the bow.

When doing the one deck job on our boat (tack for reef 3) it is always done with extreme care, harness, crawling, twin hooks to clip to inner stay to reach mast. That is done with great care and planning.
It is the thoughtless/ impetuous that are most likely killers - and coming back from pub in dinghy, often without any safety gear at all

 

[RunAgroundHard]

Gosh. Where to begin?

Well first of all, none of the stuff is ce marked as safety kit, so none of it is properly tested by an independent body. Maybe the safety harness is. In climbing no ce mark means it can't be sold as climbing equipment period. That goes for the bolt through the deck, the jack stay itself( if wire, then wire and swages), the clips on the lifeline and the tether itself. Having said that i don't think sailing is plagued with loss of of life from regular breakages of the listed items. But it is banged into climbers heads that the impact forces that can be generated by an 80kg body falling even a metre can be enormous, hence the 'joke' comment.

Watch this:

There are standards for harnesses and lanyards.
A person who weighs 80kg and falls 1m before striking an object would impact with a force of 80.027 kgf; not very massive, but painful, could break a wrist or ankle. Even less force falling down a canted hull.

It is not falls from height that is the issue here. It’s tethered to the boat, being trailed through the water with a tether attached to the front of the person a bit above sternum height.

Impact from green water is the likely force multiplier agent rather that gravity.

Type approval is all very well, until the type approved thing doesn’t fit your boat. A rather better approach would be an industry guidance on best practise. I really prefer a hands off, voluntary approach, except in a commercial setting.

 

[Roberto]

Easy answer, adjustable length tether.

I have made this type, I found the lazy part of the tether gets in the way while crawling on deck so I eventually fitted it fixed to the mast: it is quite useful as my mainsail headboard is very high, I lengthen it when in need to work with the sail/halyard (in which case I have to unclip from the "regular" tether) , shorten it when it's winching at the mast base.
Kong "Slyde" plate, + Tango hook, 9mm climbing rope (I found that regular sailing rope diameters 8mm and 10mm do not work well)

 

[IanCC]

There are standards for harnesses and lanyards.
A person who weighs 80kg and falls 1m before striking an object would impact with a force of 80.027 kgf; not very massive, but painful, could break a wrist or ankle. Even less force falling down a canted hull.

It is not falls from height that is the issue here. It’s tethered to the boat, being trailed through the water with a tether attached to the front of the person a bit above sternum height.

Impact from green water is the likely force multiplier agent rather that gravity.

Type approval is all very well, until the type approved thing doesn’t fit your boat. A rather better approach would be an industry guidance on best practise. I really prefer a hands off, voluntary approach, except in a commercial setting.

No you are not right. 80kgf is the same as having 80kg resting on your big toe not landing on your toe from a distance.

 

[RunAgroundHard]

No you are not right. 80kgf is the same as having 80kg resting on your big toe not landing on your toe from a distance.

I don't disagree. However, if you fall 1m at 80kg, the distance to stop I assumed to be 1m as we move to dampen impact. Even if the distance to stop is 0.5m it is still only about 160kgf. On boats we do not fall far and certainly will attempt to dampen the impact. It is not massive.

The point is that we don't need certified equipment to prevent falling overboard, as that is not the hazard. When it happens, and you are still attached to the boat, you need a harness that will tow you from the back, or not have a harness on at all.

 

[rogerthebodger]

I don't disagree. However, if you fall 1m at 80kg, the distance to stop I assumed to be 1m as we move to dampen impact. Even if the distance to stop is 0.5m it is still only about 160kgf. On boats we do not fall far and certainly will attempt to dampen the impact. It is not massive.

The point is that we don't need certified equipment to prevent falling overboard, as that is not the hazard. When it happens, and you are still attached to the boat, you need a harness that will tow you from the back, or not have a harness on at all.

No, it all about Newtons law

Force = mass x deceleration. It not the fall its the sudden stop at the end

I fell from about 1500mm on to the deck of the next boat to me. It was not the fall it was the sudden stop broke the heal of my foot.

If i had fell from the same height into the water I would have had no damage as the stop is much slower (less deceleration)

 

[WannabePirate]

I’ve fallen less than 10cm onto a 60cm static sling before that was anchored about 50cm above me.

No damage, but the level of immense pain from that almost immediate stop really reinforced with me how much I do not want to fall onto an entirely static system.

But that’s why threads like this are good…the adjustable climbing lanyard at the mast was the exact kind of thing I was imagining, and the dynamic line stops the static fall.

In places with jack stays, there is some stretch in these, to provide some braking.

Then a lot of modern safety tethers I’ve seen have what I would call a “screamer”, a small strip of folded over and stitched webbing designed to elongate the force of a fall.

It’s not hard to introduce a suitable bit of dynamic fall arrest into the system, and it appears to me most boats do it by accident/without fully intending.

 

[Mudisox]

I find it odd and totally unrealistic to carry out MOB exercises in relatively calm conditions. Good for manoeuvrability skills but try it in real {+ force 7} conditions. I did it some 50 years ago for 6 months every fortnight testing crews for the 1st Whitbread, finding the "casualty" was always the problem, [less than 10% chance] and the crew being thrown around if you did manage to find and get near the dummy was pretty likely to lose another person.

Moral really quickly learnt by all, was " DON'T FALL IN", in the first place.

 

[capnsensible]

Why not attach two safety lines to your harness or lifejaket strong point? It's not like they are heavy....

 

[lustyd]

No, it all about Newtons law

Force = mass x deceleration. It not the fall its the sudden stop at the end

I fell from about 1500mm on to the deck of the next boat to me. It was not the fall it was the sudden stop broke the heal of my foot.

If i had fell from the same height into the water I would have had no damage as the stop is much slower (less deceleration)

Jackstays are very long and made of Nylon or Polyester so there won't be rapid deceleration. Generally hard attachment points are used only when in cockpit or attaching at the mast so there is even less chance of a fall. Don't overthink it.

 

[dunedin]

I find it odd and totally unrealistic to carry out MOB exercises in relatively calm conditions. Good for manoeuvrability skills but try it in real {+ force 7} conditions. I did it some 50 years ago for 6 months every fortnight testing crews for the 1st Whitbread, finding the "casualty" was always the problem, [less than 10% chance] and the crew being thrown around if you did manage to find and get near the dummy was pretty likely to lose another person.

Moral really quickly learnt by all, was " DON'T FALL IN", in the first place.

But the Whitbread RtW race is hardly typical usage for most cruising sailors. And do most MOB happen in F7 plus amongst cruisers?

For offshore racers being clipped on is priority one. But also the technology has moved on and as Clipper MOB's have shown, AIS PLB beacons hugely help locate casualty.

 

[rogerthebodger]

Jackstays are very long and made of Nylon or Polyester so there won't be rapid deceleration. Generally hard attachment points are used only when in cockpit or attaching at the mast so there is even less chance of a fall. Don't overthink it.

Newtons law still applies

With Jack stays there will be sideways movement that will slow the deceleration down quite a lot

s I said it is no the fall its the sudden stop.

If the stop is by hitting the life lines those then these can cause you to be tipped over or to be cut into by the wire.

This is why my life lines are 38 mm dis tube ans are crutch high to try to stop you from being tipped over and being damaged by a sharpish wire to rail.

The arrangement of jackstays and the teeters are important to arresting any fall and the tensions of the jackstays caannot be too loose other wish it will not restrain the faller. If its too tight it will stop you too quickly and ut more stress on the jackstay and teether

My view is to have a back teether with a quick release and an easy way to stop the boat even for a single hander.

The alternative is to have a way to get back to the MOB quickly with inexperience crew.

Getting a MOB back on the boat is easy for me as I have extending latter that can be lowered from the water nd lifting closkc to life a disabled MOB up out or the water.

The issue is finding the MOB which can be gone with DSC . AIS transponder or PLB. The issue with PLB is that the closeted asset , the boat , has no contact with the PLB so the boat and crew do not know where to go to find the MOB

My MOBi can be connected to my DSC radio, a AIS transponders as well as a plotted. I also have MOB buttons at both helm stations and I could also cnnect a radio remote control button if need be