Self-rescue tether D4S

Patent FR2979097

Return to www.design4sea.com

Self-rescue tether (model TV3E)

Self- rescue tether?

The self-rescue tether is used like a tether. Secure it on your harness and/or life jacket, and clip it on a deck lifeline and.or a strong point. In case of fall overboard, the self-rescue tether helps you to climb aboard alone.

Precautions: the harness or life jacket must be equipped with crotch straps otherwise it may slip out while you are dragged in the water.

Avoid clothing that may become dangerous in water. Sea boots are especially dangerous, but also gloves that you cannot remove with the teeth, open jackets ...

Fall overboard: impossible to climb aboard alone (1998, 2012)

Against intuition, it is almost impossible to climb aboard alone after falling overboard even if you wear harness and tether. Furthermore, without adequate equipment and training, it is very difficult for a single person to lift you aboard.

This was demonstrated in a study by the Seattle Sailing Foundation, 1999 (pdf). More recently, a yachting review claimed that it was impossible to climb aboard when the boat is running. In both cases, the "proof" was made with classical commercial tethers.

Falling overboard is a deadly risk for single-handed sailors and short-handed crews with little experience. Every year, sailors die in the water ... more.

Yes, we can save our lifes

We capsized in 2010. We have been hanging outside the hull by our tethers in big seas (6m waves, breakers) unable to climb aboard. So, we designed a new tether. In fact, it is more than a tether. See video

Boat: Beneteau Oceanis 44, school boat of Academia Nautica Probanza.

Under engine + partially furled genoa at 5 knts, speed decreasing slightly (4.5knts) at the end of the test (crossed waves)

Participant: male > 50 years old, 70kg.

Clothes: trousers, t-shirt + sweater, sea jacket, deck shoes. Weight of wet clothes: 5 kg.

Safety gear: harness with tight strap, self-rescue tether TV3E3

Fall in water through open lateral door.

Equivalent to worst case: deck safety line pulled outside, anchoring point at deck level, like when stanchions/lifelines are broken.

Time to climb aboard: less than 2 minutes.

How it works

Hoist yourself. The device works like a hoist, i.e., it can be shortened.

For instance, the initial length ~1.40m becomes 45cm. As the length decreases, the self-rescue tether lifts you towards the deck.

Reduced effort to lift you up. The device contains several loops of straps (3) that divide the effort by 6.

For instance, if your weight is 90kg (including wet clothes + water caught in rope/boots), you only have to lift 15 kg.

The speed of the boat adds some weight, but not much. Observe carefully the video...

Minimal effort to hold you up. The loops are made of strap instead of rope, because the friction is much higher.

The friction (capstan friction + surface friction) reduces the effort to holds the strap, which allows pauses.

With a rope, the holding effort remains high, it is not possible to take a pause.

To secure yourself, tie a simple knot with the extremity of the strap you pulled out.

Several sections. The device contains 3 sections, i.e. 3 short hoists instead of a large one.

One single hoist may get stuck at the edge of the deck or on the lifelines. With 3 sections, there are two hoists left.

Stirrups to finish climbing aboard. After you reached the deck level, your body is still outside and below.

There are 3 independent stirrups of different length packed in the last section.

Climbing aboard without stirrups is possible but demanding, and you may be exhausted by the stress of the fall.

Self-rescue tether, complete and shortened (model TV3)

Shortening the self-rescue tether (model TV2S). From left to right: shortenable section, open sleeve, section is shortened.

This is illustrated in these two videos, one recorded from deck and the other from the water.

Safety gear: self-inflatable life vest Certec, model Rafale. Self-rescue tether D4S.

Resistance

Laboratory tests ISO 12401: the device (model TV3) passed all the laboratory tests of ISO12401.

Dynamic load, sea water, magnetic test, usability. APAVE,Grenoble, France, May 2012 pdf (details: pdf, pdf).

Preliminary tests. At Chantier Naval Socoa. 160kg concrete block, 2.20m fall, static rope.

The static rope integrally transmits the impact. The test gave a wide security margin for ISO 12401 (100kg , dynamic rope).

a

Preliminary tests before ISO certification. 160kg concrete block, platform ~3.5m above ground.

Validation

Falls and rescues. The device was tested by voluntary participants on the boat of the Academia Naútica Probanza.

Classical safety equipment (tethers, harnesses, life jackets, trailing lines..) and techniques (e.g., lifting a person from the deck) were also tested.

Usability. The device was used in a 7-months single-handed sailing to Cape Horn and Antarctica. See Matxitxako Horn

After a fall overboard

The tether is tangled (líneas de estribos, cintas..). However it can be checked, rearmed and used again (unless there is a structural damage). It does not contain any disposable part (like gas cartridges).

We recommend a revision by the manufacturer (contact us) or your distributor.

In case of necessity, the user can rearm the device alone. Follow carefully the instructions.

Standard model

3 sections, 3 stirrups

Length ~135 cm.

Weight < 800 g .

3 shortenable sections. Length at rest ~40 cm, shortened ~8 cm.

Semi-automatic snaphook .

Textile loop for harness binding.

3 stirrups in independent sleeves. Length deployed 80 cm, 110 cm, 140 cm, folded ~25 cm.

Size adapters for stirrups (3 dyneema loops to enlarge stirrups).

Belt pouch.

Plasticized instructions.

Options

TV3E3Q: Quick release system (fast release snap hook + textile loop).

TV3E3A: Omni-anchoring line (Technora elastic line + light snap hook; replaces double anchoring on classical tethers).

TV3E3L: Higher strength ratio (8:1 instead of 6:1), reduces the effort to hoist oneself.

TV4E3: Additional section (augmented length 1.75 m).

Options can be combined.

Custom models on demand

Features

Snaphook

Kong series 706.12. Semi-automatic (1/4 turn blocker) for professional use (certified EN 362), polished aluminium 12 mm thick.

Rupture load >= 2200 kg.

Harness binding

Dyneema loop 4mm diameter spliced around a stainless steel ring.

Length deployed ~ 15cm, tied ~ 5 cm.

Rupture load > 2000 kg (rupture load of rope: 1250 kg).

Binding to harness: lark's head knot.

Shortenable sections

Length at rest ~40 cm, shortened 8 cm.

Doubled strap of polyester 25mm wide, forming 3 loops between stainless steel rings.

No structural sewing.

12 layers of strap (3 loops x 2 threads x 2 layers ). Rupture load of each layer of strap > 500 kg.

Sleeve-handle: PU-coated nylon fabric, sewn on a 25mm polyester strap (handle).

Fastening of handle: self blocking loop on two stainless steel rings, AISI316, welded, 5 mm thick.

Structural rings

Stainless steel AISI 316, welded, 8 mm thick x 40mm internal diameter

Stirrups

Loops of 2mm dyneema braid, spliced, deployed length ~ 80 cm, 110 cm 140 cm, folded ~25cm.

Steps: compact polycarbonate, covered with reflectant SOLAS material, not structural (weight supported by the dyneema loop).

Individual sleeves made of reflective fabric, length 25cm, secured to the stirrup (not lost at sea).

Rupture load of a stirrup >= 500 kg (rupture load of the rope > 400 kg).

Visibility

Reflective material SOLAS grade on handles and steps. Total surface on handles 37.5cm2, on steps 102 cm2.

Luminescent material long lifetime SOLAS grade on handles. Total surface on handles: 37.5 cm2.

Maintenance

Periodic maintenance: clear water, soft soap, 3-in-1 oil.

Can be dismounted entirely without tools.

Every part can be replaced separately.

Reusability

The device is reusable inasmuch as there is no structural damage.

The device contains no disposable parts (counter-example: gas cartridge for life vest).

Environment.

No waste in water after use.

Reusable conditioning (harness pouch, to keep the device and/or carry tools).

Exploded diagram

Return to www.design4sea.com

Design 4 Sea is a registered trademark. Disclaimer, Terms of use, Credits and Copyrights