Page 71: of Marine Technology Magazine (September 2022)

L L L L L L L L L L L L L L L L L L L L LA A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A AN N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N ND D D D D D D D D D D D D D D D D DE E E E E E E E E ER R R R R R R R R R R R R R R R R R L L L L L L L L L L L L L L L L L L L L L L L LA A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A AB B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4

FUSIBLE LINK (FLASH WIRE) Developed by DesertStar for their ARC-1 acoustic release, a large capacitor is fully charged, then power dumped through a high resistance nichrome wire, causing it to instantaneously vaporize. Sometimes called a “? ash wire”, the ARC-1 trig- gers just 10 seconds from the release command, and the trig- ger process itself takes just 0.03 seconds. The ARC-1 has only a single moving part, making it very reliable. Biofouling would not be a concern for the ? ash wire, though it may gum up the lever arm. It also operates in fresh water. Since its introduction, the system has accumulated tens of thousands of release cycles.

Figure 11 One can imagine the combination of a ? ash wire release, A SubSeaSonics LK-80 release link electrically isolated pressure sensor, and programmable controller for bottle clo- from the steel chain with a plastic link. sure that would allow the collection of water samples at pre- cise depths by a free-ascending lander, now a pro? ling ve- hicle. A series of CTD casts could occur quickly with a small number of untethered free ascent rosettes.

PRESSURE

The trigger is pressure. This is a sensor that activates a cir- cuit at pre-determined depth, or a mechanical element that reacts to increasing ambient pressure in such a way as to initi- ate a release.

MELT

Hot wire

Weed whacker nylon cord or heavy mono? lament nylon

Figure 12 ? shing line can directly attach an anchor weight to a lander Galvanic time releases frame. Crossing the mono? lament like a bow on a cello, is a length of Nichrome wire. Current through the wire causes the nichrome to heat up, slicing its way through the nylon.

Performance may be improved with thermal insulation from the environment.

Ice

Ice has a very high compressive strength, as evidenced by Ti-

Desert Star Systems Kevin Hardy Ocean Appliances, Australia Kevin Hardy tanic’s head-on collision with that iceberg, or a USAF C-130

Figure 13 cargo plane landing on an Antarctic ice sheet.

Featuring the fastest release of any release system,

As a result, ice makes an easy, cheap, and strong release ca-

DesertStar’s ACR-1 opens in under a 1/10 sec.

pable of holding up to 300-lbs. Enclosed in the thermally insu- lating PVC, the release can take up to an hour to release. The

Figure 14 ice will de? nitely melt, so a release is assured, though time

Standard 1” sch 40 PVC pipe may vary with water temperature. makes an ice release that will hold 300-lbs for up to an hour. An

DISSOLVABLE eye bolt passes through the top

Lifesaver cap, with a ? at washer and nut

I remember reading an in-house technical brief shared with on the interior, and sealed with me by Scripps machinist Mert Ingraham, written by a Scripps

RTV. A slot at the bottom allows grad student in the 1960’s describing the use of Lifesavers as for a loop of line to be inserted. a release. That student used a lever arm to multiply the force

The release is then turned with to hold a larger anchor.

the slot up, ? lled with tap water, then placed in the freezer. www.marinetechnologynews.com

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