In 1817 there was a comparison between the "common cork jacket" and William Mallison's "Seaman's Friend." The Admiralty concluded that "any trifling superiority of buoyancy of the Seaman's Friend clearly resulted from the greater weight of cork being contained in it" and declined to consider it further (Estimates).
However, it does appear that Mallison's device featured a crotch strap that was not part of the standard jacket (Brooks). Its importance is illustrated by the case of the yacht Ouzo (2006). Not wearing the straps, the "jackets slipped up the torso, thereby altering their floating angle to near vertical." In two cases, the heads then slipped through the collar, and they ended up face down. The third remained vertical, since he had fitted his lifejacket more tightly, but when he lost consciousness through hypothermia, his neck muscles could no longer support the weight of his head" (Gelder 8).
In 1854 Royal National Lifeboat Institution Inspector Captain John Ward proposed a vest-style jacket that "consisted of small blocks of cork sewn onto canvas, which allowed sufficient freedom for rowing or swimming" (Pickthall 66). It had a buoyancy of 25 pounds (RNLI).
Cork had its problems. Its bulk and rigidity made it uncomfortable to wear and thus discouraged it being worn as a matter of course. Also, when you jumped into the water, it could recoil against you. In the Titanic sinking (1912), it "broke the jaws of some people and rendered others unconscious" (Pickthall). The US Army (10) later warned against wearing a cork jacket when jumping from a vessel, as it could injure the neck or head.
Balsa wood was also used, particularly after WW1. It is even less dense than cork (~16% water) and was native to the New World (unlike cork, which was from an Old World tree). Otherwise, it shared cork's disadvantages.
Bamboo. A stem of bamboo has a low effective density (50% water—Kumar) because it is composed of sealed chambers filled with air. The Chinese were aware of the buoyancy of whole bamboo at an early time. Indeed, Needham believes that the "earliest vessels of east Asia were rafts of bamboo" (695). In 1656 Nieuhoff "sketched a 'floating village,' i.e. a great bamboo raft, on the Yellow River . . ." (390d).
In 1730, a ship on the Batavia-China run encountered a typhoon, and it was feared that the ship would founder. A British passenger observed that the Chinese merchants came on deck in a "bamboo habit." This consisted of eight bamboo stems, four horizontal (two in front and two in back), and four vertical (two on each side). They put this over their heads and tied it to their body (WilkinsonSP vi). An even simpler bamboo life preserver used on nineteenth-century Chinese houseboats was made of just four stems, crossed to form a "#" (Forbes). While I have not been able to document use of any sort of bamboo lifejacket prior to the Ring of Fire, my suspicion is that they existed.
Kapok. The seed hair fibers obtained from the fruit of the kapok tree (native to the neotropics and west Africa) weigh only one-eighth as much as cotton (Britannica.com). Also, the fiber contains a water-repellent oil (PopMech1915). They were first approved by the US Coast Guard as a stuffing for lifejackets in 1902 (Stein 652). I believe that the kapok was originally stuffed inside canvas (RNLI) but later nylon was used (Army).
It was softer and more flexible than cork or balsa. Unfortunately, kapok had some problems. First, "there is a great difference in buoyancy in the kapok grown in different parts of the world, though it all looks pretty much alike (PopMech1915). Second, it was more flammable than cork. Third, if compressed for long periods (during storage, or when sat upon), or if it came into contact with fuel oils, it lost buoyancy (Brooks).
1999CG specifies that kapok should be of a quality "equal to that grown in Java," processed without undue pulverizing, and provide a fresh water buoyancy of at least 48 pounds per cubic foot [164.003].
Gas Inflated. The big advantage of an inflatable PFD is that when uninflated, it is very comfortable.
The modern inflatable life jacket was invented by Peter Markus (1928) and nicknamed the "Mae West." It was "made of rubberized fabric and inflated by carbon dioxide cartridges or by mouth." The gas filled tubes in the front of the jacket and (to keep the head upright) around the back of the neck (Army).
The use of confined air for buoyancy of course was an old idea. The basic problem was making sure that the device did not collapse or leak under water pressure. In 1783, MacPherson reported that he had constructed an "air jacket" (presumably using leather or oilcloth since rubber wasn't yet available) and found that "when first made, and in perfect order, [it] was well adapted for enabling a man to float and swim; but it was a bulky affair, not easily made, still less easily kept in order, [and] expensive . . . " (MacPherson 10).
Another issue was whether the victim would be able to inflate it if it wasn't self-inflating. I believe that nowadays inflatables are used mostly by aircrews and not on marine vessels.
Fibrous Glass. During WW2, it became difficult to obtain kapok. A research program led to the development of silicone-coated fibrous glass as a substitute (Webster). Glass fibers were used pre-RoF for decorative purposes, but fibers with a diameter under 0.00015 inches are preferred for lifejackets and this may be harder to achieve. (The smaller the fiber diameter, the smaller the capillary passages and the greater the pressure required to force water into them—Blefeld.) The silicone, which would have to be reinvented in the new timeline, renders the surface non-wettable.
Closed cell foam. Closed cell foam was first used in PFDs in the 1970s (Arken). The foam is usually polyethylene, polyurethane, or polyvinylchloride. Thanks to the trapped air pockets, densities run 2-3 pounds per cubic foot, versus 62 for fresh water. For more on foamed plastics, see Cooper, "Industrial Alchemy, Part 5: Polymers" (Grantville Gazette 29).
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Legislation and Regulation
In 1852, the US Congress required every passenger steamer "to be provided with a good life-preserver, made of suitable material, or float well adapted to the purpose, for each and every passenger, which . . . shall always be kept in convenient and accessible places . . . in readiness for the use of such passenger." The first British lifejacket legislation was in 1888.
Article 51 of the 1914 SOLAS required that ships carry life jackets, or equivalent appliances capable of being fitted on the body, for every person on board. The regulations (Art. XLV) required that the life-jacket be capable of supporting at least 31 pounds of iron in fresh water for 24 hours. It also required that they be placed where they were "readily accessible" (there was much dispute as to whether they should be in the living quarters or up on the main deck) and "known to the persons concerned."
In the twentieth century, there were numerous instances in which rescuers found sailors who were wearing lifejackets, but were found drowned, floating face down in the water. It was not until 1940 that it was demonstrated that an unconscious human wearing a standard lifejacket would sink, and the lifejackets were redesigned to provide self-righting and head support (Brooks, Macintosh).
SOLAS 1974 required that passenger ships must carry a 5% surplus of jackets. The lifejacket had to be of a highly visible color and equipped with a whistle. Finally, it had to be constructed to eliminate as far as possible all risk of being put on incorrectly, and to be capable of lifting the face of an exhausted or unconscious person out of the water and of turning the body in the water from any position to a safe floating position (inclined backward).
Why inclined backward? Remember the assumption is that the person is unconscious. In supine horizontal, there is risk of death from choking on the tongue. In prone horizontal, the lifejacket must be very bulky to have enough buoyancy to keep the mouth and nostrils clear of the water. In vertical, there is less resistance to vertical oscillations (TransportCanada).
To achieve the desired position as quickly as possible, the lifejacket was designed so its center of buoyancy was in front of the chest (to turn from prone) and as far from the center of gravity of the wearer as possible (to maximize the turning moment). Buoyancy is also needed to support the head. The jacket also should shield the face from spray (I
d.)
By 1996, the Coast Guard was phasing out cork and balsa wood life preservers. Buoyancy could still be provided by kapok, "fibrous glass," or "unicellular plastic foam" pad inserts. (Note that does not include inflatables!) The inserts are inside a pad formed by heat-sealing two pieces of vinyl film together. The kapok and fibrous glass preservers are a vest type, with each side being a "cotton drill" envelope having two front pockets and one back pocket to receive the pads [180.71, 160.002, .005, .055]. They must provide at least 22 pounds buoyancy in fresh water for 48 hours [160.001]. The required amount of buoyant material was 24 ounces (kapok) or 46 (fibrous glass). The foam preservers are a single piece of vinyl-coated foam with a neck hole and body slit, or three sections in a cloth envelope.
CG1999 requires that lifejackets bear retro-reflective material and lights [199.70].For passenger vessels, an extra 5% lifejackets are required [199.212].
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According to canon, several up-time powerboats, notably the Outlaw, came through the Ring of Fire. Given that Grantville was far from the ocean, the chances are that these were used mostly on rivers or lakes and thus were likely equipped only with type II (near-shore) or even type III (flotation aid) life jackets. These are unlikely to have self-righting features. However, the owners of those boats may have books or magazines that provide further information on PFDs.
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Clothing, Swimsuits, and Survival Suits
Ordinary clothing has the advantages of potentially trapping air and thereby reducing heat loss. However, it does hinder movement in the water. Simple swimsuits reduce drag when swimming, but probably provides less thermal insulation than ordinary clothing.
Nowadays, a passenger told to abandon ship might be handed a "thermal protective aid." Typically, it is a suit made of aluminized polyethylene (MYLAR), which is waterproof and reduces heat loss. I don't expect polyethylene to be available until the 1640s; see Cooper, "Industrial Alchemy, Part 5: Polymers" (Grantville Gazette 29). Even if another polymer would do, in new timeline 1636, aluminum is available only in limited quantities, and aluminizing plastic would also require being able to produce a high vacuum (see part 4).
Wetsuits and drysuits provide protection from hypothermia, but can be difficult to put on quickly. The original wetsuit (1952) was made of closed cell foamed neoprene, and later versions sandwiched this between layers of tougher material, such as nylon and spandex (lycra). Both thermal protection and some buoyancy are provided by the gas pockets within the foamed neoprene.
In a wetsuit, water does seep in at the neck, wrists and ankles, and possibly also at the seams and zippers, but is trapped between the suit and the body and warmed. Ideally, flushing (replacement of the warm water with cold) as a result of movement is minimized.
A drysuit features additional sealing features in order to exclude water. The first drysuit was made in the late 1800s by sandwiching a layer of vulcanized rubber between layers of twill canvas, and was used as a diving suit. Dry suits are waterproof but not necessarily insulated.
An immersion suit is a dry suit intended for use in involuntary immersion situations. Merriman (1872) developed a suit composed of "pair of rubber pants and shirt cinched tight at the waist with a steel band and strap. Within the suit were five air pockets the wearer could inflate by mouth through hoses." It was used by the "Fearless Frogman" (Paul Boyton) when he crossed the English Channel in 1875 (Wikipedia). In 1930, it was possible to buy a "safety suit"—a pair of "coveralls" modified to include "locking levers," "life-preserving pads" (flotation), and weighted soles (Pop. Mech. March, 1930).
An anti-exposure suit is "a protective suit designed for use by rescue boat crews and marine evacuation system parties"; it provides extended thermal protection as well as inherent buoyancy.
Wearing a survival suit (with clothing underneath) can double or triple survival time in cold water (GBCAA 3). 1999CG required cargo vessels operating outside tropical waters to carry immersion suits and to conduct donning drills [46 CFR 199.03]. Immersion suits and thermal protective aids were to be carried by passenger vessels beginning in 2003 [199.10]. The rescue boat crew and marine evacuation system member crew for vessels operating outside tropical waters must carry immersion suits or anti-exposure suits [199.70].
Under 1999CG, each passenger vessel must carry at least three immersion suits for each lifeboat on the vessel, and thermal protective aids for each person not provided with an immersion suit [199.214]. Cargo vessels must carry an immersion suit for each person on board, and extra ones for remote watch stations [199.273].
Wearing a dry suit (including a survival suit) for long periods out of the water may result in hyperthermia (overheating) if air temperatures are high.
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PFDs: Life Buoys
Back in 1538, Wyman taught that a good swimmer could equip himself with a flotation device, such as a plank of wood, and swim it out to a person in distress (McManamon)
Of course, it could take time to swim out to the victim, and sea conditions might render swimming too dangerous, so better if the PFD can be tossed to him (but not at him). In early times, these were improvised PFDs. Lucian mentions throwing cork markers for anchor cables to men who had fallen overboard (Pitassi) and in the 1850s, a sailor fell off the Russian brig-rigged steamer Possocchob and was tossed a hatch grating (Mercieca).
Eventually it was recognized that there was an advantage to having a PFD designed for this usage. These life preservers (ring buoys, Kisbee rings) are usually of a donut or horseshoe shape, and have a connecting line so the swimmer can be pulled to safety. The donut shaped version is attributed to Thomas Kisbee (1792-1877) (Nauticapedia).
"Rather than trying to climb up on the buoy, the man pushed his head up through the center, or capsized it so it came back over his head, and he then supported himself on his elbows" (Harland 289).
A variety of improvements were made on the basic concept during the nineteenth century. For example, making it easier to grab hold (a rope around the circumference of the buoy, with possibly hanging grab lines attached to it) or bringing the user up out of the water (providing a frame to sit on)."In the German Navy, cans filled with oil-soaked oakum were attached to the buoy, to help smooth the surrounding sea" (Id.).
The "Franklin lifebuoy" featured two stanchions, several feet tall, holding water-ignited calcium phosphide flares. These would burn for twenty minutes or so, a great advantage for a night rescue, but it should be noted that the reaction with water produces phosphine, a poisonous gas.
SOLAS 1974 required that a lifebuoy be inherently buoyant rather than buoyant as a result of inflation, and provide at least 32 pounds buoyancy for 24 hours. They must be capable of being rapidly cast loose and of a highly visible color. At least half had to have self-igniting lights (there are batteries activated by contact with saltwater; see Cooper, "Portable Power," Grantville Gazette 84) and at least two of these had to have self-activating smoke signals. The required number of lifebuoys was based on the length of the ship (the idea being, I believe, to minimize the distance a sailor on deck would have to run in order to reach a lifebuoy).
1999CG required that "each lifebuoy must be capable of being rapidly cast loose" and "readily available on each side of the vessel," with at least one "near the stern." Lifelines attached to buoys were required to be buoyant, at least 8mm diameter and 30 meters long, non-kinking, and strong [199.70]. And even the shortest vessels must carry at least eight lifebuoys [199.211, 199.271].
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Distress Signals and Radiobeacons
Distress Signals. The point of a distress signal is to attract helpful attention, and in a pinch, anything out of the ordinary will do.
An early practice—I am not sure how early—was to hoist a flag upside-down, assuming that it looked sufficiently different in an inverted position. Another was to tie a knot in the ensign, making what was called a "waft" ("weft"/"wheft"/"whift"). Mainwaring (1644) refers to it as "a common signe of some extremetie. . . ." (OED)
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If ships are traveling in a group, they hopefully have a prearranged accident signal. Lord Howe (1776) directed his ships to fly "white over red flag in the mizzen topmast shrouds" when "in want of immediate assistance" (Prothero)
Some distress signals were already mentioned in connection with lifebuoys. I mentioned rockets equipped with parachute flares and signal pistols in part 4 (Grantville Gazette 71).
Twentieth-century international distress signals include firing a gun at one-minute intervals, continuous sounding of a foghorn, raising a square flag having above or below it a ball or anything resembling a ball, flames on the vessel (e.g., a burning oil barrel), orange-colored smoke signals, red light flares, and slowly and repeatedly raising and lowering arms outstretched to each side.
Radio beacons. During the 1920s, after the sinking of the Titanic, some lifeboats were equipped with spark-gap transmitters. The antenna wires could be held up by kites or balloons (Wikipedia/Survival Radios). In WW2, German aircraft were equipped with vacuum tube-based emergency radio transmitters (NSG2) which were powered by a hand-crank and automatically generated an SOS. This technology was copied by the Allies (Meulstee). There's no point in discussing more modern designs as they aren't likely to come into play in the new timeline 1630s.
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Line Throwing Devices
These were mostly used by rescuers on shore to throw a line to a stranded or wrecked ship. The Manby mortar (1807) was the first such device to be extensively used. It is mentioned, but not described, by EB11. This was apparently a standard 24-pound mortar, but it fired a spherical shot with an eyebolt to which the line was attached (SSVLB).
Grantville Gazette Volume 93 Page 13