Why is a young surfer called a "grommet" or a "grom"?
A grommet is derived from the French word, gremmete (modern-day gourmette) meaning curb of a bridle. Etymonline furthermore states
1620s, "ring or wreath of rope,"
Extended sense of "metal eyelet" first recorded 1769.
The French word, gourmette, means a small chain bracelet, and if you have ever looked at one closely, you'd know that a chain is made of small metal rings connected or linked with one another. Hence today's modern slang grommet means someone who is small i.e. young, and inexperienced.
Oxford Dictionaries says of its modern-day meaning
grommet
INFORMAL , chiefly Australian A young or inexperienced surfer or skateboarder.
Does it feel weird now that, let's be honest, you're not a grommet anymore, and there's expectations and pressure for you to deliver a world title?
Was it hard going being a grommet at school making a lot of money at such a young age?
Below the more conventional (its original meaning) grommets and their use.
Grommet (also Grom, Gremmie, Grem) appears to derive from the term Gremlin:
Grommet:
- A grommet (grom) is a young participant in extreme sports. Originally, a grommet was a surfer under the age of 16. In recent years, this has expanded to include other extreme sports, most notably skateboarding and snowboarding.
The first contextual use:
of the word appears in a 1964 article by the journalist, Nicholas Tomalin, who on a visit to Newquay in Cornwall noted that: "A surfer who is no good or just beginning is a 'gremmie'."
The word "Gremmie", which was used in the United States in the 1940s and 1950s, was derived from the word "Gremlin".
The term "grommet" was used in Lockie Leonard, Legend by Tim Winton: "Things are never as simple as they seem, not even for grommets".
The word was originally a derogatory term for an inexperienced surfer, but has become an accepted term for all young participants. For example, the British Surfing Association offers a Grommet Surf Club for young surfers.
Source:www. wikipedia.org
The term "grommet" has several different meanings in naval history and I would assume that the nautical-ness found its way into surfing culture.
From the Oxford Companion to Ships and the Sea, grommet is described to be "a ring formed by laying up a single strand of rope three times, and used originally to form eyes on the boltropes of sails." Today, these reinforced holes in sails for fittings are accomplished with metal fittings called grommets, but one can still learn how to make old-school rope grommets, or even buy them from crafty people on etsy.
The second definition for grommet provided by the Oxford companion is "gromet or grummett: from the medieval Latin gromettus, a youth or servant in the British Navy. Gromets ranked above ship's boys and below ordinary seamen." I would have assumed that they called these young sailors this as a sort of endearing way to say they are small, lowly, and plentiful, but still important. A further Google search provides this quote from A Descriptive Catalogue of the Naval Manuscripts in the Pepysian Library at Magdalene College - "In every ship 21 men and a garcion or boy, which is called a Gromet' The word is derived from the Dutch grom, or Low Latin gromettus, one occupied in a servile office."
A further search of Oxford English Dictionary confirms that grom refers to a young surfer, with the word being shortened from grommet, and in-use by the 1980's. It also mentions an Australian origin, and you have mentioned South Africa as well - both places with naval histories. In conclusion, I would say that the original spirit of nicknaming a younger person after this small piece of nautical hardware is where the surfing term originates.
None of the answers posted thus far have noted the earlier sexual meaning of grommet in English, U.S., and Australian slang. Jonathon Green, Slang Dictionary (2008) notes both that meaning but and the "surfer" meaning, but doesn't claim that one arose from the other:
grommet n.1 {S[tandard] E[nglish] grommet, a ring of rope, a washer} {late 19C–1940s} (US) 1 the vagina; thus generic for an attractive woman. 2 (Aus.) the anus. 3 sexual intercourse.
grommet n.2 {surfing use, grommet, a novice} {1990s+ (Aus.) a surfer
Eric Partridge, A Dictionary of Slang and Unconventional English, eighth edition (1984) has only the sexual meanings (not surprising given that, according to Green, the Australian surfer meaning arose in the 1990s, although instances from the mid-1980s have since been identified):
grommet. Var. spelling of grummet, coition, hence, the female sex.
...
grummet (or grommet,-it). The female pudend: low: nautical, since mid-C.19, > low gen. Ex grummet-hole, itself ex grummet, a little ring serving merely to tie gaskets (Manwayring, Seaman's Dict[ionary], 1644—cited by [Ernest W[eekley, Etymological Dictionary of Modern English (1921).—2. Hence, coition: nautical and low: since mid-C.19.—3. Hence, girls and women, regarded as sexual objects: raffish, low and joc[ular]: since ca. 1950, ?earlier. Patrick Campbell, Come Here Till I Tell You, 1960, 'two lovely bits of grummet'. Also Aus.
Tom Dalzell & Terry Victor, The New Partridge Dictionary of Slang and Unconventional English (2013) have a small entry for grom and a much expanded entry for grommet:
grom noun a beginner surfer US An abbreviation of GROMMET. [First cited instance:] Surfing, p. 43, 14 March 1990
grommet noun 1. a novice surfer, especially one with a cheeky attitude AUSTRALIA, 1981 [First two cited instances:] — Nat Young, Surfing Fundamentals, p. 127, 1985 ... — Tracks, p. 82, October 1985 2. by extension, a zealous novice in other sports US Recorded in use by skateboarders by Dan Maley, Macon [Georgia] Telegraph and News, p.9A, 18 June 1989. 3. a child; a young person AUSTRALIA [First cited instance:] Dirk Flinthart, Brotherly Love, p. 33, 1995 4. the anus UK, 1889 [Only citations are from:] —Robert S. Close, Love Me Sailor p. 4 [and p, 158 and p. 221], 1945
Robert Chapman & Barbara Kipfer, Dictionary of American Slang, third edition (1995) has this:
grommet n by 1986 An early teenage or subteen person in a surfing milieu[.] Apparently a borrowing from Australia, where it is also spelled grummit: ... an ersatz club scene for junior high-schoolers, grommets, kiddies ... —Los Angeles Times {origin unknown; grummit and grommet are found by the 1890s in the sense "vulva," where the reference is probably to various rings used in ship's rigging, but the semantic connection here is uncertain}
Several slang dictionaries associate the earlier sexual meaning of grommet with rope rings used in ship rigging, and report that this slang usage was known in the UK, the United States, and Australia. For its part, the "young surfer" meaning of grommet may have arisen in Australia by 1981 and certainly existed by 1985; it is also recorded in the United States by 1986.
I am not convinced that the surfer term grommet has any connection (beyond coincidence) to the earlier sexual term grommet. However, the sexual term was known in Australia prior to the emergence of the surfer term, and the fact that the sexual term has a fairly long history in English at least deserves notice in connection with the posted question.