This quote from Paul Johnson’s news article may be the best definition I’ve seen: “surf music is best understood as the west coast regional variation of the larger rock-instrumental form, which had enjoyed enormous acclaim nationwide all through the prior history of rock ‘n roll”.
Having been a child, growing up in the upper Midwest, at the time, the distinction was a bit less obvious. From the perspective of a kid in Minnesota, California was cool cars, beaches, drag racing and warm winters. Most of what I knew about California was from the artwork on model-car boxes, or what I saw in Hot Rod Magazine. Then there was TV and movies, which meant the Beverly Hillbillies, and movies. It seemed that a lot of TV and movies were set in California. I use the name California, because it was all the place, if you went by what was presented on TV. For all I knew, the Beverly Hillbillies walked to the end of their driveway and directly to the beach. 
In all seriousness, the perspective of someone 1,900 miles away, it was more like being a spectator and we probably were more likely to associate The Beach Boys or Jan & Dean with surfing than the music. As Paul mentions in this article, https://surfguitar101.com/news/story/724/, they started out playing the Rock instrumentals and found themselves gaining the attention of surfers, whom identified the sound of that music with surfing. That leads me to think that the Fender reverb unit had a lot to do with all of this. From what limited experience I have on Pacific coast beaches, I know that the roar can be quite persistent. It’s no huge leap of imagination to link that to the sound of a 6G15, cranked up.
Reading Paul’s article has given me new perspective on Surf Music. It comes down to viewpoint, or as Einstein would have said, frame of reference. Had you approached me on my 8th birthday, in Minnesota, and asked me what Surf Music was, I would have said The Beach Boys, and this makes sense from a frame of reference which had no way of knowing what was actually going on in Southern California, at that time. If you had asked me where surfing was happening at that time, I would have pointed to the southwest, in the general direction of California, and I would have been right. The distinction between Huntington, Doheny, Malibu, etc. would have been lost on me, at that time. Likewise, I would have lumped Dick Dale, the the Chantays, etc. together with Duane Eddy or the Ventures. The factors which distinguished these as not being Surf Music were essentially invisible from my location and ranges of experiences, at the time. The first time I saw the Pacific was nearly 3 years later.
Then there’s the thorny issue of music recorded by session musicians. The Ship of Theseus is a philosophical puzzle about a famous wooden ship, kept as a museum piece. As individual boards deteriorated and were replaced, at which point was it no longer the Ship of Theseus? Likewise, if someone were to venture to coastal, Southern California in 1962, and copy a Surf tune, which they took back home and played that song, is it still Surf Music?
By one definition, it is a copy of Surf Music, but what if that person is an avid surfer and drives from Yuma, AZ to go surfing every other weekend? I don’t mean to indulge pointless scenarios, but this serves to illustrate the point that the tighter you try to nail down the definition, the more slippery it becomes. While Surf Music was initially a phenomenon of the Surf Culture of Southern California, it grew far beyond those roots and became a national phenomenon, but the frame of reference was different.
Likewise, if a mature session guitarist played a Surf song, is it still Surf Music? From the perspective of someone in a SoCal Surf band, the answer would be no, but from the perspective of a kid in Minnesota that heard Pipeline earlier in the day and wanted more of the same music, The Marketts were just fine.
It all comes down to definitions, and frame of reference. I loved hearing Duane Eddy on the radio, when I was quite young. I loved the Ventures, I loved Apache, I loved Pipeline and Wipeout. I still do. About 1/3 of the material Clutch Draggin’ and the Lug Nuts plays, is Surf. Much of the rest would be non-instrumentals from the early to mid ‘60s. We started out playing local car shows and Surf was very popular at those gigs.
One other thought comes to mind, which may well be lost on someone born in the sixties and beyond, is the role of instrumental music at the time that Surf Music emerged. Lawrence Welk had Top 40 hits at the time and was hitting the Hot 100 into the mid ‘60s. For guitar based songs, played by younger artists to venture into instrumentals was a bold step. Most of the instrumentals up to that time had been played by orchestras, or Big Bands. For some kids to show up with guitars, a bass and drum, expecting to be taken seriously was a real change in direction. Most amazing is how well it caught on.
Throughout the rest of the ‘60s, twangy guitar with reverb and/or tremolo became a staple in instrumentals that made no claim of being, in any way, related to Surfing. These might take the form of lush orchestral arrangements with a twangy electric guitar playing the melody. The original “Charade”, as used in the movie, started with a sparse arrangement of percussion with an electric guitar playing the melody. It then grows into a much more lush orchestral arrangement, ending up with the guitar playing the melody with the orchestra in the background. Before Surf Music, that was a very unlikely pairing. Beyond that, the Ventures were quite prolific in the ‘60s, with an audience far beyond the youth market. My father, whose tastes in music were quite conservative, loved The Ventures. Likewise, there was the Spy genre, the Space genre and Western soundtracks.
I would see this as a “long tail” effect of Surf Music. Not so much derived from Surf, but the basic guitar sound grew into other genres. Surf sort of paved the way for this expansion, although, to be fair, you could credit it back to Duane Eddy just as easily. Perhaps the best thing to say would be that the popularity of Surf helped bring this sound to a greater audience, and helped it make the leap from the youth market to acceptance in movies, etc.
bigtikidude wrote:
I’d say jazz was a big influence on surf.
also possibly exotica and Hawaiian music.
do you mean that I the sense of instrumental melodic lines being out front?
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The artist formerly known as: Synchro
When Surf Guitar is outlawed only outlaws will play Surf Guitar.