The fantastic creature above was posted to his Deviant Art account by "Pristichampsus" (Tim Morris) as illustrating one of Bruce Champagne's Sea Serpent types. In order to deal with this better, we shall need to go back to the original statement Bruce had made. The summary of the type and the reconstruction illustrating the type are reproduced below:
4B Sailfin: An elongated animal of possible mammalian or reptilian identity reported from 12 to 85 feet long. It has a long neck with a turtle-like head and a long continuous dorsal fin. Cosmopolitan.
My comments were as follows:
"4B is obviously the same as the Valhalla Sea-Serpent. I do not know why BC gives it such a wide size range nor Geographic range, although I was aware of other reports of the type (Heuvelmans calls one a "Marine Dimetrodon"). I actually do not know what it is, but with that head and neck it is presumably related to the Plesiosaurs."
Now as to what Tim Morris had said:
4B Sailfin as fish
This was also followed by:
Going back to the oarfish idea there is probably more to it than any of us realized before.
Oarfish are large, greatly elongated, pelagic Lampriform fishes comprising the small family Regalecidae. Found in all temperate to tropical oceans yet rarely seen, the oarfish family contains four species in two genera. One of these, the king of herrings (Regalecus glesne), is the longest bony fish alive, at up to 17 metres (56 ft) in length [One of the sources cited says "over sixty feet"].
The Oarfish have three aspects that are important here. Firstly, the back fin of the sailfin from the neck on back is much the same as the oarfish. Secondly, the geographic range is the same as the oarfish's range and thirdly, the alleged size range is close to the alleged size range for the oarfish. In the case of Tim Morris' depiction, it struck me right off that the head of the creature even has an indication for the "Oars" of the oarfish in the "Barbels" it has, and swimming by means of wiggling the back fin is also a trait of the oarfishes. So in general I think we have a category that includes some non-standard Longneck sightings (including probably both the Valhalla and Soay SS sightings) intermixed with some mistaken reports of probably just plain oarfishes.
In other words, Longnecks plus oarfishes equals the Sailfin sightings of this Bruce Champagne Sea Serpent category: