This has got to be one of my favorite boards in the collection. I found it in the roof space of a 'Money Lend' shop in Rockdale.
The 'Clinker Bottom' design is a combination of extreme vee and deep channels, usually four, placed between centre and side fins. Initially it was introduced on twin fin designs like this one, circa 1979 by Laurie Byrne at Byrne Brothers Surfboards, Wollongong, NSW and later used on 3 fin designs. Its 5'9" and has a single fly coming off the side channels with a swallow tail. It has really large base fins for this length of board. The spray is incredible, fading on the deck and striped down the rails finished with delicate pin lines. But it is the spray work in the channels that blows me away.
I've heard that its hard to get a good channel botom any more, not because the design isnt functional, but because glassers refusse to get in there and do all that extra work of glassing and sanding channels.