MANUFACTURER: McGrigor Surfboards, 238 Harbord Road, Brookvale. 93 4965
DESIGN: Tri fin
Foam blank, 1/4" redwood stringer, Volan glassed with tint. Diminshed rail lap on bottom.
Nose: semi pin
Rails: thick down
In Australia this design had a short but well publicised life circa 1971 - 1972.
Following the experimentation with the Twin fin 1, several designers used variations of tri-fin configurations. The rail fins were usually small and long based, the inside often foiled flat. Position varied enomously from behind to well in front of the central fin.
This early experimentation established the principle that pocentral fin would stiffen the board and make it track, while a position in front of the fin would loosen up the board and make it msitioning behind the ore manourvable.
Narrowing the angle of attack and tipping out of the side fins was a progressive process that produced the Cambell Bros.' 1973 Bonzer, a combined fin and bottom design based on Ruellego Delta designs. The original design , with leading rail fins, was retained on many kneeboards 1971 to 1976, see Crozier #58
The Tri fin was to reach its peak with the development of Simon Anderson's Thruster (1981) design, placing three similar fins at the tail extemities to maximize manouvreability in small waves. It was subsequently found to superior to all previous designs.
Bob McTavish, Tri fin and Dog,
Barry Bennett Surfboards, 180 Harbord Road, Brookvale 1971
From... Mike Davis :Design Through Development in The Best of Tracks 1973.
Mc Grigor Surfboards Advertisment
Tracks magazine, January 1971 Number 4
Note : The two boards shown are in fact Twin Fin 1
Text reads : on shapes. on glass, on finish, on sand, on buff, on pinline, Geronimo on till.