MANUFACTURER HISTORY
The Side-Slipper was a stock design for Farrelly Surfboards in Nov 1969, along with Midget Farrelly's Rounded Pintail and Squaretail 'White Kite' designs. 
At a cost of $125.00, it was a premium product trading on Midget Farrelly's designs and an  immaculate finish that set the benchmark for the rest of the industry. 

DESIGN HISTORY
The Side Slip (Fin Drop Out Stall) was first identified in 1967 by Bob McTavish in an  article titled...
bob mctavish is in this  wave. he probably had a plan to get out of it, 
(Surfing World Magazine January 1967 Pages 15 to 21).

A compendium of (long board) manouvres , it includes...

FIN DROP-OUT STALL
is by far the most efficient, most difficult.
If performed correctly, it can eliminate a cutback.
Everyone has experienced a fin drop-out and its main effect - loss of forward motion. 
When emerging from a hot hollow section it's possible to remove the fin from the wave intentionally, and establish a sideways drift towards the beach.
Perfect stall.
No forward motion. 
As the wave recovers and starts to wall, drop the fin in by back-peddling, recover some sort of trim, and move out. 
Nat Young and I spent two days at Noosa working on this, succeeded about four times each. 
The big problem is knowing just when the fin is going to break out. 
We are working on special nose and fin shapes for this purpose."

IMPORTANT : Not to be confused with "slipping the board " - a nose riding manouvre taht does not dis-engage the fin.
As demonstrated by Miki Dora in Bruce Brown's The Endless Summer, 1964.
This was described by Bob McTavish in the above article as...

 SIDE SLIPS can be performed anywhere on the front half of the board. 
They throw the board out of an inside rail stall, and set up a highly efficient trim for half a second while the board is banked outwards. 
This half second or so allows the board to leap forward. 
The acceleration is noticed as soon as the sideslip is checked, and the momentum gained from the small drop is redirected.

Side slipping became an recognised manourve in 1969, as demontrated  in John Severson's Pacific Vibrations, 1970.
Particually well executed by Jock Sutherland, the film also featured extreme spinning 360's..

	Left : Dick Brewer, Reno Abellira, Oahu, 1969 Inter-Island Surfboards, Hawaii. Photograph by (David?) Darling Kampion page 51   Below : Inter-Island Surf Shop decal,  Collection : Cary B. Weiss Schiffer, page 39
	Image left :(Wide tail)  Inter-Island Flip Tip. What Reno rode in '69! www.oneworldsurf.com/restorations 16 December 2000

 
Reno Abellira and Inter-Island Side Slipper with hyper-kicked nose,  Huntington Pier, California, 1969.
Photograph Art Brewer - Nat Young : History,  Page 104

A flat bottom with a down soft rail that reduced the possiblility of catching edges was used to control the side-slip and re-engage the fin 
Subesquent to this design down soft rails  became an industry standard.

A hyperkicked nose reduced the chance of burying the nose and helped in recovery.
Nose lift and bottom rocker variations would be extensively explored by designers for the next 30 years.

In Australia the down soft rail, with a release edge, was developed through the experiments of Gordon Merchant. (Find relevant articles)

In Australia the design was taken up by Midget Farrelly (Farrelly Surfboards) and Terry Fitzgerald at Shane Surfboards.

---

---

---

Shaun Tomson (then 14 years old) noted that at the 1970 World Contest, he and Western Australia's Ian Cairns:

Although Reno Abellira and Midget Farrelly rode Side Slipper designs, there are no contest photographs of them (or others) side slipping.
The situation is similar in Paul Witzig's Sea of Joy, 1971.

Due to the lack of suitable wave conditions, the required high skill level, the potential for confusion in crowed conditions and/or the rejection  by contest officials: side slipping receeded dramatically.

While the Side Slipper appeared to be a minor deviation, it did have  major design influence...
- down soft rails  became an industry standard.
- encouraged research into fin boxes ( by 1972 the Bahne system became an industry standard).

The manouvre, despite all predictions, would re-appear in the late 1980's initially as the Floater, credited to Mark Sainsbury.
In an extended re-entry the ridder dis-engages the fin and slides the board across the back of the crest.
Such a manouvre was unthinkable in 1969 without the performance, particually the recovery control, provided by Simon Anderson's Thruster.
Along with the development or "getting - air " , modern surfing (circa 2004) commonly incorporates variations of the side slip.

Due to the ten year gap, the connection between side slipping in the 1969 and the 1980's was, understandably,  largely ignored by commentators.
REFERENCES:
Other Keyo surfboards 
See Keyo Surfboards
Film
John Severson : Pacific Vibrations, 1970.
Paul Witzig : Sea of Joy, 1971
Bruce Brown : The Endless Summer, 1964
Books
Nat Young : History,  Page 104
Walding, page 76.
CONDITION: 5