Here is a carrier/tower look-a-like to the lake yarder! Picture from 1963.
In the end sixties it seems Skookum introduced their own style spars, here a clip from "What's new in logging" 1969:
New Skookum Spars
The Skookum Company, Portland, Oregon
Two new mobile-spar models have been introduced by Skookum Company. Designated Model R and Model H, they replace the old Model S in the company’s line. The new models have many advanced design features. Most noteworthy is the completely redesigned hydraulic raising system which now lifts the spar to an almost vertical position. Skookum says that, in addition to the increased angle, the speed of both raising and lowering the spar has been substantially increased also.
Both new models are 90-feet tall and are designed for use with 1 3/8 in. mainline. The Model R is intended for use with conventional three-drum yarders. Model H has an extra fair- lead and other features making it ideally suited to four-drum yarders. The Model H will also appeal to loggers who like to use the Gravity Outhaul yarding system with a three-drum yarder.
These new models, like other Skookum spars, give the logger the choice of yarding with the spar in a vertical position or leaning it forward or away from the yarder. The adjustability of spar position is useful in locating the lines to the best advantage for landing logs.
Models R and H are available in an engineered package consisting of the spar, tractor undercarriage and Skookum-Tyee yarder. “This integrated unit”, says a company spokesman, “is the quickest moving and most versatile yarding machine of its size ever built”.