Thanks to Archer Koch of MultiRotorCam.com, we are updating this story with his great aerial video of the wave motor pumping it out in February, 2015.

Along West Cliff Drive, just east of Natural Bridges State Beach, is a strange concrete cork feature on the edge of the sea cliff. Locals know it as the blowhole. If the waves and tide are just right, you’ll see and hear water being forced up and out of its three holes with a huge “THWUMP.” It’s pretty impressive. The concrete cap covers a shaft that is the last remaining evidence of a wave motor built in 1898 by local brothers, William and John Armstrong.

The motor dates from an era around 1890-1900 when several wave and tidal energy projects were undertaken in California (including several in San Francisco near the Cliff House and one on the Capitola Wharf in 1895). While most tried to generate electricity and failed, this one, designed only to pump water, was one of the few successes.
Its purpose was to pump ocean water into a large storage tank on a high platform. The water was later used to fill a smaller tank on a horse drawn carriage and sprinkle what was then Cliff Drive to keep the dust down for the tourists. The wave motor was commissioned by the City of Santa Cruz in 1897 after the Armstrong brothers created a successful prototype at Black Point (about 5 miles east of here). The venture was a great success. Cliff Drive’s dirt streets were dust free and sparkled with salt from the sprinkled ocean water for about 12 years until the coming of pavement made the need for sprinkling sea water…evaporate.

How Did it Work?

The installation consisted of two shafts drilled 30 feet into the cliff, one eight feet in diameter and the other five feet. In one shaft was a huge 600-pound float that drove a piston within a pump in the neighboring shaft. As the wave surge entered, the heavy float in the ocean-ward shaft and the pump in the landward shaft both rose. The float and piston were attached via a cable to a rigid bar, which acted as a lever. The rising float caused the lever to pull upward on the one-way piston-pump and squeeze water up into the discharge pipe. As the wave surge went out, the heavy float dropped and check valves in the piston and piping prevented backward flow of water. On the next wave, the cycle was repeated.

Some accounts of the wave motor report that there was a check valve in the tunnel that went out to the ocean. If this is true, when the wave surge ebbed, water would have been prevented from leaving, and (despite the piston moving downward) water could still have been forced upward through the pump cylinder, creating continuous pumping of water. To stop pumping, they simply removed the water from the barrel counter weight. The heavy float still bobbed up and down but the force was not transmitted to the rigid bar.

An Idea Ahead of Its Time

The technology available to harness wave energy in the late 1800s was a bit short of the task. Over a century later, harnessing tidal energy is again an idea being tried. In fact, France’s La Rance station has successfully generated about 250 megawatts since 1966 and there are 7 other projects around the globe in operation today generating from 1 to 254 megawatts. Several other plants are currently being planned or built, including one in New York City on the East River that is supposed to open in 2014 and generate 2.4GWh of electricity annually.

The Site Over Time

The local sea cliffs are made of the fairly erosion resistant Santa Cruz Mudstone and the small peninsula on which the wave motor stood has not eroded much since the 1890s. Both wave motor shafts were intact until at least 1979. By 2004 the oceanward shaft was breached but you could still see the curved surface of the bore. The landward shaft was filled with a concrete plug in 2005.

While the cliffs have not changed too noticeably over time, the houses across the street at 2244 West Cliff Drive have. In 1979 there was a small house with few windows, surrounded by many open lots. By 2004 it had been replaced with a house that had many windows, occupied the whole lot, and was wedged in with similarly large lot-filling homes. The current house was built in 2008/9, also fills the lot, and has fewer but extra large windows. The changes follow the post 1960’s trend of increasing use and cost of oceanfront property and the desire to maximize home size and ocean view.

Take the Self-Guided Mobile Tour

This piece is part of the West Cliff Drive Tour. Download the free app with many tours of the Santa Cruz area and beyond.

Further Information

• About tidal energy
• Local Historian Frank Perry’s Website
• Sandy Lydon’s web page on the wave motor