As the Coast Guard works to replace a navigational tower toppled in a car crash at Kewalo Basin, it is also busy modernizing its extensive network of beacons and buoys.

The goal is to keep boats off the rocks and reefs.

It's a tall order. Despite its best efforts—and a $1.5 million annual maintenance budget for so-called “;aids to navigation”;—the Coast Guard district here saw 23 recreational boats run aground from 2005 through 2008, an average of nearly six per year. So far this year, four recreational vessels have hit the reef.

Each year, an equal number of incidents afflict commercial vessels around Hawaii, including charter and fishing boats, but the tally includes bumping into a pillar or pier, incidents the vessels are required to report, Coast Guard officials say.

Two of the more infamous mishaps are the grounding of the cruiser USS Port Royal off the reef runway earlier this year and the grounding of the oil tanker Exxon Houston off Barbers Point in March 1989, which foreshadowed the catastrophic spill from its sister ship Exxon Valdez in Alaska only three weeks later.

“;We are definitely first-responders, but we put a lot of effort into prevention—so there is no need to respond, and that is hard to measure,”; said Lt. Cmdr. Rocklyn McNair, who directs the maritime-safety education efforts of 400 Coast Guard Auxiliary members in the U.S. Pacific isles.

Prevention efforts include a system of 67 lighthouses and light towers at harbors and hazardous points like Diamond Head, Makapuu and Kilauea, Kauai. Converted to solar power in February was the light tower at Lahaina Harbor, which occupies the site of the first lighthouse in Hawaii, ordered erected by Kamehameha III in 1840.

Getting smaller lights off the power grid is possible through light-emitting diode (LED) technology, which is cheaper, more durable and requires less electricity. The light at Maui's McGregor Point became the first in Hawaii to receive LED technology and solar power in May 2008, followed in September by the Merry Point light in Pearl Harbor.

Also spreading is a system that allows ships and major channel buoys to share their positions almost instantaneously via satellite, said Lt. Cmdr. Dale Shepardson, chief of the Coast Guard's local Waterways Management Branch, in an interview Friday. The Nationwide Automatic Identification System, authorized by law in 2002 and set up two years later, allows the transmission of data, like GPS position, course and speed, digitally at very high frequencies.

It provides a far more accurate and timely picture than radar, Shepardson said. But right now only big ships have it.

Meanwhile, the Coast Guard is studying the extent to which it can incorporate newer technology or better materials as it replaces the tower that fell at Kewalo Basin June 21. That tower, first erected in 1929, was rebuilt in 1961.