Alaskans sometimes get suspicious when the federal government comes to town, but with the arrival this month of two National Oceanic and Atmospheric Administration research ships, this time, the federal government is really here to help you.

Its help mariners can appreciate: a two-year program NOAA calls Hydropalooza to map the Kachemak Bay coastline and sea floor that will result in updated nautical charts and water depth and coastline maps. Researchers hold a meeting at 7 p.m. Tuesday at the Alaska Islands and Ocean Visitor Center to explain the project.

Hydropalooza brings some of NOAA's latest technology to the bay. Along with the two 70-foot ships, NOAA also will do light detecting and ranging, or lidar, measurements from a Cessna Citation jet. That project maps the topography of the land-water profile as the jet flies up and down the coast.

Hydropalooza will result in information useful to the state, the city of Homer and the Kenai Peninsula Borough, particularly as governments grapple with issues like coastal erosion.

"A lot of other people can use this data. We're trying to build in those requirements," said Kris Holdereid of NOAA, co-director of the Kasitsna Bay Laboratory.

Along with its research ships, NOAA has set up tide gauges at Kasitsna Bay and Bear Cove, and a highly-accurate GPS station at the old Kachemak Bay Research Reserve office on Kachemak Drive. Autonomous underwater vehicles untethered robotic submarines also explore the bay to measure temperature and salinity key readings when doing sonar soundings.

"If you're using sound to measure water depth, you want to do it really accurately," Holdereid said.

The project also explores the limits of some of NOAA's equipment: using sensitive, high-tech equipment in a sub-Arctic environment with extreme tides.

"Doing it in Kachemak Bay is really challenging," Holdereid said. "That was my push to them: this is the perfect place to test it out."

An open house for one of the NOAA ships, the Fairweather or the Rainier, also is held Aug. 23. For more information, visit www.nos.noaa.gov/hydropalooza.

Michael Armstrong can be reached at michael.armstrong@homernews.com.