The Harbor Column:

Ahoy,

We are approaching the summer season, and along the coast, we are having the usual June gloom. The hot daily inland temperatures pull in the cooler marine air, creating the low-lying clouds along the coast typically called the marine layer. It usually burns off by afternoon, but another byproduct of this weather condition is fog.

Fog is a boater’s nightmare, especially when you are trying to enter Newport Harbor while you are glued to the radar and the global positioning system. I regularly encounter fog on the Pacific.

The fog is so thick in San Francisco that on many voyages I never see the Golden Gate Bridge when cruising underneath and looking up. San Francisco is more difficult to enter than Newport because of the ship traffic and the rougher waters.

When you encounter fog, what should you do? First and foremost, slow down the boat’s speed. There is not a set speed limit on the ocean, but the rules state that you must have your vessel under control. That means you must be able to identify, change course or stop to avoid a collision, so set your speed accordingly. Remember that not everything on the water will show up on the radar screen, so post a bow watch.

There are whistle signals for boaters. Proper maritime nomenclature calls the vessel’s horn a whistle and a honk a blast. You may signal either a one-second “short” blast or a four- to six-second “prolonged” blast as the only two types of whistle blasts.

In the fog, a vessel under power may signal at least every two minutes one prolonged blast and listen for a response from a nearby vessel. Two prolonged blasts may be given by any vessel underway but not making way, hence drifting.

Sailboats or towboats can signal with one prolonged blast and two short blasts. Again, there are many signals, so please review the International versus Inland Waters regulations.

Tip of the week is to contact the Maritime Institute ( www.maritimeinstitute.com) and order the Mariner’s Guide to Rules of the Road cheat sheet. This flat or folded guide lists the lights, day shapes, and sounds that you can carry aboard your boat for reference. I carry one in my sail bag on every voyage.

Remember to tune in 11 a.m. Saturdays to Capt. Mike Whitehead’s Boathouse Radio Show. For channel listings go to www.BoathouseTV.com.

MIKE WHITEHEAD is the Pilot’s boating columnist. Send marine-related thoughts and story suggestions to mike@boathousetv.com or go to www.boathousetv.com .