Over the last few weeks this column has examined two big issues with boating along the Inland Waterways: locks and dams. Today we’ll look at the final item of interest – bridges, especially drawbridges.

A lot of the bridges that are encountered while under way are easy for most recreational vessels to pass under without difficulty. Preparing to come upon a bridge is actually quite easy. Most nautical charts give some good basic information including the height and width. This basic information allows boaters to make some initial decisions. However, an even better reference is the Coast Pilot.

What’s a Coast Pilot? Most boaters realize that nautical charts are wonderful documents. However, they are limited in what they provide. Granted, they can give a height and width of a bridge, but a prudent mariner needs much more. To bridge this information gap (pun intended), and many others which can develop while cruising, the National Ocean Service developed the U.S. Coast Pilot. These are nine such published documents. They cover the entire continental United States and its territories. This publication provides you all kinds of data, including, in the case of bridges, effects of tides, height cleared at mean high water, etc. It is an incredible reference.

Boatsafe.com provides some very beneficial guidance after you have reviewed the chart and the Coastal Pilot. &uot;As you approach a bridge there are several things that you should look for. You should check the right side of the bridge opening for the ‘clearance board.’ This will give you the minimum clearance, in feet, from the water level to the bridge structure. This will determine whether you can clear the bridge or will need to have it open. Speaking of opening a bridge, you should know the vertical height of your boat prior to getting to the bridge. Do not cause unnecessary openings – it is illegal!&uot; You can face both criminal and civil penalties for making unnecessary requests.

Boatsafe.com continues, &uot;Even if you can navigate under the bridge with plenty of clearance, always slow down and do so at idle speed. You can not see if another boater is on the other side, out of view, until the boat suddenly darts out into the bridge channel.

&uot;Other things to look for as you approach the bridge is a blue sign with what looks like a telephone receiver with a lightning bolt through it. This will give you the radio frequencies that the bridge monitors (usually 16 and 13 or 9). It is customary, at least in most areas, to contact the bridge tender by VHF radio to request an opening, however, there is a sound signal that can be used.

To sound the signal, the bridge uses one prolonged blast followed within three seconds by one short blast. The bridge tender will acknowledge an OK with the same signal. If there is a problem in opening at that time the bridge tender will answer with a &uot;NO&uot; by sounding five short blasts. You acknowledge your understanding of the &uot;NO&uot; by responding with five short blasts.&uot;

Next week we will look at special operating procedures and light configurations which are all part of the nautical road. Until then: Boat Safe…and Boat Smart!

LCDR Joe DiRenzo III is a resident of Suffolk and a regular News-Herald columnist.