Cruising/Navigating the GIWW in Alabama

Perdido Key, AL to Dauphin Island, AL

The Alabama portion of the Gulf Intracoastal Waterway (GICW) has its beginning near the eastern point of Ono Island, AL at (MM "170.0") at 30°18.6’N / 87°27.3’W.

From this point, the Alabama section of the GICW runs generally in a westerly direction for 58.9 miles ending at 30°15.0’N / 88°23.5’W (MM "111.1") in Mississippi Sound about 3.0 NM NNE of Petit Bois Island’s eastern tip.

Navigation

Buoyage

Alabama’s GICW is marked with your standard Aids to Navigation. In addition they display yellow triangles or yellow squares. When westbound along this section of the Gulf Intracoastal Waterway, marks displaying yellow triangles should be kept on your starboard hand and those marked with yellow squares should be kept to port. While typically the yellow triangles will be found on red markers and yellow squares are found on green markers, caution should be exercised around Mobile Bay where the GICW intersects or coincides with channels marked by the Lateral Buoyage System.

Charts

NOAA chart coverage of this portion of the GICW beginning at mile marker “170.0 EHL” to mile marker “111.1 EHL” is provided by charts #11378 and #11374. These charts can be viewed by clicking on the links below:

Chart #11378 - Santa Rosa Sound to Dauphin Island
Chart #11374 - Dauphin Island to Dog Keys Pass

Distances and Mileages

All distances along the Alabama Gulf Intracoastal Waterway are given in statute miles unless otherwise noted. Statute miles are used in order to conform to the distances shown on the small craft charts typically used along this route.

This portion of the GICW between Ono Island and just north of Petit Bois Pass (Alabama / Mississippi State Line) is measured based on decreasing mileage (East of Harvey Lock - EHL) from (MM “170.0 EHL”) to (MM "111.1 EHL".)

Channels

The Federal Project Depth for this portion of the Gulf Intracoastal Waterway provides for a channel depth of 12 feet. While every effort is made to maintain this project depth, the actual controlling depths in the channels may vary due to shoaling reducing the available water depth until maintenance dredging can be accomplished.

Communications

• All operating bridges in Alabama guard VHF Channel 13.
• The U.S. Coast Guard advises all vessels to exercise caution in any area where the GICW intersects major shipping channels. A “Security Call” on VHF channel 13 is requested prior to crossing any shipping channels, especially during periods of restricted visibility.

Bridges, Locks, & Overhead Power Lines

Bridges

At last count, a total of 3 bridges cross the Gulf Intracoastal Waterway between Perdido Key and Dauphin Island, AL. The fixed bridges along this route provide a minimum vertical clearance of 73’.

This list is believed to be accurate as of January 2025. If any errors or omissions are noted, please e-mail us at with any corrections or recommendations.

The above table can be downloaded for your personal and private use. They list the bridges, their schedules, and restrictions in statute miles, nautical miles, and kilometers along Alabama’s segment of the Intracoastal Waterway from Ono Island, FL west to Dauphin Island, AL.

Alabama Gulf Intracoastal Waterway Bridge Schedule - Download

GICW/GIWW Bridge and Lock Schedule (Florida to Texas) - Download

Locks

None

Overhead Cable and Power Lines

The minimum authorized clearance of overhead cables crossing this section of the GICW is 93 feet and is found at (3) locations along the Alabama GICW: (MM “158.2 EHL”), (MM “154.7 EHL”), and (MM “127.7 EHL”).

Caution - Many of the overhead cables over the waterway carry high voltage, and an extra margin of safety should be allowed when the weather is threatening.

Tides

Tidal ranges are fairly small along Alabama’s coast. Under normal conditions the mean range of tide averages slightly more than 0.5’ at Perdido Pass and increases to a little more than 1.2’ at the western end of Dauphin Island.

The type of tide experienced in this area is typically a "Diurnal Tide" - exhibiting (1) high tide and (1) low tide each day.

Entrances, Inlets, and Passes

There are very few Entrances, Inlets, or Passes between the deep waters of the Gulf of Mexico and the Alabama Gulf Coast. Between Perdido Pass in the east and Petit Bois Pass to the west, there were (4) at last count in January 2020. All provide access to sheltered inland waters with (3) providing access to the Gulf Intracoastal Waterway.

While most of these can be considered navigable for most vessels, (1) is only suitable for shallow draft vessels and/or local knowledge. We have listed them on the next page along with useful information on each to aid you in deciding if you wish to use a particular inlet.

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