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May 30, 2020

This page last modified:
March 21, 2001

Boating Tips In Seagrass Beds

by Pam Wingrove

University of Florida/Monroe County Cooperative Extension

Florida Bay Education Project

Hundreds of calls come into marine law enforcement offices each year from vessel operators who need assistance in removing their boats from seagrass and sand flats. As the coastal population grows, this becomes an increasingly serious concern for resource management. Monroe County ranks number 1 in amount of damage to seagrass habitats in the State of Florida. Not only does this pose a serious threat to the animals who rely on seagrass for food and shelter, grounding and prop dredging in seagrass habitat also has consequences to personal property.

In 1997 there were 206,301 registered powerboats in South Florida including Lee, Collier, Monroe, Dade, Broward, and Palm Beach counties. That figure has grown from 186,855 registrations in the same area for 1993. Monroe County alone has 23,079 registered boats. The growing number of vessels on the water means increasing pressure on marine resources. Alarming reports of ships running into coral reefs are all too familiar and upsetting. Less recognized but no less important are seagrass beds that take a beating from repeated groundings and prop scarring.

Expenses can really add up during a grounding incident. First, consider the damage to vessel engines, hulls and propellers that often occur when a vessel grounds in seagrass or shallow bottom habitat. Add to that towing fees generally charged by companies who assist grounded vessels. Basic assistance begins around $125.00 per hour and is charged from the time that the assisting vessel leaves the dock until it returns home. If you need assistance at night, that figure goes to around $150.00 per hour. The fee for refloating a grounded vessel is about $5 to $10 per foot of vessel. If your vessel requires any special services, costs will be higher.

In addition to costs for repairs and removal of the grounded vessel, groundings resulting in damage to seagrass habitats are considered offenses and subject to both federal and state fines and penalties. Civil penalties, costs of assessment of damage, restoration of habitat and long-term monitoring of restored habitat are also assessed to the operator of a grounded vessel. Fines can add up quickly for instance, in the Florida Keys National Marine Sanctuary penalties for seagrass damage include $100 per incident under one square yard of damage, and $75 for each additional square yard up to 10 square yards. A grounded vessel can be charged up to $100,000 per day.

A 1998 grounding case from Biscayne National Park resulted in fines and damages totaling $63,377, or $125 per square yard. The initial violation fine for disturbing natural resources in Everglades National Park is $150 while violations for damaging plants (including seagrasses) on a National Wildlife Refuge can result in fines beginning at $250. Many insurance companies will not cover fines resulting from grounding.

The key to avoiding prop dredging and grounding is having local knowledge gained from experience on the water. Every vessel operator should carry and be able to use a detailed navigational chart of the area. These charts have marked channels and depth readings to assist the operator. Always stay within marked channels. They indicate areas known to be deep enough for your vessel to navigate. Don't operate your vessel in water less than 3 feet deep. Finally, learn to read the water. The sun's angle can make this a challenge. Remember the rhyme, "blue blue, sail on through; white white you just might; green green, nice and clean; brown brown, run aground!" Shallow water appears very dark or brown to the observer while deeper water appears blue or green. Sand covered areas appear white and may or may not be deep enough for your vessel to navigate.

Keep track of the tides. The greatest range of tides (shallowest and deepest water) occurs during a full moon and new moon. Use extra caution when boating on a low tide.

When in doubt about the depth, slow down and idle. Make sure the bow of the boat is down and the motor is trimmed or tilted up. If you do run into a seagrass flat, you will be leaving a sediment trail behind your boat, making the water murky and probably cutting seagrass roots. Stop immediately and tilt your engine.

Prop dredging and seagrass scarring is an unnecessary impact to the natural resources that you can control. Remember to study your charts, read the waters and know your depth and draft.

For more information on this research, contact the Florida Bay Education Project at 305-852-3592. Additional information on a variety of topics is available from the University of Florida/Monroe County Cooperative Extension Service, 5100 College Road, Stock Island or call at 292-4501; fax: 292-4415; email: or visit our web site Our services are free and available to all without regard to race, color, sex, or national origin.

The Florida Bay Education Project is an archived site. For more information go to NOAA's South Florida Ecosystem Education Project at