Boating 101: What to Do if You Run Aground
Many groundings happen on soft bottoms, so often you can get off without help — if you move quickly and employ the right tactics.
A moment’s inattention and you find yourself straying from the channel, firmly stuck in the mud. Now what?
First things first:
Don’t Waste Time
If you go aground and the tide is falling, the right maneuver in the first few minutes may make the difference between easily getting off or sustaining damage.
Quickly Assess the Bottom
Much of what we tell you here won’t apply to rocky bottom or reef. Determine whether you hit soft mud, hard sand, rock, or some other type of bottom. If you don’t know, find out by looking at the chart or by scooping up bottom material with an anchor. Next, verify that your hull hasn’t been damaged; check immediately to be sure you’re not taking on water.
Silt and Sand
Any time you use the motor when aground, you may suck a lot of the silt and sand stirred up from the bottom into the raw-water side of your engine cooling system. After the fun is over, it’s a good idea to pull the impeller on the raw-water pump and check it. Look for scoring on the outer, rounded edges of the impeller. Check for cracks where its blades join the hub. (To do this, you must pull the impeller out of the pump and flex the blades to the side.) Look inside the pump for abrasion of the soft (probably bronze) surfaces and the wear plate. Also watch for engine overheating. The silt will occasionally clog the heat exchangers or other passages, and you may need to clean them also.
The Status of the Tide
Is it going up or down? How far does it have to go? A rising tide is often all you need to escape. Local tide conditions may be different from those at the reporting site on VHF weather channels or on chartplotters. Check such local indicators as current, tide lines on a day beacon, and tide lines on the shore. Remember that in many areas, the current may actually be running in although the water level is still dropping, or vice versa. Check out “The Rule of Twelfths” for more information.
Assess the Weather
If you see signs of a storm coming, you have less time than you think. Consider whether the waves, wind, or current are likely to push you into deeper water or into shallower areas.
Consider the Hull Configuration
You should know how much clearance your props and rudders have above the bottom. If your props and rudders are deeper than the hull’s protected area, the grounding may have already damaged them. But if you let the boat settle even more deeply into the bottom, you’ll damage them for sure.
READ more at https://www.boatus.com/expert-advice/expert-advice-archive/2016/january/what-to-do-if-you-run-aground