There are a few key points about owning a boat that every boat owner must know.
One of those key points is knowing how deep your boat can go in water. What is too shallow for your boat and what to know about navigating shallow waters.
Every boat is different, but let’s give you a general idea of how deep of water your boat can navigate.
3 Feet – Don’t Go Below This!
Every boat is different, but in general, you should not drive your boat in no less than 3 feet of water.
Every boat is different, sail boats and large cruisers need more, pontoons can go a little lower, and ski boats can be split. But overall, 3 feet is a good starting point for most average boat owners.
There are several good reasons for 3 feet, even though your boat draft maybe 18 or 24 inches. Let’s go over why 3 feet is a good starting point and why you should not go lower.
Why 3 Feet For Depth?
The lowest point of your boat will be the lower-unit from your boat engine. If your boat is going to hit anything, that will mostly be the thing to get hit. Better yet, the skeg will get hit, as it’s the little fin/rudder below the prop.
For many boats, they only need 2 feet, or even less, to float.
But floating and driving are two very different things.
When the engine is on and the boat put into gear, the prop spins and kicks up everything around it. This means rocks, sand, sea life, plant life and more gets kicked up and can beat or jam up the prop. Not only that, but your boat’s water pump can suck it up and get clogged. The water pump on your boat is used to keep your boat engine cooled, and the intake is near the prop.
It also makes it harder to see the bottom of the water, which is usually hard enough to see.
The Damage You’ll Do When Driving In Shallow Water
- Propeller Damage: One of the most common damages incurred while driving a boat in shallow water is to the propeller. If the propeller hits the bottom or encounters debris, it can become bent, chipped, or even broken.
- Hull Damage: The hull can get scratched, dented, or punctured if it strikes rocks, logs, or other submerged objects. Such damages can lead to leaks or compromise the structural integrity of the boat.
- Rudder or Skeg Damage: The rudder or skeg can also get damaged if they come into contact with the bottom. This can affect the boat’s ability to steer.
- Engine Damage: Sand, mud, or debris can get sucked into the cooling system, causing the engine to overheat. Debris can clog up the intake and damage the impeller. Long-term operation in shallow water might cause accelerated wear on the engine due to bad cooling.
- Grounding: The boat can get stuck or grounded, especially in muddy or sandy areas. This can be a great inconvenience, and you might need assistance to free the boat.
- Environmental Damage: Boating in shallow waters can disturb the habitat of marine life. The propeller’s motion can stir up the bottom, resuspending sediments, and potentially releasing nasties or pollutants trapped in the sediment. This can also destroy aquatic vegetation, which is essential for many species.
- Seagrass Scarring: In areas with seagrass beds, the propeller can create scars or trails in the seagrass. This not only damages the immediate area but can have longer-term ecological impacts as these areas may take a long time to recover.
- Noise and Vibration: In shallow water, the noise and vibration from the boat can be more pronounced, potentially disturbing marine life.
- Navigation Risks: In shallow waters, there’s a higher risk of collision with submerged objects, other boats, or fixed structures, especially if the water isn’t clear.
- Increased Wear and Tear: Operating in shallow waters might put added strain on the boat’s systems, leading to accelerated wear and tear.
Shallow Water Boats
Of course, all this depth talk depends on the boat, and some boats are made to go in shallow water.
For example, an airboat can go in the most shallow of water, even land if you like, as it has a flat bottom and uses a large impeller to propel it.
When I give the 3 feet advice, it’s for most general purpose boats. Not the airboats, not the sail boats, and definitely not the large cruisers, even though it’s still good advice for some outliers.
We’re talking about the average person’s pontoon, bowrider, skiboat and similar.
Don’t Trust Depth Finders
Modern digital depth finders are quite good, but a lot of them have a dirty secret.
You need to know if your depth finder works while underway or when standing still. Many depth finders can only take a measurement when standing still, which makes it hard if you operate your boat in shallow waters.
I suggest sticking with the fish finder and depth finder combos as they work better and ten to update even when the boat is in motion. Avoid the cheaper options, and get something good, as the cheaper ones often only read when standing still or going really slow.
I would not make my depth finder my one true source for depth, especially when getting below 5 feet. Your eyes and gut feeling need to be given more weight, as I’ve had depth finders read too late or read the wrong depth far too many times.
Trolling In Shallow Waters
If you raise your engine out drive or motor and put down the trolling motor, you can get away with more shallow waters. It then comes down to the draft of your hull, which your owner’s manual tells you the depth.
This is a common thing for fisherman to do, but they also have boats that can go in shallower waters.
For most boats, I would not start the engine and move away until you get above 3 feet of water to protect your boat.
Jet Boats In Shallow Water
Since a jet boat impeller is tucked inside, that must mean it can go in shallow water, right?
No, a jet boat should stay above the 3 feet water rule too.
A jet boat is just a giant vacuum, and going in shallow water will suck up sand and rocks, which will jam up the jet drive system and even stop the engine.
While a jet boat may not have anything hanging low like other boats, it still can only go so deep in the water.
I know there are outboards that have the jet drive setup, but I still suggest staying above 3 feet. Too low, and you suck up sand and rocks, and you’ll learn the lesson the hard way eventually.