Article by Capt. Mark Sampson
If you haven't noticed, the tides this summer have been a little crazy with more higher-highs and lower lows than we typically have. Known as “spring tides” or “king tides” this situation usually occurs when the sun and moon line up in a way that the gravitational pull on the water is intensified. It’s not uncommon for this to happen for a few days each month or so but it seems like it’s been happening more often than usual this season. At the low end of such extreme tidal ranges it can be really interesting to poke along the edge of familiar bulkheads, shorelines, or docks and see what’s been revealed and the view from the Rt. 50 Bridge can be amazing, not only can you clearly see all the bars to the immediate north and south, but as long as the water is clear by looking straight down over the railing one can see the concrete rubble and other debris that is so attractive to the fish that we all pursue.
While shallow water is interesting to look at from the land, if you’re in a boat it’s not usually what you want to see. Every boat has a minimum depth or “draft” that they can operate in without striking bottom and when the depth of the water is less than the draft of the boat that boat is going to come to a grinding halt! Running aground or “grounding” is something every boater in every size boat anywhere on the planet needs to be wary of because no matter if they’re paddling a canoe that needs three-inches beneath the hull to float or steering a cruise ship that requires thirty-feet, at some point they might find themselves in the wrong place during the wrong state of the tide and “oops” suddenly slam to a complete stop, or at the very least start churning mud.
Anyone who spends much time navigating the back-bay waters around Ocean City must accept the fact that sooner or later they'll run aground, there’s just too many shoals and shallow water not to. I’ve grown up on these waters and still find myself grinding sand more than just a few times each year. Channels fill in, sandbars shift, new shoals form after storms, or sometimes you just don’t pay close enough attention to where you are and suddenly two feet of draft meets one foot of water. Depending upon the vessel and what’s going on aboard it at the time, running a boat aground can result in a minor inconvenience or catastrophic event – I think that an Italian cruise ship a few years ago proved that one out.
Fortunately most of the boats that operate in our local bay waters are either outboards or inboard-outboards that have the wonderful ability to lessen their draft by raising the lower unit. With just the push of a button a two-foot draft can be reduced to a foot and allow the operator to slowly motor their way out to deeper water. The key word there is “slowly” because with the motor trimmed up the boat simply won’t perform any other way. Even if it cannot be powered out of the shallow water, raising the lower unit allows a boat to be more easily pushed or pulled from the shallows with little risk of damage.
Inboard boats with fixed running gear (propellers, shafts, rudders) typically fare worse in a grounding because nothing is retractable. When an inboard is “stuck” she’s typically going to be there until the tide rises enough to float the boat up or another vessel pulls it off. Unless the vessel has a deep keel to protect the running gear, grounding an inboard often leads to costly repairs if the prop, rudder or shaft strike bottom hard enough to be bent or broken. Plenty of inboard boats are used in our back-bays but the operators typically know that they must take extra caution to stay in deep water to avoid the inherent pitfalls of their vessel’s design.
Operators of vessels propelled by water-jet type engines such as small (or large) jet-boats or personal watercraft (jet-skis) have the advantage that they have no prop, rudder or lower unit projecting below the hull and so are able to skitter across much shallower water than other vessels of the same size. That’s the “good” part about that type of propulsion system. The downside is that even though a jet-boat can shoot over a sandbar just inches of water, when that vessel is not running up “on plane” the hull will settle back down into the water and have a deeper draft. For example; a 20-foot jet-boat that draws 15-inches of water going slow might only need five inches under the hull when it’s running hard so it should be able to easily get across a sandbar that’s 6-inches deep. However, if that boat were to slow down or stop in 6-inches of water it now needs 15-inches under the hull to float and it’s going to be very high and very dry and will in no way be able to get off the bar without a lot of help either by Mother Nature in the form of a rising tide (let’s hope they didn’t ground at high tide!) or by a strong pull by a towboat (let’s hope they didn’t ground so far up on a shoal that a tow line won’t reach them). Jet-boats can be great for traveling across shallow water, but every boat, even a canoe, has its minimum operating depth, and when a jet-boat grounds – it’s grounded!
Every boater must consider the risk of grounding and take steps to minimize the risk as well as have a plan of action in case a grounding does occur. Getting a small skiff unstuck might be as simple as hopping off and pushing out to deeper water, but that simple act gets more complicated in the winter when the water is dangerously frigid or if no one in the crew is physically capable of doing such. In some cases a stout boat-hook or push-pole might be all that’s needed to get to deep water without getting wet. Big boats can rarely be pushed off by hand so the knowledge of how to get towing assistance is crucial. Of course the best option is not to get stuck in the first place, knowing the water will help with that. Preparing ahead of time and always traveling at a safe speed can go a long way to ensure that, if a vessel does find the bottom, the result is only a minor inconvenience - not a major catastrophe.§
