Navigation in shallow waters, whether for pleasure or for work and rescue, requires suitable boats, some important precautions and above all maximum caution. The experience of Stem Marine and its fleet of professional boats.
Navigation in shallow waters allows you to explore by boat areas close to the coast, as well as lagoons, river deltas and canals. Naturally, shallow waters are not suitable for all types of boats and present some technical difficulties that engage the skipper and crew, as well as requiring maximum caution. The greatest risks of navigating in shallow waters are in fact possible collisions, but also groundings and silting up.
The same professional operators who dedicate themselves to rescue, firefighting and patrolling in shallow waters use special naval vessels and are trained to manage this type of navigation. So let’s see what navigation in shallow waters involves, which boats are most suitable and what precautions to take to maneuver safely.
A fundamental concept: draft
Before seeing which boats can be used safely in shallow water, there is a concept that needs to be explored: the so-called “draft”. Indicated in the technical data sheet of each boat, the draft is nothing more than the height of the part of the hull that remains immersed, considering all the possible appendages (keel, rudders, foils). In other words, the draft expresses the quantity of water that a boat needs to float and navigate.
Often in the case of boats with outboard motors, the draft is indicated with the wording “engine up” or “engine down”. In most boats it varies from about 15 cm (for example a dinghy) to several meters in the case of hulls with a keel (an offshore sailing cabin cruiser). When it comes to boats with tilting engines, as a general rule of thumb, add about 10 inches to the draft with the engine raised to get an idea of how much depth the boat needs to be safe to sail.
Static, dynamic draft and loads on board
However, it is important to consider a further note: the draft values usually indicated refer to the so-called “static draft” which is measured when the boat is stationary. However, motorboats also have the so-called “running draft”, or the amount of water they need when they are planing. When a boat starts planing, it rises significantly from the water and this can reduce the draft by a few centimetres or even more. To give you an idea, a planing boat with a static draft of 60 centimetres is able to navigate in 30 centimetres or a little more of water without ever running aground. However, it must be considered that if in these conditions the planing is lost for some reason, the shallow water becomes a problem.
Especially in smaller boats, the draft can be significantly increased by a heavy load of on-board equipment and fuel. The weight of the load, in fact, can modify the draft of any vessel, but on boats less than 6 meters, a couple of extra passengers can already modify the draft by 30 centimeters or more.
Best boats for shallow waters
The ideal boats for sailing safely in shallow waters are naturally those with a shallow draft and flat bottom. We are talking about inflatable boats and ribs, for example, as well as small fishing boats or passenger boats. Sailing dinghies, multihulls, small boats and canoes or kayaks also fall into this category. Among sailing cabin cruisers, the most suitable for shallow waters are those with a mobile or tilting keel. This design allows them to reduce the boat’s draft according to the conditions. Equally effective are multihulls, catamarans or trimarans, which, given their shallow draft and bayonet keels, can easily run aground in some cases.
Motor boats with an outboard engine are particularly suitable for sailing and maneuvering in shallow waters, thanks to the possibility of adjusting the height of the engine and the propeller. Finally, jet boats are very popular for sailing in shallow waters. In this system, traditional propellers are replaced by a low-draft propulsion system. The hydrodynamic thrust is ensured by a jet of water conveyed and accelerated by an axial pump or a centrifuge placed under the hull.
Tips for navigating in shallow waters
It is important to follow some tips to navigate safely in shallow water areas.
Reduce speed
The first and most important tip is to reduce the speed of the boat, which increases reaction times in case of critical situations. Running aground at high speed is dangerous and can seriously damage the vessel with the risk of getting stuck without being able to lift the boat from the bottom. Not to mention the risk of injury or worse to the crew due to the impact. If you run aground slowly, the danger is minimal and you have a much better chance of saving yourself.
Study the area
It is also essential to study nautical charts, pilot books, tide tables and bathymetric lines of the area, considering that even in the case of updated data, the seabed may vary slightly from what is reported due to tides and currents. When navigating, it is always essential to use a compass, Gps and electronic or manual sounder. These are all mandatory tools among the equipment of both work and pleasure boats.
Waves and water color
In unknown areas, to evaluate the depth of the seabed, you need to keep an eye on changes in the color of the water. Channels and deeper waters often appear dark in color, while shallows appear as light spots in the water. However, changes in color can also be misleading: dark-looking seabeds of algae, for example, could be shallower than the surrounding waters. Also observe waves that repeatedly break in the same place, which indicates that the seabed is shallower there.
Teamwork
Before entering a shoal, it is always a good idea to divide the tasks among the crew members. The person at the helm follows the compass and nautical chart. Another crew member monitors the depth sounding, while someone stands at the bow on the lookout and the others are ready to maneuver the sails. Whether it is work on professional boats or for leisure, it is always necessary to work as a team.
Shallow water rescue: the Stem Marine fleet
Navigation in shallow waters is a challenge not only for pleasure boaters, but also for maritime professionals, including crews dedicated to rescue, firefighting and patrolling. These operators in their activities at sea, on lakes, rivers, canals and lagoons, need absolutely versatile nautical vehicles that can access any place near the coast, even in the presence of shallow waters.
For this reason, Stem Marine, a leading company in the sector of rescue and safety in water, has in its catalogue a fleet of professional boats that meet all the needs of those who must operate in shallow waters, even in emergency situations. We are talking about Firefighters, Coast Guard, maritime health workers, law enforcement and maritime authorities. Professional multifunctional boats such as Stem 12, Stem 12 Fire/Rescue, Stem 12 Ambulance, Stem Ten, Rescue 750 Jet, Patrol 750, are all made with low-draft hulls and optimized hull lines to navigate and maneuver easily and quickly even in shallow water areas. As for propulsion, as an alternative to traditional propeller engines, these boats have the possibility of installing innovative hydrojet engines, even safer for rescuers in the water and more performing in shallow waters.
Among the various boats in action we can mention the Stem Ten, a fire-fighting vessel that since 2015 continues to navigate the Mekong River in Vietnam, which has many stretches of shallow water.
In conclusion, the condition of navigation in shallow waters is very particular but equally frequent, just think of the entrances to ports and canals. These are challenging situations for both boats and crews. It is necessary to prepare, plan and always proceed with the utmost caution.
