Learning More About Boats With Shallow Draft - Articles - Ship Building Shipyard Indonesia - Ratson


Learning More About Boats with Shallow Draft

 January 16, 2020

As the title says, this article will focus on the draft of the boat. Draft or draught is the depth of the boat that is immersed in the water. It is measured by the distance between the waterline and the bottom of the hull. The thickness of the hull is also included in the measurement of the draft level. The draft of every boat is different based on its design. Furthermore, the same boat can have a different level of draft when it is sailing on seawater or freshwater, depending on the density of the water. Furthermore, the same boat will also have a different level of draft based on its content or laden/ unladen condition.

The draft level of a boat can determine several things. First, the higher the draft, the better the boat sailing condition when crossing the sea. Having a high level of draft will help the boat to reduce the effect of the wind when it is sailing. That is why larger ship tries to maintain their draft level on an unladen condition by filling out their ballast tank. Second, the draft level of a boat will determine which route they can take for sailing. For example, a high-level draft boat cannot sail in shallow water such as a river. At the same time, a shallow draft boat will have difficulty on sailing in the deep water. Third, the draft level of the boat will also determine the facility available to be used by the vessel. Bigger boat identic with a higher draft, and the higher the draft level, the more limited facility that can accommodate the boat. For example, the port facility and Canal size.

Most of the boats with shallow drafts are having the same hull shaped. U-shaped hull is commonly used to make shallow draft boats. U-shaped hull is also known as the flat hull which can make the boat more stable when sailing in the calm water. Furthermore, the flat hull will allow the boat to have more buoyancy because of the wider surface area that sustains the boats to float. However, this hull shape makes the boats become less stable when sailing in choppy water because flat hull shape makes the boat to travel “on” the water, not “through” the water. Meanwhile, the V-shaped hull will be able to sail calmly in the choppy water because it has a higher draft level and sailing “through” the water.

There are many types of boats with shallow drafts. Starting with a pleasure boat, ferry, landing craft tank, self-propelled barge/ oil barge, barges, tug boat, and many other boats. Most of this bost is used in the shallow water or river in the archipelago countries. Having a shallow draft makes the boats easy to control because of the small water resistance level when the boats want to do a maneuver (depending on the dimension of the boat). In addition, the shallow the boat, the easier to get more speed on the boat because of the shallow the draft, the less the surface area that is blocked by the water when sailing. However, the speed of the boats is designed based on the purpose of the boats. For example, you cannot expect an LCT or SPOB to run at 30 or 40 knots.

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