Let’s begin to describe this symbolism that we find on the hulls of ships
NO TUG / TUG
Surely you have seen that on both sides of the ship we find these two words. Tug in the Anglo-Saxon language means tugboat. NO TUG means NO TUG. This great symbol is generally found in the doors or openings where the platforms are set up to embark or disembark passengers from and to the tenders when the ships are at anchor. It is an area considered as delicate or sensitive and when it is closed it indicates that the tugs when they approach the boat, cannot and should not lean on it. There are some ships of some shipping companies that not only have this indication expressed in this way, but also indicate where they can do it using the word TUG with an arrow pointing down.
STABILIZERS AREA (LYING BOTTLE)
As I said before, I am not going to use nautical terminology, but visual, since this signaling is the one that most resembles a lying bottle. You will tell me when you see it what drink this bottle will be, but for me it is beer. Well, the truth is that it indicates at the height that the stabilizers of the ship are, those that we wait so long to open when the sea is rough and we need a bit of stillness. The stabilizers are designed to reduce the rocking motion of the ship, thus making the ship move more smoothly, reducing the possibility of seasickness among passengers. Neither can tugs lean on their maneuvers over this area.
Ahead, where the bow almost ends and on both sides, we find this symbol, to indicate where the so-called bow bulb begins to emerge.
The bulb of the boat is that bulge in the bow which must be submerged in the water when sailing. Its main function is to create a second wave train that interacts with the one created by the bow, trying to make the crest of one coincide with the sine of the other, and vice versa, and thus, following the law of superposition of effects, reduce the resistance to the advance of the vessel due to wave formation. It has been shown that the bulb in these large ships considerably increases the performance of the propeller, as well as the speed of the ship. Not all boats have a bulb. This indication is so that small boats are informed that if they come across a large boat, they may run into the bulb they carry at water level.
AZIPOD OR ROTATING HELIX
Azipod is a marine drive unit consisting of a fixed pitch propeller mounted on a steerable nacelle which houses the electric motor that drives the propeller.
On the other hand, in the Azipod unit, the electric motor is housed inside the propulsion unit and the propeller is connected directly to the motor shaft. By avoiding the use of a traditional propeller shaft, the propeller can be positioned under the stern of the boat in an area of free water flow, thus resulting in greater hydrodynamic and mechanical efficiency. In addition, this configuration increases the flexibility in the layout of the power plant of the ship (Wikipedia source). As you may have noticed here, I have no choice but to resort to a technical definition. In easy words: a fundamental element for the propulsion of the boat that some boats have it and others do not.
THRUSTERS OR PROPELLERS FOR MANEUVERING
We all love to see when the ship leaves the port and develops that quick maneuver that seems so simple to take off from the platform where she is docked. We see that on one side of the ship it begins to occur as a revolution in the water that propels the ship to the opposite side of the dock. This is where we welcome THRUSTERS or MANEUVER HELICES. They are the central propulsion of displacement vessels that are mainly used for docking, low-speed maneuvering, emergency direction change, and holding at full stop or at very low speed.
The draft of a ship or vessel is the vertical distance between a point on the waterline and the base line or keel, with the thickness of the hull included; if not included, the draft would be obtained. Drafts are measured on scales on each side, fore and aft, and on some ships also at the middle perpendicular. Scales are measured in decimeters, in which case, the numbers represented are even, or in feet, with both even and odd figures. The draft of a ship can vary due to multiple factors, even without considering the increase or decrease in displacement.