Hydrographic survey vessel
The wet map maker's boat.
Work
A hydrographic survey vessel is a ship or boat specially designed and outfitted to do hydrographic survey work. Such work includes mapping the sea floor, measuring currents and tides, locating wrecks, finding oil and minerals. Identifying dangerous places or places that are in danger.
Design
Obviously ocean going ships are bigger then boats that are specially designed to do coastal work. The later have often a very shallow draft and are very manoeuvrable to do their work.
Equipment
To do their work hydrographic survey vessels are packed with measuring equipment. Ranging from the old-fashioned sounding line (A weight on the end of a rope.) and sextant, to both towed and fixed three-dimensional scanning SONARs, buoys (such as ODAS) that can be deployed, RADAR and several kinds of Satelite Navigation.
Knights of Rhodes
Royal Navy
Royal Netherlands Navy
United States Coast Guard
Vereenigde Nederlandsche Oost Indische Compagnie
Signal
A hydrographic survey vessel busy with surveying can be recognized by recognized by an orange flashing light. Which isn't an official part of the give way rules, but it's a generally accepted tradition that any other ship will give way to make sure the survey vessel can keep on the courseline and their measurements accurate.
I like that other ships will tend to give way so that their measurements are not messed up. Is draft how deep their hull sits in the water?
Explore Etrea | March of 31 Tales
Yes draft is how far down a hull goes.