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What Is an in-Water Survey?

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  • Written By: Lori Kilchermann
  • Edited By: Lauren Fritsky
  • Last Modified Date: 20 August 2016
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An in-water survey is the process of inspecting a ship's hull for damage, organic buildup or any other abnormality in lieu of a dry-dock inspection. Commonly conducted by divers, the in-water survey can be beneficial in finding and repairing cracks, broken welds and rivet problems as well as simply cleaning the hull of a ship prior to painting. It is normal for a company conducting an in-water survey to take many pictures as well as video of the ship's hull. Commentary from the diver as recorded from inside the diving helmet as the inspection is being made is also used as evidence of the survey's findings regarding hull condition.

A ship must be inspected periodically to investigate the condition of the ship's hull. Damage, organic life and the condition of the paint must be verified through actually viewing the condition of the hull. This can be accomplished in one of two methods: dry-docking — which is costly and time-consuming —, or an in-water survey, which does not require the ship to be removed from the water.

Periodically, a ship is required to go through a dry-dock procedure where the hull is cleaned, inspected and painted. When allowed, the in-water survey allows the ship to be inspected while tied up at dock. This process is much faster and less costly than the dry-dock alternative.

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During an in-water survey, a diver will descend to the bottom of the ship's hull and scrape away any organic matter that has accumulated on the hull. A visual inspection of the hull will be taken to determine the condition of the paint as well as the steel. Various tests will be conducted and pictures of the hull will be taken. Both digital and film pictures will typically be taken and given to the ship's owners as well as the investigatory board overseeing the testing.

The ship's propeller and rudder system will also be examined during the in-water survey, occasionally resulting in the polishing of the propeller. This service allows the propeller to slice more efficiently through the water and create better speed as well as better fuel consumption. Occasionally, an unmanned robotic diving machine will accompany the diver to the bottom of the hull. This is done to provide light for the in-water survey as well as a method for carrying the required tools and supplies for the diver. The diving machine will also often film the diver completing the in-water survey.

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indemnifyme
Post 3

@ceilingcat - Well, I think there are divers who specifically get paid to do these dives. It's probably not gross or scary to them! I don't think I would want to do it either though.

Anyway, I think eventually we'll probably be able to have unmanned robotic divers complete in-water surveys. Some divers already take them down to assist, so I doubt it will be too long before they invent a robot to just do the whole job.

I think this would make the most sense. You could probably do in-water survey more often if you had robots to do it, and it would minimize the risk to the human members of the ships crew.

ceilingcat
Post 2

@starrynight - Don't forget, they can also do an in-water survey when the ship is docked. Then if they find serious damage, dry dock is always an option.

I personally think the idea of diving under a ship to go look at sounds really scary. What if you got stuck on a propeller or something? Or the ship started moving by accident? I'm sure neither of those things is very likely, but these are the kinds of things I worry about.

Plus, the idea of scraping organic buildup off the hull of a ship just sounds plain gross to me!

starrynight
Post 1

An in-water survey sounds like it's a really great thing for a ship on a long journey. Obviously if you're making a long journey by water, you can't stop to dry dock your ship to take a look at the hull. But you can have someone dive down and go take a look!

I'm sure the ship has to stop for this to take place, but like the article said, and in-water survey is much less time consuming than other options. Also, if you're not planning on painting the hull and it hasn't been too long since you last dry docked, an in-water survey is probably the most sensible option.

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