What is a Floating Crane?

Lori Kilchermann

A floating crane is type of sea vessel that has a crane mounted on it. The earliest floating crane designs were no more than old ships converted to include a large crane mounted on the deck. Later, purpose built, catamaran and semi-submersible designs replaced these converted mono-hulls due mainly to increase lifting capacity and improved stability.

Floating cranes have a variety of capabilities on the water.
Floating cranes have a variety of capabilities on the water.

There are many uses for a floating crane. Offshore construction is the primary duty for a floating crane, which has proved extremely important in the drilling industry. With these vessels' ability to lift and maneuver extremely heavy and large sub-assemblies into position, floating cranes make it possible to assemble massive projects from many smaller assemblies in most weather conditions.

Floating cranes are often used in slipways and other inland ports.
Floating cranes are often used in slipways and other inland ports.

Beyond building platforms for drilling, projects such as retrieving sunken ships often involve the use of a floating crane. The operators are able to bring a retrieval vessel alongside of the sunken ship and raise the sunken ship to the surface by working in unison with each other. These types of missions are often made increasingly difficult by rough sea conditions. It requires an experienced operator and crew to successfully complete a lift in these conditions.

The semi-submersible floating crane allows projects in rougher waters to be completed with less danger to the project and crew. This type of vessel arrives on the work site and then pumps its on-board ballast tanks full of sea water. This allows the structure to essentially sink into the ocean, giving it much more stability and control as the seas get rougher. This also permits the crane to lift heavy items without having to raise them as high into the air.

The advent of the heavy lifting cranes also allows contractors to assemble an off-shore oil rig in a matter weeks. The same job would have taken months to construct without the large crane vessels. During the off-shore building boom of the 1970s, there were several companies operating these behemoth cranes around the globe. However, in the mid-1980s the offshore boom ended and many companies were forced to merge to avoid closing, meaning fewer floating cranes in the ocean.

Semi-submersible crane vessels remain relevant in the Gulf of Mexico, North Sea and pretty much any body of water that sees major construction projects, be them reclamation jobs or new drilling platforms. These floating cranes created on a semi-submersible platform are able to withstand much rougher seas and lift a greater amount of weight than previous designs.

Floating cranes may be used in the construction of offshore oil rigs.
Floating cranes may be used in the construction of offshore oil rigs.

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Discussion Comments


@jmc88 - I understand and respect your opinion, but I do have to say that when you look at some of these cranes they are not exactly attached to very large vessels most of the time.

Some of the pictures that involve NAVY floating cranes show that the crane is really as large as the ship and is quite a sight to see.

Also, there are not very many of these floating cranes left nowadays, due to the consolidation of many businesses, and the companies that own these floating cranes hold a major monopoly on the business enterprise.

Since there are very few of these left it means that they are rare to find and they become a sight to see, when they are in operation. These few machines that still exist are wonders in modern engineering and there is a reason why there are so few of them.


I think that people feel that floating cranes are a model in modern engineering, but to be totally and completely honest I am not that impressed by them.

I feel like all a floating crane is, is a giant crane attached to a large ship. In reality the ship is the thing holding the crane down and I do not find that at all to be that impressive.

When it comes down to it a crane is a basic engineering design and is not at all that impressive.

Now there are very large cranes that I find to be very impressive due to the immense size, however I am not very impressed by a crane floating on the water, simply because it is being held down by a very massive ship, or is in fact stationary and attached to something underneath the surface of the water.


@titans62 - I understand your amazement in the floating crane. However, I do have to say that these types of cranes have been around a long time to bring up ships and it was not unusual for one of those cranes to be used to bring up the Titanic.

Now I know that the Titanic was a massive ship, and that means you would have to have a very large crane attached to a very massive ship in order to bring it up. However, it does not surprise me that eighty years after the Titanic was constructed that a larger ship was available and out on the oceanic waters to bring up ships as large as the Titanic.


I have heard that a floating crane was used to lift up part of the hull of the Titanic about ten or twelve years ago.

Being a fan of the Titanic I was very impressed that they were able to create a floating crane that was able to lift such a giant ship from the bottom of the ocean.

It was only about fifteen years earlier that the Titanic had been found, after people had been looking for it for seventy years. It was hard to find due to the water being so murky and the depth of it. Yet in only a little over a decade after it had been discovered, technology had advanced enough that not only could they dive down to it, but they were able to completely bring the vessel to the surface.

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