Amgram Ltd, Shoreham based naval architects had a rather unusual job inclining HMS Caroline. The inclining experiment is the naval architects traditional route to determining the stability of a vessel. Amgram Ltd, who mainly specialise in small craft, were delighted to be awarded the contract to incline a full battleship!
Although now decommissioned, at the time of her inclining HMS Caroline was the second oldest ship in RN service- the oldest being the Victory. Launched and commissioned in 1914, she was the last remaining British World War One light cruiser in service, and the last survivor of the Battle of Jutland still afloat. Until her decommissioning she acted as a static headquarters for the Royal Naval Reserve, moored in Belfast.
As a first step the original lines plan for Caroline was sent from MoD archives, redrawn on computer and then translated to a hydrostatics software package.
The inclining experiment requires the ship to be heeled by a series of known weight and deflections measured, both to port and starboard to even out errors. Generally inclining experiments are carried out in shipyards, where there is a good availability of weights, craneage and access to all engineering facilities.
In the case of HMS Caroline, effectively a dead ship, the engineers had to find calibrated weights, up to 20 tonnes and mobile cranes with sufficient outreach to lift those weights over the ship to the outboard side. Since the condition of the decks was unknown, as a precaution props were put in place to prevent any distortion. Any doubts about the structure were proved unfounded as these props proved to be completely unnecessary!
When carrying out an inclining, it is necessary to have some idea of the answer you are seeking- to allow the right weights to be selected. Amgram engineers found a 1914 Admiralty document suggesting that a similar ship might have a GM (metacentric height) of around 3 feet (or 0.914m). In fact by the time the inclining trial finished, the GM was recorded as 2ft-9” (or 0.831m)
Since the objective of the exercise was to determine the stability of the ship if she were to be moved, Amgram then carried out further calculations showed HMS Caroline shows sufficient stability to satisfy the IMO criteria for a ship experiencing severe wind and rolling conditions.
Belfast provided a calm still day perfect for inclining and Amgram engineers worked to position cranes, load weights then shift weights and record the deflections. A necessary process of inclining is to assess the condition of the ships tanks and bilges, so as a bonus the team had to go through the whole vessel, giving modern naval architects a great opportunity to inspect shipbuilding of 100 years ago.