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The reports on Freedom of the Seas include mention of a 580 ton swimming pool being fitted. This will of course include the weight of the water in the pool. I thought members may be interested in a brief history of swimming pools in passenger ships and some of the problems they create.
Many liners operating through the tropics rigged an improvised, temporary pool in a cargo hatch trunk. It is thought that the first permanent onboard swimming pool was installed in the White Star liner Olympic (the earlier sister of Titanic). This was located low down in the ship on F deck, forward on the starboard side. It was reserved for the use of First Class passengers only and had 13 changing cubicles.
Olympic started a trend and from then onwards most transatlantic liners carried an indoor swimming pool. Most occupied three decks, including one deck for the water tank. The next development came with the Hamburg America liners Reliance and Resolute (1920) where their pools were located within the superstructure at boat deck level and were covered by a large skylight, which could be opened in good weather. These ships were intended for Atlantic service in summer and cruising in winter. Generally, however, transatlantic liners were built with indoor pools, fitted low in the ship. This was because outdoor pools were unsuited to year-round Atlantic use and because of the designers’ concerns about the pools’ adverse impact on ship stability. The water in the pool is a considerable weight well above the nominal centre of gravity and provides completely unrestrained free surface effect on the movement of the ship. (As the ship rolls, the surface of the water in the tank remains approximately horizontal, with an increasing depth of water in the direction of the roll. This shifts weight onto the downward moving side of the deck, exaggerating the intensity of the roll and opposing the ship’s natural stabilising forces.)
Nevertheless outdoor pools began to be used in ship designs. The first was in the North German Lloyd liner Columbus (1922) and they were featured in the Italian superliners Rex and Conte di Savoia of 1932. The latter pair had extensive lido areas complete with sand for added effect!
Passenger demand for outside pools on cruise ships has created additional problems, especially in converted line vessels and the smaller, earlier new-built cruise ships. These problems were so severe in some of these older ships that the pool had to be emptied if the ship reached “arrival condition” (minimum fuel/water/food) after a long voyage.
I know that most of the old salts on this site do not believe me, but the big modern cruise ships are far more stable than the old smaller ships. It is a combination of factors that are responsible, including different hull forms and broader beam in relation to length. One significant change is that because the new ships are so much bigger that the swimming pool is proportionately smaller in relation to the beam of the new ships. As a result designers began to use two or three pools and then started to lengthen the pools, whilst retaining approximately the same width. This solved the pools’ adverse effect on the stability of the ship but a new problem emerged.
The first attempt at a really long pool was made in the Carnival Fantasy (1990). The main midships pool was about twice the length of a standard pool, with an offset at the midway point. Although for the first time ever, this enabled passengers to enjoy more than a couple of strokes before needing to return, it was not a success. The inevitable slight pitching motion of the ship produced a resonance in the pool that led to a build-up of large surging wave formations that made swimming at best difficult and at times dangerous. The only answer was to divide the pool with a perforated baffle plate capped with a teak bench, thus abandoning the idea of providing passengers with a facility for a longer swim.
Pitch resonance problems were also encountered in Holland America’s Statendam. In this ship the pool was standard sized but the difficulty was that the ship has such high stability that her pitching motion is far less than normal. The unfortunate result was that the period of pitch of the ship matched that of the pool. A further problem was that at one end of the pool there was a leaping dolphin sculpture set upon a circular base recessed into the forward end of the pool. As waves surged forward they collected in the dolphin base recess, which were channelled upwards in spectacular waterspouts that reached great heights. It was great fun, but not for swimmers. A Perspex sheet was placed in front of the recess, and was promptly shattered by the force of the waves.
An extensive series of model tests were undertaken at the Vienna Model Basin to solve the problem. Various combinations of pool depths, bottom contours and recess protection arrangements were tried until an optimum solution was found.
A similar problem of matching pool and ship pitch resonance was experienced in Home Lines cruise ship Homeric. Shortly after she was delivered by Meyer Werft, Home Lines was bought by Holland America, who decided to lengthen the ship. Once this work was completed the pool problem vanished. Of course, if the pitch resonance should coincide, altering the length of the ship is not the usual option!
Swimming pools on cruise ships are a necessity. They are also a major headache for designers.
Fred (Thumb)
Many liners operating through the tropics rigged an improvised, temporary pool in a cargo hatch trunk. It is thought that the first permanent onboard swimming pool was installed in the White Star liner Olympic (the earlier sister of Titanic). This was located low down in the ship on F deck, forward on the starboard side. It was reserved for the use of First Class passengers only and had 13 changing cubicles.
Olympic started a trend and from then onwards most transatlantic liners carried an indoor swimming pool. Most occupied three decks, including one deck for the water tank. The next development came with the Hamburg America liners Reliance and Resolute (1920) where their pools were located within the superstructure at boat deck level and were covered by a large skylight, which could be opened in good weather. These ships were intended for Atlantic service in summer and cruising in winter. Generally, however, transatlantic liners were built with indoor pools, fitted low in the ship. This was because outdoor pools were unsuited to year-round Atlantic use and because of the designers’ concerns about the pools’ adverse impact on ship stability. The water in the pool is a considerable weight well above the nominal centre of gravity and provides completely unrestrained free surface effect on the movement of the ship. (As the ship rolls, the surface of the water in the tank remains approximately horizontal, with an increasing depth of water in the direction of the roll. This shifts weight onto the downward moving side of the deck, exaggerating the intensity of the roll and opposing the ship’s natural stabilising forces.)
Nevertheless outdoor pools began to be used in ship designs. The first was in the North German Lloyd liner Columbus (1922) and they were featured in the Italian superliners Rex and Conte di Savoia of 1932. The latter pair had extensive lido areas complete with sand for added effect!
Passenger demand for outside pools on cruise ships has created additional problems, especially in converted line vessels and the smaller, earlier new-built cruise ships. These problems were so severe in some of these older ships that the pool had to be emptied if the ship reached “arrival condition” (minimum fuel/water/food) after a long voyage.
I know that most of the old salts on this site do not believe me, but the big modern cruise ships are far more stable than the old smaller ships. It is a combination of factors that are responsible, including different hull forms and broader beam in relation to length. One significant change is that because the new ships are so much bigger that the swimming pool is proportionately smaller in relation to the beam of the new ships. As a result designers began to use two or three pools and then started to lengthen the pools, whilst retaining approximately the same width. This solved the pools’ adverse effect on the stability of the ship but a new problem emerged.
The first attempt at a really long pool was made in the Carnival Fantasy (1990). The main midships pool was about twice the length of a standard pool, with an offset at the midway point. Although for the first time ever, this enabled passengers to enjoy more than a couple of strokes before needing to return, it was not a success. The inevitable slight pitching motion of the ship produced a resonance in the pool that led to a build-up of large surging wave formations that made swimming at best difficult and at times dangerous. The only answer was to divide the pool with a perforated baffle plate capped with a teak bench, thus abandoning the idea of providing passengers with a facility for a longer swim.
Pitch resonance problems were also encountered in Holland America’s Statendam. In this ship the pool was standard sized but the difficulty was that the ship has such high stability that her pitching motion is far less than normal. The unfortunate result was that the period of pitch of the ship matched that of the pool. A further problem was that at one end of the pool there was a leaping dolphin sculpture set upon a circular base recessed into the forward end of the pool. As waves surged forward they collected in the dolphin base recess, which were channelled upwards in spectacular waterspouts that reached great heights. It was great fun, but not for swimmers. A Perspex sheet was placed in front of the recess, and was promptly shattered by the force of the waves.
An extensive series of model tests were undertaken at the Vienna Model Basin to solve the problem. Various combinations of pool depths, bottom contours and recess protection arrangements were tried until an optimum solution was found.
A similar problem of matching pool and ship pitch resonance was experienced in Home Lines cruise ship Homeric. Shortly after she was delivered by Meyer Werft, Home Lines was bought by Holland America, who decided to lengthen the ship. Once this work was completed the pool problem vanished. Of course, if the pitch resonance should coincide, altering the length of the ship is not the usual option!
Swimming pools on cruise ships are a necessity. They are also a major headache for designers.
Fred (Thumb)
