Portobello Bathing Pool

Nicknamed the Porty, one of it’s claims to fame is that Sean Connery was a lifeguard here in the 1950’s. The pool had a wave making machine installed at a cost of £7,000. Luckily next door to the local power station, the pool water could be heated to 20 degrees. 10,000 spectators were present on opening day despite the terrible weather.

A second claim to fame is that this pool and its iconic diving stage featured on the cover of Janet Smith’s book, Liquid Assets.

Another pool claiming to be the largest of its kind in Europe when it opened but there were already 5 pools with a larger water capacity in existence. It’s not clear what criteria is being used to make this statement although it is not the only pool to claim this by any stretch! Look at the pools by water volume link in the main menu to see where the Porty comes in the league table.

Feature article from Baths and Bath Engineering, July 1936

New Open-air Bathing Pool, Portobello – City of Edinburgh Scheme

“The bathing pool at Portobello is the largest venture of this kind we have undertaken, and I am certain it will rank for a long time to come as one of the most spacious, well equipped, and beautifully constructed bathing pools in Britain.

The facilities which it affords to bathers and spectators for convenience comfort and healthy recreation are unrivalled, and I hope that its success will far exceed the most sanguine expectations of all who have had to do with its promotion and construction.”

This remark was expressed in a letter from the Lord Provost of Edinburgh, the Right Hon. Louis S. Gumley, who opened the new open-air bathing pool at Portobello on May 30 last.

The pool is situated at the west end of Portobello between the promenade and High Street, on a site which was formerly covered with industrial buildings and dwelling houses The area covered by the pool and buildings is approximately 2.9 acres, while the water area of the pool is 1.13 acres.

The pool is 330 ft. by 150 ft. and varies in depth from 1 ft. to 6 ft. 6 in. at the deep end. It is assumed that most races will take place across the pool, but should 100 m. or 110 yd. laps be desired, the water level can be raised so that the minimum depth will be 3 ft.

On the east side of the pool, a deep diving area has been made, giving a depth of water of 15 ft. A high diving tower has been constructed of reinforced concrete and has been provided with an internal staircase. There, are five diving stages: First, 12 ft.; second, 16.4 ft. (or 5 m.); third, 22 ft. 3 in.; fourth, 27 ft. 6 in.; fifth, 32:8 ft. (or 10 m.). On this side of the pool there are also two 3 m. springboard diving stages, and two 1 m. springboards. On the south end, two high curved chutes with stainless steel plates are provided, while two smaller ones are provided for children in the shallow water.

A water polo area has been marked out in the centre of the pool and is such that all partaking in the game will have to swim all the time and not be able to stand on the bottom for a period.

Purification Plant.

The purification plant which has been installed by the Pulsometer Engineering Co., of Reading, incorporates several unusual features and deserves a rather detailed description.

The swimming pool lies close to the power station. and advantage has been taken of an almost unlimited supply of warmed water from the condenser outfall to raise the temperature of the water in the pool to some extent, a continuous stream of some 30,000 gal. per hour being drawn from the outfall and passed on through the plant to the pool. Two unusual problems confronted the purification plant manufacturers in providing this warmed water supply, one purely hydraulic and the other a treatment problem.

The hydraulic problem was that the condenser outfall is part of a siphon and at the point of connection, some 120 ft. from the plant, the vacuum varies from 5 to 12 in. of mercury according to the state of the tide. A foot valve in the outfall was out of the question as if it failed, access to it was impossible without breaking the vacuum and interfering with the power station. It was consequently decided that the whole of this 9 in. suction pipe should be primed by exhausting itfrom the plant end.

The plant has to run continuously. The usual self-priming type of pump was, therefore, out of the question and the problem had to be tackled from another angle.

The water, under certain conditions of wind and tide, is bad, so it was decided to adopt the Pulsometer ”Hydrair” device and pump out the air hydraulically. Furthermore, a considerable amount of air in solution in the water was expected to separate out as the vacuum rose so that the ‘ Hydrair” had to be kept working continuously. A small booster pump was accordingly coupled to the tail end of the main pump, drawing from a small operating tank, and discharging through the “Hydrair” back to the tank. The “Hydrair” suction was coupled to the main suction pipe with an auxiliary connection to the pump suction chamber.

A vacuum as high as 21 in. of mercury can be pulled, and the main exhausted under the worst conditions in about 7 min. The froth and bubbles on the surface of the operating tank even when the plant is pumping shows the amount of air that separates out in the suction pipe and is diverted through the ” Hydrair ” to atmosphere instead of air locking the pump.

The other problem was the treatment of this raw water on its arrival at the filter room. It had already been found that raw sea water at Portobello may, under certain circumstances, contain as much as 1 per cent. of solid matter of such agummy nature that a filter bed will choke up in 15 min. It was impossible therefore to pass the water straight to the filters and a sedimentation tank has been introduced in the circuit to precipitate the mud after it arrives at the filter room. Coarse solid matter that would otherwise damage or choke the pump is arrested by a strainer box in the suction main.

After sedimentation, the top water runs over a weir into a clear water chamber, the sludge being periodically ejected to drain through a purging valve.

The capacity of the pool is 1 and one quarter million gal. of water passed completely through the filters twice a day. The water is supplied to the pool by flowing over two weirs situated at the shallow end.

The horizontal pressure filters – two in number – are each 9 ft. in diameter and 30 ft. long divided midway to facilitate washing. Washing is carried out by compressed air and a reverse flow of water. The air is provided by a ‘* Hydrair ” motorless compressor operating on the same principle as the priming device and is quiet and oil free, no oil traps or separators being required.

The circulating pump is of the split-casing type, specially modified in design to provide a   characteristic suitable for this type of work and dangerous overloads on the filter bed immediately after washings are impossible. Due to the “Hydrair” priming and air compressing apparatus, the two pumping units are the only mechanically moving units in the whole filtration plant.

Sterilisation is by the chloramine process. In view of the size of the scheme the instruments selected are a chlorinator of the MSVM automatic vacuum type and a BDPAM ammoniator operating on anhydrous ammonia gas. Both these instruments are of Messrs. Wallace and Tiernan’s manufacture.

Full metering equipment has been supplied. There is a set of clarity tubes enabling the attendant to watch the results obtained from the plant without leaving the control platform.

Wave-Making Installation.

The wave-making installation, the largest in existence, is only the second to be fitted in this country and it is the first of its kind, being a new patent brought out by Messrs. Brown Brothers and Co., Ltd., Rosebank Ironworks, Edinburgh, by whom it was built and installed at the pool. As the design of the plant is entirely new the makers. before deciding on the final lay-out, carried out extensive experiments with a 1/10^th scale model oi the pool and we understand that the results obtained at the pool agree very closely with those of the model. The waves are produced by specially shaped wave generators reciprocating vertically in recesses formed in the wall at the deep end of the pool. There are four of these generators each being about 23 ft. long and of cross section as shown at A in sectional elevation. They are of all welded construction with suitable internal bracing and are guided by means of rollers at each end working in channel section guides secured to the walls of the recesses. To the back of each generator are fitted two driving pins to which re coupled connecting rods 13 linking the  generator to the levers C which are secured to rocking shifts D passing through stuffing  boxes in the end wall into the machinery compartment where the four rocking shafts  on each side are connected together by vertical levers F and links F with a master lever  (G keyed to one shaft on each side so that the two generators on either side of the centre line are operated in unison but may be operated independently of the other pair

Coming now to the main drive, in order that the wave effects may be varied at will it is  essential that the stroke and speed of the generators may be varied and for this reason a  variable speed motor is fitted and means are provided for varying the stroke infinitely  from zero to maximum on either pair of generators independently or simultaneously. This is affected as follows: The motor, which is an a.c. variable speed, commutator type of 140 h.p. drives through roller chains the secondary shafts on both sides and the drive is continued by the spur reduction gears to the variable crank discs, the total gear ratio being about 33/1. On each of the crank discs is fixed a hydraulic cylinder with piston packed with cup leathers, the piston rod being secured to the variable crank pin H which is coupled by a connecting rod to the master lever G. A “V.S.G.” variable delivery pump is fitted at K and driven by chain off the secondary shaft. The pump is connected to the hydraulic cylinders through piston control valves and the system is charged with oil. Each control valve is operated by a floating lever, one point of which is operated by a small hydraulic control cylinder, and another by hunting gear attached to the variable crank pin so that the hydraulic piston will stop automatically at any desired position.

The control cylinder is in turn controlled by timing valves which can either be operated by hand or by an automatic timing device. By this arrangement of control gear the stroke of both pair of generators can be varied as desired and the result is a pleasing variety of wave effects. For example, if both pairs are operated at maximum stroke a full wave is  created across the whole width of the pool, and if one pair be cut down to no stroke the  waves from the other pair travel diagonally across the pool giving breakers full across  the shallow sloping ” beach ” while leaving one side of the deep end undisturbed. Other combinations of generator stroke cause waves from the two sides to cross each other, producing a very lively sea for surf bathing, while on the other hand the results can be reduced to a gentle swell breaking in a foot of surf. By means of the automatic timing device the installation can be set to produce and repeat for as long as required a predetermined cycle of these varying effects. The numbers of the new Letters Patent for this system are 2052 /35 and 6217/35.

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Accommodation.

Accommodation is provided for at least 6,000 spectators: 2,000 of whom are seated under a covered stand. The roof of the stand is on the cantilever principle, thereby giving a clear, uninterrupted view of the whole pool. There is also locker accommodation for 1,278 bathers of both sexes, i.e., 639 males and 639 females. Additional accommodation on the wire basket system has been provided for 750 male bathers.

On the Portobello promenade, the buildings consist of an entrance hall for spectators, flanked on either side by a shop and a public shelter. The entrance hall gives access, by means of two staircases, to a lounge hall and restaurant, as well as the spectators’ promenades. Provision has been made for open-air tea gardens adjoining the restaurant, and ample lavatory accommodation for the sexes.

The buildings in Rosebank Lane consist of an entrance hall for bathers and spectators. The bathers’ accommodation consists of bays of cubicles on either side of the entrance hall and under the covered stand, laid out in bays of approximately 22 cubicles per bay, with a two-tier double-sided cabinet of steel lockers. The floor has a cork inlay along the corridors and into each cubicle. Lavatory accommodation is provided at the ends of the corridor, just before reaching the footbaths and spray room. The only access bathers have to the pool is through the footbath, and special foot-washing pedestals are provided, over and above the footbath.

General.

Provision has also been made to instal underwater lighting.

The bathers’ promenade surrounding the pool, varies in width from 20 to 23 ft. It is laid in panels with a non-slip preparation. A fully equipped first-aid room is provided with an exit stair at the south end, so that in the event of any accident, the injured person may be removed without any inconvenience to either bathers or spectators. At the north end of the bathers’ promenade, two rest rooms have been provided, one for male and one for female bathers. Arrangements have been made to obviate the mixing of spectators and bathers.

Music for the entertainment of patrons will be by means of amplifiers suitably placed in the buildings, and by means of land lines it will be possible to broadcast band performances taking place in other parts of the city. Announcements and urgent requests for individuals can also be made on this equipment, through a microphone situated in the pond master’s office.

A complete and ample kitchen has been provided in the restaurant.

Mr. W. A. Macartney, Assoc.M.Inst.C.E., the city engineer, has been responsible for carrying through the scheme. The pond master is Mr. R. M. Hogg, M.N.A.B.S.

Contractors.

The principal contractors for the construction of scheme were Messrs. Wm. Arnott M’Leod and Co., Ltd., Edinburgh. Among the sub-contractors were Filtration plant, Messrs. Pulsometer Engineering Co., Ltd., Rending; wave-making machinery, Messrs. Brown Bros. and Co., Ltd. Edinburgh; faience tiling, Messrs. Shaw’s Glazed Brick Co., Ltd., Darwen, Lanes; sanitary ware, Messrs. Steele Bros. and Sons, Ltd., Portobello; flooring, Messrs. Attoc Blocks, Ltd., London: loudspeaker equipment, Andrew F. Baird, Edinburgh, Scottish selling agent for Philip’s Industrial (Philips Lamps, Ltd.), London.