20 ISLE OF MAN EXAMINER www.iomtoday.co.im Tuesday, October 20, 2020 BUILDINGS AT RISK Sea defences played vital role in preserving beaches

Buildings at Risk covers buildings and structures and how they contribute to our island. This week Frank Cowin, a Fellow of the Royal Institute of Chartered Surveyors who grew up on Douglas Promenade, looks at sea defences and in particular the reasons for erecting and retaining effective groynes on our vulnerable beaches

romenades are for even reaching the height seeing and being of the buildings opposite seen. The being and large quantities of wa- seen is possibly of ter threatening to flood the less importance roadway. Pthese days than in the past When in the 1930s the when those who felt them- Promenade was widened to selves to be ‘a cut above’ would create the sunken gardens parade to show themselves off and the wide walkway it was on the Promenade. realised that to allow some In more recent times they of the weight of the water to became places to congre- pass through the ironwork gate to mix and meet friends sections it would reduce the while the young would be impact and the height the hoping to make new friends spray rose, while enabling usually of the opposite sex. any water arriving on the Promenades were often walkway to quickly and easily places of entertainment return to the sea with little and Douglas was no excep- chance of it being trapped on tion with its bandstand and the walkway. Power of the waves striking Douglas seafront prior to the promenade being widened pierot shows forming a focal The ironwork also opened point. up the view to the sea and The Harris Promenade beach without people hav- easily and quickly be closed the ground throughout the in heaps and hoping the tide was the high point of all this ing to lean over the wall or when storm conditions are area and many readers will will take it away cannot be activity becoming so busy at children having to climb on anticipated. remember the pumps which described as being very suc- times as to warrant the erec- top with all the risks that in- The original sea wall was were needed to keep the cessful. Our forefathers re- tion of ‘Keep Right’ signs. volved. behind the hotels and board- ‘Clarendon Grill’ at the Vil- moved the seaweed to spread The construction of the A more suitable meth- ing houses where the one liers Hotel free of water. it on the land – could another Loch Promenade was in- od of providing protection surviving short length of Perhaps fortunately the profitable use have been tended to extend this with against future rises in sea lev- this is on the rear wall of WH tide in the ground in that found for it? Clarendon Grill beneath The the naming of the southern el without interfering with Smith’s in the lane off How- vicinity runs at about 20 The recent removal of the Villiers Hotel which was protected end ‘The Loch Parade’ show- the views from the prom- ard Street. minutes behind the sea so groynes from the beach can by pumps at high tide ing the hopes of the Town enade would be to strength- One other piece which that its rise and fall are much only add to the problems of Fathers. en and slightly increase the had survived and was sup- reduced! the sea running over the road way on the ‘Town Side’ and However, with its high height of the outer wall of posed to be incorporated The one area where an in the Queens Promenade push it up and slightly across cement-faced wall it never the gardens with protecting into the ‘Villiers Site Town edge-of-Promenade wall is area. That problem has only and the stone will follow achieved the hoped for popu- overlapping walls built onto Square’ disappeared over required is to shelter the War arisen because of the lack of the retreating wave straight larity. the walkway giving adequate one weekend in unexplained Memorial. This should be maintenance afforded to the down as it recedes. Indeed early postcards access to the throughways to circumstances. treated as an architectural groynes in recent years. The stone will gradually show its main popularity was the roadway. As the tide has little re- feature suitable for receiv- cross the concrete in a saw- for watching the waves break These were to be fitted gard for man-made defences ing memorials to others los- LONGSHORE DRIFT & GROYNES tooth fashion until it drops high over it with the spray with storm gates that could it flows in and out beneath ing their lives in conflict and The purpose of the groynes on off again on the Derbyhaven suitable for the display of the our beaches is to inhibit the side. Following tides will main memorial wreaths. ‘longshore drift’ – the move- move it on until it comes Attention needs to be ment of sand and stone, along to rest alongside the Golf given to the junction of the the coast, by the sea. Course where the path is now War Memorial platform On the island, longshore much further from the drop with the reduced width of drift is normally, but not to the beach than it used to the Harris Promenade. The always, from south to north. be. angle between the two faces The action of the waves The results of the action concentrates the power of moves sand and stones slow- of the sea in this way can waves, consequently causing ly but surely along. be seen at the Point of Ayre damage especially when the A place where this action where the tidal streams run waves ‘decorate’ the railings can actually be watched is against the coasts of the with seaweed and the in- the slipway to the beach from Northern Plain, scouring the creased surface area means Castletown Promenade. Ice Age alluvial deposits from that the force is sufficient to At the right state of the the coastline. damage the rails. tide and with a reasonable The nature of the mate- It must be said that the wave height an incoming rial is such that at the worst present way of dealing with wave will ‘flip’ a stone onto affected areas, on both sides, Harris Promenade, with one of its ‘Keep right!’ signs highlighted the sea weed by piling it up the foot of the concrete slip- there is erosion to the aver- Tuesday, October 20, 2020 www.iomtoday.co.im ISLE OF MAN EXAMINER 21 BUILDINGS AT RISK

The former drop to the beach opposite the Crescent

A postcard showing parading on the Promenade

Height of the sea wall at Laxey where shingle hasn’t built up

The former drop to the beach opposite the Palace Hotel

age extent of 1.5 metres a ‘hollows’ are larger stones the sea when built in 1818. As Memorial northwards. year. Some years little is lost, grading gradually to small the stones built up, and the At Queen’s Promenade but at other times 10 metres stones at the top and increas- Pont extended North-East, it where in my youth there was or more can be lost in a night. ing in size again as you de- was found necessary in 1890 a drop in excess of four me- Here not only does the scend into the next hollow. to erect the ‘Winky’ light to tres to the beach, the top of Other parts of the Laxey wall are increasingly ineffective because of the tidal run move the materi- Meanwhile the now- mark the edge of the land; the shingle is now nearly at build-up of shingle als along the coast but also combined tidal run carries and then in 1926/7 move it footpath level. In storm con- moves the various constitu- the sand Eastward where it from its original site – where ditions at high tide the waves ents at differing speeds. is deposited as the waters the remains of the foghorn can run up the shingle and Heavy stones move very disperse and slow. The de- are situated – to near the new across the footpath and at Groynes, sea walls and breakwaters slowly but the smaller the posited material forms the edge of the sea, where it now times also the road. stone the faster it moves. The King William and Bahama stands once again well inland At the Crescent the drop A sea wall fine material, grains of sand banks, dangerous shallows, from the tide line. was in excess of two metres Principally defends against the height of the tide, stopping ‘over-top- and soil, are suspended in once marked by a lightship Longshore drift in the but again is now very small. ping’ when the water level is too high, as sometimes seen around our the water and can be moved but now with warning buoys. island is usually south-to- A similar situation occurs harbours can protect a vulnerable land-edge from erosion can be faster than you can run. These banks force marine north but there can be local in Laxey where the shingle the final barrier to waves washing debris ashore As a result the stones are traffic to pass unusually tidal eddies. The southern has been allowed to build up deposited where the two close inshore at the Point end of this North-East coast not only to footpath level but A groyne tidal streams collide at the of Ayre to keep clear of the is one of the areas affected by almost the full height of the Is usually constructed at right-angles to the shore reduces long- Point of Ayre. They end up as sandbanks. a local southern longshore existing wall. shore drift which causes both erosion and unwanted build of shingle low banks of stone wrapping The extent of the build-up drift causing a build-up of A high wall is not neces- which in turn means waves roll more easily ashore themselves around the Point, of material at the Point can stones beyond the wall at the sarily the answer as wit- where if you walk across readily be seen as the light- southern end of Ramsey’s nessed by what happened A breakwater them you can see that in the house was close to the edge of North Promenade where at Loch Promenade before Is usually constructed parallel to the shore, or across the mouth of a nature reclaims it and plants the gardens were built, and harbour breaks the force of the waves before they reach the shore start to grow, where the what happens at the north or the harbour swimming pool / ‘Talk of the end of the Promenade where Town’ once stood. the Port Jack road has so fre- of the present ‘build up’ of Douglas North Quay, Laxey quently to be closed. stones from the north end of and Ramsey and where used DOUGLAS The trick in these situ- Douglas Promenade and use must be designed to fit in In a similar fashion at Doug- ations is to make sure that them to help form an ‘outer with both the appearance las the sea scours the beach the waves have lost their full work’ to protect the South- and use of the area involved. at the foot of the southern energy before they arrive at ern end. ‘One fix’ does not fit all end of the Promenade wall the final barrier. Continu- Walls can help, but in but we can often find that and slowly but surely moves ing beach management has general their use should be our forefathers had fore- Ineffectual skeletal remains of neglected groynes on Douglas beach, which the material along and dis- to be a major part of this, in- restricted to sheltered areas thought which we ignore at were recently removed tributes it beyond the War cluding the removal of much such as the harbour sides at our peril.