The Orkney Image Library
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"Polo" blocks outside Orkney Builder's hangar heading for Burwick. The purpose of these blocks is to absorb wave energy. There are still a lot of these blocks stored in a few places. I wonder why they are not being used at the fourth barrier? Photo 1989.
Picture added on 10 August 2012 at 14:38
They'd be better used at the second barrier, lol.
Anonymous comment added on 10 August 2012
Maybe not the 4th barrier. I meant the one where the wave wall is.
Added by Sandy on 10 August 2012
Sandy, these hollow blocks are adequate for 'wind waves' but not for the bigger swell waves that cause the problems at No2 barrier. For swell, bigger, heavier concrete units, the four legged tetrapod or six legged accropode are used to absorb the wave energy, these made the cuboid 'barrier blocks' obselete in the 1950's. The cuboid blocks don't self-drain well and trap backwash water on the slope which allows successive waves to climb higher. This might explain the rogue waves that reach the road even near low tide at No2 barrier.
Added by Karl Cooper on 10 August 2012
Or even the second barrier Sandy.
Added by Neil Johnstone on 12 August 2012
St Ola
