Page 25: of Marine Technology Magazine (November 2018)

The use of buoys vs. ? oating top marks

Buoys are an excellent solution for river channels with a constant ? ow as their mooring can be designed with a long scope and their movement perpendicular to the axis of the channel will be minimal.

In the Douro River Balizamar buoys work perfectly with 3 knots of current. However, when ? ow is not constant having buoys on long mooring scopes may present a problem due to their swing radius, particularly where there are narrow chan- nels and cross winds.

For this reason, in the Douro River piles are being used in the shallower and narrower parts of the channel, buoys in the deeper and broader parts of the river. Generally, the narrow and shallow sections occur close to dams on the downstream side and deeper water close to dams on the upstream side.

The development hinges around the concept of a ? oating top mark that acts as a buoy when moored to the top of the pile. When water level rises the impulse of the top mark- buoy will release the unit from the pile at which point it will ? oat away down river until the mooring line is taught.

The unit will then act as a buoy remaining vertical and up- right when a? oat in low current speeds, although it is im- probable the unit will remain vertical in strong currents as the use of counter weights had to be avoided to facilitate re- placement. Once water level subsides the maintenance team will have to re- place the units on their piles.

Resulting design

This innovative buoy works as a ? xed and ? oating mark and it’s designed for rivers or channels with a high water level variation whilst maintaining a high pre- cision when water levels are low.

The project was selected for presentation under the conferences’ innovation section at the 19th edition of IALA Conference in

Incheon (South Korea), which took place in May 2018, and it was present- ed by Almarin’s general manager and technical director, Patrick Lindley.

Almarin, an IALA in- dustrial member since 2008, pre- sented its new AtoN catalogue too, with a wide offer of buoys, beacons and towers for ports, lantern rooms and solutions for the marking of bridges and structures under navi- gation channels. www.marinetechnologynews.com

MTR #9 (18-33).indd 25 MTR #9 (18-33).indd 25 12/4/2018 9:27:28 AM12/4/2018 9:27:28 AM