Eco-Mooring Anchors

Recently we have been working on our underwater installation options to help our customer achieve an environmentally friendly mooring option. The journey began back in last year, (concept video)  and we were delighted to have been able to successfully install the anchors under water.

Our mooring anchors have recently been featured on the news, showing how the use of our anchors can protect the seabed and protect the wildlife within.

Below you can find further detail on our screwpiles and their application under water, should you have any questions please don't hesitate to contact us.

ABC anchors are the preferred supplier of helical screw mooring anchors, compatible with Hazelett, Seaflex and other Advanced Mooring Solutions (AMS). We have exhibited our products at the Plymouth Boat Show, on thegreenblue stand together with The Ocean Conservation Trust stand at Sail GP in Plymouth.

Test installations have been carried out at Studland Bay and Cawsand, where in conjunction with an AMS the regrowth of sea grass right up to the head of the anchor is truly impressive.

Helical screw anchors are installed to pre-determined torque to ensure a predictable pull out performance.

As a rough guide, a single 60R anchor when installed to 50% of maximum torque delivers the same performance as a concrete block weighing 5 tonnes.

Clearly some sea beds are very soft and may require an additional 2m extension, whilst other rocky sea beds will not allow the anchor to penetrate - evidenced by a lack of torque.

In general, the mooring rode attached to a screw pile can be much shorter than a conventional setup. The rated pull out capacity corresponds to a vertical force, which would reduce the holding power of a concrete block, already reduced by its immersion in water.

For seagrass beds, it is important to prevent the mooring rode rubbing on the seabed so the ability to shorten this allows savings in material and permits closer spacing. Where unitary synthetic rodes are used, a camera can crawl down to carry out routine inspection, and aid removal when necessary.

In the Tamar River at Calstock concrete block moorings are frequently displaced when fallen trees wrap round moored boats. None of the screw-anchored boats has moved over two seasons.

Alexander Mitchell invented the helical anchor in the 1830’s and in wide use today, both as a tension and compression-resisting element. Naturally, they are generally buried out of sight, but practically every Telecom and Electricity pole has a helical stay anchor installed to resist lateral loads.

ABC Anchors designs and manufacturers helical anchors and installation equipment so we are uniquely placed to monitor real world situations and help our Approved Installers achieve consistently excellent results in the most challenging of situations.

For marine installations, we have hand held hydraulically powered torque heads, suitable for use by divers, excavator or crane mounted equipment and are developing a road transportable barge for multiple moorings.

We work with local mooring contractors whose site specific knowledge of the ideal combination of gear is essential to ensure a satisfactory result, we are, of course ready to train operators using our experience to date.

Underwater Installation of an Environmentally Friendly Mooring System

A special revision of our 400H can be used by divers to install and environmentally friendly mooring system in depths up to 10m.

The unique hollow shaft 400H can drive ABC 60R screw anchors from the centre lugs, and then the end, of leads and 2m extensions.Hydraulics power is usually from a petrol power pack at the surface.

The driver operator maintains full control using the integral control valve. An extended torque reaction arm engages with the seabed for safety. A Mooring swivel is bolted to the final extension prior to being driven just below the seabed to prevent boat grounding damage. At maximum torque and 3:1 factor of safety the working load exceeds 40kN (4 Tonnes). The driver will also extract an anchor when necessary.