Sub Surface Buoys

The Materials

As with surface buoyancy, there are two application dependent material parameters to sub surface buoyancy:

• The foam material which forms the core of the product
• The external coating material

Based upon the use to which our products are being put, and the depths to which they need to be rated, we select from a number of possible material combinations to ensure maximum product life and integrity at minimum cost.

Foams

For shallower depths, we are typically offering either high density polyethylene foam or expanded polymer foam. The significant benefit which both these foams offer over the polyurethane foam, which most other manufacturers will offer for these depths, is that the foams we offer are of a closed cell nature.

This means that if the outer skin of a Hippo shallow water buoy is breached, our customers can be assured that the result will not be a rapid and catastrophic absorption of water followed by failure of the product.

For deepwater applications, we are formulating and processing our own pure syntactic foam into which we will then generally introduce moulded macrospheres to reduce the weight and the ultimate cost of the product.

External Coatings

There are 3 main material possibilities for encapsulating the core of Hippo subsurface buoys:

• Polyurethane Elastomer is a highly abrasion resistant, reinforceable coating which we can either spray apply or cast around the foam core. For ultimate durability, this form of coating can be Kevlar™ reinforced.
• Rotationally Moulded Polyethylene is a cheaper and more uniform method of mass producing a protective shell for the foam core in applications where the resilience and flexibility of PU elastomer is not required.
• PU Paint is mainly used in applications where the core material is resilient in itself but requires some level of protection from UV degradation.

Applications

The primary product applications for these materials are:

• Pipeline installation buoys
• Modsyn™ top up buoys, general subsea installation buoys
• Transponder collars
• Modular subsea buoys
• Distributed buoyancy modules
• Submersible/ROV/AUV buoyancy systems