Preventative maintenance system for underwater pipes

An apparatus suitable for passing cable through an underwater intake pipe, comprising:

• a cone-shaped device having a forward end and a rear end;
• the cone-shaped device including an outer cone element and an inner cone element, said cone elements having narrow ends adjacent each other and wide ends adjacent each other at said rear end,
• wherein the cone elements have a substantially common axis;
• the outer and inner cone elements being radially spaced apart from each other to provide a conical air pocket therebetween.

Apparatus for passing a cable through an underwater pipe through which water flows, comprising:

• (a) an outer hull having a generally conical exterior surface, a forward narrow end, and a rear wide end;
• (b) an inner hull located substantially wholly within and connected directly or indirectly to said outer hull and having a forward end and a rear end, said forward ends being proximate each other, said rear ends being proximate each other;
• (c) a pocket of buoyant gas between said outer hull and said inner hull, said pocket extending substantially completely around a longitudinal axis of the apparatus;
• and
• (d) a connection device for connecting to the cable, the connection device being mounted directly or indirectly to a selected one of said hulls.