Subsea payload installation system

A method of landing and securing a payload to a subsea assembly, utilizing a surface vessel and a vessel cable extending from the surface vessel, the method comprising:

• providing a submersible payload package including a package cable extending from the payload package;
• providing a floatation device attached to the payload package;
• suspending the payload from the package cable;
• lowering the package and the payload subsea toward the assembly via the vessel cable;
• connecting a guide cable extending from the package to the assembly;
• thereafter activating the floatation device such that the package becomes positively buoyant, thereby making the guide cable taunt and relaxing the vessel cable to de-couple the package from the surface vessel;
• thereafter lowering the payload onto the subsea assembly via the payload cable, with the guide cable remaining taunt;
• thereafter connecting the payload to the assembly;
• thereafter de-activating the floatation device such that the package is not positively buoyant, thereby making the vessel taunt and the guide cable relaxed to re-couple the package to the surface vessel;
• and
• thereafter retrieving the package to the surface vessel.

Apparatus for landing and securing a payload to a subsea assembly utilizing a surface vessel and a vessel cable extending from the surface vessel, the apparatus comprising:

• a submersible payload package suspended from the vessel cable;
• one or more guide cables extending from the payload package for securing to the subsea assembly;
• a submersible floatation device connected to the payload package selectively activatable to render the payload package positively buoyant and selectively de-activated so that the payload package is not buoyant;
• a powered vessel winch on the vessel for controllably lowering and raising the submersible payload package;
• and
• a powered package winch connected to the payload package for selectively lowering the payload with respect to the payload package.