An offshore production system, comprising: a surface vessel; a tubular tendon extending between the surface vessel and a lower connection system disposed at a seabed, the tubular tendon coupled to the surface vessel with an upper connection system; and an electrical cable extending through a central passage of the tubular tendon and configured to heat sea water in the central passage of the tubular tendon; wherein the upper connection system comprises a connector that physically supports the electrical cable; characterised by a cooling system including a cooling joint disposed subsea along the tubular tendon, wherein the cooling joint comprises: a first port; a second port positioned above the first port; a seal assembly positioned along the central passage within the cooling joint between the first port and the second port; wherein the seal assembly extends radially from the electrical cable to the cooling joint, wherein the seal assembly is configured to prevent the flow of sea water through the central passage of the tubular tendon between a first portion of the central passage below the seal assembly and a second portion of the central passage above the seal assembly; wherein the first port is configured to vent sea water flowing upward through the first portion of the central passage of the tubular tendon via natural convention and allow cooling of the electrical cable extending through the first portion of the central passage; wherein the second port is configured to allow sea water to enter the central passage or vent sea water from the central passage of the tubular tendon. a surface vessel; a tubular tendon extending between the surface vessel and a lower connection system disposed at a seabed, the tubular tendon coupled to the surface vessel with an upper connection system; and an electrical cable extending through a central passage of the tubular tendon and configured to heat sea water in the central passage of the tubular tendon; wherein the upper connection system comprises a connector that physically supports the electrical cable; characterised by a cooling system including a cooling joint disposed subsea along the tubular tendon, wherein the cooling joint comprises: a first port; a second port positioned above the first port; a seal assembly positioned along the central passage within the cooling joint between the first port and the second port; wherein the seal assembly extends radially from the electrical cable to the cooling joint, wherein the seal assembly is configured to prevent the flow of sea water through the central passage of the tubular tendon between a first portion of the central passage below the seal assembly and a second portion of the central passage above the seal assembly; wherein the first port is configured to vent sea water flowing upward through the first portion of the central passage of the tubular tendon via natural convention and allow cooling of the electrical cable extending through the first portion of the central passage; wherein the second port is configured to allow sea water to enter the central passage or vent sea water from the central passage of the tubular tendon. a first port; a second port positioned above the first port; a seal assembly positioned along the central passage within the cooling joint between the first port and the second port; wherein the seal assembly extends radially from the electrical cable to the cooling joint, wherein the seal assembly is configured to prevent the flow of sea water through the central passage of the tubular tendon between a first portion of the central passage below the seal assembly and a second portion of the central passage above the seal assembly; wherein the first port is configured to vent sea water flowing upward through the first portion of the central passage of the tubular tendon via natural convention and allow cooling of the electrical cable extending through the first portion of the central passage; wherein the second port is configured to allow sea water to enter the central passage or vent sea water from the central passage of the tubular tendon.