A method for retrieving a mobile platform (30) from inside a tank (10) having a hatch (24) and at least partially filled with an energetic substance (12, 14), the method characterized by:
- configuring a retrieval carrier (100) to have at least an intermediate span (102) and an attachment end (104, 104a), wherein a majority of a cross-sectional area of the intermediate span (102) includes a braided synthetic fiber rope (120) having a porosity of at least ten percent, wherein the braided synthetic fiber rope (120) has an elastic compressibility sufficient to reduce the porosity of the braided synthetic fiber rope (120) by at least fifty percent, wherein the intermediate span (102) does not have a fluid tight passage enabling fluid communication between a location outside of the tank (10) and the mobile platform (30);
- configuring the mobile platform (30) to have at least:
- at least one enclosure (32) and at least one propulsion system (36) positioned at least partially inside the at least one enclosure (32);
- configuring a retrieval assembly (200) to have at least:
- a retrieval frame (220), an energetic substance extractor (240), and a retrieval winch (280), wherein the retrieval frame (280) supports the retrieval carrier (100), the energetic substance extractor (240) is positioned between the retrieval frame (220) and the mobile platform (30), and the retrieval winch (280) is connected to the retrieval carrier (100);
- configuring the energetic substance extractor (240) to have at least:
- a plurality of opposing surfaces (256, 258) defining a passage (254), the passage (254) being sized to cause the opposing surfaces (256, 258) to have rolling contact with and compress the intermediate span (102) of the retrieval carrier (100) in the passage (254);
- moving the mobile platform (30) in the tank (10) using the at least one propulsion system (36) while the mobile platform (30) is submerged in a liquid energetic substance (12);
- positioning at least the energetic substance extractor (240) of the retrieval assembly (200) adjacent to the hatch (24);
- retrieving the mobile platform (30) from inside the tank (10) using the retrieval carrier (100), wherein the retrieval carrier (100) is connected to the mobile platform (30) by the attachment end (104, 104a), the retrieving done by at least:
- operating the retrieval winch (280) to pull the intermediate span (102) of the retrieval carrier (100) toward the retrieval winch (280), and
- passing the intermediate span (102) of the retrieval carrier (100) through the passage (254) while the intermediate span (102) of the retrieval carrier (100) is being pulled to the retrieval winch (280),
- wherein the intermediate span (102) of the retrieval carrier (100) passing through the passage (254) applies a torque at the rolling contact with the plurality of the opposing surfaces (256, 258), and wherein the applied torque rotates the opposing surfaces (256, 258), and
- wherein the intermediate span (102) of the retrieval carrier (100) was submerged in the liquid energetic substance (12) and retains a residue (50) of the liquid energetic substance (12) upon entering the passage (254);
- and
- compressing the intermediate span (102) of the retrieval carrier (100) between the plurality of the opposing surfaces (256, 258), wherein the compression extracts from the intermediate span (102) in the passage (254) a majority of the residue (40) of the liquid energetic substance (12) retained by the intermediate span (102) of the retrieval carrier (100) upon entering the passage (254).