US 11,884,368 B2
Launching elongate subsea structures
Philip Derek Brown, Dyce (GB); and Eric Fletcher McEwan, Kingswells (GB)
Assigned to SUBSEA 7 LIMITED, Sutton (GB)
Appl. No. 15/733,869
Filed by Subsea 7 Limited, Sutton (GB)
PCT Filed Jun. 21, 2019, PCT No. PCT/GB2019/051742
§ 371(c)(1), (2) Date Nov. 30, 2020,
PCT Pub. No. WO2019/243834, PCT Pub. Date Dec. 26, 2019.
Claims priority of application No. 1810310 (GB), filed on Jun. 22, 2018.
Prior Publication US 2021/0221475 A1, Jul. 22, 2021
Int. Cl. F16L 1/16 (2006.01); B63B 21/66 (2006.01); B63B 21/20 (2006.01); B63B 22/18 (2006.01); B63B 35/03 (2006.01); F16L 1/24 (2006.01)
CPC B63B 21/66 (2013.01) [B63B 21/20 (2013.01); B63B 22/18 (2013.01); B63B 35/03 (2013.01); F16L 1/24 (2013.01); F16L 1/163 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A method of launching an elongate subsea structure into water, the method comprising:
providing buoyant support to the structure by displacing water with a hollow buoyancy unit that applies buoyant upthrust to the structure; and
by lowering the buoyancy unit in the water to bring at least one permanently open aperture of the buoyancy unit beneath a surface level of the water, flooding the buoyancy unit with water through the or each permanently open aperture to reduce the buoyant upthrust applied to the structure;
wherein the method further comprises dragging at least part of the structure along a seabed while launching the structure.