Marine Lifting
Fehmarnbelt: IVY's 1,600-Tonne Load Test
Fehmarnbelt's September load test addressed a change in transport geometry. The first special tunnel element has a basement and must travel higher in the water than a standard element. Raising it reduces buoyancy and transfers more load to the immersion vessel IVY. Sund & Bælt reported on 11 September 2026 that the fourth standard element had been loaded with an additional 1,600 tonnes, distributed between water bags on its roof and tanks inside it, and lifted to the height required for transporting the special element. [1]
A higher transport position changes the load
The special element is 39 m long, 47 m wide and 13 m high. Its basement houses technical installations. IVY comprises two pontoons, each approximately 105 m long and 45 m wide, which support the tunnel element at its ends. IVY lowers the unit using winches and steel cables. [1][2] The owner's October factsheet records four standard elements immersed and connected off Denmark. The full tunnel uses 79 standard elements, each 217 m long, and ten special elements positioned at approximately two-kilometre intervals. [3]
The support force follows submerged volume
In a quasi-static lift, the combined vertical support reaction balances the element's weight less its hydrostatic buoyancy. With mass held constant, bringing more of the element above water removes part of that buoyant support. For an illustrative seawater density of 1.025 tonnes/m3, a 100 m3 reduction in submerged volume transfers about 102.5 tonnes-force, or 1.01 MN, to the handling system. The calculation needs the submerged geometry at the specified transport elevation. The reaction at each end also depends on the moments of the element's weight and buoyancy about the supports. Ballast location, centre of gravity and centre of buoyancy therefore matter alongside total mass. In September, the test combined additional ballast with a raised transport position [1]. Those two changes both increased demand on IVY. A comparison between test and planned move must reproduce their combined effect, including the load distribution between the pontoons.
Evidence conclusion
The test condition carries through to the transport estimate
The short special element introduces a different handling condition into a production sequence built around 217 m standard units. Its basement drives the higher transport position; that position transfers load from the water to IVY. For an estimator pricing a comparable move, the controlling quantity is the maximum reaction at each support through the transport sequence. That reaction governs the required handling arrangement and the pontoons' corresponding draft, trim and freeboard. The operational estimate also needs the ballast adjustment and checks required between the test condition, harbour departure and lowering. Changing the approved transport height can alter both plant demand and route clearance. The resulting sailing-window decision commits the element, pontoons, support vessels and harbour space for a defined period. Pricing that commitment requires a transport condition with an elevation and ballast state, followed through to individual support loads and the available route water depth.
Outstanding evidence
- Special-element transport elevation, ballast arrangement and measured support reactions
- Route water levels, pontoon draft and the approved tow-out operating envelope
- Owner's subsequent first-special-element operation and installation record
Subject index
Related subjects
These subject pages bring together related projects, technical articles, reports, and evidence methods.
Sources used 3
- Immersion Pontoon IVY ready to immerse special elements with a basement Sund & Bælt / Femern, 11 September 2026
- IVY - The special vessel used to immerse the elements of the Fehmarnbelt tunnel Femern / Sund & Bælt, Undated one-page owner factsheet; accessed 5 November 2026
- Fact sheet on the Fehmarnbelt Tunnel, pp. 1-4 Femern / Sund & Bælt, October 2026