Hull Deflection Calculator

Description

This excel-based app can be used to calculate Hull girder vertical and along-ship deflections at specified ship frame and longitudinal locations along the main deck of a Tanker-shaped hull (as measured from Aft Peak and C.L).

Hull girder vertical and along-ship deflections at specified ship frame and longitudinal locations along the main deck of a Tanker-shaped hull (as measured from Aft Peak and C.L) are calculated. These
deflections are of interest in the design of supports of deck-mounted structures (e.g. topsides modules) as well as in the monitoring of hull deformation during ship loading and unloading operations.
Local Results forward and aft of a User-Specified reference frame (3 aft and 3 fwd) and up to four longitudinal locations at each of the seven local frames are reported for User defined stillwater

The impact of ship main deck camber is accounted for in the calculated along-ship deflections. Hog-sag deflections along the tank-tops of sideshell sponsons can also be determined.
This App is geared toward evaluating hog/sag deflections in Tankers ranging in size from Suexmax to VLCC but is applicable to any ship hull that conforms to Euler beam assumtions.
Selected spot input and output checks are included to alert user to inconsistencies in the data.
An interactive results querying feature is included to permit the User to plot selected global and local hog and sag deflection results

Reported Results
1 All results are presented on Worksheet “Outputs”
2 Specific Hog & Sag deflection results reported for the local main deck area of interest are:
a Summary of the Input
b Plots of GLOBAL Vertical and Along-Ship Deflections (Relative to AP) via USER Interactive Query
c Plots of LOCAL Vertical and Along-ship Deflection Combinations (Relative to the Reference Frame

d Detailed Local Hog-Sag Support Displacements by Design Condition with respect to the Reference Frame
e SACS JOINT PERSET input for Specified Support Joints (FUTURE)
f StaadPro support displacement input for Specified Support Joints (FUTURE)

Limitations
Validity of calculation is restricted to ships having hull girder where application of Euler beam theory is valid.
ie Lpp/ D is greater than 5 and where planar cross-sections are assumed
to remain plane in bending i.e. no warping of cross-section. In the present version of this App, relative
support displacement output to structural analysis input is limited to 7 hull frames including the reference frame.

References
1. DnVGL-RU-SHIP, Pt 3, Ch 4, Jan 2017
2. Colin Caprani, Structural Analysis III Lecture Notes, Chapter 5, The Moment-Area Method
3. MacMillan et al., “Effective FPSO/FSO Hull Structural Design”, Offshore Technology Conference, 2001
4. If available for the hull of interest, the Stability Booklet (for SWBM data).