24th International HISWA Syposiu on Yacht Design and Yacht Construction 14 and 15 Noveber 2016, Asterda, The Netherlands, Asterda RAI Convention Centre SEMI-SUBMERSIBLE YACHT CONCEPT RETHINKING BEHAVIOUR AT ANCHOR AND GENESIS OF THE COMFORT DRAFT
PRESENTATION OUTLINE 2 Introduction of the project Back to basics Stability requireents Finding a concept solution (finding Neo ) Seakeeping calculations Conclusion & Further work
INTRODUCTION OF THE PROJECT The NEMO concept was discovered by MARIN at the MYS 2015 when eeting Edwin van der Mark. The concept derives fro study on subersible and sei-subersible yachts developed jointly by Edwin van der Mark and Harley O Neill. This new design allows the Yacht to suberge partially at anchor and give to the guests splendid views above and below the water s surface. The ain goal was pure aesthetical and design. 3
INTRODUCTION OF THE PROJECT MARIN thought that this feature could bring also hydrodynaic advantages at zero speed given soe adaptation of the design. If this could be achieved, the nae of the suberged draft could be so-called a cofort draft. DESIGN + HYDRODYNAMICS = INNOVATION + ENGINEERING = PRODUCT 4
INTRODUCTION OF THE PROJECT MARIN thought that this feature could bring also hydrodynaic advantages at zero speed given soe adaptation of the design. If this could be achieved, the nae of the suberged draft could be so-called a cofort draft. DESIGN + HYDRODYNAMICS = INNOVATION + ENGINEERING = PRODUCT 5
BACK TO BASICS 6
BACK TO BASICS Effect of varying the etacentric height on roll response 7
BACK TO BASICS Existing ships of floaters changing drafts in operations 8
BACK TO BASICS Goal is then to change the loading condition (while changing draft) in order to reduce the etacentric height and iprove the seakeeping (ainly roll) 9
STABILITY REQUIREMENTS The intact stability requireent according to the IMO code of intact stability applicable to the onohull Yacht (13-36 passengers) The area under the righting lever curve (GZ curve) is to be not less than 0.055.rad up to θ =30 angle of heel. The area under the righting lever curve is to be not less than 0.09.rad up to θ =40 angle of heel or the angle of down flooding θf if this angle is less than 40. The area under the righting lever curve between the angles of heel of 30 and 40 or between 30 and θf, if this angle is less than 40, is to be not less than 0.03.rad. The righting lever GZ is to be at least 0.20 at an angle of heel equal to or greater than 30. The axiu righting ar is to occur at an angle of heel preferably exceeding 30 but not less than 25. The initial etacentric height GM0 should be not less than 0.15. 10
STABILITY REQUIREMENTS The interior spaces that could be used to ballast the ship and attain the required suberged draft were used to calculate the new stability. Sybol Figure 2: GZ Curves By calculating the GZ curves corresponding to the second loading conditions, we realize that the first odel hull doesn t respect the intact stability requireent. 11 Magnitude Unit Lpp B T V 105 17,4 4,2 3526,8 105 17,4 6,8 7202 3 GMt 1,4 0,9 KM KG LCG 8,01 6,6 54,7 7,795 6,9 52,53 Cb C Cp 0,52 0,79 0,66 0,71 0,84 0,71 -
FINDING A CONCEPT SOLUTION (FINDING NEMO ) In order to : Satisfy the stability requireent; Reduce the ship otions; Reduce the capacity of the ballast water necessary to suberge the Yacht. We have conceived different hull fors, where, instead of ballasting to change draft and reduce the GM, we would reduce the stability also by changing the hull for when sinking. This is achieved by changing the waterline area while changing draft. 12
FINDING A CONCEPT SOLUTION (FINDING NEMO ) Changing the waterline area while changing draft Cross opening full width 13
FINDING A CONCEPT SOLUTION (FINDING NEMO ) Changing the waterline area while changing draft Dock 14
FINDING A CONCEPT SOLUTION (FINDING NEMO ) Changing the waterline area while changing draft Side gangway over the full length 15
FINDING A CONCEPT SOLUTION (FINDING NEMO ) Changing the waterline area while changing draft Mixed solution that could correspond to gangway and side openings. 16
FINDING A CONCEPT SOLUTION (FINDING NEMO ) Sybol Magnitude Unit Lpp B T V 105 17,4 4,2 3526,8 105 17,4 6,8 6831,6 3 GMt 1,4 0,9 KM KG LCG 8,01 6,6 54,7 zy 6,5 5.6 Cb C Cp 0,52 0,79 0,66 0,57 0,77 0,74 - Figure 3: GZ Curves An expected side effect of the reduced waterline area was that the vertical plane otions could also be affected, on top of the roll 17 54,7
FINDING A CONCEPT SOLUTION (FINDING NEMO ) Design draft (departure) GMt=1.4 M G T=4.2 The capacity of the ballast needed to suberge the vessel is around 3387 3. The space dedicated to habitability is 40% less copared to a yacht of the sae size. cofort draft (anchor) GMt=0.9 T=6.8 M' G'
FINDING A CONCEPT SOLUTION (FINDING NEMO ) 19 Based on the concept, the designer ade a new superstructure and rendering. Such solution brought by hydrodynaic consideration proved to be even ore creative than the original concept!
SEAKEEPING CALCULATIONS The calculations are represented in ter of RAO, at anchor (zero speed) in bea seas, for 2 loading conditions in order to copare the behaviour of the vessel at the initial draught (Config_1) and when it suberges (Config_2) Description Lpp Bwl Ta Tf Displaceent Awp GMt LCB KB LCG KG 20 Value 105 15.4 4.2 4.2 3526.8 1238,7 1.4 54.8 2.5 54.7 6.6 105 16,7 6,8 6,8 7026,3 1189,8 0.9 52,53 3,97 52,53 5.6 Unit [] [] [] [] [3] [2] [] [] [] [] [] 10.816 15,87 [s] kxx kyy 6.9 26.25 6,9 26.25 [] [] kzz 26.25 26.25 []
SEAKEEPING CALCULATIONS Figure 5: Roll Excitation Force Figure 4: Roll RAOs in 1 aplitude (u=90 ) 21
SEAKEEPING CALCULATIONS 22
SEAKEEPING CALCULATIONS 23
SEAKEEPING CALCULATIONS Figure 6: Heave RAOs in 1 aplitude (u=90 ) 24
SEAKEEPING CALCULATIONS 25
SEAKEEPING CALCULATIONS 26
SEAKEEPING CALCULATIONS Figure 7: Scatter diagra of the Mediterranean Sea 27
CONCLUSION & FURTHER WORK Creating a cofort draft concept can inherently iprove the perforance at anchor of yachts. This is obtained by working on iersion of the hull and odification of the hull characteristics. The principle of the cofort draft is: Change of waterline area to reduce stability and thus odify excitations; New waterline area is achieved in the present concept by the recesses created in the hull which are iersed when changing draft; Such new waterline area could also be achieved by creating side opening (like with garage doors) and by flooding part of the waterline area at intact draft. Further work should obviously be addressed for the engineering of such solution (interior arrangeents, daaged stability study, noise & vibration ballasting systes and strength calculation), the possible side effect during ballasting operations (safety, free surface effects), and the acceptation of such concept for the yards and owners, as well as requireents fro classification societies. 28
THANK YOU! Design draft (departure) GMt=1.4 M G T=4.2 cofort draft (anchor) GMt=0.9 T=6.8 M' G' 29