Theoretical simulations are compared with drop test experiments of vessel free-fall impact on calm water, with zero and nonzero initial heel angles. The impact force and moment are predicted by using a theory described in Xu et al. (1998). The resulting motions of vessels at asymmetric impact include vertical water entry and transverse rolling. The downward deceleration equation combines the hydrostatic and hydrodynamic forces and the weight of hull, while the rolling equation takes into account the restoring moments due to asymmetry. Another simplified approach of a water entry dynamics and injury model (Gollwitzer and Peterson, 1996) is also applied to evaluate the impact acceleration for symmetric cases. The experiments were conducted at the Coastal Systems Station, Panama City, Florida, using a 2 ft × 8 ft (0.61 m × 2.44 m) prismatic hull model with 20 deg deadrise. The comparisons between the asymmetric impact theory and experiment shows varying degrees of qualitative and quantitative agreement.

1.
Boef
W. J. C.
,
1992
, “
Launch and Impact of Free-Fall Lifeboats. Part II. Implementation and Applications
,”
Ocean Engineering
, Vol.
19, 2
, pp.
139
159
.
2.
Gollwitzer, R. M., and Peterson, R., 1994, “Shock Mitigation on Naval Special Warfare High Speed Planing Boats, CSS Technical Assessment,” CSS Technical Report, TR-94/33, Coastal Systems Station, Panama City, FL.
3.
Gollwitzer, R. M., and Peterson, R., 1996a, “Repeated Water-Entry Shock Mitigation for High Speed Planing Boats,” Proceedings, 66th Shock and Vibration Symposium, Biloxi, MS.
4.
Gollwitzer, R. M., and Peterson, R., 1996b, “Drop Tests and Planing Boat Dynamics Modeling for Investigation Repeated Water-Entry Shock Mitigation,” Proceedings, Small Craft Marine Engineering, Resistance and Propulsion Symposium, Ann Arbor, MI.
5.
Gollwitzer, R. M., Peterson, R., and Wyman, D., 1996, “Hinged-Step Technology for Planing Boat Shock Reduction,” Proceedings, Performance Enhancement Maritime Applications Conference, Newport, RI.
6.
Kim, D. J., Vorus, W. S., and Troesch, A. W., and Gollwitzer, R. M., 1996, “Coupled Hydrodynamic Impact and Elastic Response,” 21st Symposium on Naval Hydrodynamics, Norway, June.
7.
Lai
C.
, and
Troesch
A. W.
,
1995
, “
Modeling Issues Related to the Hydrodynamics of Three Dimensional Steady Planing
,”
Journal Ship Research
, Vol.
39
, p.
1
1
.
8.
Peterson, R., 1996, “Characterization of Stiffening and Damping Materials for Planing Boat Shock Mitigation,” CSS Technical Report, TR-96/20, Coastal Systems Station, Panama City, FL.
9.
Peterson, R., Wyman, D., and Frank, C., 1997, “Drop Tests to Support Water-Impact and Planing Boat Dynamics Theory,” CSS Technical Report, TR-97, Coastal Systems Station, Panama City, FL.
10.
Troesch, A. W., and Kang, C. G., 1986, “Hydrodynamic Impact Loads on Three-Dimensional Bodies,” 16th Symposium on Naval Hydrodynamics, University of California, Berkerley, July.
11.
Troesch, A. W., and Kang, C. G., 1988, “Evaluation of Impact Loads Associated with Flare Slamming,” SNAME 13th STAR Symposium, Pittsburgh, June.
12.
Tulin, M. P., 1957, “The Theory of Slender Surfaces Planing at High Speeds,” Schiffstechnik, Vol. 4.
13.
von Karman, T., 1929, “The Impact of Seaplane Floats During Landing,” NACA TN 321, Washington, D.C., October.
14.
Vorus, W. S., 1992, “An Extended Slender Body Model for Planing Hull Hydrodynamics,” SNAME Great Lakes and Great Rivers Section Meeting, Cleveland, OH.
15.
Vorus
W. S.
,
1996
, “
A Flat Cylinder Theory for Vessel Impact and Steady Planing Resistance
,”
Journal of Ship Research
, Vol.
40
, pp.
89
106
.
16.
Wagner
H.
,
1932
, “
Uber Stoss-Und Gleitvorgange and Der Oberflache von Flussigkeiten
,”
ZAMM
, Vol.
12
, p.
193
193
, August.
17.
Wyman, D., 1991, “Variable Deadrise (Shock Mitigation) Bottom for Planing Hull,” Independent Research/Independent Exploratory Development, CSS Annual Report, TR435-91, Coastal Systems Station, Panama City, FL.
18.
Xu, L., 1998, “A Theory for Asymmetrical Vessel Impact and Steady Planing,” Ph.D. dissertation, Department of Naval Architecture and Marine Engineering, The University of Michigan, Ann Arbor.
19.
Xu
L.
,
Troesch
A. W.
, and
Vorus
W. S.
,
1998
, “
Asymmetric Vessel Impact and Planing Hydrodynamics
,”
Journal of Ship Research
, Vol.
42
, No.
3
, pp.
187
198
.
This content is only available via PDF.
You do not currently have access to this content.