Bow & Stern Ramps
  • ABS Classification Requirements for High Speed Naval Craft

Case: Meeting Heavy Weight Requirements with Light Materials

You can’t always sacrifice strength for speed. Such was the case recently when a military client needed to deploy heavy machinery quickly from onboard a swift vessel.

Specifically, what the client required was a ramp on the bow of a vessel that could onload and offload cargo while on the beach, piers, or ocean platforms. It needed to be both structurally sound as well as quickly deployable on a fast boat that would regularly travel at speeds of up to 40 knots in multiple sea states.

Not many could meet the challenge of allowing steep reduced weight requirements without being able to rely on hardened steel, which hindered the client’s search for a partner.  Fortunately, SIT’s substantial knowledge around both aluminum fabrications and articulating structural designs allowed it to take on the work.

SIT made sure to carefully achieve each requirement, one by one. Engineers conducted in-depth finite element analysis to confirm the application would perform. In the end, there were numerous critical design reviews performed alongside naval architects to ensure alignment of the design parameters.

The project has since passed all evaluations and is expected to soon get ABS approval. With the ramp in place, the client has improved tactical capacity, with a new prototype they can continue to improve upon.


Major Components:
  • Bow ramp: 400 inches long, 17 ft. wide
    • Fully articulating bow ramp to fold-up and lock into hull (functions as part of the bow)
    • Near watertight design when closed and locked
    • Custom aluminum fabrication
    • Hydraulic cylinders (7 and 6 inch bore) plus manifolds
  • Stern ramp: 17 ft. long, 17 ft. wide
    • Custom aluminum fabrication
    • Hydraulic cylinders (7 inch bore) plus manifolds
  • Central HPU (handles bow ramp, stern gate, and kedge anchor winch)
  • PLC controlled with HMI touchscreen portable controllers
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