THE SECURING OF VEHICLES ON ROLL-ON/ROLL-OFF SHIPS

The paper, which is divided into two parts, reviews the background to the development of mathematical models for the estimation of the loads in the lashing systems of road trailers on board ro/ro ships. The theoretical basis employs a defined case of ship motion representative of the behaviour of such vessels in severe conditions. The mathematical model allows a range of lashing configurations and characteristics to be explored, together with the effect of parameters such as trailer torsional stiffness, suspension stiffness, tyre stiffness, height of the centre of mass of the load and tyre and trestle friction with respect to the deck. The effects on the magnitude of the loads induced in the lashings by altering the motion of the ship and the position of the trailer torsional stiffness, suspension stiffness, tyre stiffness, height of the centre of mass of the load and tyre and trestle friction with respect to the deck. The effects on the magnitude of the loads induced in the lashings by altering the motion of the ship and the position of the trailer on the ship is also investigated. Attention is drawn to the particularly high trestle loads that result from the trailer's movement. The model is shown to give results in line with the limited range published in 1984, the only other attempt known to the authors to determine theoretically or practically the loads experienced by lashing systems in a seaway. In part II, the paper gives an account of how the mathematical model was used in the preparation of the lashing charts in the UK Department of Transport publication: "Roll-on/Roll-off-Ships -Stowage and Securing of Vehicles - Code of Practice". The paper concludes with a discussion of the service application of lashing systems in the light of results from the model which shows that, even in the case of a well secured vehicles, the strongest practical lashing systems are close to their effective limits of strength when operating under the severe conditions considered. This leads on to a discussion of "safe working load" and how to avoid confusion in this field with the statutory requirements covering lifting tackle.

• Supplemental Notes:
  • RINA Trans, v 137 pt A, 1995, p 37 [15 p, 8 ref, 24 fig]
• Authors:
  • Turnbull, S R
  • Dawson, D
• Publication Date: 1995

Language

• English

Subject/Index Terms

• TRT Terms: Mathematical models; Roll on roll off ships; Stowage
• Old TRIS Terms: Cargo stowage; Ro/ro lashings
• Subject Areas: Marine Transportation; Vehicles and Equipment;

Filing Info

• Accession Number: 00710431
• Record Type: Publication
• Source Agency: British Maritime Technology
• Files: TRIS
• Created Date: Aug 14 1995 12:00AM