Raft on a Highline: Loads and Trim

Chris Onions MRes
R3 Safety & Rescue Ltd
LL21 9HH

Loel Collins DProf PGCert
Institute of Coaching and Performance
University of Central Lancashire

Email chris.onions@R3SAR.com



This study examines the loads associated with the positioning of a 4.5m raft on a high line in moving
water. Testing was conducted within a flow-calibrated channel demonstrating representative stream
velocities typical (0.6 – 5.4ms/ also MPH) of those encountered during water related rescues. The raft
was positioned from a high line mid-stream, and a load cell was utilised to collect force/time data. The
independent variables of trim (relative positioning of the load within the boat) and average stream
velocity were investigated. The findings challenge assumptions regarding the impact of trim on the
loads within a highline, the relationship between flow rate and loads on highline and make
recommendation for training and practice. The study contributes to understanding the loads placed on
high lines by representative rafts during operational rescues.

KEY WORDS: High line, trim, force, current vector, water rescue training.

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