EFFECTS OF VESSEL LENGTH AND DESIGN ON MOTIONS, SAFETY AND DOWNTIME. DON BASS (MUN)

Wave Periods on NE Coast

Wave Heights on NE Coast

Percentage 0ccurrence of Waves over 3 m. by Month

Simulations using MOTSIM  3 m significant wave height for various wave periods. Typical to severe Fall weather conditions. Speed 5 knots in head seas.  Boats used in the simulations  65 foot fiberglass boat with 26 foot beam  90 foot fiberglass boat with 19 foot beam (scaled version of the above 65 foot vessel)  75 foot steel boat 22 foot beam (extended 65 footer)  100 foot steel with 24 foot beam (extended 65 footer)  65 foot aluminum catamaran fishing boat

65 Foot Fibre Glass Boat

90 foot Fibre Glass Boat

75 foot Steel Boat

100 Foot Steel Boat

Predictions of Pitch Motions of the Lauzier at 10 Knots

Pitch Motion Predictions of the Lauzier at 6 knots

Pitch Motions In 3 M Head Seas

Heave Motions In 3 M Head Seas

Motion Induced Interrupts  Measure of the ability of someone at some location on a moving platform to complete certain tasks.  Measure of the likelihood of an accident occurring due to slipping or tipping.  Number of “Loss-of-Balance Incidents” per minute

Formulae for Motion- Induced Interrupts

MII RISK LEVELS Risk Level MII's per Minute 1 =Possible =Probable =Serious =Severe =Extreme 5.0

MII for 65 ft, 75 ft,90 ft and 100ft Vessels in 3 m Head Seas averaged over points in middle third of the Main Deck

Loss of Fishing Days Due to Weather  Based on the assumption that fishing activity becomes difficult or dangerous if MII per minute exceeds 1.5, the 65-footer would need to avoid 3 m seas and the 100 foot vessel, 4 m seas.  Taking the average wave height over a 5-day period we can determine how many 5-day trips could be completed with an average wave height below either 3 m or 4 m.  Based on wave statistics off the NE coast over the past 10 years.

Possible Number of Fishing Trips per month over a 10 year Period for the 65 foot fishing vessel.

Number of Possible Trips for 65 and 100 footers (10 year averages)

CONCLUSIONS  Difficult to come up with precise quantitative data on the number of fishing days lost due to weather related factors.  Rough estimate based on MII approach shows considerable down time in the Fall for vessels 65 foot and under.  It is clear that vessel length and design play important roles in determining that number.