4 methodes of calculation from BHP of the vessel:
1. BP = 1.1 x (root)BHP (plus 10% for nozzles) > 5000 HP
2. BP (in Pounds) = FACTOR x BHP (F= 22 (open propeller), 24 (cp open propeller), 26 (nozzles), 32 (cp nozzles)
3. 100 SHP = 1 tonne BP (open propeller) 1.2 to 1.5 for nozzles
4. Approx 1% BP will give a minimum value
•BHP =BRAKE HORSEPOWER (the power available for propulsion delivered to the shafts)
•BHP SOMETIMES IN KILOWATT/KILONEWTON
•KILOWATT TO HORSEPOWER X 1.39
•KN TO TONNES (divide by 9.81)
•Sometimes IHP (indicated Horse Power) is quoted which is power at the engine itself and BHP is about 75% of IHP normally
•Bollard pull is very important for any vessel involved in towing and / or anchor handling
•For offshore vessels it is particularly important as they may be working close to the limits
•Insurance requirements for offshore rig moves require a certain bollard pull which must be complied with
•Remember older vessels (as used in TI) may not have the same power as when they were new!
•The TI tender should specify a recent bollard pull certificate (no more than 3 years old) must be provided by owner as part of the tender specifications
Winch Power
Winch, tow wire, and all deck fittings must match the BP of the vessel with sufficient reserve to allow for dynamic forces
•
•Winch brake at least 2 x BP
•Winch pull at least 1.5 x BP
•
•Winch drum diameter at least 14 x tow wire diameter to avoid damage
•When full of wire the winch pull is much less (normally winch pull is quoted on empty drum or first layer only)
•
Effective pull = Max Pull x radius empty drum ÷ radius full drumTow wire BS at least 2 x BP Anchor Handling Gear
•- Open stern AHTS or AHT with stern roller (Pennant or suitcase buoy)
•- A Frame AHT (suitcase buoy only)
•- Quarter Pins (Norman pins)
•- Tow pins (Pop ups)
•- Shark Jaw or Karmoy fork
•- Pelican hook as back up (chain and wire)
•- Loose equipment , shackles, snatch blocks, bulldog grips, wedges, tools
•- Buoy catcher / lassoes
•- J hook and Grapnel
•- Boat Hook
•- Tuggers
