Skip to main content

Bonjean Curves

  • Curve plotted on lines plan of ship is calls bonjean curve, here the longitudinal section of the vessel is divided in 10 stations.
  • At each station transverse section and each draft, we calculate e area and moment of area., these moments then plotted on the lines plan....
  • Use: fo calculation of hydrostatics like displacement block coefficient centre of floatation TPC etc.
  • Enable the users to calculate the displacement and the centre of buoyancy for a given waterline, in an upright condition
  • curves of areas of transverse sections and their moments about the baseline of a ship used in making calculations (as to determine the force of buoyancy during launching)
  • The Bonjean curve had as its ordinate the cross sectional area at that section, up to the waterline concerned. Each curve was usually plotted with its axis The vertical axis was traditionally at ship scale.
  • Their main uses were for launching (end launching) and longitudinal strength.
  • For launching, prior to stern lift, the progressive waterlines would be set up on the ship profile with the Bonjean curves.
  • Where this waterline cut the vertical axis was the local draft at that section. Bonjean area was read at each such intersection, and then integrated longitudinally for both volume and moment.
  • These gave the volume of buoyancy and its longitudinal moment about the fore poppet for each successive waterline, to match against moment of weight force about the fore poppet, defining the point of stern lift.

Labels:

Comments

Post a Comment

If you have any doubts.Please let me know

Popular posts from this blog

Manganese bronze is not typically used as a propeller material .Why

1. High cost: Manganese bronze is a costly alloy, making it less economical for large propellers. 2. Low strength-to-weight ratio: Compared to other propeller materials like nickel-aluminum bronze or stainless steel, manganese bronze has a lower strength-to-weight ratio. 3. Susceptible to corrosion: Manganese bronze can corrode in seawater, especially when exposed to high velocities and turbulence. 4. Poor cavitation resistance: Manganese bronze is more prone to cavitation damage than other materials. 5. Difficult to cast and machine: Manganese bronze is challenging to cast and machine, making it less desirable for complex propeller geometries. 6. Limited weldability: Manganese bronze has poor weldability, making repairs and modifications difficult. Nickel-aluminum bronze or stainless steel are commonly used for propellers due to their: - High strength and durability - Excellent corrosion resistance - Good cavitation resistance - Ease of casting and machining - Weldability
107 comments
Read more

MAN B&W MC Engine VIT Pump

The pump is basically a jerk type with a plunger moving in a matched barrel, using two helical grooves machined in the plunger to control the end of injection by uncovering spill ports and causing the discharge pressure to drop rapidly, thus causing the needle valve in the injector to close. Oil is supplied to the barrel via the spill ports and a suction valve. The suction valve, situated at the top of the barrel opens when the pressure in the  barrel falls below the supply pump pressure; i.e. during downward stroke of plunger, while spill ports are covered by plunger. Replaceable erosion plugs  are fitted in the pump housing opposite the spill ports. The high pressure oil, spilling back, as the edge of the helix uncovers the s...
Post a Comment
Read more

Main engine interlocks

Interlocks are provided so that the engine can be started or reversed only when certain conditions have been fulfilled. When there is a remote control of engines, it is essential to have interlocks. This reduces the possibility of engine damage and any hazards to the operating personnel. Turning gear Interlock . This device prevents the engine from being started if the Turning gear is engaged. Running Direction Interlock . This prevents the fuel from being supplied if the running direction of the engine does not match the Telegraph. Starting Air Distributor in end position . This prevents starting from taking place if the shifting of the Distributor has not been completed. Main Lube. oil pressure, Piston cooling pressure, Jacket water pressure, and important parameters must be above the required minimum. Auxiliary Blower Interlock . The Auxiliary Blower is provided in case of Constant pressure turbo charging. Air Spring pressure Interlock . In case of the present generation...
9 comments
Read more