Hydrostatics



BANJERS' HYDROSTATIC DATA
(If you have problems copying the images from here, you may ask Guillermo for a digital or paper copy.)


NOTES:

- These hydrostatic data have been obtained by digitalizing Banjer's lines from not greatly accurate copies of Lines Plans and processing them trhough the program of naval Architecture DFHYDRO.
- Draught (T) is measured from the bottom of the keel, astern.
- Longitudinal measurements origin is at the rear end of hull.
- Supposed Sea Water density: 1.026 Tonnes/M3
- Calculated data is for a 0.00 meters trim. Data are also available for other trims, so you may ask Guillermo for them.
- Waterline length for  a 1.4 m draught is around 9.7 m

Notes

1.- Trustabilty of data.
In accordance with these hydrostatics, Banjers seem to be more heavy than spec. For a 1.4 m draught, they seem to weigh  13.74 metric tons (tonnes) or  13.53 long tons. If they weigh really 12 tonnes, then draught should be more in the proximity of 1.32 m.
We'd like to carefully analize this apparent contradiction with Banjer's original data. All collaborations , by means of other known info, data measured aboard, etc., will be most welcome.

2.-Stability curves.
If any of you perform an inclining test for his Banjer and provide me with the obtained data, I will be most glad to make the stability calculations for you and give you back the Center of Gravity position and GZ curves (Levering arms) for both light ship and full load conditions (Based on hydrostatic data in this page).

To perfom the test:
- Either completely empty or full all tanks.
- Preferably remove all (And this means all!) cargo from aboard, or then carefully note weights and their positions (3 axis: longitudinal, vertical and lateral).
- Measure freeboards from deck at bow and stern tips up to half centimeter, at least. Milimeters should be great. Measure from outside the boat, as your weight would influence on measurements. Be careful to accurately discount gunwhales and/or deck gear height, to fit measurements to deck level.
- In calm waters, with no wind and loosen warps, move a couple of known weights from side to side located amidships at the corridors (about 100 kgrs each should be enough for light ship condition. Try first, to obtain a heel angle between 1.5º and 2º). Measure carefully the weights, their center of gravity height over deck and longitudinal position, the transverse translation distance among their c.g's.,  and the heel angles obtained with a digital clinometer or a pendulum (moving weights both sides). Mark and note first the "zero" with one weight on each side (Boat should be level or with a neglectable heel).
- Note weight and position of person measuring the angle, if on board (You can also measure the angle from the dock by using a water pendulum at the bows. IMS measurers use to have this kind of instruments. In this case no person should be on board)
- Send me all data.
Guillermo.





BANJER LINES DRAWINGS
(Not to scale)

Main measurements:

Hull lenght: 11.13 m
Beam: 3.48 m
Moulded depth: 2.45 m


Transverse Sections




Vertical proyection & Water lines




Lateral proyection & Buttock lines






Meaning of symbols.
(if any of you have doubts, please ask Guillermo)

Symbol
Unit
Meaning
T
M
Moulded draught (amidships); meters.
VOL
M3
Volume; cubic meters.
DIS
MT
Displacement; metric Tons (1 Tonne = 1000 kg).
XB
M
Longitudinal position of Center of Buoyancy; meters.
ZB
M
Heigth over base line (keel astern) of Center of Buoyancy
WPA
M2
Water Plane Area; square meters.
XWP
M
Longitudinal position of waterplane geometry center; meters.
WS
M2
Submersed hull area; square meters
KML
M
Heigth of longitudinal metacenter; meters.
KMT
M
Height of transverse metacenter; meters.
TPC
Tons (metric) per cm of increased depth; MT / cm
MCT
Moment to trim one cm; MT x m / cm
CB
Block coefficient; adimensional.
CM
Main transverse section coefficient; adimensional.
CWP
Water plane area coefficient; adimensional
CP
Prismatic coefficient

Access to an useful units converter:    Megaconverter