Page 47 - Practical Ship Design

18 Chapter 1

Macsurf and Wolfson concentrate on CAD, whilst Senermar and Kockums
continue through to CAM. Whilst CAM is beyond the scope of this book it is worth
mentioning that an integration of CAD and CAM can have big benefits to a
shipyard, both because it results in a big reduction in the input task and because it
should reduce errors since all users will know the wide use to which the data has
been or will be put.
The range of CAD programs offered by each of the companies differs, but most
of the items in the following list are available from at least two of the companies
mentioned above.
1. Lines plan production - either from program data based on main dimen-
sions, block coefficient and LCB or from the digitising of an approximate
lines plan; fairing of lines; production of offsets.

2. Deck, bulkhead and other outlines based on lines plan data to feed into CAD
draughting.

3. Shell development for plate ordering.
4. Weights and centres - can be used in the make up of a lightship weight or
in developing a stability condition.
5. Space - capacity and centres.
6. Hydrostatics and cross curves of stability.

7. Stability conditions.
8. Damaged stability deterministic and probabilistic.

9. Grain stability.
10. Floodable length curves.
11. Longitudinal strength - bending moment and shear force.

12. Freeboard and tonnage.
13. Ship motions - roll, pitch, heave, yaw, sway for a variety of sea spectra.
14. Manoeuvring.

15. Powering - resistance and effective horsepower.
16. Powering - propulsion factors, quasi propulsive coefficient and propeller
design.

Some of these items, or sometimes a particular firm’s approach to them, merit a
few comments: