is NavCad ?
is a software tool for the prediction and analysis of vessel speed
and power performance. It also provides for the selection of suitable
propulsion system components - engines, gears and propellers.
is built around a multiple document interface for reports and
graphs. This interface also holds a Project View
and a Performance Summary.
Project View contains a tree (much like Windows Explorer) that
you can use to quickly open data entry forms and run calculations.
It also contains a "snapshot" of the project's principal parameters
- such as Displacement, L/B or engine power.
Performance Summary is a spreadsheet of the current system performance.
It is a complete look at the results of your project calculations,
from resistance all the way through engine power, fuel rate and
cavitation. The Performance Summary also underscores the fundamental
nature of NavCad - where all performance items are related through
a Hull-Propulsor-Engine equilibrium.
What is the "minimum hull drag" analysis ?
Sample NavCad main screen
hull data has been entered and a resistance prediction built,
you can analyze and optimize your hull with the Minimum hull drag
analysis. You define search ranges and intervals for significant
data items (e.g., length, beam, LCB), and NavCad predicts the
drag for the configurations and then ranks it. The configuration
with the minimum drag is displayed at the top of the list, with
the difference from minimum displayed in percent of drag. The
calculation also has the ability to review a compromise analysis,
using a time-weighted average of two speeds.
What is the Method Expert ?
Sample NavCad minimum hull drag screen
contains HydroComp's Method Expert prediction method
ranking system. This feature takes your vessel data and ranks
all monohull prediction methods based on speed regime, ranges
of hull parameters and the availability of hull details (e.g.,
if waterplane coefficient or trim, for example, has been entered
and is used in the method). It also takes into account HydroComp's
extensive knowledge about prediction method behavior and reliability.
Warnings are raised if a method has shown poor results for the
given vessel information.
What propulsor types are supported by NavCad ?
Sample NavCad Method Expert screen
greatly extends your propulsor options. In addition to the popular
B-series, Gawn and Kaplan propellers, NavCad 3.6 includes surface-piercing
and cycloidal propellers, cupped propeller prediction, use of
custom Kt/Kq data and the much anticipated waterjets.
NavCad evaluate cupped propellers ?
prediction of cupped propeller performance is based on novel developments
from HydroComp's technical staff. The results of this study were
presented at SNAME Propellers '97 [MacPherson, D.M., Small
Propeller Cup: A Proposed Geometry Standard and a New Performance
Model]. A version of this prediction technique has been used
in HydroComp PropExpert™ since 1997 with great success.
do I use my Kt/Kq model test data ?
file types have been added to allow you to enter Kt and Kq versus
J data from your propeller model tests or wake-adapted calculations.
These simple ASCII files are then used as the source of propeller
performance for Shaft Power and System Analysis calculations.
NavCad even properly applies scale correction during the calculations.
At the current time, these files cannot be used for Optimum Propeller
calculations (since the propeller P/D ratio, number of blades
and blade area ratio are already defined).
Tell me about waterjets in NavCad ?
a number of years of looking at the problem of waterjets, we concluded
that a suitable first-principals solution was not possible. Part
of our review included the development of two new coefficients
- coefficients which would allow waterjet performance to be defined
in a manner suitable for NavCad's ASCII file formats. Through
the use of these new coefficients, the waterjet calculation algorithm
determines the proper thrust and power for a given speed and equilibrium
all NavCad files, the format for the waterjet files is available
from HydroComp. We also provide a Microsoft Excel
template to help create waterjet files. Many files are already
being made available to NavCad users who are up-to-date on their
support and update subscription.
Can I create my own programs to use with NavCad ?
much the same way as NavCad can be run from other programs, you
can launch other programs from within NavCad. Standard ASCII-based
NavCad job files are used as the data exchange format.
Sample NavCad user application screen