This article deals with
loading a polar diagram for your sailboat into qtVlm. You will see
later why qtVlm needs a polar and a grib.. in order to prepare a
route based on weather, tide and your boats
performance.
A polar diagram is an electronically readable
summary of how your boat behaves at various points of sail at different wind strenghts . (Many of us sail smaller bilge keel boats that go sideways
just as well as forwards..and don't go to windwards very
well..if at all !)
qtVlm allows you to load up a polar.. if you
don't have one for your own boat, you can choose from a
large and growing embedded list. You could choose a boat profile
similar to yours, then you can fine tune that profile with various
parameters. For cruising types you could choose something similar
then downgrade the windward performance significantly.. as you
don't want to be sailing on your ear at all if it can be
avoided !
Setting a polar in qtVlm. Boat
>>> Boat(s) Settings
Set parameters..give the boat a
name, and either import your polar if you have one..or go to the
polar server and choose one from the long listings.
If yours isn't listed
there, choose something similar:
In our case we've chosen
an Oceanis 31, and DETUNED it's upwind efficiency to 82% of
max. Overall the best plan is to choose similar boat and de-tune
it to suit your style of sailing. Many other parameters can be
set..including at what point you give up and start your
engine..
Anyway, we'll soon see how
qtVlm can use the parameters you've entered, plus the
loaded gribs to make an efficient route.
Coming soon: qtVlm made routes
using your parameters.
For those with Windows
machines (who may also want qtVlm on Android or iPad) UNIFIED CHARTS from mid April 2018 also support
qtVlm (as well as the already supported programs and apps.) For
those with Macs, Linux, RaspberryPi etc.. We now make CROSS
PLATFORM charts that'll work on anything that qtVlm will
run on. CLICK HERE 
