Sam-
Please note that to use the EWDS, you'll need
this base alarm as well.
The beauty of the EWDS system is that you can start out with just the basic alarm if you don't have the boat bucks to go the full monty.
And then add the full alarm to get the detailed warning (and comfort) the EWDS gives you.
Just give Ken (in parts) a call and he'll walk you thru it.
EDIT - I just realized... how ironic that the system Sam is looking for was invented by our "west coast guru".... Neil (ndutton)