This thread is a couple years past, but as I've just bought a 2002 Parker 1801, I'm now following this forum, AND experiencing a similar issue. I've been finding 1-2" of salt water in my console. I'd been perplexed where it was coming from. Bilge was dry. Not taking waves over the bow. When I'd check inside before heading out on the water the area would be dry or barely any water, but after boating around a bit I'd come back to the dock I'd have 1" or so of water in there.
So, I got talking to a "boat encyclopedia" friend of mine, described the symptoms, he immediately said "speedometer cable is loose or unconnected". I hadn't known but he explained how the speedometer uses water pressure to gauge hull speed, drawing water from the exterior of the hull up through a hose to the speedometer. I had remembered then that I had seen what I before assumed was a loose wire sheathing coming out of the central wiring porthole, and I had wondered what wires it was supposed to house (had even cut a little of the hose back to see if there were wires down further inside).
So yesterday I went to my boat, looking below the speedometer, there was, in fact, a nozzle. Taking the loose hose, I worked the hose back into the nozzle, and will see next time I'm out boating (hopefully soon) if this fixes the issue. Pretty confident it will.
Just thought I'd share in the case someone else was experiencing anything similar.