Blown anode cables/speedometer tube

I just purchased a new 2009 Yamaha 115 4 stroke on a Ventura pontoon. My speedometer stopped working and I could not find the pitot tube. In getting ready for the lake, I noticed that the cables that ground the lower end to the rest of the motor (I assume for corrosion control) had been fried, as well as a gray plastic tube that was near them. Apparently my engine has the pitot built into the lower end for measuring water speed (never would have guessed that) and it got burned up when the grounding cables were toasted. I never felt that the speedometer accurately measured my boat speed and have always seen separate pitot tubes mounted on the hull of boats. Is this common for Yamaha motors? I'm also being told that the cables were fried because I lost a good ground while starting my motor. This sound right?

[boats.net]

Yes Yamaha does have the pitot built into gearcase and the tubing is the pitot tubing. Yes check all engine grounds, battery cable connections are clean and tight and if there is a wire in boat grounded to boat frame or fence.