They're pretty much the same motor. Turbo's injectors etc. Fuel efficiency is about the same.
Have you called Viking? They know where everything is mounted on all of the boats they've built.
N+G engineering out of Hollywood, FL. They do excellent work. Call them at 954-709-893 six (gabriel)
You have an air leak between the raw water pump and thru hull or could have a bad water pump.
Seahawk makes a good one for aluminum yachts. But 18 month lifespan for bottom paint is pretty normal.
I agree with running at hull speed, but also keep in mind to run at cruise every 4-6 hours for 30 minutes to keep the engine cylinders and air...
It's the age of the cord. They don't last forever and I'd replace both. They're not that expensive from Glenndenning. Also you were most likely...
I'm pretty sure there is. Grab a Ryobi moisture meter and run it along the deck, you should get drastically different readings where the plate is.