for your boat you don't need much, it says 21 foot, s1000 Raymarine is your unit probably. Jim at BOE will be $1387 +/- $1 for that unit installed...I'd be willing to be...only cause he quoted me the same unit for my boat. great unit, Alan (Justchillin) has one and it sold me...no need for something elaborate for what you want it for. It'll tie into your GPS, etc...I have done tons of research on it, but am tired of typing...PM me if you need info
Mark