CONTINUOUSWAVE

[The] port engine’s battery [on my 2019 250 OUTRAGE has failed, or] so it appears.

The Port battery switch says says it is for the Port engine and house. The Starboard battery switch is only for Starboard engine.

When looking at the batteries in the battery cubby, the Starboard batteries are in parallel.

The port [battery] is connected alone.

Batteries 1 [and] 2 appear in parallel [and] are Starboard engine only.

Battery 3 [associated with the] Port engine is rigged alone; it is the house battery and the engine battery.

My inference is there is possibly a mistake from Boston Whaler.

Q1: [for other owners of a 2019 250 OUTRAGE:] have you observed this mistake on your boat?

My guess about why there is a conflict between how the documents and signs and labels on the boat describing the battery wiring and the actual wiring of those circuits: the boat may have been shipped from Boston Whaler with the three batteries not installed. The selling dealer may have installed the batteries and connected them to the battery cables improperly.

Check the actual bill of sale to see if the dealer sold you the batteries. If so, the dealer installed them. Even if your order included the factory optional battery package for dual engines, the batteries may have been shipped separately.

ASIDE: for many boat mechanics the realm of electrical circuits is foreign territory.

My second guess: if the battery trays are below deck, the guy connecting the cables to the batteries may have been facing aft and become confused about athwartship directions Port and Starboard.

My third guess: if the battery trays are below deck, and you were facing aft, you may have become confused about athwartship directions Port and Starboard.

Call the selling the dealer and ask about this apparent mix up.

Also, if you are not the original buyer of the boat, a previous owner may had made the error.