LED flashlight w/ lithium cell/s, half-dozen Cliff bars, a few liters bottled water, SAK or multi-tool, Dramamine for seasickness. Sunscreen, wide brimmed hat. and cotton tee shirt if the weather is warm. Poly-fleece jacket, windproof/waterproof shell w/ hood, watch cap if cooler. Remember that conditions overlap at sea. Sun in the frigid regions can be brutal and things get windy and surprisingly cold in the tropics.

When a modern ship loses power it loses housekeeping, (lights, potable water, AC/heat, sewerage). It also loses steerage, the ability to control its orientation and navigation. Which means the inside gets uncomfortable, and the ship is at the mercy of the wind and waves so it can be quite unstable. With the aesthetics and smell of a drunk tank, and rocking and rolling like a country bar bull, your looking at potentially violently ill people. Which improves the aesthetics ... not at all.

With the interior gone south in a big way you are going to want to be seeking fresh air. Which means you are looking at wind, sea spray, sun, heat/cold; whatever the nature provides. Plan to spend the rest of the trip on or near the deck.

If and when things go south in a big way, conflagration/ sinking, something requiring abandoning ship. Being near the deck is a bonus. A full-on exposure suit would be handy if you need to jump but it seems extreme in this case.