I've been working on developing a custom campaign setting for 4e, centered around high-seas adventures. One of my primary methods of world building is to create a specific story for the setting and then build around that, as odd as that may sound. So, I decided to create an adventure module for this setting, which I'll use as the base for the setting's foundation. To develop the synopsis for it, I brainstormed up various ideas in sets of 6, then started putting them together. What I came up with was the following template:

"People who visit the [Location] have been coming back with a disease called [Disease]. The area is also home to [Ship], the ship of the famous pirate captain [Captain]. In the captain's quarters is a chest containing [Artifact], an artifact rumored to [Power]."

This is pretty much locked in as the outline for the adventure. Next, I wanted to decide how strong the PCs would start out, then use that to work out the adventure's balance. Currently, I'm thinking it's meant for a party of 3-5 PCs at Level 5, with 250gp, 1 magic weapon up to level 7, 2 magic armor items up to level 5, 3 potions of healing, and a ring of sending. Here's where I'm sort of hitting a roadblock.

I've had the opportunity to run a campaign in 4e, but it was set in a landlocked region. This is meant to primarily take place on, in, and around the ocean, so I don't think it's appropriate to just slap a few goblin tribes in and call it a day. Also, there's something about that PC setup that doesn't feel right. It sort of seems like they might be a little over-equipped, but since I haven't been able to decide what encounters will be in this, it's hard to say.

So, what I'm wondering is this: What's reasonable starting equipment for a 3/5-person party at level 5, and what sort of encounters could they expect, in an adventure of moderate challenge with the final rewards being a powerful magical artifact and a famous pirate ship? This entire thing is meant as a way to introduce players to the setting with a bang and some nice loot, but not in such a manner as to create a Monty Haul campaign.