Looks interesting. It's great you have put a lot of effort into making the app easy to use, but here are some suggestions if you really want to be a nautical ch

Looks interesting. It's great you have put a lot of effort into making the app easy to use, but here are some suggestions if you really want to be a nautical chart app "done right": (1) Don't just use the published RNCs; they are only released at 100 pixels per cm, which is too low to look good (especially on the awesome resolution of the iPad screen). If you send a FOIA to NOAA, they will give you the RNCs at 300 pixels per cm (nine times the resolution), which is what they actually use when printing them. It will also give you a unique advantage over the 20 other similar apps. (2) Show the user what charts overlap their location, in order of scale, and let the user control which chart they want to see at a particular time. The existing apps all try to guess which scale chart to show and they switch between them as the user zooms. (Your web app does the same thing.) It's never quite right. (3) Use the (geo-aligned) ENC vector chart to provide clues to the UI, even if you don't actually render the ENC. The user should be able to tap on a feature (e.g. a buoy) and get information about it and set it as a waypoint. The user should be able to plot a course to a waypoint that keeps in mind the draft of the vessel vs. the depth of the water. The user should get an alarm if their course will take them over a shoal or into a mark. (4) Make clear on your Web site what distinguishes your app from the 20 other apps that also display RNCs aligned with the iPad's GPS fix. E.g., MX Mariner is $7 and perfectly servicable if no-frills -- what do you have that they don't? How about my Raymarine chartplotter that came with my boat -- why is this better? Right now the marketing ("modern," "done right") resembles the puffery that seemingly every app spouts (you're missing "beautiful" and "exquisitely-crafted" but otherwise you check most of the boxes). If you want actual mariners to buy your app over others, it wouldn't hurt to make it a bit more expert-friendly and show what makes it special. More screenshots would help! I worry that no matter how hard you work on making it easy to get started, you are just yet another app displaying lowres RNCs as a dumb raster that can't take advantage of semantic information contained in the chart. That's not "modern" or "done right" and it's not something a professional mariner would be caught dead using. Which may be ok -- you're not aiming your product at professional mariners. But better to be clear about what your app does and doesn't do than have it be an unwelcome surprise.