Our chief engineer (video, not aerodynamics
) has just loaded a Jeppesen marine navigation app onto his iPhone and iPad called Jeppesen Marine Plan2Nav. The app itself is free but the charts you have to pay for. He said the chart (package?) he got for the Puget Sound area where he boats was $32. He said this got him chart coverage from the Columbia River to Nanaimo, BC or thereabouts.
In the app store the app has a review rating of two stars but there have apparently been updates. I have not loaded the app so have zero familiarity with it. But so far our engineer seems quite impressed with it. So I'm not recommending it, simply pointing out that it's there and perhaps worth checking out.
Or maybe someone here's already tried it and has a user's opinion he/she can share.