APPS:

Consult your Apple or Google app store.

My Radar

Real time weather radar info.

Windfinder

Wind, temps, tides, wave heights and precipitation all in one place.

Tide Charts

Tides, weather and radar

Weather Bug

Free or paid premium products

Navionics

Nautical and fishing charts

RadarX

Real time radar

NOAA

Various apps available

Isailgps

Allows free downloading of RNC charts

Animatedknots.com

Not an app but internet tool