Waterspeed lets you manage your equipment and assign up to 3 in any activity. You can have Boards, Fins, Sails, and more with size, details, and a photo.
You can also define 3 default Equipment per sport, that will be automatically added to the activity as soon as saved.
Equipment is available in filters in Graphs and in the Diary, so you can see the total of hours you used a piece of equipment or the fastest speed reached with that.