There are two versions an U.K. App. and an U.S. App. so be careful reading the SeaNav advertising package for which one needed. As you should know there are considerable difference between the U.K./E.U. system and U.S. systems. In the International Association of Lighthouse Associations (IALA) buoyage systems the U.S. uses IALA-B (thankfully) and the U.K./E.U. IALA-A, which NAUTICAL LOG detests it being difficult to see the topmarks (in poor visibility) which can give a whole different meaning to what is being marked. The IALA-B system is simpler and straight forward so in our opinion a safer system for seafarers particularly recreational boaters.
Enjoy looking into this planning system.
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