Rule of Twelfths

Rule of Twelfths

When you need to know approximately how much water is below your boat at a particular time of day, in a particular place, and you have access to the tide tables, the "Rule of Twelfths" will serve you well. It's an easy-to- use guide for...

Navigation Rules/Rules of the Road

Pecking order of vessels. There is a basic order, in the navigation rules, that governs who stays out of the way of whom. Essentially, the hardest to maneuver vessels are stand-on while the easiest to maneuver vessels are give-way. In the following list vessels...

Rules of Thumb for Tides: 50/90, Thirds, Twelfths

Rule of 50/90 is used to estimate current speed at the end of each hour of the six-hour tidal period 50/90 Rule gives you “… the SPEED OF THE CURRENT at the end of each hour.” Counting from slack, the current will flow at 50% of its maximum speed at the...

1809 Rochester Industrial Dr, Rochester Hills, MI 48309, USA


1809 Rochester Industrial Drive, Rochester Hills, MI 48309

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Corona Virus Update

Corona Virus Update

Due to Corona Virus/Covid-19 and State Government Mandate, Waterproof Charts has to temporarily close for the following 3 weeks starting March 24th until at least April 13th. Orders placed between now and then will be shipped when we come back after April 13th. 

If anything changes we will update our message. 

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