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With the southern migration underway to warmer anchorages, we wanted to share the following blog posting from our friends and partners at Aquamap:Savvy navigators know that planning a passage includes a careful blend of seamanship, navigation, meteorology, and oceanography. Even if the trip is one you make every season, the solution will differ because some variables will change. I developed this 10-step methodology to ensure that all the bases are covered, and I use it when teaching marine weather and passage planning to students, and when planning my own voyages. It breaks the process into discrete, manageable chunks and is scalable for short hops or long voyages. Following these steps will allow you to optimize all the factors involved for a safe, efficient passage. - Know your boat – performance and constraints. This includes performance under both sail and power. Sailing polars are part of the picture, but ensure they are scaled for a cruise-laden boat with a non-racing crew. When inshore, will your boat’s mast height or draft be a factor? Assess your boat’s cruising speed, available fuel, and range under power. Consider your available fresh water, including tankage and watermaking capacity. Does your crew have constraints, whether timing or physical? Do you have the communications gear to support your navigation plan? Evaluate your distance offshore against the range of VHF, cellular, or satellite communications.
- Climatology. Studying long-term patterns for weather and currents over a geographic area is often the most overlooked step in the passage-planning process. There are numerous resources, including pilot charts (paper and digital), cruising guides, the National Hurricane Center, and NOAA’s 6-month Climate Forecast System (CFS) model. Studying climatology helps you select the right ocean for the right season and provides insight into what to expect and prepare for. Some sources provide route guidance based purely on climatology – that’s a great starting point for long-range planning.
- Navigation plan. Whether you prefer paper or electronic, you need to use reliable, accurate charts of an appropriate scale. I like to have a planning chart that depicts the entire route, and to supplement it with large-scale (small-area) charts for the departure, destination, and en route portions that require high-resolution data. You can find the correct scales in chartbooks or in electronic apps like Aqua Map. If you primarily use a chartplotter underway, be sure to have backup charts on a smartphone or tablet. Plot the shortest navigable route to your destination, considering your draft and air draft. Use meaningful, transferable waypoints, especially if you’re working between paper and electronic charts. Modify your route based on climatology (e.g., do you need to get east before turning south, anticipating trade winds?). Using a realistic cruising speed (remember step 1) and the distance on your navigable route, calculate the estimated time en route. Plot your anticipated daily progress on your chart – this will help focus your weather analysis.
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