River Landing Marina/4-Mile River Operational Manual:
This safe passage tracker is engineered to manage navigation constraints caused by shallow shifting sandbars outside the Four Mile River. Calculations are tailored for Mark's center console boat that drafts 19" and has a Bimini top.
Bridge Clearance: The boat's Bimini top clears the overhead bridge structures at all water levels, including extreme high tides. Our navigation is never restricted by vertical clearance, but yours may be (especially if you have a t-top).
Sandbar Clearance: Shifting sandbars outside the river mouth restrict travel based strictly on water depth. When carrying a full load of passengers and gear, the boat drafts significantly deeper, requiring conservative depth margins. However, we've found if it's lightly loaded with gear and one person, we can make passage.
Reading the Grid: Scan the timeline horizontally to track safe water windows, solar boundaries, and marine fishing regulations simultaneously. You'll note the lowest lows and highest highs of the tide are also timestamped.
SAFE PASSAGE FULL BOAT (Daytime)
SAFE PASSAGE FULL BOAT (Nighttime)
SOLO ZONE (Daytime): Shallow. It MAY be safe to pass for solo trips with minimal gear.
SOLO ZONE (Nighttime): Shallow. It MAY be safe to pass for solo trips with minimal gear.
IMPASSABLE (Clear Blocks): Sandbar is too shallow. Extreme grounding risk.
IMPASSABLE (Grey Blocks): Sandbar is too shallow at night. Extreme grounding risk.
🌙 MOON WINDOW: Strong current window surrounding New/Full moons (+/- 3 days). Exact phases marked: 🌑 New, 🌓 First Qtr, 🌕 Full, 🌗 Last Qtr.
⚡ BOLD GOLD LINE: Sunrise & Sunset.
🟥 ADVISORY OVERRIDE: Active Small Craft/Storm Advisory. Exercise Extreme Caution.
DP: 65° When the dewpoint is highlighted, there's a high risk of marine fog developing.
