diff --git a/frontend/js/map.js b/frontend/js/map.js
index b2e9df0..45da51d 100644
--- a/frontend/js/map.js
+++ b/frontend/js/map.js
@@ -1355,17 +1355,17 @@ window._chartCells = {};                  // cell_id → { bbox: [w,s,e,n], band
 const _HIDDEN_CELLS = new Set();          // mutated on moveend by _recomputeHiddenCells
 
 // Band zoom ranges: [minZoom, maxZoom].
-// Band 0 = custom/unknown (e.g. BARRANQUILLA) → always visible [0, 24].
-// Standard NOAA cells: restore max-zoom cutoffs so overview cells don't
-// render on top of harbour cells (causing the Miami appear/disappear bug).
-// The _recomputeHiddenCells logic hides lower-band cells when a higher-band
-// cell dominates, but only works reliably when max-zoom bounds are in place.
+// maxZoom = 24 for ALL bands — never cut a cell because of an upper zoom limit.
+// Hiding lower-band cells when a higher-band cell is available is handled
+// exclusively by _recomputeHiddenCells (≥40% viewport overlap).
+// Without this, a custom cell like "CO1CO01M" (band-1 per IHO cell-ID convention)
+// would disappear above zoom 10 even though it's the only chart in its area.
 const BAND_ZOOM_RANGES = {
   0: [0,  24],   // custom / unknown → always visible
-  1: [0,  10],   // Overview         (1:600 000+)
-  2: [3,  12],   // General          (1:350 000)
-  3: [6,  15],   // Coastal          (1:90 000)
-  4: [8,  18],   // Approach         (1:25 000)
+  1: [0,  24],   // Overview         (1:600 000+)
+  2: [3,  24],   // General          (1:350 000)
+  3: [6,  24],   // Coastal          (1:90 000)
+  4: [8,  24],   // Approach         (1:25 000)
   5: [10, 24],   // Harbour          (1:7 500)
   6: [12, 24],   // Berthing         (1:2 000)
 };