diff --git a/qml/pages/DetailPage.qml b/qml/pages/DetailPage.qml
index 30ca0b1..ae4c482 100644
--- a/qml/pages/DetailPage.qml
+++ b/qml/pages/DetailPage.qml
@@ -27,6 +27,11 @@ Page {
     function init() {
         nearPort = null
         nearKm = 0
+        console.log("[tide] DetailPage.init custom:", custom, "port:", port ? port[0] : "UNDEFINED")
+        if (!port) {
+            console.log("[tide] DetailPage.init: port undefined, niente da caricare")
+            return
+        }
         if (custom && port.length > 5 && port[5] !== "") {
             var np = Tides.nearestPort(port[2], port[3])
             if (np.port !== null) {
@@ -38,36 +43,44 @@ Page {
     }
 
     function refresh() {
-        if (!port) return
-        // eventi
-        eventsModel.clear()
-        var ex = Tides.extrema(port, new Date(), days)
-        var n = Math.min(ex.length, 6)
-        for (var i = 0; i < n; i++) {
-            eventsModel.append({
-                kind: ex[i].kind,
-                date: Tides.fmtDate(ex[i].t),
-                time: Tides.fmtHM(ex[i].t),
-                height: Tides.fmtH(ex[i].h, unit)
-            })
+        if (!port) {
+            console.log("[tide] refresh: port UNDEFINED")
+            return
         }
-        // astro
-        var mp = Tides.moonPhase(new Date())
-        moonLabel.text = mp.icon + " " + moonNames[mp.idx] + " (" + qsTr("age %1 d").arg(mp.age.toFixed(1)) + ")"
-        var st = Tides.sunTimes(port[2], new Date())
-        sunLabel.text = Tides.fmtHM(new Date(0, 0, 0, st.rise, 0)) + " / " + Tides.fmtHM(new Date(0, 0, 0, st.set, 0)) + " " + qsTr("(solar time)")
-        rangeLabel.text = "±" + ((port[4][1][0] + port[4][2][0]) * 2).toFixed(2) + " m"
-        // info curva
-        var f = port[5] || ""
-        if (f.indexOf("near:") === 0) {
-            var p = f.split(":")
-            curveInfo.text = qsTr("Constants of the port of %1 (distance %2°)").arg(p[1]).arg(p[2])
-        } else if (f === "synth") {
-            curveInfo.text = qsTr("Estimated constants from lat/lon (synthetic model)")
-        } else {
-            curveInfo.text = qsTr("Z₀ %1 m · 7 harmonic constituents").arg(port[4][0].toFixed(2))
+        console.log("[tide] refresh:", port[0], "days:", days, "unit:", unit)
+        try {
+            // eventi
+            eventsModel.clear()
+            var ex = Tides.extrema(port, new Date(), days)
+            var n = Math.min(ex.length, 6)
+            for (var i = 0; i < n; i++) {
+                eventsModel.append({
+                    kind: ex[i].kind,
+                    date: Tides.fmtDate(ex[i].t),
+                    time: Tides.fmtHM(ex[i].t),
+                    height: Tides.fmtH(ex[i].h, unit)
+                })
+            }
+            // astro
+            var mp = Tides.moonPhase(new Date())
+            moonLabel.text = mp.icon + " " + moonNames[mp.idx] + " (" + qsTr("age %1 d").arg(mp.age.toFixed(1)) + ")"
+            var st = Tides.sunTimes(port[2], new Date())
+            sunLabel.text = Tides.fmtHM(new Date(0, 0, 0, st.rise, 0)) + " / " + Tides.fmtHM(new Date(0, 0, 0, st.set, 0)) + " " + qsTr("(solar time)")
+            rangeLabel.text = "±" + ((port[4][1][0] + port[4][2][0]) * 2).toFixed(2) + " m"
+            // info curva
+            var f = port[5] || ""
+            if (f.indexOf("near:") === 0) {
+                var p = f.split(":")
+                curveInfo.text = qsTr("Constants of the port of %1 (distance %2°)").arg(p[1]).arg(p[2])
+            } else if (f === "synth") {
+                curveInfo.text = qsTr("Estimated constants from lat/lon (synthetic model)")
+            } else {
+                curveInfo.text = qsTr("Z₀ %1 m · 7 harmonic constituents").arg(port[4][0].toFixed(2))
+            }
+            cv.requestPaint()
+        } catch (e) {
+            console.log("[tide] refresh error:", e)
         }
-        cv.requestPaint()
     }
 
     property var moonNames: [
@@ -300,11 +313,15 @@ Page {
             ctx.fillText((d.getHours() < 10 ? "0" : "") + d.getHours() + ":00", x + 3, h - 3)
         }
 
-        // Z0 tratteggiata
-        ctx.setLineDash([4, 4])
+        // Z0 tratteggiata (disegno manuale: setLineDash non garantito su Qt 5.6)
         ctx.strokeStyle = Theme.rgba(Theme.secondaryColor, 0.6)
-        ctx.beginPath(); ctx.moveTo(pad, Y(port[4][0])); ctx.lineTo(w - pad, Y(port[4][0])); ctx.stroke()
-        ctx.setLineDash([])
+        var zy = Y(port[4][0])
+        for (var zx = pad; zx < w - pad; zx += 10) {
+            ctx.beginPath()
+            ctx.moveTo(zx, zy)
+            ctx.lineTo(Math.min(zx + 5, w - pad), zy)
+            ctx.stroke()
+        }
 
         // curva
         ctx.strokeStyle = Theme.highlightColor