diff --git a/rust/cli_player/src/ui_screens/set_boats_layout.rs b/rust/cli_player/src/ui_screens/set_boats_layout.rs
index 6693694..b0c1bea 100644
--- a/rust/cli_player/src/ui_screens/set_boats_layout.rs
+++ b/rust/cli_player/src/ui_screens/set_boats_layout.rs
@@ -133,16 +133,36 @@ fn ui<B: Backend>(
 ) -> CoordinatesMapper {
     let errors = model.layout.errors(rules);
 
+    // Color of current boat
     let current_boat = ColoredCells {
         color: Color::Green,
         cells: model.layout.0[model.curr_boat].all_coordinates(),
     };
 
+    // Color of invalid boats
+    let mut invalid_coordinates = vec![];
+    for (idx, pos) in model.layout.boats().iter().enumerate() {
+        if idx == model.curr_boat {
+            continue;
+        }
+
+        if !model
+            .layout
+            .check_present_boat_position(idx, rules)
+            .is_empty()
+        {
+            invalid_coordinates.append(&mut pos.all_coordinates());
+        }
+    }
+    let invalid_boats = ColoredCells {
+        color: Color::Red,
+        cells: invalid_coordinates,
+    };
+
+    // Color of other boats
     let mut other_boats_cells = vec![];
     for boat in &model.layout.0 {
-        for pos in boat.all_coordinates() {
-            other_boats_cells.push(pos);
-        }
+        other_boats_cells.append(&mut boat.all_coordinates());
     }
 
     let other_boats = ColoredCells {
@@ -163,6 +183,7 @@ fn ui<B: Backend>(
     let mut game_map_widget = GameMapWidget::new(rules)
         .set_default_empty_char(' ')
         .add_colored_cells(current_boat)
+        .add_colored_cells(invalid_boats)
         .add_colored_cells(other_boats)
         .set_title("Choose your boat layout")
         .set_yield_func(|c, r| {
@@ -174,7 +195,7 @@ fn ui<B: Backend>(
         })
         .set_legend(legend);
 
-    // Colorate neighbors if boats can not touch
+    // Color of neighbors if boats can not touch
     if !rules.boats_can_touch {
         let mut boats_neighbors_cells = vec![];
         for boat in &model.layout.0 {
diff --git a/rust/sea_battle_backend/src/data/boats_layout.rs b/rust/sea_battle_backend/src/data/boats_layout.rs
index 7d79fe2..fc3e45f 100644
--- a/rust/sea_battle_backend/src/data/boats_layout.rs
+++ b/rust/sea_battle_backend/src/data/boats_layout.rs
@@ -276,6 +276,39 @@ impl BoatsLayout {
         true
     }
 
+    /// Check a boat already present in the layout has a valid position
+    pub fn check_present_boat_position(&self, boat: usize, rules: &GameRules) -> Vec<&'static str> {
+        let mut errors = vec![];
+
+        // Check boat coordinates
+        let boat_i_coordinates = self.0[boat].all_coordinates();
+        if boat_i_coordinates.iter().any(|c| !c.is_valid(rules)) {
+            errors.push("A boat goes outside the game map!");
+        }
+
+        for boat_j in 0..self.0.len() {
+            if boat == boat_j {
+                continue;
+            }
+
+            let boat_j_coords = self.0[boat_j].all_coordinates();
+            if boat_i_coordinates.iter().any(|c| boat_j_coords.contains(c)) {
+                errors.push("A collision between two boats has been detected!");
+            }
+
+            if !rules.boats_can_touch
+                && self.0[boat]
+                    .neighbor_coordinates(rules)
+                    .iter()
+                    .any(|c| boat_j_coords.contains(c))
+            {
+                errors.push("Two boats are touching!");
+            }
+        }
+
+        errors
+    }
+
     /// Check if this boats layout is valid or not
     pub fn errors(&self, rules: &GameRules) -> Vec<&'static str> {
         let mut errors = vec![];
@@ -296,31 +329,7 @@ impl BoatsLayout {
         }
 
         for boat_i in 0..self.0.len() {
-            // Check boat coordinates
-            let boat_i_coordinates = self.0[boat_i].all_coordinates();
-            if boat_i_coordinates.iter().any(|c| !c.is_valid(rules)) {
-                errors.push("A boat goes outside the game map!");
-            }
-
-            for boat_j in 0..self.0.len() {
-                if boat_i == boat_j {
-                    continue;
-                }
-
-                let boat_j_coords = self.0[boat_j].all_coordinates();
-                if boat_i_coordinates.iter().any(|c| boat_j_coords.contains(c)) {
-                    errors.push("A collision between two boats has been detected!");
-                }
-
-                if !rules.boats_can_touch
-                    && self.0[boat_i]
-                        .neighbor_coordinates(rules)
-                        .iter()
-                        .any(|c| boat_j_coords.contains(c))
-                {
-                    errors.push("Two boats are touching!");
-                }
-            }
+            errors.append(&mut self.check_present_boat_position(boat_i, rules));
         }
 
         errors
@@ -330,6 +339,11 @@ impl BoatsLayout {
         self.errors(rules).is_empty()
     }
 
+    /// Get the list of boats
+    pub fn boats(&self) -> &[BoatPosition] {
+        &self.0
+    }
+
     pub fn find_boat_at_position(&self, pos: Coordinates) -> Option<&BoatPosition> {
         self.0.iter().find(|f| f.all_coordinates().contains(&pos))
     }