diff --git a/Rover/sailboat.cpp b/Rover/sailboat.cpp
index 99a876dc7d6049..f5d796a0589882 100644
--- a/Rover/sailboat.cpp
+++ b/Rover/sailboat.cpp
@@ -385,7 +385,7 @@ bool Sailboat::tacking() const
 
 // returns true if sailboat should take a indirect navigation route to go upwind
 // desired_heading should be in centi-degrees
-bool Sailboat::use_indirect_route(float desired_heading_cd)
+bool Sailboat::use_indirect_route(float desired_heading_cd) const
 {
    
     if (!tack_enabled()) {
diff --git a/Rover/sailboat.h b/Rover/sailboat.h
index ddac302fd20704..5ad1a902acf4cb 100644
--- a/Rover/sailboat.h
+++ b/Rover/sailboat.h
@@ -66,7 +66,7 @@ class Sailboat
     bool tacking() const;
 
     // returns true if sailboat should take a indirect navigation route to go upwind
-    bool use_indirect_route(float desired_heading_cd);
+    bool use_indirect_route(float desired_heading_cd) const;
 
     // calculate the heading to sail on if we cant go upwind
     float calc_heading(float desired_heading_cd);