diff --git a/SceneGeom.cpp b/SceneGeom.cpp
index d2dbbc1..da5df17 100644
--- a/SceneGeom.cpp
+++ b/SceneGeom.cpp
@@ -205,7 +205,7 @@ Scene::DrawGeoObj( const IGdbIterator& iIter, int nPass, MdStMk siObj)
             return false ;
         // calcolo la grafica
          PolyLine PL ;
-         pVector->GetDrawWithArrowHead( 0.1, PL) ;
+         pVector->GetDrawWithArrowHead( 0.1, 10, PL) ;
          pGraphics->Clear() ;
          pGraphics->AddColor( cCol) ;
          pGraphics->AddPolyLine( PL) ;