diff --git a/adapters/chrono/CMakeLists.txt b/adapters/chrono/CMakeLists.txt
index 46f30a5..ae95378 100644
--- a/adapters/chrono/CMakeLists.txt
+++ b/adapters/chrono/CMakeLists.txt
@@ -24,19 +24,25 @@ target_include_directories(seastack_chrono_adapter
 
 # Chrono MBS YAML registers TSDA/RSDA force functors without copying damping onto the link;
 # simulation_export reads damping_coefficient from model YAML when GetDampingCoefficient()==0.
-find_package(yaml-cpp CONFIG QUIET)
-if(NOT yaml-cpp_FOUND)
-    find_package(yaml-cpp QUIET)
-endif()
-if(TARGET yaml-cpp::yaml-cpp)
-    set(_seastack_yaml_cpp_target yaml-cpp::yaml-cpp)
-elseif(TARGET yaml-cpp)
-    set(_seastack_yaml_cpp_target yaml-cpp)
-elseif(TARGET Chrono::yaml-cpp)
-    # Chrono's config often provides yaml-cpp as an imported target without a system package.
+#
+# Prefer Chrono's bundled yaml-cpp when available so that the yaml-cpp headers
+# (which come from Chrono's chrono_thirdparty/yaml-cpp/include via Chrono::Chrono_core)
+# match the linked library. Mixing a system libyaml-cpp.so with Chrono's headers can
+# produce link errors against internal symbols (e.g. YAML::FpToString, YAML::Emitter::Write).
+if(TARGET Chrono::yaml-cpp)
     set(_seastack_yaml_cpp_target Chrono::yaml-cpp)
 else()
-    message(FATAL_ERROR "yaml-cpp not found (required for Chrono adapter).")
+    find_package(yaml-cpp CONFIG QUIET)
+    if(NOT yaml-cpp_FOUND)
+        find_package(yaml-cpp QUIET)
+    endif()
+    if(TARGET yaml-cpp::yaml-cpp)
+        set(_seastack_yaml_cpp_target yaml-cpp::yaml-cpp)
+    elseif(TARGET yaml-cpp)
+        set(_seastack_yaml_cpp_target yaml-cpp)
+    else()
+        message(FATAL_ERROR "yaml-cpp not found (required for Chrono adapter).")
+    endif()
 endif()
 
 target_link_libraries(seastack_chrono_adapter
diff --git a/adapters/chrono/src/simulation_export.cpp b/adapters/chrono/src/simulation_export.cpp
index 5e7a60c..c9e55c2 100644
--- a/adapters/chrono/src/simulation_export.cpp
+++ b/adapters/chrono/src/simulation_export.cpp
@@ -1082,13 +1082,18 @@ void SimulationExporter::RecordStep(::chrono::ChSystem* system) {
     }
 
     // ── Generic joint reactions (level-gated) ───────────────────────────────
+    // GetReaction1/2 and GetFrame1Abs/2Abs are virtual on ChLinkBase, so they
+    // work for every concrete joint type (ChLinkLock, ChLinkUniversal,
+    // ChLinkRevoluteSpherical, ...). Previously this code dynamic_cast<>'d to
+    // ChLinkLock* only, silently writing zeros for every other joint type --
+    // including the ChLinkUniversal joints used by the 5SA articulated WEC demos.
     for (auto& j : impl_->joints) {
         auto* L = j.link;
-        if (auto* lock = dynamic_cast<::chrono::ChLinkLock*>(L)) {
+        if (L) {
             try {
-                auto w1 = lock->GetReaction1();
-                auto F1 = lock->GetFrame1Abs().TransformDirectionLocalToParent(w1.force);
-                auto T1 = lock->GetFrame1Abs().TransformDirectionLocalToParent(w1.torque);
+                auto w1 = L->GetReaction1();
+                auto F1 = L->GetFrame1Abs().TransformDirectionLocalToParent(w1.force);
+                auto T1 = L->GetFrame1Abs().TransformDirectionLocalToParent(w1.torque);
                 j.react_force_b1.insert(j.react_force_b1.end(), {F1.x(), F1.y(), F1.z()});
                 j.react_torque_b1.insert(j.react_torque_b1.end(), {T1.x(), T1.y(), T1.z()});
             } catch (const std::exception& ex) {
@@ -1098,9 +1103,9 @@ void SimulationExporter::RecordStep(::chrono::ChSystem* system) {
             }
             if (!is_compact) {
                 try {
-                    auto w2 = lock->GetReaction2();
-                    auto F2 = lock->GetFrame2Abs().TransformDirectionLocalToParent(w2.force);
-                    auto T2 = lock->GetFrame2Abs().TransformDirectionLocalToParent(w2.torque);
+                    auto w2 = L->GetReaction2();
+                    auto F2 = L->GetFrame2Abs().TransformDirectionLocalToParent(w2.force);
+                    auto T2 = L->GetFrame2Abs().TransformDirectionLocalToParent(w2.torque);
                     j.react_force_b2.insert(j.react_force_b2.end(), {F2.x(), F2.y(), F2.z()});
                     j.react_torque_b2.insert(j.react_torque_b2.end(), {T2.x(), T2.y(), T2.z()});
                 } catch (const std::exception& ex) {
diff --git a/apps/seastack/gui/vsg_config.h b/apps/seastack/gui/vsg_config.h
index 99d237d..bfe5bad 100644
--- a/apps/seastack/gui/vsg_config.h
+++ b/apps/seastack/gui/vsg_config.h
@@ -25,7 +25,14 @@ inline constexpr int kColorVariationCycle = 8;
 inline constexpr float kWaterR = 0.01f;
 inline constexpr float kWaterG = 0.20f;
 inline constexpr float kWaterB = 0.35f;
-inline constexpr float kWaterOpacity = 0.55f;
+// NOTE: Material opacity must stay at 1.0 on Linux.
+// With opacity < 1.0, Chrono's wrapIfTransparent() wraps the runtime-added
+// water node in vsg::DepthSorted (bin 10), which crashes the VSG renderer
+// at vsg::Bin::add during the first record traversal. The animated water
+// surface is added to the scene after pVis->Initialize(), bypassing the
+// BindAll() compile path that built-in Chrono demos rely on.
+// TODO: enable proper translucency via a runtime compile traversal.
+inline constexpr float kWaterOpacity = 1.0f;
 inline constexpr float kWaterSpecular = 0.6f;
 inline constexpr float kWaterRoughness = 0.05f;
 inline constexpr float kWaterMetallic = 0.0f;
diff --git a/apps/seastack/gui/vsg_water_surface.cpp b/apps/seastack/gui/vsg_water_surface.cpp
index ecc097a..6c86e50 100644
--- a/apps/seastack/gui/vsg_water_surface.cpp
+++ b/apps/seastack/gui/vsg_water_surface.cpp
@@ -501,7 +501,7 @@ void AnimatedWaterSurface::InitializeWireframe() {
     // Faint blue-gray material.
     auto wire_material = ::chrono_types::make_shared<::chrono::ChVisualMaterial>();
     wire_material->SetDiffuseColor(::chrono::ChColor(0.1f, 0.2f, 0.3f));
-    wire_material->SetOpacity(0.35f);
+    wire_material->SetOpacity(1.0f);
     wire_material->SetRoughness(0.9f);
     wire_material->SetMetallic(0.0f);
 
diff --git a/apps/seastack/single_run.cpp b/apps/seastack/single_run.cpp
index 3c3b36b..56d8918 100644
--- a/apps/seastack/single_run.cpp
+++ b/apps/seastack/single_run.cpp
@@ -123,7 +123,7 @@ namespace {
 class HCParser : public ::chrono::parsers::ChParserMbsYAML {
   public:
     HCParser() : ChParserMbsYAML() {}
-    void SetScriptDir(const std::string& dir) { m_script_directory = dir; }
+    void SetScriptDir(const std::string& dir) { m_file_handler.SetReferenceDirectory(dir); }
 };
 
 static std::shared_ptr<::chrono::ChBody> FindBodyByName(::chrono::ChSystem& system,
diff --git a/data/demos/run_seastack/5sa/bimodal/5sa_bimodal.hydro.yaml b/data/demos/run_seastack/5sa/bimodal/5sa_bimodal.hydro.yaml
index 32569c1..1159c59 100644
--- a/data/demos/run_seastack/5sa/bimodal/5sa_bimodal.hydro.yaml
+++ b/data/demos/run_seastack/5sa/bimodal/5sa_bimodal.hydro.yaml
@@ -1,20 +1,31 @@
 hydrodynamics:
   bodies:
+    # Surge/sway/heave/roll/pitch/yaw damping mirrored from the spreading
+    # case. The bimodal swell + wind sea combination contains spectral
+    # energy near the chain's heave natural frequency, and with zero
+    # linear and quadratic damping in heave/pitch/yaw the rigid-body
+    # heave mode runs away after ~200 s of accumulation (body z-position
+    # exceeded 10 m above SWL by t=280 s in the previous configuration).
     - name: body1
       h5_file: ../assets/hydroData/5sa_directional.h5
-      linear_damping: [0, 100000, 0, 500000, 0, 0]
+      linear_damping:    [20000, 80000, 80000, 500000, 200000, 200000]
+      quadratic_damping: [10000, 40000, 40000, 250000, 100000, 100000]
     - name: body2
       h5_file: ../assets/hydroData/5sa_directional.h5
-      linear_damping: [0, 100000, 0, 500000, 0, 0]
+      linear_damping:    [20000, 80000, 80000, 500000, 200000, 200000]
+      quadratic_damping: [10000, 40000, 40000, 250000, 100000, 100000]
     - name: body3
       h5_file: ../assets/hydroData/5sa_directional.h5
-      linear_damping: [0, 100000, 0, 500000, 0, 0]
+      linear_damping:    [20000, 80000, 80000, 500000, 200000, 200000]
+      quadratic_damping: [10000, 40000, 40000, 250000, 100000, 100000]
     - name: body4
       h5_file: ../assets/hydroData/5sa_directional.h5
-      linear_damping: [0, 100000, 0, 500000, 0, 0]
+      linear_damping:    [20000, 80000, 80000, 500000, 200000, 200000]
+      quadratic_damping: [10000, 40000, 40000, 250000, 100000, 100000]
     - name: body5
       h5_file: ../assets/hydroData/5sa_directional.h5
-      linear_damping: [0, 100000, 0, 500000, 0, 0]
+      linear_damping:    [20000, 80000, 80000, 500000, 200000, 200000]
+      quadratic_damping: [10000, 40000, 40000, 250000, 100000, 100000]
 
   # Bimodal sea state: swell along +X, wind sea from beam (90 deg).
   waves:
@@ -42,6 +53,11 @@ hydrodynamics:
           type: cos2s
           s: 8
 
+  # Bimodal sea: swell and wind-sea have different headings, so excitation
+  # must be evaluated in the frequency domain (matches spreading case).
+  excitation:
+    method: frequency_domain
+
   radiation:
     method: rirf_convolution
     smoothing:
diff --git a/scripts/unix/build.sh b/scripts/unix/build.sh
old mode 100644
new mode 100755
diff --git a/scripts/unix/ctest_suite.sh b/scripts/unix/ctest_suite.sh
old mode 100644
new mode 100755
diff --git a/scripts/unix/run_benchmarks.sh b/scripts/unix/run_benchmarks.sh
old mode 100644
new mode 100755
diff --git a/scripts/unix/run_chrono_free_tests.sh b/scripts/unix/run_chrono_free_tests.sh
old mode 100644
new mode 100755
diff --git a/scripts/unix/run_comparison_tests.sh b/scripts/unix/run_comparison_tests.sh
old mode 100644
new mode 100755
diff --git a/scripts/unix/run_regression_tests.sh b/scripts/unix/run_regression_tests.sh
old mode 100644
new mode 100755
diff --git a/scripts/unix/run_seastack_demo_smoke.sh b/scripts/unix/run_seastack_demo_smoke.sh
old mode 100644
new mode 100755
diff --git a/scripts/unix/run_unit_tests.sh b/scripts/unix/run_unit_tests.sh
old mode 100644
new mode 100755
diff --git a/scripts/unix/run_verification_tests.sh b/scripts/unix/run_verification_tests.sh
old mode 100644
new mode 100755