diff --git a/doc/scilab_tests/macrorugo_resultats_complementaires.sci b/doc/scilab_tests/macrorugo_resultats_complementaires.sci
index dc2f5365ac79937992f17eef431769bcae8dec71..cf33ff8556d3bfcd7348459a03a4bc4d41bf2d9c 100644
--- a/doc/scilab_tests/macrorugo_resultats_complementaires.sci
+++ b/doc/scilab_tests/macrorugo_resultats_complementaires.sci
@@ -35,7 +35,7 @@ function macrorugo_resultComp(z_amont, S, long, Q, L, pf, C, Cd0, h, D)
             q_technique=0.815*(pf/D)^1.45*S^0.557*C^(-0.456)*(9.81*D)^0.5.*D*L;
             V_technique=4.54*(pf/D)^0.32*S^0.56*(9.81*D)^0.5;
         end
-        coeff_contraction=0.2*Cd0+0.9;
+        coeff_contraction = (Cd0 * 0.4 + 1.21) / 1.5;
         Vmax=Vg.*coeff_contraction*calcfFr(Fr);
         print_r("Vmax");
         print_r("V_technique");
diff --git a/spec/macrorugo/macrorugo.spec.ts b/spec/macrorugo/macrorugo.spec.ts
index 045d46bd2db9e2590309111440d0a4121aa42ed6..d0cbdb341ab89a199aad61251c741117cc9a6639 100644
--- a/spec/macrorugo/macrorugo.spec.ts
+++ b/spec/macrorugo/macrorugo.spec.ts
@@ -23,7 +23,7 @@ Vg: 1.804786,
 Fr = 0.743902
 P = 566.066964
 flowcond = emergent
-Vmax = 2.722572
+Vmax = 2.673954
 V_technique = 1.991299
 q_technique = 0.561860
 Strickler = 7.255093
@@ -54,7 +54,7 @@ const macroRugoExtraResultEmergentCd11: { [key: string]: number | MacroRugoFlowT
     Vg: 1.804786,
     Fr: 0.743902,
     PV: 566.066964,
-    Vmax: 2.722572,
+    Vmax: 2.673954,
     Strickler: 7.255093
 };
 
@@ -78,7 +78,7 @@ Vg: 1.255512,
 Fr: 0.517500,
 PV: 393.788411,
 flowcond: emergent,
-Vmax: 2.047863,
+Vmax: 2.163235,
 V_technique: 1.991299,
 q_technique: 0.561860,
 Strickler: 5.047056
@@ -98,7 +98,7 @@ const macroRugoExtraResultEmergentCd26: { [key: string]: number | MacroRugoFlowT
     Vg: 1.255512,
     Fr: 0.517500,
     PV: 393.788411,
-    Vmax: 2.047863,
+    Vmax: 2.163235,
     Strickler: 5.047056
 };
 
diff --git a/spec/verificateur/verificateur.spec.ts b/spec/verificateur/verificateur.spec.ts
index 3880f57eeaa060eedfcf078f3707a54a098dfa5a..6784b9706ad0b509b363e8fe96f97b9e1c6c9d91 100644
--- a/spec/verificateur/verificateur.spec.ts
+++ b/spec/verificateur/verificateur.spec.ts
@@ -1010,7 +1010,7 @@ describe("vérificateur de franchissement −", () => {
         it("Largeur franchissable insuffisante", () => {
             // contexte
             Session.getInstance().clear();
-            Session.getInstance().unserialise(`{"header":{"source":"jalhyd","format_version":"1.3","created":"2021-02-13T10:21:53.436Z"},"settings":{"precision":1e-7,"maxIterations":100,"displayPrecision":3},"documentation":"","session":[{"uid":"b2tnbW","props":{"calcType":"MacroRugoCompound","inclinedApron":"INCLINED"},"meta":{"title":"M-Rugo complexe"},"children":[{"uid":"MHV3dW","props":{"calcType":"MacroRugo"},"children":[],"parameters":[{"symbol":"ZF1","mode":"SINGLE","value":12.052},{"symbol":"B","mode":"SINGLE","value":0.894}]},{"uid":"aDJrOG","props":{"calcType":"MacroRugo"},"children":[],"parameters":[{"symbol":"ZF1","mode":"SINGLE","value":12.156},{"symbol":"B","mode":"SINGLE","value":0.895}]},{"uid":"MXF4cW","props":{"calcType":"MacroRugo"},"children":[],"parameters":[{"symbol":"ZF1","mode":"SINGLE","value":12.26},{"symbol":"B","mode":"SINGLE","value":0.894}]},{"uid":"czE5Y2","props":{"calcType":"MacroRugo"},"children":[],"parameters":[{"symbol":"ZF1","mode":"SINGLE","value":12.364},{"symbol":"B","mode":"SINGLE","value":0.895}]},{"uid":"ajZteW","props":{"calcType":"MacroRugo"},"children":[],"parameters":[{"symbol":"ZF1","mode":"SINGLE","value":12.458},{"symbol":"B","mode":"SINGLE","value":0.722}]}],"parameters":[{"symbol":"L","mode":"SINGLE","value":1},{"symbol":"If","mode":"SINGLE","value":0.05},{"symbol":"Ks","mode":"SINGLE","value":0.01},{"symbol":"C","mode":"SINGLE","value":0.2},{"symbol":"PBD","mode":"SINGLE","value":0.4},{"symbol":"PBH","mode":"SINGLE","value":0.6},{"symbol":"Cd0","mode":"SINGLE","value":2.6},{"symbol":"Z1","mode":"SINGLE","value":13.1},{"symbol":"ZRL","mode":"SINGLE","value":12.5},{"symbol":"ZRR","mode":"SINGLE","value":12},{"symbol":"BR","mode":"SINGLE","value":4.3},{"symbol":"DH","mode":"SINGLE","value":3}]},{"uid":"Z215Y2","props":{"calcType":"Verificateur","nubToVerify":"b2tnbW","speciesList":["dDZzOX"]},"meta":{"title":"Vérification"},"children":[],"parameters":[]},{"uid":"dDZzOX","props":{"calcType":"Espece","divingJetSupported":"NOT_SUPPORTED","species":"SPECIES_CUSTOM"},"meta":{"title":"Espèce"},"children":[],"parameters":[{"symbol":"OK","mode":"CALCUL"},{"symbol":"DHMaxS","mode":"SINGLE","value":0.35},{"symbol":"DHMaxP","mode":"SINGLE","value":0.35},{"symbol":"BMin","mode":"SINGLE","value":0.3},{"symbol":"PMinS","mode":"SINGLE","value":1},{"symbol":"PMinP","mode":"SINGLE","value":1},{"symbol":"LMinS","mode":"SINGLE","value":2.5},{"symbol":"LMinP","mode":"SINGLE","value":2.5},{"symbol":"HMin","mode":"SINGLE","value":0.3},{"symbol":"YMin","mode":"SINGLE","value":0.6},{"symbol":"VeMax","mode":"SINGLE","value":2},{"symbol":"YMinSB","mode":"SINGLE","value":0.2},{"symbol":"YMinPB","mode":"SINGLE","value":0.3},{"symbol":"PVMaxPrec","mode":"SINGLE","value":150},{"symbol":"PVMaxLim","mode":"SINGLE","value":800000}]}]}`);
+            Session.getInstance().unserialise(`{"header":{"source":"jalhyd","format_version":"1.3","created":"2021-02-13T10:21:53.436Z"},"settings":{"precision":1e-7,"maxIterations":100,"displayPrecision":3},"documentation":"","session":[{"uid":"b2tnbW","props":{"calcType":"MacroRugoCompound","inclinedApron":"INCLINED"},"meta":{"title":"M-Rugo complexe"},"children":[{"uid":"MHV3dW","props":{"calcType":"MacroRugo"},"children":[],"parameters":[{"symbol":"ZF1","mode":"SINGLE","value":12.052},{"symbol":"B","mode":"SINGLE","value":0.894}]},{"uid":"aDJrOG","props":{"calcType":"MacroRugo"},"children":[],"parameters":[{"symbol":"ZF1","mode":"SINGLE","value":12.156},{"symbol":"B","mode":"SINGLE","value":0.895}]},{"uid":"MXF4cW","props":{"calcType":"MacroRugo"},"children":[],"parameters":[{"symbol":"ZF1","mode":"SINGLE","value":12.26},{"symbol":"B","mode":"SINGLE","value":0.894}]},{"uid":"czE5Y2","props":{"calcType":"MacroRugo"},"children":[],"parameters":[{"symbol":"ZF1","mode":"SINGLE","value":12.364},{"symbol":"B","mode":"SINGLE","value":0.895}]},{"uid":"ajZteW","props":{"calcType":"MacroRugo"},"children":[],"parameters":[{"symbol":"ZF1","mode":"SINGLE","value":12.458},{"symbol":"B","mode":"SINGLE","value":0.722}]}],"parameters":[{"symbol":"L","mode":"SINGLE","value":1},{"symbol":"If","mode":"SINGLE","value":0.04},{"symbol":"Ks","mode":"SINGLE","value":0.01},{"symbol":"C","mode":"SINGLE","value":0.2},{"symbol":"PBD","mode":"SINGLE","value":0.4},{"symbol":"PBH","mode":"SINGLE","value":0.6},{"symbol":"Cd0","mode":"SINGLE","value":2.6},{"symbol":"Z1","mode":"SINGLE","value":13.1},{"symbol":"ZRL","mode":"SINGLE","value":12.5},{"symbol":"ZRR","mode":"SINGLE","value":12},{"symbol":"BR","mode":"SINGLE","value":4.3},{"symbol":"DH","mode":"SINGLE","value":3}]},{"uid":"Z215Y2","props":{"calcType":"Verificateur","nubToVerify":"b2tnbW","speciesList":["dDZzOX"]},"meta":{"title":"Vérification"},"children":[],"parameters":[]},{"uid":"dDZzOX","props":{"calcType":"Espece","divingJetSupported":"NOT_SUPPORTED","species":"SPECIES_CUSTOM"},"meta":{"title":"Espèce"},"children":[],"parameters":[{"symbol":"OK","mode":"CALCUL"},{"symbol":"DHMaxS","mode":"SINGLE","value":0.35},{"symbol":"DHMaxP","mode":"SINGLE","value":0.35},{"symbol":"BMin","mode":"SINGLE","value":0.3},{"symbol":"PMinS","mode":"SINGLE","value":1},{"symbol":"PMinP","mode":"SINGLE","value":1},{"symbol":"LMinS","mode":"SINGLE","value":2.5},{"symbol":"LMinP","mode":"SINGLE","value":2.5},{"symbol":"HMin","mode":"SINGLE","value":0.3},{"symbol":"YMin","mode":"SINGLE","value":0.6},{"symbol":"VeMax","mode":"SINGLE","value":2},{"symbol":"YMinSB","mode":"SINGLE","value":0.2},{"symbol":"YMinPB","mode":"SINGLE","value":0.3},{"symbol":"PVMaxPrec","mode":"SINGLE","value":150},{"symbol":"PVMaxLim","mode":"SINGLE","value":800000}]}]}`);
             const v = Session.getInstance().findNubByUid("Z215Y2") as Verificateur;
             // résultat
             const res = v.CalcSerie();
diff --git a/src/macrorugo/macrorugo.ts b/src/macrorugo/macrorugo.ts
index 38fd3cf176f4c9ec4b7ab147ac531422b8531481..c1f2990ecfc612ed14c81ad3fadfd531f16b3839 100644
--- a/src/macrorugo/macrorugo.ts
+++ b/src/macrorugo/macrorugo.ts
@@ -431,12 +431,12 @@ export class MacroRugo extends FishPass {
 
     /**
      * Calcul du ratio entre la vitesse moyenne à l'aval d'un block et la vitesse maximale
-     * r = 1.1 pour un plot circulaire Cd0​=1.1 et r = 1.35 pour un plot à face plane Cd0​=2.6
+     * r = 1.1 pour un plot circulaire Cd0​=1.1 et r = 1.5 pour un plot à face plane Cd0​=2.6
      * Voir #283
      */
     private get r(): number {
         if (this._cache.r === undefined) {
-            this._cache.r = this.prms.Cd0.v / 6 + 11 / 12;
+            this._cache.r = (this.prms.Cd0.v * 0.4 + 1.21) / 1.5;
         }
         return this._cache.r;
     }