diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/data/GanttDate.java b/ganttzk/src/main/java/org/zkoss/ganttz/data/GanttDate.java
new file mode 100644
index 000000000..8c761e3f8
--- /dev/null
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/data/GanttDate.java
@@ -0,0 +1,202 @@
+/*
+ * This file is part of NavalPlan
+ *
+ * Copyright (C) 2009-2010 Fundación para o Fomento da Calidade Industrial e
+ *                         Desenvolvemento Tecnolóxico de Galicia
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.zkoss.ganttz.data;
+
+import java.util.Date;
+
+import org.apache.commons.lang.Validate;
+import org.joda.time.LocalDate;
+
+/**
+ * @author Óscar González Fernández
+ *
+ */
+public abstract class GanttDate implements Comparable<GanttDate> {
+
+    public static LocalDateBased createFrom(Date date) {
+        if (date == null) {
+            return null;
+        }
+        return createFrom(LocalDate.fromDateFields(date));
+    }
+
+    public static LocalDateBased createFrom(LocalDate localDate) {
+        if (localDate == null) {
+            return null;
+        }
+        return new LocalDateBased(localDate);
+    }
+
+    @Override
+    public final boolean equals(Object obj) {
+        if (obj == this) {
+            return true;
+        }
+        if (obj instanceof GanttDate) {
+            GanttDate other = (GanttDate) obj;
+            return isEqualsTo(other);
+        }
+        return false;
+    }
+
+    protected abstract boolean isEqualsTo(GanttDate other);
+
+    @Override
+    public abstract int hashCode();
+
+    public interface ICases<R> {
+        public R on(LocalDateBased localDateBased);
+
+        public R on(CustomDate customType);
+    }
+
+    public static abstract class Cases<T extends CustomDate, R> implements
+            ICases<R> {
+
+        private final Class<T> klass;
+
+        public Cases(Class<T> klass) {
+            Validate.notNull(klass);
+            this.klass = klass;
+        }
+
+        @Override
+        public R on(CustomDate customType) {
+            return onCustom(klass.cast(customType));
+        }
+
+        protected abstract R onCustom(T customType);
+    }
+
+    public abstract <R> R byCases(ICases<R> cases);
+
+    // TODO remove this method
+    public abstract Date toDateApproximation();
+
+    public static class LocalDateBased extends GanttDate {
+
+        private final LocalDate localDate;
+
+        public LocalDateBased(LocalDate localDate) {
+            Validate.notNull(localDate);
+            this.localDate = localDate;
+        }
+
+        public LocalDate getLocalDate() {
+            return localDate;
+        }
+
+        public <R> R byCases(ICases<R> cases) {
+            return cases.on(this);
+        }
+
+        @Override
+        public int compareTo(GanttDate o) {
+            return o.byCases(new ICases<Integer>() {
+
+                @Override
+                public Integer on(LocalDateBased localDateBased) {
+                    return localDate.compareTo(localDateBased.localDate);
+                }
+
+                @Override
+                public Integer on(CustomDate customType) {
+                    return -customType.compareToLocalDate(localDate);
+                }
+            });
+        }
+
+        @Override
+        public Date toDateApproximation() {
+            return localDate.toDateTimeAtStartOfDay().toDate();
+        }
+
+        @Override
+        public boolean isEqualsTo(GanttDate other) {
+            return other.byCases(new ICases<Boolean>() {
+
+                @Override
+                public Boolean on(LocalDateBased localDateBased) {
+                    return localDate.equals(localDateBased.localDate);
+                }
+
+                @Override
+                public Boolean on(CustomDate customType) {
+                    return false;
+                }
+            });
+        }
+
+        @Override
+        public int hashCode() {
+            return localDate.hashCode();
+        }
+
+    }
+
+    public static abstract class CustomDate extends GanttDate {
+
+        public CustomDate() {
+        }
+
+        protected abstract boolean isEqualsToCustom(CustomDate customType);
+
+        @Override
+        protected boolean isEqualsTo(GanttDate other) {
+            return other.byCases(new ICases<Boolean>() {
+
+                @Override
+                public Boolean on(LocalDateBased localDateBased) {
+                    return false;
+                }
+
+                @Override
+                public Boolean on(CustomDate customType) {
+                    return isEqualsToCustom(customType);
+                }
+            });
+        }
+
+        @Override
+        public <R> R byCases(ICases<R> cases) {
+            return cases.on(this);
+        }
+
+        @Override
+        public int compareTo(GanttDate o) {
+            return byCases(new ICases<Integer>() {
+                @Override
+                public Integer on(LocalDateBased localDateBased) {
+                    return compareToLocalDate(localDateBased.localDate);
+                }
+
+                @Override
+                public Integer on(CustomDate customType) {
+                    return compareToCustom(customType);
+                }
+            });
+        }
+
+        protected abstract int compareToCustom(CustomDate customType);
+
+        protected abstract int compareToLocalDate(LocalDate localDate);
+    }
+
+}
diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/workingday/IntraDayDate.java b/navalplanner-business/src/main/java/org/navalplanner/business/workingday/IntraDayDate.java
index a98b5ea3d..6a6f030d4 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/workingday/IntraDayDate.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/workingday/IntraDayDate.java
@@ -134,4 +134,12 @@ public class IntraDayDate implements Comparable<IntraDayDate> {
         return getDate().plusDays(1);
     }
 
+    public int compareTo(LocalDate other) {
+        int result = this.date.compareTo(other);
+        if (result != 0) {
+            return result;
+        }
+        return isStartOfDay() ? 0 : 1;
+    }
+
 }
diff --git a/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/TaskElementAdapter.java b/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/TaskElementAdapter.java
index a2b9c4948..9cc8d9cc1 100644
--- a/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/TaskElementAdapter.java
+++ b/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/TaskElementAdapter.java
@@ -62,12 +62,17 @@ import org.navalplanner.business.resources.daos.ICriterionDAO;
 import org.navalplanner.business.resources.entities.Criterion;
 import org.navalplanner.business.resources.entities.Resource;
 import org.navalplanner.business.scenarios.entities.Scenario;
+import org.navalplanner.business.workingday.IntraDayDate;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.context.annotation.Scope;
 import org.springframework.stereotype.Component;
 import org.zkoss.ganttz.adapters.DomainDependency;
 import org.zkoss.ganttz.data.DependencyType;
+import org.zkoss.ganttz.data.GanttDate;
+import org.zkoss.ganttz.data.GanttDate.Cases;
+import org.zkoss.ganttz.data.GanttDate.CustomDate;
+import org.zkoss.ganttz.data.GanttDate.LocalDateBased;
 import org.zkoss.ganttz.data.ITaskFundamentalProperties;
 import org.zkoss.ganttz.data.constraint.Constraint;
 import org.zkoss.ganttz.data.constraint.DateConstraint;
@@ -146,6 +151,74 @@ public class TaskElementAdapter implements ITaskElementAdapter {
     public TaskElementAdapter() {
     }
 
+    public static GanttDate toGantt(IntraDayDate date) {
+        return new GanttDateAdapter(date);
+    }
+
+    public static IntraDayDate toIntraDay(GanttDate date) {
+        return date.byCases(new Cases<GanttDateAdapter, IntraDayDate>(
+                GanttDateAdapter.class) {
+
+            @Override
+            public IntraDayDate on(LocalDateBased localDate) {
+                return IntraDayDate.startOfDay(localDate.getLocalDate());
+            }
+
+            @Override
+            protected IntraDayDate onCustom(GanttDateAdapter customType) {
+                return customType.date;
+            }
+        });
+    }
+
+    public static LocalDate toLocalDate(GanttDate date) {
+        return toIntraDay(date).getDate();
+    }
+
+    static class GanttDateAdapter extends CustomDate {
+
+        private final IntraDayDate date;
+
+        GanttDateAdapter(IntraDayDate date) {
+            this.date = date;
+        }
+
+        protected int compareToCustom(CustomDate customType) {
+            if (customType instanceof GanttDateAdapter) {
+                GanttDateAdapter other = (GanttDateAdapter) customType;
+                return this.date.compareTo(other.date);
+            }
+            throw new RuntimeException("incompatible type: " + customType);
+        }
+
+        protected int compareToLocalDate(LocalDate localDate) {
+            return this.date.compareTo(localDate);
+        }
+
+        public IntraDayDate getDate() {
+            return date;
+        }
+
+        @Override
+        public Date toDateApproximation() {
+            return date.toDateTimeAtStartOfDay().toDate();
+        }
+
+        @Override
+        protected boolean isEqualsToCustom(CustomDate customType) {
+            if (customType instanceof GanttDateAdapter) {
+                GanttDateAdapter other = (GanttDateAdapter) customType;
+                return this.date.equals(other.date);
+            }
+            return false;
+        }
+
+        @Override
+        public int hashCode() {
+            return date.hashCode();
+        }
+    }
+
     private class TaskElementWrapper implements ITaskFundamentalProperties {
 
         private final TaskElement taskElement;