diff --git a/src/NmeaParser/Nmea/Dpt.cs b/src/NmeaParser/Nmea/Dpt.cs
new file mode 100644
index 00000000..00286116
--- /dev/null
+++ b/src/NmeaParser/Nmea/Dpt.cs
@@ -0,0 +1,71 @@
+//  *******************************************************************************
+//  *  Licensed under the Apache License, Version 2.0 (the "License");
+//  *  you may not use this file except in compliance with the License.
+//  *  You may obtain a copy of the License at
+//  *
+//  *  http://www.apache.org/licenses/LICENSE-2.0
+//  *
+//  *   Unless required by applicable law or agreed to in writing, software
+//  *   distributed under the License is distributed on an "AS IS" BASIS,
+//  *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//  *   See the License for the specific language governing permissions and
+//  *   limitations under the License.
+//  ******************************************************************************
+
+using System;
+using System.Globalization;
+
+namespace NmeaParser.Messages
+{
+    /// <summary>
+    ///     Water depth relative to the transducer, the depth offset of the transducer, and maximum depth that the sounder can detect a sea-bed (all in metres only).
+    ///     Positive offsets provide distance from the transducer to the water line. Negative offsets provide distance from the transducer to the keel.
+    ///     Not all NMEA 0183 devices that output this sentence can have their depth offset changed. In this case, the depth offset will always be zero, or not included.
+    ///     NMEA 0183 v2.0 sentences will not include the maximum depth range value at all, as it was added in v3.0.
+    /// </summary>
+    /// <remarks>
+    ///     <para>
+    ///         Format: $xxDPT,DATA_METRES,OFFSET_METRES, MAXIMUM_METRES*hh
+    ///         1.: Data
+    ///         2.: Offset
+    ///         3.: Maximum
+    ///     </para>
+    ///     <para>
+    ///         Depth
+    ///     </para>
+    /// </remarks>
+    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "SdDpt")]
+    [NmeaMessageType("--DPT")]
+    public class Dpt : NmeaMessage
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Dpt"/> class.
+        /// </summary>
+        /// <param name="type">The message type</param>
+        /// <param name="message">The NMEA message values.</param>
+        public Dpt(string type, string[] message) : base(type, message)
+        {
+            if (message == null || message.Length < 3)
+                throw new ArgumentException("Invalid Dpt", "message");
+
+            DepthMeters = double.Parse(message[0], CultureInfo.InvariantCulture);
+            DepthOffsetMeters = double.Parse(message[1], CultureInfo.InvariantCulture);
+            MaxDepthRangeMeters = double.Parse(message[2], CultureInfo.InvariantCulture);
+        }
+
+        /// <summary>
+        ///     Depth, in meters
+        /// </summary>
+        public double DepthMeters { get; }
+
+        /// <summary>
+        ///     Depth offset, in meters
+        /// </summary>
+        public double DepthOffsetMeters { get; }
+
+        /// <summary>
+        ///     Maximum depth range, in meters
+        /// </summary>
+        public double MaxDepthRangeMeters { get; }
+    }
+}
\ No newline at end of file
diff --git a/src/NmeaParser/Nmea/Hdt.cs b/src/NmeaParser/Nmea/Hdt.cs
new file mode 100644
index 00000000..8aebaf21
--- /dev/null
+++ b/src/NmeaParser/Nmea/Hdt.cs
@@ -0,0 +1,64 @@
+//  *******************************************************************************
+//  *  Licensed under the Apache License, Version 2.0 (the "License");
+//  *  you may not use this file except in compliance with the License.
+//  *  You may obtain a copy of the License at
+//  *
+//  *  http://www.apache.org/licenses/LICENSE-2.0
+//  *
+//  *   Unless required by applicable law or agreed to in writing, software
+//  *   distributed under the License is distributed on an "AS IS" BASIS,
+//  *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//  *   See the License for the specific language governing permissions and
+//  *   limitations under the License.
+//  ******************************************************************************
+
+using System;
+using System.Globalization;
+
+namespace NmeaParser.Messages
+{
+    /// <summary>
+    ///     Heading from True North
+    /// </summary>
+    /// <remarks>
+    ///     <para>
+    ///         1.: Heading in degrees
+    ///         2.: Indicates heading relative to True North
+    ///     </para>
+    ///     <para>
+    ///         Actual vessel heading in degrees True produced by any device or system producing true heading
+    ///     </para>
+    /// </remarks>
+    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "HeHdt")]
+    [NmeaMessageType("--HDT")]
+    public class Hdt : NmeaMessage
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Hdt"/> class.
+        /// </summary>
+        /// <param name="type">The message type</param>
+        /// <param name="message">The NMEA message values.</param>
+        public Hdt(string type, string[] message) : base(type, message)
+        {
+            if (message == null || message.Length < 2)
+                throw new ArgumentException("Invalid Hdt", "message");
+
+            // Extract the heading in degrees
+            HeadingInDeg = double.TryParse(message[0], NumberStyles.Float, CultureInfo.InvariantCulture, out var heading)
+                ? heading 
+                : double.NaN;
+
+            HeadingRelToTrueNorth = message[1] == "T";
+        }
+
+        /// <summary>
+        ///     Heading in degrees
+        /// </summary>
+        public double HeadingInDeg { get; }
+
+        /// <summary>
+        ///     T: Indicates heading relative to True North
+        /// </summary>
+        public bool HeadingRelToTrueNorth { get; }
+    }
+}
\ No newline at end of file
diff --git a/src/NmeaParser/Nmea/Xdr.cs b/src/NmeaParser/Nmea/Xdr.cs
new file mode 100644
index 00000000..c65c60c5
--- /dev/null
+++ b/src/NmeaParser/Nmea/Xdr.cs
@@ -0,0 +1,71 @@
+//  *******************************************************************************
+//  *  Licensed under the Apache License, Version 2.0 (the "License");
+//  *  you may not use this file except in compliance with the License.
+//  *  You may obtain a copy of the License at
+//  *
+//  *  http://www.apache.org/licenses/LICENSE-2.0
+//  *
+//  *   Unless required by applicable law or agreed to in writing, software
+//  *   distributed under the License is distributed on an "AS IS" BASIS,
+//  *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//  *   See the License for the specific language governing permissions and
+//  *   limitations under the License.
+//  ******************************************************************************
+
+using System;
+
+namespace NmeaParser.Messages
+{
+    /// <summary>
+    ///     Measurement data from transducers that measure physical quantities such as 
+    ///     temperature, force, pressure, frequency, angular or linear displacement, etc. 
+    ///     Four fields 'Type-Data-Units-ID'
+    /// </summary>
+    /// <remarks>
+    ///     <para>
+    ///         1.: Transducer type
+    ///         2.: Measurement data
+    ///         3.: units of measure
+    ///         4.: transducer ID
+    ///     </para>
+    /// </remarks>
+    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "Xdr")]
+    [NmeaMessageType("--XDR")]
+    public class Xdr : NmeaMessage
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Xdr"/> class.
+        /// </summary>
+        /// <param name="type">The message type</param>
+        /// <param name="message">The NMEA message values.</param>
+        public Xdr(string type, string[] message) : base(type, message)
+        {
+            if (message == null || message.Length < 4)
+                throw new ArgumentException("Invalid Xdr", "message");
+            Type = message[0];
+            Data = StringToDouble(message[1]);
+            Unit = message[2];
+            ID = message[3];
+        }
+
+        /// <summary>
+        ///     Transducer Type
+        /// </summary>
+        public string Type { get; }
+
+        /// <summary>
+        ///     Measurement data
+        /// </summary>
+        public double Data { get; }
+
+        /// <summary>
+        ///     Unit of measure
+        /// </summary>
+        public string Unit { get; }
+
+        /// <summary>
+        ///     ID
+        /// </summary>
+        public string ID { get; }
+    }
+}
\ No newline at end of file
diff --git a/src/UnitTests/NmeaParser.Tests/NmeaMessages.cs b/src/UnitTests/NmeaParser.Tests/NmeaMessages.cs
index b6cbc1cb..50ed8cdd 100644
--- a/src/UnitTests/NmeaParser.Tests/NmeaMessages.cs
+++ b/src/UnitTests/NmeaParser.Tests/NmeaMessages.cs
@@ -124,6 +124,18 @@ public void IgnoreChecksum()
             Assert.ThrowsException<ArgumentException>(() => NmeaMessage.Parse(input, ignoreChecksum: false));
         }
 
+        [TestMethod]
+        public void TestDPT()
+        {
+            string input = "$--DPT,149.5,000.5,1000.0*7F";
+            var msg = NmeaMessage.Parse(input);
+            Assert.IsInstanceOfType(msg, typeof(Dpt));
+            Dpt dpt = (Dpt)msg;
+            Assert.AreEqual(149.5, dpt.DepthMeters);
+            Assert.AreEqual(0.5, dpt.DepthOffsetMeters);
+            Assert.AreEqual(1000, dpt.MaxDepthRangeMeters);
+        }
+
         [TestMethod]
         public void TestGprma()
         {
@@ -296,6 +308,30 @@ public void TestGPGGA_Empty()
             Assert.AreEqual(-1, gga.DgpsStationId);
         }
 
+        [TestMethod]
+        public void TestHEHDT()
+        {
+            const string input = "$HEHDT,13.37,T*29";
+            var msg = NmeaMessage.Parse(input);
+            Assert.IsInstanceOfType(msg, typeof(Hdt));
+            Hdt hdt = (Hdt)msg;
+            Assert.AreEqual(13.37, hdt.HeadingInDeg);
+            Assert.IsTrue(hdt.HeadingRelToTrueNorth);
+        }
+
+        [TestMethod]
+        public void TestKMXDR()
+        {
+            string input = "$KMXDR,P,123.4,M,DEPTH*32";
+            var msg = NmeaMessage.Parse(input);
+            Assert.IsInstanceOfType(msg, typeof(Xdr));
+            Xdr xdr = (Xdr)msg;
+            Assert.AreEqual("P", xdr.Type);
+            Assert.AreEqual(123.4, xdr.Data);
+            Assert.AreEqual("M", xdr.Unit);
+            Assert.AreEqual("DEPTH", xdr.ID);
+        }
+
         [TestMethod]
         public void TestPtlna()
         {