diff --git a/inst/include/interface/rcpp/rcpp_objects/rcpp_data.hpp b/inst/include/interface/rcpp/rcpp_objects/rcpp_data.hpp
index 3f25e3f7e..13df67d96 100644
--- a/inst/include/interface/rcpp/rcpp_objects/rcpp_data.hpp
+++ b/inst/include/interface/rcpp/rcpp_objects/rcpp_data.hpp
@@ -120,6 +120,73 @@ class AgeCompDataInterface : public DataInterfaceBase {
 #endif
 };
 
+/**
+ * @brief Rcpp interface for length comp data as an S4 object. To instantiate
+ * from R:
+ * acomp <- new(LengthComp)
+ */
+class LengthCompDataInterface : public DataInterfaceBase {
+ public:
+  int lmax;                          /**< first dimension of the data */
+  int ymax;                          /**< second dimension of the data */
+  Rcpp::NumericVector length_comp_data; /**<the length composition data*/
+
+  /**
+   * @brief constructor
+   */
+  LengthCompDataInterface(int ymax = 0, int lmax = 0) : DataInterfaceBase() {
+    this->lmax = lmax;
+    this->ymax = ymax;
+  }
+
+  /**
+   * @brief destructor
+   */
+  virtual ~LengthCompDataInterface() {}
+
+  /** @brief get the ID of the interface base object
+   */
+  virtual uint32_t get_id() { return this->id; }
+
+#ifdef TMB_MODEL
+
+  template <typename Type>
+  bool add_to_fims_tmb_internal() {
+    std::shared_ptr<fims_data_object::DataObject<Type>> length_comp_data =
+        std::make_shared<fims_data_object::DataObject<Type>>(this->ymax,
+                                                             this->lmax);
+
+    length_comp_data->id = this->id;
+    for (int y = 0; y < ymax; y++) {
+      for (int l = 0; l < lmax; l++) {
+        int i_length_year = y * lmax + l;
+        length_comp_data->at(y, a) = this->length_comp_data[i_length_year];
+      }
+    }
+
+    std::shared_ptr<fims_info::Information<Type>> info =
+        fims_info::Information<Type>::GetInstance();
+
+    info->data_objects[this->id] = length_comp_data;
+
+    return true;
+  }
+
+  /**
+   * @brief adds parameters to the model
+   */
+  virtual bool add_to_fims_tmb() {
+    this->add_to_fims_tmb_internal<TMB_FIMS_REAL_TYPE>();
+    this->add_to_fims_tmb_internal<TMB_FIMS_FIRST_ORDER>();
+    this->add_to_fims_tmb_internal<TMB_FIMS_SECOND_ORDER>();
+    this->add_to_fims_tmb_internal<TMB_FIMS_THIRD_ORDER>();
+
+    return true;
+  }
+
+#endif
+};
+
 /**
  * @brief Rcpp interface for data as an S4 object. To instantiate
  * from R: