diff --git a/grib/src/main/java/ucar/nc2/grib/collection/Grib1Collection.java b/grib/src/main/java/ucar/nc2/grib/collection/Grib1Collection.java
index a17aeddadb..4b53f9984f 100644
--- a/grib/src/main/java/ucar/nc2/grib/collection/Grib1Collection.java
+++ b/grib/src/main/java/ucar/nc2/grib/collection/Grib1Collection.java
@@ -6,7 +6,6 @@
 package ucar.nc2.grib.collection;
 
 import javax.annotation.Nullable;
-import ucar.nc2.dataset.NetcdfDatasets;
 import ucar.nc2.grib.coord.CoordinateTimeAbstract;
 import ucar.nc2.*;
 import ucar.nc2.constants.DataFormatType;
@@ -23,7 +22,6 @@
 import ucar.nc2.grib.grib1.tables.Grib1Customizer;
 import java.io.IOException;
 import java.util.Formatter;
-import ucar.unidata.io.RandomAccessFile;
 
 /**
  * Grib1-specific subclass of GribCollection.
@@ -43,9 +41,7 @@ public ucar.nc2.dataset.NetcdfDataset getNetcdfDataset(Dataset ds, GroupGC group
       FeatureCollectionConfig gribConfig, Formatter errlog, org.slf4j.Logger logger) throws IOException {
     if (filename == null) {
       Grib1Iosp iosp = new Grib1Iosp(group, ds.getType());
-      RandomAccessFile raf = (RandomAccessFile) iosp.sendIospMessage(NetcdfFile.IOSP_MESSAGE_RANDOM_ACCESS_FILE);
-      NetcdfFile ncfile = NetcdfFiles.build(iosp, raf, getLocation(), null);
-      return NetcdfDatasets.enhance(ncfile, NetcdfDataset.getDefaultEnhanceMode(), null);
+      return buildNetcdfDataset(iosp, getLocation());
 
     } else {
       MFile wantFile = findMFileByName(filename);
@@ -56,9 +52,7 @@ public ucar.nc2.dataset.NetcdfDataset getNetcdfDataset(Dataset ds, GroupGC group
           return null;
 
         Grib1Iosp iosp = new Grib1Iosp(gc);
-        RandomAccessFile raf = (RandomAccessFile) iosp.sendIospMessage(NetcdfFile.IOSP_MESSAGE_RANDOM_ACCESS_FILE);
-        NetcdfFile ncfile = NetcdfFiles.build(iosp, raf, getLocation(), null);
-        return NetcdfDatasets.enhance(ncfile, NetcdfDataset.getDefaultEnhanceMode(), null);
+        return buildNetcdfDataset(iosp, getLocation());
       }
       return null;
     }
@@ -70,9 +64,7 @@ public ucar.nc2.dt.grid.GridDataset getGridDataset(Dataset ds, GroupGC group, St
       FeatureCollectionConfig gribConfig, Formatter errlog, org.slf4j.Logger logger) throws IOException {
     if (filename == null) {
       Grib1Iosp iosp = new Grib1Iosp(group, ds.getType());
-      RandomAccessFile raf = (RandomAccessFile) iosp.sendIospMessage(NetcdfFile.IOSP_MESSAGE_RANDOM_ACCESS_FILE);
-      NetcdfFile ncfile = NetcdfFiles.build(iosp, raf, getLocation() + "#" + group.getId(), null);
-      NetcdfDataset ncd = NetcdfDatasets.enhance(ncfile, NetcdfDataset.getDefaultEnhanceMode(), null);
+      NetcdfDataset ncd = buildNetcdfDataset(iosp, getLocation() + "#" + group.getId());
       return new ucar.nc2.dt.grid.GridDataset(ncd); // LOOK - replace with custom GridDataset??
 
     } else {
@@ -84,9 +76,7 @@ public ucar.nc2.dt.grid.GridDataset getGridDataset(Dataset ds, GroupGC group, St
           return null;
 
         Grib1Iosp iosp = new Grib1Iosp(gc);
-        RandomAccessFile raf = (RandomAccessFile) iosp.sendIospMessage(NetcdfFile.IOSP_MESSAGE_RANDOM_ACCESS_FILE);
-        NetcdfFile ncfile = NetcdfFiles.build(iosp, raf, getLocation(), null);
-        NetcdfDataset ncd = NetcdfDatasets.enhance(ncfile, NetcdfDataset.getDefaultEnhanceMode(), null);
+        NetcdfDataset ncd = buildNetcdfDataset(iosp, getLocation());
         return new ucar.nc2.dt.grid.GridDataset(ncd); // LOOK - replace with custom GridDataset??
       }
       return null;
diff --git a/grib/src/main/java/ucar/nc2/grib/collection/Grib1Partition.java b/grib/src/main/java/ucar/nc2/grib/collection/Grib1Partition.java
index ddd548a313..61481d8cb0 100644
--- a/grib/src/main/java/ucar/nc2/grib/collection/Grib1Partition.java
+++ b/grib/src/main/java/ucar/nc2/grib/collection/Grib1Partition.java
@@ -10,13 +10,11 @@
 import thredds.featurecollection.FeatureCollectionConfig;
 import ucar.nc2.constants.CDM;
 import ucar.nc2.dataset.NetcdfDataset;
-import ucar.nc2.dataset.NetcdfDatasets;
 import ucar.nc2.ft2.coverage.CoverageCollection;
 import ucar.nc2.grib.GribUtils;
 import ucar.nc2.grib.coverage.GribCoverageDataset;
 import java.io.IOException;
 import java.util.Formatter;
-import ucar.unidata.io.RandomAccessFile;
 
 /**
  * PartitionCollection for Grib1.
@@ -35,9 +33,7 @@ public ucar.nc2.dataset.NetcdfDataset getNetcdfDataset(Dataset ds, GroupGC group
       FeatureCollectionConfig config, Formatter errlog, org.slf4j.Logger logger) throws IOException {
 
     ucar.nc2.grib.collection.Grib1Iosp iosp = new ucar.nc2.grib.collection.Grib1Iosp(group, ds.getType());
-    RandomAccessFile raf = (RandomAccessFile) iosp.sendIospMessage(NetcdfFile.IOSP_MESSAGE_RANDOM_ACCESS_FILE);
-    NetcdfFile ncfile = NetcdfFiles.build(iosp, raf, getLocation(), null);
-    return NetcdfDatasets.enhance(ncfile, NetcdfDataset.getDefaultEnhanceMode(), null);
+    return buildNetcdfDataset(iosp, getLocation());
   }
 
   @Override
@@ -45,9 +41,7 @@ public ucar.nc2.dt.grid.GridDataset getGridDataset(Dataset ds, GroupGC group, St
       FeatureCollectionConfig config, Formatter errlog, org.slf4j.Logger logger) throws IOException {
 
     ucar.nc2.grib.collection.Grib1Iosp iosp = new ucar.nc2.grib.collection.Grib1Iosp(group, ds.getType());
-    RandomAccessFile raf = (RandomAccessFile) iosp.sendIospMessage(NetcdfFile.IOSP_MESSAGE_RANDOM_ACCESS_FILE);
-    NetcdfFile ncfile = NetcdfFiles.build(iosp, raf, getLocation(), null);
-    NetcdfDataset ncd = NetcdfDatasets.enhance(ncfile, NetcdfDataset.getDefaultEnhanceMode(), null);
+    NetcdfDataset ncd = buildNetcdfDataset(iosp, getLocation());
     return new ucar.nc2.dt.grid.GridDataset(ncd);
   }
 
diff --git a/grib/src/main/java/ucar/nc2/grib/collection/Grib2Collection.java b/grib/src/main/java/ucar/nc2/grib/collection/Grib2Collection.java
index 2d17f4f42e..0430891b54 100644
--- a/grib/src/main/java/ucar/nc2/grib/collection/Grib2Collection.java
+++ b/grib/src/main/java/ucar/nc2/grib/collection/Grib2Collection.java
@@ -6,7 +6,6 @@
 package ucar.nc2.grib.collection;
 
 import javax.annotation.Nullable;
-import ucar.nc2.dataset.NetcdfDatasets;
 import ucar.nc2.grib.coord.CoordinateTimeAbstract;
 import ucar.ma2.Array;
 import ucar.nc2.*;
@@ -21,7 +20,6 @@
 import ucar.nc2.grib.GribTables;
 import ucar.nc2.grib.coverage.GribCoverageDataset;
 import ucar.nc2.grib.grib2.table.Grib2Tables;
-import ucar.unidata.io.RandomAccessFile;
 import ucar.unidata.util.StringUtil2;
 import java.io.IOException;
 import java.util.Formatter;
@@ -45,9 +43,7 @@ public ucar.nc2.dataset.NetcdfDataset getNetcdfDataset(Dataset ds, GroupGC group
 
     if (filename == null) {
       Grib2Iosp iosp = new Grib2Iosp(group, ds.getType());
-      RandomAccessFile raf = (RandomAccessFile) iosp.sendIospMessage(NetcdfFile.IOSP_MESSAGE_RANDOM_ACCESS_FILE);
-      NetcdfFile ncfile = NetcdfFiles.build(iosp, raf, getLocation(), null);
-      return NetcdfDatasets.enhance(ncfile, NetcdfDataset.getDefaultEnhanceMode(), null);
+      return buildNetcdfDataset(iosp, getLocation());
 
     } else {
       MFile wantFile = findMFileByName(filename);
@@ -58,9 +54,7 @@ public ucar.nc2.dataset.NetcdfDataset getNetcdfDataset(Dataset ds, GroupGC group
           return null;
 
         Grib2Iosp iosp = new Grib2Iosp(gc);
-        RandomAccessFile raf = (RandomAccessFile) iosp.sendIospMessage(NetcdfFile.IOSP_MESSAGE_RANDOM_ACCESS_FILE);
-        NetcdfFile ncfile = NetcdfFiles.build(iosp, raf, getLocation(), null);
-        return NetcdfDatasets.enhance(ncfile, NetcdfDataset.getDefaultEnhanceMode(), null);
+        return buildNetcdfDataset(iosp, getLocation());
       }
       return null;
     }
@@ -73,9 +67,7 @@ public ucar.nc2.dt.grid.GridDataset getGridDataset(Dataset ds, GroupGC group, St
 
     if (filename == null) {
       Grib2Iosp iosp = new Grib2Iosp(group, ds.getType());
-      RandomAccessFile raf = (RandomAccessFile) iosp.sendIospMessage(NetcdfFile.IOSP_MESSAGE_RANDOM_ACCESS_FILE);
-      NetcdfFile ncfile = NetcdfFiles.build(iosp, raf, getLocation() + "#" + group.getId(), null);
-      NetcdfDataset ncd = NetcdfDatasets.enhance(ncfile, NetcdfDataset.getDefaultEnhanceMode(), null);
+      NetcdfDataset ncd = buildNetcdfDataset(iosp, getLocation() + "#" + group.getId());
       return new ucar.nc2.dt.grid.GridDataset(ncd); // LOOK - replace with custom GridDataset??
 
     } else {
@@ -87,9 +79,7 @@ public ucar.nc2.dt.grid.GridDataset getGridDataset(Dataset ds, GroupGC group, St
           return null;
 
         Grib2Iosp iosp = new Grib2Iosp(gc);
-        RandomAccessFile raf = (RandomAccessFile) iosp.sendIospMessage(NetcdfFile.IOSP_MESSAGE_RANDOM_ACCESS_FILE);
-        NetcdfFile ncfile = NetcdfFiles.build(iosp, raf, getLocation(), null);
-        NetcdfDataset ncd = NetcdfDatasets.enhance(ncfile, NetcdfDataset.getDefaultEnhanceMode(), null);
+        NetcdfDataset ncd = buildNetcdfDataset(iosp, getLocation());
         return new ucar.nc2.dt.grid.GridDataset(ncd); // LOOK - replace with custom GridDataset??
       }
       return null;
diff --git a/grib/src/main/java/ucar/nc2/grib/collection/Grib2Partition.java b/grib/src/main/java/ucar/nc2/grib/collection/Grib2Partition.java
index 1f7073b59a..6ab3716d76 100644
--- a/grib/src/main/java/ucar/nc2/grib/collection/Grib2Partition.java
+++ b/grib/src/main/java/ucar/nc2/grib/collection/Grib2Partition.java
@@ -11,15 +11,11 @@
 import thredds.featurecollection.FeatureCollectionConfig;
 import ucar.nc2.Attribute;
 import ucar.nc2.AttributeContainer;
-import ucar.nc2.NetcdfFile;
-import ucar.nc2.NetcdfFiles;
 import ucar.nc2.constants.CDM;
 import ucar.nc2.constants.DataFormatType;
 import ucar.nc2.dataset.NetcdfDataset;
-import ucar.nc2.dataset.NetcdfDatasets;
 import ucar.nc2.ft2.coverage.CoverageCollection;
 import ucar.nc2.grib.coverage.GribCoverageDataset;
-import ucar.unidata.io.RandomAccessFile;
 
 /**
  * PartitionCollection for Grib2.
@@ -38,9 +34,7 @@ public ucar.nc2.dataset.NetcdfDataset getNetcdfDataset(Dataset ds, GroupGC group
       FeatureCollectionConfig config, Formatter errlog, org.slf4j.Logger logger) throws IOException {
 
     ucar.nc2.grib.collection.Grib2Iosp iosp = new ucar.nc2.grib.collection.Grib2Iosp(group, ds.getType());
-    RandomAccessFile raf = (RandomAccessFile) iosp.sendIospMessage(NetcdfFile.IOSP_MESSAGE_RANDOM_ACCESS_FILE);
-    NetcdfFile ncfile = NetcdfFiles.build(iosp, raf, getLocation(), null);
-    return NetcdfDatasets.enhance(ncfile, NetcdfDataset.getDefaultEnhanceMode(), null);
+    return buildNetcdfDataset(iosp, getLocation());
   }
 
   @Override
@@ -48,9 +42,7 @@ public ucar.nc2.dt.grid.GridDataset getGridDataset(Dataset ds, GroupGC group, St
       FeatureCollectionConfig config, Formatter errlog, org.slf4j.Logger logger) throws IOException {
 
     ucar.nc2.grib.collection.Grib2Iosp iosp = new ucar.nc2.grib.collection.Grib2Iosp(group, ds.getType());
-    RandomAccessFile raf = (RandomAccessFile) iosp.sendIospMessage(NetcdfFile.IOSP_MESSAGE_RANDOM_ACCESS_FILE);
-    NetcdfFile ncfile = NetcdfFiles.build(iosp, raf, getLocation(), null);
-    NetcdfDataset ncd = NetcdfDatasets.enhance(ncfile, NetcdfDataset.getDefaultEnhanceMode(), null);
+    NetcdfDataset ncd = buildNetcdfDataset(iosp, getLocation());
     return new ucar.nc2.dt.grid.GridDataset(ncd);
   }
 
diff --git a/grib/src/main/java/ucar/nc2/grib/collection/GribCollectionImmutable.java b/grib/src/main/java/ucar/nc2/grib/collection/GribCollectionImmutable.java
index f1790e43cd..53dc60f9b5 100644
--- a/grib/src/main/java/ucar/nc2/grib/collection/GribCollectionImmutable.java
+++ b/grib/src/main/java/ucar/nc2/grib/collection/GribCollectionImmutable.java
@@ -14,9 +14,13 @@
 import ucar.nc2.Attribute;
 import ucar.nc2.AttributeContainer;
 import ucar.nc2.AttributeContainerMutable;
+import ucar.nc2.NetcdfFile;
+import ucar.nc2.NetcdfFiles;
 import ucar.nc2.constants.CDM;
 import ucar.nc2.constants.CF;
 import ucar.nc2.constants.FeatureType;
+import ucar.nc2.dataset.NetcdfDataset;
+import ucar.nc2.dataset.NetcdfDatasets;
 import ucar.nc2.ft2.coverage.CoverageCollection;
 import ucar.nc2.ft2.coverage.SubsetParams;
 import ucar.nc2.grib.*;
@@ -31,6 +35,7 @@
 import ucar.nc2.grib.grib1.Grib1Variable;
 import ucar.nc2.grib.grib1.tables.Grib1Customizer;
 import ucar.nc2.grib.grib2.table.Grib2Tables;
+import ucar.nc2.iosp.AbstractIOServiceProvider;
 import ucar.nc2.time.CalendarDate;
 import ucar.nc2.time.CalendarDateRange;
 import ucar.nc2.util.cache.FileCacheIF;
@@ -1113,6 +1118,13 @@ String getDataRafFilename(int fileno) {
     return mfile.getPath();
   }
 
+  protected static NetcdfDataset buildNetcdfDataset(AbstractIOServiceProvider iosp, String location)
+      throws IOException {
+    RandomAccessFile raf = (RandomAccessFile) iosp.sendIospMessage(NetcdfFile.IOSP_MESSAGE_RANDOM_ACCESS_FILE);
+    NetcdfFile ncfile = NetcdfFiles.build(iosp, raf, location, null);
+    return NetcdfDatasets.enhance(ncfile, NetcdfDataset.getDefaultEnhanceMode(), null);
+  }
+
   ///////////////////////
 
   // stuff needed by InvDatasetFcGrib