RedactedNarrative: On May 16th, 2020 around 15:00 hours a non-injury single vessel boat crash occurred on Flathead Lake north of Matterhorn Point. This boat crash was a partial grounding that occurred on a submerged shoal that extends northward off Matterhorn Point. The operator of the vessel was recreationally cruising heading east in order to enter The Narrows and then head into Polson Bay. This was the operator’s first time on Flathead Lake. The operator of the vessel was also the owner. The boat operator has 15 years of boating experience with inboard boats of the same type on different waterbodies. This was a 23’8” wakeboard boat with a 409 hp inboard propeller. In addition to the operator there were three other occupants on board the vessel during the crash. All occupants, including the operator had lifejackets.  
  
  	The weather on May 16th, 2020 was mostly clear. The air temperature was 64°F. The water temperature was approximately 48°F. There were light 5 mph winds out of the West. Visibility was good and there was very little wave action that day. Weather does not appear to be a factor in this crash. Flathead Lake is a dam-controlled lake where water levels generally fluctuate at least ten feet from the winter to summer levels. On May 16th, 2020 Flathead Lake was 6 feet below its average full pool level.  When lake levels are low there are more underwater hazards present on this dam-controlled lake.  
  
  	The operator of the vessel reported that they were traveling on an east heading (90°) from the Big Arm Bay area of the lake towards the main body of the lake. The operator of the vessel believed he was 300 yards from the point. The operator believed they were traveling at a speed of 35-40 mph when the rudder and propeller grounded on the shoal. The force of the grounding ripped the rudder and the rudder shaft from the boat. This caused the boat to leak in the engine compartment where the rudder shaft passes through. The propeller was badly damaged, including the propeller shaft which was bent upwards and towards the port side of the boat. The boat sustained fiberglass damage to hull around the keel area on the stern side of the boat. The fiberglass damage appears to be mostly tears caused by the force of the rudder being ripped out and the propeller being grounded. Some of the cuts to the fiberglass appear to be from the propeller itself and the rudder impacting the boat. There was some minor damage/streaking along the fiberglass hull on the starboard side.  The tracking fin on the keel of the boat was also damaged.
  
  
  
  