YMS Minesweeper Deck Plans

Located in Lake Washington are three YMS minesweepers.  Two of these vessels are very much intact.  Our team has been using the below deck plans to explore these three vessels over the last several years.  These deck plans are for YMS series 135-409.

Please note that these plans should be used only for general reference.  The vessels in Lake Washington have been modified following their military use and do not fully match the structural diagrams.  Additionally, the two groups conducting penetration dives on the newest minesweeper both experienced partial structural collapse.  The latest collapse was quite serious and could easily have been life threatening.   Both dives required a zero visibility exit from the vessel.

Penetration dives on the Lake Washington Minesweepers should not be undertaken.

The below files are high resolution PDF files:

Outboard Profile

Inboard Profile & Deck Plans

Main Deck, Forecastle, Chart House & Pilot House

Exploration of the YMS 359

On Saturday April 19th 2008 Scott Christopher, a Seattle area NAUI Technical Dive Instructor, and “Northwest Grateful Diver” Bob Bailey dove the wreck of the YMS 359. The YMS 359 was a YMS-1 Class Auxiliary Motor Minesweeper : Laid down September 12th, 1942 by Robert Jacob Inc., City Island, NY; Launched April 9th, 1943; Completed August 20th 1943. It was struck from the Naval Register February 7th, 1947. It was then sold January 6th, 1948. The vessel was sunk in the middle of Lake Washington straight out from Carillon Point, Kirkland, WA at a depth of 200 feet.

The ship has the following specifications : Displacement 270 t.; Length 136'; Beam 24' 6"; Draft 8'; Speed 13 kts; Complement 50; Armament one single 3"/50 gun mount; Propulsion two 880 shp General Motors diesel engines, two shafts.

YMS359-Profile-2008-04-19.gifThe dive team descended to 190 feet and tied in a primary reel. The ship was located within seconds. The Scott Christopher carefully tied off the primary reel mid-ship and lead the teams exploration toward the bow section. The wreck is in fair condition. There are several side compartments panels that have been removed that will allow easy access for future penetration. This wreck was easy to identify as the military numerical markings are still present on each side of the ship. The Starboard side was explored from mid ship to the bow. The team continued exploration around the bow, surveying the upper portion of the port side of the vessel. The cabin structure is still clearly identifiable.

This wreck is covered with exploration line that was left, either by careless explorers or abandoned due to an emergency that arose. Our dive team operations will plan a future expedition to this site in order to remove this unwanted and potentially deadly hazard. Our goal is to restore this vessel to the original condition in which it sank.

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YMS 359 – Side scan imagery of the shipwreck in Lake Washington

This image is a picture of the YMS 359 located in 200’ fresh water in Lake Washington. The image is taken from the stern and the minimal angle results in the sharp shadow from the bow. This image was taken at 3 knots using a range setting of 600 feet. 


Shaun Gardner acted as captain on all these scans.  He is getting very good at capturing higher speed, longer range images.








NewTargetPublic.gifThe second image is the original general scan we had some time ago when we mapped that section of the lake.  As dives are slowing down on YMS #3 we are going back and picking-up several unknow targets.

YMS Minesweeper #2 – YMS 359

This minesweeper is in quite good condition and has been extensively explored by SCRET and identified as the YMS 359 based on the numerical marking still located on the bow of this vessel. Puget Sound Divers currently has just 4 dives on this wreck as it has been primarily exploring the third minesweeper this year.

Sitting at 200’ and offering several penetration opportunities this is certainly a nice wreck to dive. On the aft deck both holds have been cut open for engine removal and scuttling but several equipment items remain and the holds are open enough for easy exploration. The bottom is silty so line should certainly be laid.