Though this stripped hull doesn't leave much for identification purposes, the fantail does bear three words:
POLAR MERCHANT SEATTLE.

A quick search of the normal resources gives no answers. In fact, the only POLAR MERCHANT Miramar would lead one to believe existed is a product tanker built in 2007. Definitely not this relic, though, ironically, she does exist in Miramar under a different name, but I'll get to that later.

However, a Google search does produce vague mention of a Pacific Northwest tugboat named POLAR MERCHANT, which is a much more likely identity. This doesn't exactly look like a tugboat hull, but it was a possibility. Contacting a local maritime historian got me some more info, including some pictures of her as an active tug.

Further digging revealed her previous guise of TIGER, which she bore until 1975. It is that name that does appear in Miramar, as it turns out she was launched in 1927 as the US Coast Guard Cutter TIGER (WSC-152) of the Active Class. While serving, one must note her presence on December 7th, 1941 at Pearl Harbor, Hawaii, where she patrolled the harbor entrance during the Japanese attack, at different points coming under fire from both sides. Her military career ended in 1947, and her civilian life began, eventually leading to her end as a part of a breakwater at Tacoma's Tyee Marina, as seen here.

Characteristics (as TIGER)
Length: 38.1 meters
Beam: 7.2 meters
Tonnage: 210 GT
Year of Build: 1927
Builder: American Brown Boveri, Camden, NJ
Yard Number: 346