This looks like it might be an opportunitiy to test the lethality of our 57mm guns. We have a tug that needs to be disposed of. Let’s see how well a Bertholf’s 57mm Mk110 does against this small target.
In April 2012 we had an opportunity to exercise our weapons against a derilect Japanese fishing vessel that had been adrift since the Tsunami of 11 March 2011. USCGC Anacapa let loose with her 25mm and probably scored over a hundred hits, but ultimately had to use fire hoses to sink the little ship. I used this as an example of how hard it is to sink a ship with gunfire.
To be fair lets make sure that all the tugs few bulkheads are watertight; you would want to make sure they were before towing it anyway. To make it interesting, start shooting from between 10,000 and 12,000 yards, and fire say 20 rounds at that range. Then close to about 7,000 and shoot another 20. If the tug hasn’t sunk, close to no less than 4,000 and try to finish it off.
Would be very interested to see the results, including how long it takes to sink the ship? How many hits at what ranges? It would be good for an aircraft to get some video of the damage, as it progresses too. The Navy might also be interested in the results.
Chuck Hill's CG Blog 
I’d say move to 2000 yards or closer for the last shots. It is, after all, just a six-pounder.
I want to see if they can sink it in a timely manner, while staying outside the effective range of improvised armaments.
On orders from D5, as XO COWSLIP in the spring of 1991 I had the conn and had the opportunity to sink a 65-75 ft derelict wood hull F/V with .50 cal. gunfire. The F/V was full of foam insolation and would not sink after several hundred rounds at 200 yards or less. We finished the F/V off by ramming it 5 or 6 times opening a large hole in the hull and allowing enough water to flood the hull and overcome the buoyant effect of the foam insulation.
On MUNRO, we put 15 rounds of 76mm into a steel hulk floating by the bow… with no effect… before the Captain tired of the exercise and we sailed off. 5 BL&P followed by 5 HE-IR followed by 5 BL&P. No logic to the rounds… just what was expendable in small, odd lots in the ready service room. From that experience, one learns the value of frequent PAC fires, and the difficulty in hitting a small object.
As to the above comment about closing range… the rounds are explosive and as effective at any range. Why close?
Closing does increase the probability of hit exponentially.
Is the Bertholf scheduled to sink the tug?
No, just a suggestion that one of our ships with a 57mm,, all of which are Bertholf class, try sinking it. (Offshore Patrol Cutters are supposed to get them too.)
Isn’t going to happen, the tug is being dismantled in Juneau. http://www.uscgnews.com/go/doc/4007/2795842/