I did it
There is (WAS on my boat, '84 34') a strainer at the bottom of the fuel pickup pipe. It is recessed about 1/2 " so it can collect a whole bunch of gunk, which will lead to intermittent fuel starvation. (in my case in a 4 knot current flowing in the direction I didn't want to go with no wind). I had about 1/3 of a tank of fuel, so I had a dock mate with a large old power boat and many filters who took most of it. My tank is a bit concave at the top, so I was hesitant to do what John K did. One thing I did was use a "plumber's snake" with a rag, very securely fastened to the end, to loosen the gunk of the bottom of the tank. I had a couple of gallons which I used to flush out the tank. After about four cycles of this the fuel was clean. Haven't had any repeat, and it beat the $300 quote I was given to clean the tank and scrub the fuel.