How fare out of the entrance are you? If you are still close to the Eastern entrance, head back towards the blockships! I know this sounds counterintuitive, but the AI is dumbe enough to let the DD's chase you in straight on pursuits so if you can get them close enough they will grind themselves against the block ships.
If not keep as low and as slow as you can and I use around a 10 degree alternation on the rudder going port to starboard everyso often. I was using this to reasonable success just outside Darwin until a bugger with a Hedgehog came around and dropped a cluster right on top of me!
