Convoy Help.

Okay Ived decided to ask for help since this is the 8th time, no make that 9th I've lost a Kaluen due to a attempted convoy infiltration.

My question is, what are the steps, or procedures to infiltrating/attacking a convoy properly? every time I try I get honed down on by the escorts and bam, 4 or 5 destroyers depthcharging me, not pretty at all.

The times I have gotten inside of a convoy Ive waited until one of the escorts broke off on a sweep then sped full steam and tried to meander my way inside.

But yeah, what sort of things do you guys do when you get Convoys? becasue honestly, Im having no luck and way to hard of a time with them. And on a side note, when does allied radar become available?? because one patrol in 41 I could have sworn the ships had radar.