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The channel crossing can be VERY rough, or it can be calm and filled with life along the way. A PLB would be good to carry both for diving and attached to your lifejacket during the crossing. ACR Resqlink+ fits in a canister that can get attached to your BC.
My friend makes the crossing in his C-Dory fairly often, but will leave at dawn and chooses his days wisely. I wish I could go diving there more, as it is spectacular.