Larry..You are a lucky guy. Same thing happened to me last month, broad daylight, 2'chop, and a 10' section of 2x6, direct hit broadside at about 30mph. Split the 2x6 in half absolutly not scratch on the lower unit or prop. Somebody was watching out for me that day..because there just isn't enough time to react. You see the thing there and it takes your breath way. I thought for sure it was going to rip the transom right off the boat a piling like you encountered would have lights out for sure! Still gives me shivers to think about it. I'm glad you escaped unscathed.
Rocky