I recently pressure washed my dock. It took about three hours. One result is I have received emails or a PM from people that have noticed the difference on
www.bearchow.com I was unaware so many people watched that close. One humorous email from North Carolina requested I finish off the last section because it was bugging them.
The pressure washer when held close to the wood takes off the dead, crusty, outer layer of wood. Depending on the wood grain some areas are left a little rough and may need sanding. You can buy an electric pressure washer at a hardware store for about $150.