Thanks for your responses. In answer to some of your questions: The lake is owned by the local water authority and they do not allow floating docks or boathouses. I am located on an 80' wide channel and the boathouse cannot extend beyond 1/3 of the width, so I will build about 26' out max. At this point the water depth is about 6 feet, and this is a constant level, spring-fed lake. Bottom is moss over soft sand. The boat is a 19' ski boat that will be traded for a similarly sized bass rig in a few years when we move in down there.
There are only about 3 dockbuilders who work on this small 1500 acre lake, and they want generally between $200 and $300 each for installing pilings, depending on the materials used. For the turn-key project based upon my estimates, the owner will take about 50% of the total price as profit for him. I have figured costs of about $3,000 for materials and $3,000 for labor assuming about 7-8 days of construction time for a 4-man crew with the owner supervising part time. Kinda pricey but I guess these guys own the market so they control the price.
I prefer steel pilings, but I think a good 6' treated round post would work almost as well and be quite a bit cheaper. I just sold my interest in a lakehouse (different lake) that had a 50 ft. pier with pilings built from used telephone poles. They discourage creosoted poles now though. That pier is still solid after 35 years of heavy waves. (Thank you Dad). My property now is on a well protected, quiet cove with no heavy waves. My biggest worry is about the pilings sinking over time, especially those furthest out since they will hold the most weight because of the motor. Have seen it happen too often. Haven't considered a cantilevered dock, and it might work for part of the dock, but I will be building an overhead mounted boat lift in the boathouse. Hey, maybe a TBN dock-building party is in order? /w3tcompact/icons/grin.gif