I'm now at the stage where I'd like to put in a floating dock, preferably one that would have covered areas for two boats, each about 14 to 16 feet.
Any suggestions or experiences?
Don't use barrels, use floats made for that application.
Look at Dockbuilders Supply. They don't have engineering services, but if you can figure out what to buy, that is who I would use for a material source for floats and attaching hardware.
I bought floats from Menards and the quality is about half of what Dockbuilders is. Price at Menards is much less too tho.
If your pond level doesn't fluctuate much, I'd highly recommend looking into a fixed structure based on both stability and cost.
Esshup is right, assuming you can afford the floats....floats are better than barrels.
However if, like me, your budget doesn't allow for floats, here's how I did mine and 8 years later the dock is still stable. And that's counting the fact that I never take it out so it freezes in solid every winter.
I used food grade barrels, and I both sealed the bungs with RTV and also rotated them so the bungs were horizontal - to make sure neither one of them spent their time under water - especially important given that the barrels freeze in place each winter.
In 8 years I've only had to replace one barrel.
Just built this 12 X 14 a couple weeks ago. I used Techstar, you can order them through Home Depot, though I saved about $30 each ordering them through a local building supply co. They're built pretty close to here so they probably get them direct. Very solid feel. I secured it with concrete and chain off each corner.
I used dockbuilders as well and was happy with the service and results. The salesman was very helpful in making sure I had all the screws, brackets, etc. for my dock.
There are a few sample docks kits to see at:
http://www.dockbuilders.com/floating-dock-plans.htmI chose the "12'x12' with optional gangway" with the 6 smaller floats instead of the one with the 4 bigger floats.
I'm in the process myself. I am buying my floats at Docks on Demand out of Benbrook, TX, and got my hardware from Dock Hardware in NY. There are a couple of sites that have good info for building, and #s each float will support, but can't recall them right now.