Floating docks

[TBone]

Anybody out there have any experience with floating docks? I want to build a dock on some lake property and would like to have a covered area for a picnic table, swing, etc. Covered area would be about 20' x 20' with a 15' walkway similar to the one across the lake. I haven't been successful in finding someone to bring in a barge with pile driver and probably can't afford to have that done anyway. I was thinking I might have a floating dock built but not sure how stable they are. The little lake stays at a pretty constant level since it is spring fed. Little to no rough water to worry about. If you have a floating dock I would love to hear about your experience. Thanks.

 

[blee03]

What part of the country are you in?
Does the lake freeze up good in the winter?

 

[TBone]

South Alabama. Definitely no freezing lake here.

 

[SylvainG]

I have a 16x8 floating dock attached to a 16x4 passerelle that is attached to the shore. My lake is also mainly spring fed and very little water height movement.

If many are standing at the furthest edge of the dock, it will sink in (but will spring back above water once the weight is removed) and it can be confusing for someone not used to it.

If your lake freezes, disconnect the dock from the passerelle, move it to the shore (just row it there) and attach it to the shore using rope. Over the 15 years I've owned it, twice I got lazy and didn't disconnect it. Next spring when the lake thawed, the passerelle/dock was pushed out bending the rods holding them to the shore and pushed the concrete blocks (holding the dock in place by chains) further into the lake. I'll tell you, pulling three 50 pounds concrete blocks attached together by the chain, moving them closer to the shore (times two since there is a chain a each corner) on a dock that moves the opposite direction you're trying to move the blocks is quite exhausting!

I had that one built. I built myself a 8x8 floating dock that I can send you pictures on how I built it if you want. Make sure you leave enough chain slack to prevent from hunting for your dock next spring. Happened to me last year.

 

[fried1765]

What part of the country are you in?
Does the lake freeze up good in the winter?

The OP's profile shows "Lower Alabama".

 

[denchen]

Not docks, but done a bit with boats. So the `Law of Displacement` needs to be understood. A container that holds a gallon of water weighing 10 lbs, if the container is empty, it would take 10 lbs to push it under water. We tend to work metric so a cubic meter holds 1000 litres, and that weighs a ton. so a one cubic meter container would take a ton to push it under the water. Don`t forget the weight of the container and all thats on it. Stability, well the bigger and wider the better before we go into metacentric heights.

 

[ArlyA]

Here is a floating dock to ponder that's made with those square HDPE (plastic) tanks and been in this pound since the 90's. Of course it freezes in! Its never been out of the pond. Here is some summer/winter photos for you.

 

[Macinnis]

My family has a home at the lake of the ozarks...and this is what all of the docks and boat lifts are made of:

Encapsulated Foam - 20"

Durable polyethylene shell contains UV inhibitors and carbon black pigment to protect against ultraviolet degradation Expanded polystyrene (EPS) core meets or exceeds Hunt Absorption Test "J" bolt compatible for simple installation Ribbed sidewalls provide greater strength and more uniform...

polylift.myshopify.com

these make the dock very stable and the only movement is the occasional large wave (not people moving around on the dock).

the dock is then secured to land via a walkway and three or four metal cables secured to the dock From the sea wall. Those cables and the walkway pretty much hold the dock in place.

For a relatively calm lake, I do not see a need for driving piles to secure the dock...it’s not like you are in the ocean where the water rises and falls feet at a time.

 

[TBone]

My family has a home at the lake of the ozarks...and this is what all of the docks and boat lifts are made of:

Encapsulated Foam - 20"

Durable polyethylene shell contains UV inhibitors and carbon black pigment to protect against ultraviolet degradation Expanded polystyrene (EPS) core meets or exceeds Hunt Absorption Test "J" bolt compatible for simple installation Ribbed sidewalls provide greater strength and more uniform...

polylift.myshopify.com

these make the dock very stable and the only movement is the occasional large wave (not people moving around on the dock).

the dock is then secured to land via a walkway and three or four metal cables secured to the dock From the sea wall. Those cables and the walkway pretty much hold the dock in place.

For a relatively calm lake, I do not see a need for driving piles to secure the dock...it’s not like you are in the ocean where the water rises and falls feet at a time.

I like the sound of that. I'm gonna start looking around for somebody I can hire to build one. 20 years ago I would have already started on one myself but I'm afraid the years have caught up with me. Thanks to all for the suggestions.

 

[ruffdog]

All piers/docks where I go have to be floating and the are all pretty similar. They will have 2 or more posts that keep it from moving laterally or downstream. Those posts just get shoved or driven into the muddy bottom and the pier then is able to ride up/down on those guide posts. The OP should have 4 posts on the deck and maybe 2 more on the walkway. If you want to move it, pull the posts and float it away. The guides on the dock should be about 16" long that ride up/down on the posts.

 

[PILOON]

Lived lakeside since 1957 and built many docks from used hydro poles, 45 gal drums and currently foam filled poly floatation devices.
At one time we even used 10 inch X 2 ft x 8ft foam slabs or blocks which worked very well until
environment banned them.
We never removed them for winter.

By far the best is the manmade poly floats. (they are buoyancy rated as well)
The wider squarer your dock the more stable it will be.
A nice basic size is 12 ft x 12 ft but bigger is more stable.
20 x 20 would be a nice very stable platform.
I'd suggest 8 floatation devices with 3 per side but NONE in the center.
Center will simply create a pivot point or axis for which the dock to rotate over.
You want to basically build a huge pallet like structure* and fasten your man made floatation to the underside, flip it over and add your decking.
Galvanized corner hardware is now available as well and sure makes life easy.
Remember to use wood treatment in all drilled holes.
Pressure treated wood is my go to lumber.

A note, poly filled is great for bodies of water that freeze in winter as ice can't crush them2 but I'd suggest not needed in southern climates.

* bottom planks spaced to receive the floatation devices and serve for rigidity as well.

 

[SylvainG]

If you don't get filled one, even in summer, if something pierces it, it's done for.

 

[oosik]

I have an all aluminum floating dock and walk way. The dock is 10 x 16. Purchased new in 1992. It has a "Teck wood" deck and walk way. It's that wood product made out of old cigarette butts.

My lake will get up to 14" of ice. The ice - for reasons ukn - will never freeze up tight to the floats. So I can go out in the middle of the winter and make the dock bounce up/down.

It's an excellent dock. Requires zero maintenance. Probably not big enough to become a "party barge". Being all aluminum it's not real heavy. One person jumping up/down on the very edge would upset your party.

 

[TBone]

All piers/docks where I go have to be floating and the are all pretty similar. They will have 2 or more posts that keep it from moving laterally or downstream. Those posts just get shoved or driven into the muddy bottom and the pier then is able to ride up/down on those guide posts. The OP should have 4 posts on the deck and maybe 2 more on the walkway. If you want to move it, pull the posts and float it away. The guides on the dock should be about 16" long that ride up/down on the posts.

Question: The 16" guides that ride up and down on the posts - How much clearance should they have? 4" x 4" posts are 3 1/2" square. How big should the guides be? I'm sure they would need to be big enough not to bind.

 

[ruffdog]

Most of them here are round metal posts because they slide easy and they should not float. There needs to be plenty of clearance and movement because a floating pier will really move if big boats are near by.

 

[tomplum]

My 2 cents is to look for a source of FRP grating for the deck itself.

 

[MoKelly]

My family has a home at the lake of the ozarks...and this is what all of the docks and boat lifts are made of:

Encapsulated Foam - 20"

Durable polyethylene shell contains UV inhibitors and carbon black pigment to protect against ultraviolet degradation Expanded polystyrene (EPS) core meets or exceeds Hunt Absorption Test "J" bolt compatible for simple installation Ribbed sidewalls provide greater strength and more uniform...

polylift.myshopify.com

these make the dock very stable and the only movement is the occasional large wave (not people moving around on the dock).

the dock is then secured to land via a walkway and three or four metal cables secured to the dock From the sea wall. Those cables and the walkway pretty much hold the dock in place.

For a relatively calm lake, I do not see a need for driving piles to secure the dock...it’s not like you are in the ocean where the water rises and falls feet at a time.

We have a place at the Lake near the 10 mile mark on the main channel. The Lake is crazy with all the huge boats. Really really rough water. We are halfway into a cove and it’s ok. But it’s a blast in the summer.

MoKelly

 

[TBone]

Most of them here are round metal posts because they slide easy and they should not float. There needs to be plenty of clearance and movement because a floating pier will really move if big boats are near by.

Big boats and wakes are no problem. There are only 3 owners of the actual lake and we have agreed to no gasoline powered boats in the lake, only electric trolling motors or paddle power.

 

[MoKelly]

Big boats and wakes are no problem. There are only 3 owners of the actual lake and we have agreed to no gasoline powered boats in the lake, only electric trolling motors or paddle power.

Then you are in great shape.

Good luck.

MoKelly

 

[check]

Big boats and wakes are no problem. There are only 3 owners of the actual lake and we have agreed to no gasoline powered boats in the lake, only electric trolling motors or paddle power.

If the lake bottom right near the shore is flat enough and shallow enough, build a crib dock and attach a floater, all using PT lumber and closed-cell foam floatation. Very cheap, and very easy to make.