Screw piles in sand bottom or cheapest possible floating blocks for a floating dock?

[hakaninorr]

Does it work to screw down ground screws like https://www.byggmax.se/skruvpåle-pro-p6191022 in a sand bottom and build a fixed dock on it? How deep in the sand bottom do you need to go? How close should the piles be for, for example, a 2x4 meter dock? Alternatively, how cheap can you find floating blocks/pontoons if you don't want crumbly Styrofoam, any other suggestions than https://mobil.blocket.se/annons/flera platser/flytblock_flytponton_flytbrygga_flotte/65127588

 

[Trollskidan]

Styrofoam ground insulation XPS

The best available for floating docks, but make sure to get as large an area as possible and not height for buoyancy
Have a dock that has been in place for 30 years with the same material.
Weight 18kg/m3
Absorbs 0.02% water
So the buoyancy is 980kg/m3

 

[hakaninorr]

Styrofoam ground insulation XPS

The best available for floating docks, but make sure to get as large a surface area as possible, not focused on height for buoyancy. I have a dock that has lasted 30 years with the same material.
Weight 18kg/m3
Absorbs 0.02% water
So the buoyancy is 980kg/m3

Doesn't it crumble? But surely you'd want a thickness of a couple of decimeters for the floating element, otherwise, the framework or dock decking will sink into the water, right?

 

[Trollskidan]

No, they don't crumble.
Yes, of course, but you should build on the surface a height, then it becomes stable.
If you load the dock with 100kg and the bearing surface is 4 float pucks that are 5x5dm, the dock sinks 1dm.
If you have 4 of 10x5dm, it becomes 5cm.

 

[AndersS]

The screw piles you linked are at great risk of being moved by the ice.
The first dock was with 2" long galvanized pipes and they were pushed away by the ice and even bent them.

 

[The_Andy_Pandy]

There is a high risk that those helical piles you linked will be moved by the ice.
My first dock used 2" long galvanized pipes and the ice pushed them away and even bent them.

Do you have any tips on a better solution that won't bend or be moved?

 

[AndersS]

We have switched to using only floating docks. Built on 20L plastic jugs in a framework, but it works with other materials mentioned earlier in the thread. Regular jugs last about 10 years before those exposed to sunlight need replacing. Ours are about 2 meters wide and I wouldn't make them narrower as they risk becoming unstable. We pull them up with a 12V winch every late autumn, but some neighbors leave their floating docks in over the winter. There is a thread where people build real stone cribs if you search here on the forum.

 

[ToRy]

If you're going to have a permanent dock, probably only a stone pier, stone crib, or massive pile dimensions will suffice. Ice affected by wind or changing water levels has an enormous inherent power, and iron poles or 90x90 wooden piles can't withstand it. Of course, the location plays a significant role, but even in a sheltered bay on a small lake, the ice can move.

Personally, I prefer a floating dock. More work, but you (the dock) sleep better in the winters.

I built a dock many years ago and used plastic floatation blocks from Svenska Flytblock. But you can save a lot if you plan to possibly replace a floatation block every five years or so. Not because they absorb water or go bad, but in case they get damaged.

Tips if you're building your own floating dock: Make sure to facilitate pulling it onto the shore. Skids, winch hook attachments, and the like. And, don't make it too narrow, or it will be unstable.

Good luck!

 

[freddelegrill]

Does it work to screw down screw piles like [link] into a sandy bottom and build a fixed dock on top? How deep into the sand bottom do you need to go? How close should the piles be for a 2x4 meter dock, for example?
Alternatively, how cheap can flotation blocks/pontoons be found if you don't want crumbly polystyrene, any other suggestions than [link] platser/flytblock_flytponton_flytbrygga_flotte/65127588

Yes, I've done this in winter on ice, works well. There are guidelines for center-to-center distances depending on the dimension of the bearer. You probably don't need to follow this religiously for a dock but it can give an indication.

 

[Maggiesb]

Styrofoam ground insulation XPS

The best thing for floating docks, but make sure to get as large an area as possible and not height for buoyancy
I have a dock that has been in use for 30 years with the same material.
Weight 18kg/m3
Absorbs 0.02% water
So the buoyancy is 980kg/m3

Hi
A very interesting solution you have. I would like to know, how big is your dock WxL.
Have you covered the entire underside with ground insulation? What size are the boards WxLxH?
How high above the water surface is the dock in calm weather? If 4 adults are on the dock, how high above the water surface is the dock then? If you have any pictures, I would love to see them.

 

[AndersS]

When it was time to renovate the small pier section, the barrels I wrote about earlier were replaced.

 

[Trollskidan]

Hi
You have a very interesting solution. I would like to know, what are the dimensions of your dock BxL.
Have you covered the entire underside with ground insulation? What size are the panels LxBxH?
How high above the water surface is the dock in calm weather? If 4 adults are on the dock, how high above the water surface is the dock then? If you have a picture, I would love to see it.

I have one that is 2.4m x 2.4m. I think it has 30cm of float material. This one has 600x1200x50mm pieces in it.
I can arrange some pictures.
It's been modified because we had 50cm out on the sides, which made it unstable.

I also have one that is 3x5m, also about 30 cm float but not under the whole thing.
It's going to be rebuilt next year because the frame is from 1978.
I've also built some water ski jumps with the same material.

 

[Trollskidan]

When it was time to renovate the small dock section, the barrels I wrote about earlier were replaced.
[image][image]

Styrofoam or ground boards "XPS"

 

[AndersS]

Styrofoam or ground boards "XPS"

EPS but can't remember which, much was out of stock and no blocks. There are 3 boards in each block.

 

[Maggiesb]

Have one that is 2.4m x 2.4m I think it's 30cm float material This one has 600x1200x50mm in it I can get some pictures. it's modified because we had 50cm out on the sides became unstable

Have one that is 3x5m also about 30 cm float but not under the whole thing. It will be rebuilt this spring because its frame is from 1978. Have also built some water ski jumps with the same material.

Hi, thank you for the reply. Do you mean that you have built 6 panels on top of each other to a total of 30 cm thick? Or are there ground panels that are 30 cm thick?