How to build a floating dry dock.

[Frosty]

I have been thinking about this. I have nothing to do and ship yards or haul out facilities in this area are full and rude.

I want to build a floating dock about 100tons lift --4 50 foot keel boats for a one week anti foul job.

I want accommodation ,mess hall and a bar cafe.

Later I might want to add a crane and engine rebuild facilities with a dock on the outside for minor repairs.

It would be anchored in 4 meters high tide, mud bottom. I would plan on sitting on the bottom and pulling in the boats , then allow the tide to dry them and then lift the last meter or so.

I would need various gens and pumps that are cheap and plenty full in Thailand /Malayasia cheap labour and no welding certification of any kind , second hand steel where available.

Gens will be truck engines driving Denyo AC no AVR gens,--the simplest easiest construction.

The difficult bit is what shape is the bottom to lift in a stable manor and clear the keels dry.

I have no idea but that you have a good one! When you figure it out, I'll build a smaller version. Good luck

[CDK]

My 1th concern would be to get a permission. Even without one such a project surely will keep you busy for the next couple of years, but if it ends in a conflict with local officials you will feel miserable.

There are square plastic containers for chemicals, capacity 1200 liters, with threaded holes, available for free or almost free. These I would use for buoyancy, held in place by a galvanized steel frame with wooden planking on top.
I would start with a smaller dock for one or two boats, but weld on flanges to expand it in case business will be booming.

Where do you get these plastic containers CDK, and how would one evenly and reliably inflate and sink them?

[CDK]

Mark, if I need such containers, I ask the owner of a summerhouse nearby who lives in civilization on the mainland and he brings them to me. I live in the middle of nowhere on an island, so my well being depends on such friends.

As far as I know they are used as one-way packaging for detergents, glucose syrup and many other chemicals for the food industry. When empty they are collected and resold to individuals who mainly use them to store rainwater for beach houses or remote gardens. It seems that transport and cleaning is too expensive to reuse them.
Each container comes with a pallet bottom and a galvanized steel cage around it, so a forklift can move and stack them.

They all have a 2" threaded hole with a plastic valve at the bottom and a 4" hole on the top with a plastic plug. I use one to store diesel oil, it has an adapter from 4" to 2" and a 2" plug.
I would connect a row of such containers with ball valves on each T in case a container would get damaged. They can also be partially closed to restrict the airflow when there is uneven load distribution. Of course you need a high volume, low pressure air pump to expel the water: approx .5 bar would be enough if there is no tide.
With enough tide you need only close the valves and wait.

[jehardiman]

The most important thing in a floating drydock is stability (list and trim) during flood up and pump down. This requires NARROW tanks and lots of them. In normal docks, these are in the wing walls, which any floater should have. The wing walls are also where services and espresso machines go. As far a blocking goes, most floaters have a keelbock line and moving side blocks, any other shoring goes in after pump down. Take a look at some of the yacht haulers such as Dockwise of an idea of what things can look like.

[hoytedow]

http://www.floatingdrydock.com/

[peter radclyffe]

get an old coaster, cut one side out, reinforce the gap, flood the ballast tanks,float in the boat, pump them out, pool table on the bridge, jukebox in the mess, cabins,
bingo

Hoyt, I believe your link was about stuff that goes in a floating dry dock...

[Fanie]

Hi Frosty, good idea. Only one question though.
Won't you, after a while, get full. and rude