Model Boat Mayhem
The Shipyard ( Dry Dock ): Builds & Questions => Working Vessels => Topic started by: geids on December 20, 2011, 02:10:16 pm
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Have started a build of a floating dock (hopefully an operational one) It will be freelance, based on memories of one that used to be at Garelochead in the 60's. I will post some photo's, when there is more than just bits of plywood cut and being cut to size. It will be about 48 inches long, 30 inches broad and 15 inches high. Any hints or tips gratefully received. O0 O0 At the moment I am trying to decide on either water pumps or free filling with air pumps to empty the ballast tanks {:-{ {:-{
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Hello
Very nice project, I like it so much, I've the project to built a semi-submersible barge.
Don't forget to think about Archimedes and with one liter of water ballast you will only sink the dock for one liter volume ... That means a fool wood structure even full of water will still float !
You will need also hard ballast, please think twice on paper sheet with Archimedes in mind and volume calculations prior starting a structure.
I have seen a floating dry dock in exibition, I will try to found my pictures of it. It was working very well.
Xtian (I'm graduated naval architec ... but then worked only a couple of years in this branch ... crisis ? what crisis :embarrassed:)
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Hi Xtian, I intend to have some of the chambers that flood above the level that I will require the dock to submerge to. Hopefully this will provide the correct amount of ballast, to get the vessel down deep enough. To allow a ship to enter and then be lifted clear of the water.
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If you were to use lead flashing as the dock floor you might get away with pumping uphill .
If you end up with slight positive buoyancy it will make it easier to submerge.
Ned
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Hi Geids.
I'm reassured that you calculated and think well your project, I've seen a couple of "silly projects" one with a Mighty Servant III which is just an insult to Archimedes ... The other one is a semi-sub oil rig with same kind of unprepared work. A lot of will power and drem : let's go with wood, tools, pictures of the real one ... and a result out of Archimedes laws again !
What is the size of your dock and what weight for the lifted ship on it ?
Please post pics, I really like this kind of challenge, I used to have a student work on floating dock stability and it's a nice souvenir, don't forget to lift and sink it not horizontally to avoid lost of stability in one time.
Xtian
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Total rebuild started, not happy with sizes. <:( <:( Will now still be 48 inches long, but 20 inch broad and 20 inch high. This will hopefully allow for 6 inch of water above the deck when the dock is submerged. This should still also allow vessels with up to a 12 beam to enter the dock. :D :D
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Good idea on the resize.
One of the guys had one here in the "states".
There weren't too many boats that would fit, but it worked really well.
:-)
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a few pics here of AFD 22 may be of use to you.
Geoff
http://www.royalnavyresearcharchive.org.uk/BPF-EIF/Galleries/Gallery_AFD22.htm
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I will be following this one with interest. Some of the principles will be similar to a model submarine, in that it will have to take on enough water ballast to reach a stable trim depth, but it will also have to not only discharge enough water to fully 'surface' but in addition an equivalent weight of water for the boat it will lift. Stability could be a big problem. Great challenge though.
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@ GID....we had a British designed ....built in OZ floating dock......for 70 years & still in operation :kiss: ...naturally this was in addition to our Captain Cook graving dock.......the largest at the time in the southern hemisphere :-))
As others have mentioned........the design calculations for a floating dock are far more complicated than first appears......... Derek
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Hello
I've find the pics I took some years ago of a model floating dry dock. The actual owner (on the pic) is not the builder (both are Dutch) , then the model was shorter when built and jumboized later. It works perfectly with batteries and command outside the dock - the pumps are aboard (wirred connected).
It was at the Poitier (France) exibition Modelexpo in 2007
Really nice place with also the harbour owned by the BMB, the club I'm member - http://bmb29.free.fr/ - http://bmb29.free.fr/LEPORT.html
(http://nsa21.casimages.com/img/2011/12/29/111229041409620210.jpg) (http://www.casimages.com)
(http://nsa22.casimages.com/img/2011/12/29/111229041542422622.jpg) (http://www.casimages.com)
(http://nsa22.casimages.com/img/2011/12/29/111229041646332552.jpg) (http://www.casimages.com)
(http://nsa22.casimages.com/img/2011/12/29/11122904174865427.jpg) (http://www.casimages.com)
A+ Xtian
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Hi, Thanks for the photo's Pugwash. Xtian, I see in the photo's the dock seem's to be attached to the shore, do you know if that was the power or air supply? At present I am working on sealing x4 12 volt batteries, 1 will be secured at each of the bottom corner's of the dock. Hopefully providing ballast and additional stability due to them being as low down as possible.
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The "attach" to the shore is only electrical power to the pumps onboard the dock.
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Hi, had all sorts of idea's for making watertight compartments for the batteries. Most involved quite a bit of work <:( <:( however was shopping in Asda today and spotted plastic containers with lock-down lids. Had them weighted down in the bottom of the bath for a couple of hours, not a drop of water in them. So 4 containers at £1 each has saved a lot of effort. :-)) :-))
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Finally starting to take shape, after many changes. Gave up any idea's regarding scale, as I reckon there would have only been about 1 1/4 to 1 3/4 inch of water above the deck when the dock was submerged. Basic sizes are 48 inch long, side compartment are 5 1/2 inch wide and 19 inch high. Deck is 16 inch wide and 1 1/4 deep. Deck will be free flooding, side compartment will be free flooding to 6 inch from top. 1 12 volt battery at the bottom of all four corners for power and ballast/stability. Servo controlled valve's to allow air to vent when submerging and two air pumps to hopefully raise it, and it's passenger out of the water.
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please just keep the photos coming as the build progresses - this should be very interesting
Geoff
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please just keep the photos coming as the build progresses - this should be very interesting
Geoff
What three at a time Geoff ? {-) {-)
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We are getting a lot of duplicated posts. Some sort of Computer error, even duplicates me. (that won't please the Wife !!) %)
ken
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Hi, slow progress due to our wonderful Scottish weather . Son say's i'm a wimp, while I don't mind it being a bit cold, but when glue will either get washed away or freeze before getting a chance to dry, even I call it a day. Due to it's size, I have to work outside on it. If I was still in John Browns (now Clydebank College and a lot of waste ground) I would say the vessel is now off the slipway and in the fitting out basin. The 6mm screwed rod that can be seen is to stop the 'H' shape of the dock flexing when in operation. I have laid two 24 inch ruler's end to end to give a better impression of size and why I have to work outside on it.
John
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At last, weather has improved (above freezing and not pouring with rain) Have started installing the "works" Remote controlled 360 LPH sump pump and after a great deal of highly technical discussion and head scratching, it was suggested to me to use the item in question to control the inflow of water. No home should be without one? Just to connect a bit of 19mm hose from the pump to the one way valve, and I should be able to get the sides on.
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Hi John
What do you estimate it will weigh? Just for transport I mean and not ballasted.
This is an interesting subject you have chosen.
Dave
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It should weigh in at about 35-40 lbs, I have fitted wheels on the bottom to assist with moving. I don't think the weight is going to be the problem, but it's size. It will fit in the car but will require two to get it in and out.
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At last. It will sink and better yet, it comes back up again carrying a passenger. Next step is to test it in the clubs pond. If all goes well, I will start working on the cosmetic side of things.
John
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Very nice, How long does it take to settle and then refloat?
:-)
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Very interesting O0what a great build,
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Hi, the dock submerge's in approx 3.5 minutes and is fully floating in about 2.5 minutes. The pumps filling her are 150 litre per hour and to empty about 280 litre per hour.
John
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Hi, after a few false starts' (like what pumps do I have running, light fixed to tell me.
Photo's show it being towed into position, going down, 1:72 scale HMS Amazon in position, coming up, dock and passenger up.
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submerge's in approx 3.5 minutes and is fully floating in about 2.5 minutes.
Hi John - so can we expect to see a 6 minute video? :} :-))
Great idea to build this one John - well done.
Dave