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helga
13th Aug 2005, 07:35 PM
I am fantasising about summer already, and we have hatched a plan to build a pontoon to moor to the side of our dam so you don't have to walk through the muddy edge when getting in and out of the water. Has anybody built one or seen a plan of one? We have some pickle barrels but I'm not sure if they will float too proud of the water and be unstable. Any suggestions gratefully received. Thanks, Helga

Dion N
13th Aug 2005, 10:51 PM
How much weight will the pontoon have to bear?

To design the pontoon

1. calculate the volume of the pontoon (this lets you know how much water is displaced by the pontoon). For every 1000 cm3, the pontoon displaces 1 litre of water.

2. The displacement in litres = the weight the pontoon can take in kg. For safety, only load to 90%.

Example - say your barrel has a height of 80 cm and a diameter of 40cm (ie a radius of 20cm)

Volume of a cylinder = pi X radius squared X height
= 3.14 X 20 x 20 x 80 = 100,480cm3

Divide by 1000 to get litres = 100.48 litres

Therefore, your barrel could support a maximum of 100 kgs, although 90kg would be a safer limit.

kiwigeo
14th Aug 2005, 12:18 AM
We have some pickle barrels but I'm not sure if they will float too proud of the water and be unstable. Any suggestions gratefully received. Thanks, Helga

This project requires very careful planning. Step 1 is to aquire a half a dozen barrels brim full of fine malt whiskey. Step 2 is to empty the barrels (preferably not in one session) while you carefully develop a plan for the mighty pontoon project. By the time youve got through all that whiskey youll have a very carefully thought out plan and six empty barrels.

helga
14th Aug 2005, 06:27 PM
Thanks for suggestions dion and kiwigeo.the pickle barrels we get held pickled onions and gherkins. I don't think I could eat my way through 1200L of gherkins. I'm feeling sick just thinking about it! Luckily we get them empty. I'm guessing 3 people and the timber for the deck of it would be the weight load. I will see what the demolition yard has in the way of ladders. I'm just not sure if I should tether it to the bank or anchor it to the dam floor or both!?helga

rhack
15th Aug 2005, 03:25 PM
helga,
what we did -
4x 200 L plastic drums from mountain chemicals in Lismore (ex detergent of some sort). They have 2 screw in bungs rather than lids.

Built a treated pine deck, over a frame that sits on the drums (lying on their side at each corner). Drums end up under the frame so you don't have to look at 4 big blue things... Frame was about third of the way down the drum so they don't go anywhere, but the frame stays clear of the water. Frame wasn't fixed to the drums, so if one gets a leak, drum just drops to the bottom of the dam.
Put drums in pond. Dropped deck and frame over drums. Sat 4 people on deck and loosened bungs to let water in until the whole thing sat at a nice height in the water. Worked around the 4 progressively to get it level. If you get it so that one bung is above water level, and one below, you can adjust the floating height by loosening bottom bung, then top bung - lets in water, close top bung and use a foot pump to pump air in bottom bung to raise etc

Attached floating deck to shore with a walkway long enough to deal with low dam level - galv gate hinges between deck and walkway, couple of those concrete house stump pads on shore with more galv hinges, so it adjusts to changes in water level.

Very popular with ducks and snakes.......

-r

Dr Dee
16th Aug 2005, 01:53 PM
Helga,
I did something like rhack but used a larger number of 20l plastic drums, the squareish type used for pool chlorine. They have a screw cap and a small bung where one can screw in a tap. I had them lying on their side under the treated pine decking and had the screw cap at the top and the small hole at the bottom with the bung out. Adjusted the floating depth by loosening the cap and letting air out as required etc. More fuss getting it even with a larger number of drums, but you only have to do it once. No need to plug the bottom hole - if the air can't get out the top then the water won't go in.

The partially filled drums give the pontoon a lot of stability. A pontoon with empty drums rides high and is very lively to walk around on.

Buy a good garden broom as you will need it for regular duck poo cleaning. Our snakes are much tidier and only red belly blacks, well the browns do visit but don't lie there sunning themseleves like the blacks.

cheers

helga
17th Aug 2005, 09:12 AM
thanks guys

sounds like a lot of bunging about in the dam, will definitely have to wait for warmer weather, but at least now I know what parts to assemble. We also have yellow faced whip snakes, bandy bandy and carpet snake as well as red bellied blacks. I've only seen one brown here and it was a baby. I always think "where's mum?" when I see a baby snake.

Markw
22nd Aug 2005, 03:28 PM
If you want something that would best belong up the crick in the Beverly Hillbilly's then use the drums.

or

get a proffessional pontoon of the type used to moor small boats along side.

I used to help install these types of jetties for the mega rich in Sydney Harbour a few years ago using pacific marinas products. Dont know if they're still available but looked something like this only generally smaller

http://www.thejettyspecialist.com.au/domjet/index.html

The moving decking shown is steel with a timber top and the peiring is concrete where as we used turp piles and all jarah decking with gal pin hinges. Worked OK in Sydney during heavy winds/seas