Pontoon making buoyancy spec needed

[mtb]

Right next project is make a pontoon for my moorings .I will be collecting a large metal tank ,without measuring I'd say about 600 gallon capacity roughly 8 x 5 x 6 all imperial sizes .What I'm hoping is some one has tried this and already has an idea of the amount of buoyancy or lift this mass will have and how much concrete to use to ballast it correctely.
My thinking so far, is to weld straps on around the base then shutter up allowing 2"" of space fill with concrete then turn over weld on 2Ft section each end apply decking and then have a handy pontoon for not much money.
Some one talked about his slide rule the other day it must be possible to calculate rather than guess.
Ta Mick

http://homepage.ntlworld.com/boats
I want a big steel ex trawler / tug v/cheep or swap for tug

 

[Guest]

each gallon gives a buoyancy of 10lbs

 

[Trevor_swfyc]

How can we help you? don't you know raggies went metric years ago.

Bye for now
Trevor

 

[rich]

what sort of metal?in salt water!

rich

 

[mtb]

Now that is handy to know ,
Mick

http://homepage.ntlworld.com/boats
I want a big steel ex trawler / tug v/cheep or swap for tug

 

[mtb]

Just ordinary steel ,I will put a couple of anodes on as well as anty foul .I could use epoxy paint .
Any way I can always get another tank if it lasts four years I'll be quite happy,mind you it would not be to expensive to fill it with expanding foam
Mick

http://homepage.ntlworld.com/boats
I want a big steel ex trawler / tug v/cheep or swap for tug

 

[Col]

Bludy 'ell Mick, don't you ever sleep , or do you run on duracells ?

;-)

 

[rich]

i can't wait to see this, pontoon sumday,or doomsday.....
why not get an x army pontoon?
rich<P ID="edit"><FONT SIZE=-1>Edited by rich on Thu Feb 14 00:10:56 2002 (server time).</FONT></P>

 

[mtb]

Part of it is the challenge and the rest is cost, I would much rather spend money on some thing I cant make
Mick

http://homepage.ntlworld.com/boats
I want a big steel ex trawler / tug v/cheep or swap for tug

 

[mtb]

I buy and sell motors to keep me boats on the go .
While in the MOT station the fella was going to fail me because I couldnt stay still
HA HA .You just have to do it dont you .
I have to be doing stuff .
Mick

http://homepage.ntlworld.com/boats
I want a big steel ex trawler / tug v/cheep or swap for tug

 

[Guest]

History of metrication in the UK

Historical Perspectives: by the last Director of the Metrication Board.

I have been stimulated by some of the recollections of your recent correspondents to try to explore some of my old Metrication Board records to see when Parliament first debated the metric system, Many references suggest 1897.

In fact the first reference was 13th April 1790. One hundred years earlier. This was when parliamentarian Sir John Riggs Miller [Britain] and the Bishop of Autum, Prince Talleyrand [France] put to the British Parliament and French Assembly respectively, the proposition that the two countries should cooperate to equalise their weights and measures, by the joint introduction of the metric system.

There was no immediate progress although there were many positive debates in the second half of the 19th Century. For example, 1st July 1863 the Bill for a compulsory change to the metric system was approved by 110 votes to 75 votes. Speakers argued many of the points we hear today. On the one hand supporters argued its logic and simplicity, savings in time and money, advantages to trade and education. Opponents stressed the undesirability of following the precedent of France and the problems of conversion for the ill-educated and disadvantaged. However no specific cut-off dates were proposed.

The following year, 9th March 1864, the House of Lords debated a Bill to permit the use of metric weights and measures in trade. One supporter noted that Englishmen were notorious for liking old terms and old habits and he hoped that the new nomenclature would not be diverted by attempts at ridicule. He said the sound of the word 'metric' can be absurd to anyone but a fool who has never heard it before; but no more than a 'yard' to a man who has never heard of a 'yard' before.... !!!Parliament passed the Bill and this became the Metric Weights and Measures Act 1864.

On the 24th February 1868 a parliamentary proposal to set Imperial cut-off dates was withdrawn on promise of a Royal Commission of enquiry. The Enquiry Report was positive, and on the 26th July 1871 Britain almost became a metric country. The government lost the Bill to make metric compulsory after two years, by only 82 votes to 77 votes. An argument that might have influenced opponents was a plea that Britain would be "letting down America and our colonies" who had harmonised their systems with the ones in use in Britain. [NB At that time the American Congress had emulated Britain by allowing contracts in metric. A particularly strong USA advocate for metric was John Quincy Adams.]

There were further debates, and near misses, in the UK Parliament in 1872 and 1896, before a comprehensive debate [ 21st June - 6th August 1897] concluded by legalising the use of metric for all purposes. There were no contrary votes. NB This is the debate which most references indicate to be the genesis of metrication in the United Kingdom.

Metrication continued to be debated for the next 10 years. In 1904 The House of Lords unanimously voted to make metric compulsory after two years. It was claimed that the Austrian and German nations had successfully made metric compulsory with a changeover time of only "one week"!!!!! The Government said they would not obstruct the proposal, but the Bill was never adopted in the Commons. Two similar debates in 1907 failed. By now, the Board of Trade was expressing some reservations, claiming that metrication had failed in France and that the agricultural labourer would never ask for 0.56825 of a litre of beer. The vote against compulsion rose to 150 votes to 118 votes. Conflicts in Europe put further political consideration of metrication out of mind until the publication of a Government White Paper on Weights and Measures 10th May 1951.

The 1951 White Paper was in fact the 28th Report put to Parliament during the preceeding 100 years. This latest report was in response to the the Hodgson Committee Report published in 1949. Eventually we had the Weights and Measures Act 1963; a long series of Parliamentary questions to Ministers and the Federation of British Industries [now the CBI] lobby in favour of metrication in 1965. These initiatives culminated with the creation of the Metrication Board in 1969 by Anthony Wedgewood Benn, Minister of Technology. The target date for completion was end 1975. The transition to metrication and the role of the Board were given positive support and encouragement by Geoffrey Howe the resposible Minister of the new Government in 1972. Indeed at that time, and until circa 1977-1978, there was good, sensible and steady progress which seemed to be supported by every section of society including, for example, the small retailers and the elderly as represented by Age Concern.

Prepackaged food changed but the really difficult issue to emerge affected retailers of 'loose weight' products. They needed to be reassured there would be an agreed cut-off date for their transfer from Imperial to metric. The retail problem was that metric prices would always appear to be more expensive than their nearest Imperial equivalent. Voluntary transferees to metric found themselves commercially disadvantaged. This is because viz. 4 ozs is smaller than 125 g: one pound is smaller than 500 g and a pint is smaller than a litre. Prices are correspondingly lower. The issue of how best to explain the position to consumers dominated much of the Boards creative thinking.

The product which brought all voluntary retail initiatives to a full stop was the experience of the floor covering and carpet retailers. Their 1975 change to sales by the sq. metre started well, but in 1977 one of the major High Street retailers found enormous commercial advantage in reverting to sales by the square yard. Consumers could not be persuaded to believe that goods costing, for example, £10 per square or £12 per square metre were virtually priced the same. Consumers bought, in very significant volume, the apparently cheaper priced imperial version. Metrication of carpet sales entered into full scale reverse and the Chambers of Trade and retail associations pressed for firm Government leadership, i.e. compulsory cut-off. With hindsight one of the Metrication Board jingles may have helped spread the 'carpet' misunderstanding. This was the jingle "a metre measures about three foot three, just a bit longer than a yard you see". Consumers understandably couldn't relate an e.g. £2 per square unit price difference with the Metrication Board's "just a bit longer". Then the political nerve began to fail.

Board of Trade Ministers Shirley Williams, Alan Williams and later Roy Hattersley and John Fraser supported metrication. They seemed to recognise the setting of a cut-off date was unavoidable. They had had, by this time, the benefit of analysing the results of successful metric changes in all the Commonwealth countries. There was a wealth of information within the Department of Trade to show that a clear retail cut-off date was both desireable and inevitable....exactly as 19th Century parliamentarians had foreseen. The necessary Order, drafted by the Board of Trade in 1978, was agreed by a huge range of retail trade, industry, engineering, consumer, trade union, elderly person, sporting and educational organisations and..... the overwhelming number of parliamentarians. A small number of critics, in each political party, did voice opposition to the element of compulsion but this seemed to come from a relatively small minority within the Eurosceptic movement.

However, the initiative was in the hands of Secretary of State for Trade, Roy Hattersley and a General Election was expected in 1979. There seemed to be weeks and weeks of "will he/ won't he" allow Parliament to vote for the Order giving the final Imperial cut-off. Almost every private test of opinion indicated the Order would command a substantial majority in Parliament. Although the Opposition sensed a weakness in the resolution of the Labour Government it was acknowledged that many conservative MPs had been career-long advocates for cut-off and would therefore be likely to favour the Government Order, or at least abstain. In the event, Roy Hattersley chose not to test opinion, not to allow the vote. He withdrew the draft Order. Speculation was that he judged the issue might lose some votes in the forthcoming election. Plenty of time to introduce Imperial cut-off Orders after a Labour victory. The junior Trade Minister John Fraser made his disgust and disappointment apparent... suggesting the actions of his Secretary of State would be seen as "gutless". Many shared that view. Labour lost the election anyway and Margaret Thatcher became Prime Minister.

One Conservative backbencher, Sally Oppenheim had been almost the lone but persistent critic of the metric programme. Ironically she was appointed junior Minister of Consumer Affairs at the DTI and then metrication was added to her portfolio. In letters to MP's and associations she made it clear [a] she was not opposed the metrication in principle, metrication was not the result of Britain's accession to the EEC but [c[ she did object to measures which would compell people to adopt metric against their will. Proponents of metrication, trade and consumer organisations, officials and the Metrication Board explained and argued that a voluntary change at retail level was absolutely impossible...it could never happen. It was a recipe for confusion, waste and duplication. Government had to lead over the last hurdle. It did, it led backwards. In 1980 the Metrication Board was abolished.

In truth the Metrication Board had little else to do. Every possible programme had been agreed, consumer information campaigns composed and there was nothing to do until or unless a date was fixed for the completion of the transition. We little knew then the die was set for a further 20 years of waste, confusion and argument. Successive DTI Ministers did nothing to inform consumers or public opinion. They did nothing to refute the new 'big lie' namely, that Britain was being forced to change because of the European Commission. In fact, during the past 20 years most Commission Officials, European Politicians and businesses in Continental Europe 'couldn't have given a damn' whether Britain changed to the metric system or not. They seemed to quite like the idea of Britain shooting itself in its economic foot, by imposing upon itself the extra costs and waste of maintaining a dual system. For twenty years not one single British Minister has attempted to explain the advantages of metrication; been frank about the changes which had successfully taken place in the rest of the World or the fact that we had committed ourselves to become a metric nation long before we joined the European Community. Most tried to pretend or imply they were protecting our British culture from the European bully.

How sad, what a waste, what a pity.

Jim Humble OBE

Director of the Metrication Board

http://www.usma.demon.co.uk/history.htm

 

[vyv_cox]

The shape of your tank is not very handy for the amount of buoyancy required. You'll be using most of it up with concrete. There are quite a lot of steel buoyancy tanks under finger pontoons over here. I would guess they are mostly about 2 ft 6 ins in diameter, some a good bit less. The bigger ones are perfect for the job but some small ones sink a lot under a person's weight. Main walkway pontoons, say 6-8ft wide (?) have a full-width plastic, concrete or polystyrene block that is mostly about 2 ft deep, but very little of it under water.

If I took a guess at a handy pontoon size, say 20 ft long, 6 ft wide, timber deck, call it 3 hundredweight (150 kilos) all up, plus four people, say another 320 kilos, so 470 kilos total, that is 470 litres of water displaced, needs only 0.5 metre cubed = 110 gallons of buoyancy. Four 40 gallon drums would do it comfortably but would probably corrode away pretty smartly. Your tank dimensions are 240 cu ft., more than a cubic metre, 1440 gallons, so ample for the job. So your tank would do best cut in half down the width and weld plates on to make two at 2 ft 6 ins. How's your welding? At least if you put the new plates up there would be no need to have them perfect as the water wouldn't reach them.

I would go the tubular route, pick up some lengths of 28 inch and weld end caps on.

 

[LadyInBed]

Re: Pontoon making

I would stick a heavy duty pile at the watery end, for a bit of extra stability.

 

[mtb]

AH now today while wandering along to Wells by sea I thought about cutting down the tank . Very useful that you did the calculations for me as I hate doing it my self. The welding is easy and if I went down that road ( which is likely ) then I can add in large plates to thicken up the areas where lifting eyes and mooring eyes will be .Actually if the depth was to great at very low tides the thing would ground !!.
Nope got to be halves . I will get the tank tomorrow then after the school holiday I will do it ,I think about two /three days will be enough to get the job done .
Mick

http://homepage.ntlworld.com/boats
I want a big steel ex trawler / tug v/cheep or swap for tug

 

[mtb]

Re: History of metrication in the UK

I recone it might also be because there are some things we English men will always say are in inches or ( its 12"" but I dont use it as a rule )
Could you imagine the chat up line ere darling wan a see me 185mm not the same is it !!!
Famouse reply from an unwilling female to a bloke trying his best
Bloke , how do you like youtr eggs in the morning
female , unfertilised please.
Mick

http://homepage.ntlworld.com/boats
I want a big steel ex trawler / tug v/cheep or swap for tug