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Old 18 October 2005, 14:51   #21
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Originally Posted by codprawn
No transom is definitely the best bet - the Ocean Dynamics boats can shift 2 tons of water in seconds - no scuppers could ever match that!!!

There is one interesting school of thought that has been debated on here before. That is that a waterlogged boat become instantly a lot more stable - a RIB full of water still won't sink but because it's sitting so low it will never flip either - bit like a submerged railway sleeper!!!
Good point. I'm quite sure Dave Picton thought of that when he put his "scuppers" in the Nautique.
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Old 18 October 2005, 15:02   #22
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Well Alan Priddy would surely know what he is on about - he does have a little "experience"!!!

"If you are in a good quality rib and it h as been designed and built correctly it actualy becomes more sea worthy when it is filled with water! the boat then develops an inforced keel weight and will become part of the sea bobbing up and down until you are ready to make way again. Apart from Spirt, I have always filled my boats with water to see how they float, Do any other Rib builders do this? You do nothave to try this as I have proved that if Spirit doesnt sing neither will Magallen Alpha. ( along with all of the Ribtec range)"
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Old 18 October 2005, 15:22   #23
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Originally Posted by codprawn
Well Alan Priddy would surely know what he is on about - he does have a little "experience"!!!
I've tried to fight this but I can't..............

Unlike some!

Alan's right of course although more for an open boat than a cabin rib which he did manage sink in the end However for a leisure RIB a consequence of having the thing completely full of water is probably your electrics shorting out (unless your battery is mounted high up), possibly making everything live, and possibly knocking out your engine through flooding. That then turns a bad situation worse with the potential for a combination of incidents to spiral into a situation that leads to needing to be rescued.

Open transoms are the thing if you are workingin extreme conditions like the ocean dynamics boats do, but not really the thing for the average ribster. Apart from the bother of getting your feet wet everytime you slow down and get overtaken by your wash, you'll be forever losing things over the transom such as keys, handhelds, phones upto and including passengers!
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Old 18 October 2005, 15:43   #24
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The Ocean Dyanmics aren't that bad - they have quite a high freeboard so you don't get swamped very often.

I remember seeing a great photo of a Thousand Island thrill ride from a few years ago - the boat was filled with white water and the passengers up to their waists in water - seemed to be loving it though!!!

Good point about the electrics though - better have a sealed battery!!!
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Old 18 October 2005, 16:08   #25
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Originally Posted by Alan



However for a leisure RIB a consequence of having the thing completely full of water is probably your electrics shorting out (unless your battery is mounted high up), possibly making everything live, and possibly knocking out your engine through flooding. That then turns a bad situation worse with the potential for a combination of incidents to spiral into a situation that leads to needing to be rescued.
And that's the limiting factor no doubt!
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Old 19 October 2005, 14:01   #26
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There is one interesting school of thought that has been debated on here before. That is that a waterlogged boat become instantly a lot more stable - a RIB full of water still won't sink but because it's sitting so low it will never flip either - bit like a submerged railway sleeper!!! [/QUOTE]
No Way is a water logged boat stable. Once it sloshes to one side it'll effectively throw the boat over. It's known as the " Free Surface Effect". Crabbers carry Vivier tanks which are large tanks of seawater in which the crabs are kept alive. The tanks must be kept full and have sealed lids inorder to maintain boat stability.
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Old 19 October 2005, 15:17   #27
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What you are talking about is a different thing - the same problem that effects people who drive road tankers - liquid sloshing about so high up is deadly.

It is mainly down to the C of G - a submerged rib has most of the weight below the water.

A classic example is a coastal type oil tanker - the bow and stern are raised up but the decks are awash - in fact an oil tanker is one of the hardest boats to sink as the oil is lighter than water.
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Old 20 October 2005, 07:46   #28
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So much knowledge - in the Photo Gallery Section!!!

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Old 30 May 2006, 17:37   #29
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Another Cobra Lover

My new 6.0M Cobra (Mercury 150HP Optimax) at the services on the M6 after picking up from Dave Picton. Some Action shots on the water to follow.
2nd Pic .... The RIB I really Wanted, was intercepted by it whilst trying to sail through a maritime festival on a sailing trip in Turkey but couldnt pursuade them to sell it !!!
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Old 30 May 2006, 18:03   #30
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The Cobra is a pretty looking boat - ho[pe you have some great fun with it - keep us updated and post some more pics!!!
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