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JimC View Drop Down
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    Posted: 13 Oct 11 at 9:05pm
Originally posted by oldarn

attaches the tank side directly to the floor thus giving an I beam type stiffness strength.

And a socking great hard spot for the floor to flex around and the polyester resin to let go of the fibre... Especially with the helm stamping around on the floor. That's why sidetanks so often leak after a few years.
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Post Options Post Options   Quote Rupert Quote  Post ReplyReply Direct Link To This Post Posted: 13 Oct 11 at 9:21pm
Not noticed that double bottoms leak any less than side tanks, really.
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oldarn View Drop Down
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Post Options Post Options   Quote oldarn Quote  Post ReplyReply Direct Link To This Post Posted: 13 Oct 11 at 10:13pm
Originally posted by JimC

Originally posted by oldarn

attaches the tank side directly to the floor thus giving an I beam type stiffness strength.

And a socking great hard spot for the floor to flex around and the polyester resin to let go of the fibre... Especially with the helm stamping around on the floor. That's why sidetanks so often leak after a few years.


Never come across the problem you refer to. What classes use you to sail and who made them?  Even in 505s that tend to have heavier guys never seen the problem even in 30 to 40 year old boats.
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rogerd View Drop Down
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Post Options Post Options   Quote rogerd Quote  Post ReplyReply Direct Link To This Post Posted: 13 Oct 11 at 10:16pm
Originally posted by oldarn

Originally posted by Medway Maniac

As I've just pm'd Oldarn, the best buoyancy arrangement I've ever sailed was on Jack Holt's late-'60's Jacksnipe (here's a plus for Jack then, after the crit of his Ent!).




Double floor but with self-bailer-drained footwells that lowered he crew members' c.g.'s and gave more room under the boom. The footwells soon drained, in practice.

Even that could have done with slimmer side tanks, but mine (the prototype) was so overbuilt it floated low on its side anyway!


I vaguely remember it. How many were made?  It might be considered semi double bottomed. I assume it was complicated and/or expensive to make and most likely too heavy  but otherwise seemed a good compromise.

We considered a semi-double bottom for the AltO to the back of the c/b box, but for little gain in terms of carrying less water within and at  the expense of less comfort, less stiffness and heavier.

  
Rumour has it that a Jacksnipe( a boat we thought was long gone) has re appeared and hopefully be about for the Holt Centennial next year. Thats all I know at the moment but will let you know more as we hear news.
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Medway Maniac View Drop Down
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Post Options Post Options   Quote Medway Maniac Quote  Post ReplyReply Direct Link To This Post Posted: 14 Oct 11 at 1:02am
The join of the side tanks onto the hull certainly became a leak point (line?!) on my Vanguard 420...

Then again, i've heard the odd groaning double bottom (not on my boats!). I guess it comes down to build quality either way.

In my imperfect recall, Mr Foxwell's N12 has a double bottom but nothing in the way of side tanks, which sounds good. What's the thinking in the 12 class, Ian?
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Post Options Post Options   Quote ifoxwell Quote  Post ReplyReply Direct Link To This Post Posted: 14 Oct 11 at 9:00am
I've no idea what the class are thinking I'm afraid as we have yet to get along to any events however its my understanding that the motivation to move to double bottom was just to stop them filling up with water in waves but the side effect of effectively stiffening up the hulls then made the change essential if you wanted to be competitive. (happy to be corrected here by the more experienced 12 sailors ion here)

Side tanks/floors separating. Yup I've had that on a couple of boats and its a real bugger to fix. Bodge's don't work and if you cut it all back and fix the problem properly the best you can expect is something that is the same as it was when new... which of course was flawed in the first place or you wouldn't be fixing it!

Ian 

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