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V Twin

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ham4sand View Drop Down
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Post Options Post Options   Quote ham4sand Quote  Post ReplyReply Direct Link To This Post Topic: V Twin
    Posted: 24 Apr 12 at 8:12pm
Fill the whole mast with ping-pong balls, very practical, cough. Just have no holes in it whatsoever, apart from one hole at the mast step so that it doesnt have any chance of exploding/collapsing when going from being in hot sun to underwater. My shrouds are even attached to the base of the upper spreaders so dont even touch the mast, the caps are just put over a tang at the top, lowers and gooseneck bonded on, d1s are attached to base of bottom spreaders, I can guarantee no holes there...
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blaze720 View Drop Down
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Post Options Post Options   Quote blaze720 Quote  Post ReplyReply Direct Link To This Post Posted: 24 Apr 12 at 7:49pm
Oldbarn

Inversion ... might be easy enough to get mast to surface of course, even with a tinny mast - but getting a flooded mast 'up' from there is what makes inversion a real problem for some,  It really IS about the volume of water you have to lift above horezontal !   Of course a carbon stick helps being lighter but it is the water that is the heavy bit so a lower volume stick is a great help   A tiring crew struggling for a while will simply result in the mast heading down again ... and again.  And again.

It is VERY difficult to ensure a 6 or 7m mast will not leak when a lot of it will be several metres down when inverted.  The pressure differential is substantial even at these depths.  If you have holes it will flood and quite quickly.  If the overall boat design is good then inversion will not be very often but you really have to be able to deal with those 'not very often' occasions as well.

Ping pong balls ... I'm sure they can take a bit of pressure but they will want to float (up the mast) when inverted so do you cram them in so they cannot move ... with all those halyards under load?

Here's a test - can you capsize your hull under control with the mast comfortably on the surface and just sit there relaxed on the side until you want to get moving again ?  And then just step over as it comes back up.  If the distribution and amount of volume is good then this should be very  straightforward and easy and if it is a self-draining design it should also drain completely when  bought back up.   (Tip - a reasonably sealed mast does help and I will still argue a lower volume one helps even more from fully inverted and in the extreme case potentially flooded)

Mike L.
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Post Options Post Options   Quote gbrspratt Quote  Post ReplyReply Direct Link To This Post Posted: 24 Apr 12 at 7:24pm
Originally posted by Hector


The Xenons at one of the windy Endeavour trophies had foam pads at the top of the sail. Despite the sailors initial whinging about the shame of it, Topper insisted and actually they were hardly noticeable while sailing. I didnt capsize, but I never saw a mast with mud on it so I assume those that swam didn't invert quickly if at all. They were dayglo yellow and filled the space above the top batten on both sides. They were easy to fit or remove - just a couple of eyelets and a bit of velcro I recall.Please just remember as my post above, you only need enough to slow the inversion - not totally prevent it.


That is exactly what they are. Very simple but effective. With the right calculations you can work out how much you needed/ want and Bobs your uncle. Problem solved.
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Hector View Drop Down
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Post Options Post Options   Quote Hector Quote  Post ReplyReply Direct Link To This Post Posted: 24 Apr 12 at 7:12pm
The Xenons at one of the windy Endeavour trophies had foam pads at the top of the sail. Despite some of the sailors initially whinging about the shame of it  "don't you know who we are"?!! Wink Topper insisted and actually they were hardly noticeable while sailing. I didnt capsize, but I never saw a mast with mud on it so I assume those that did swim didn't invert quickly if at all. They were dayglo yellow and filled the space above the top batten on both sides. They were easy to fit or remove - just a couple of eyelets and a bit of velcro I recall.

Please just remember as my post above, you only need enough to slow the inversion - not totally prevent it.

Edited by Hector - 24 Apr 12 at 7:25pm
Keith
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Hector View Drop Down
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Post Options Post Options   Quote Hector Quote  Post ReplyReply Direct Link To This Post Posted: 24 Apr 12 at 6:57pm
Graeme,
You do not want this thing to float on its side. As JimC says that will at some point result in you being very alone and feeling very small somewhere in the English Channel. The Vortex has a sealed mast - Kite runs external, and the main halyard inside the mast track. It doesn't stop it inverting - thankfully.
I've been seperated from the boat a few times, but can catch it once it inverts. Once however I got seperated but as it inverted quickly started to catch it. I was horrified however when the windage on the hull was enough for it to start to blow over onto its other side  (it was F6+). Putting a spurt on didnt help, as it was soon on its side and blowing away from me very quickly. Being a reservoir I was 'only' 250m from shore, but was only half way there when the rescue boat got to me - TBH I'm not 100% sure I would have made it before cold got to me as while I'm a decent swimmer, swimming in a drysuit is horrible as you're not properly in the water and so sort of flounder about.
-
 
Back to the sealed mast - I never realised how much difference it made to rigting the boat until one day a mate capsized his Vortex. He was there ages and so after the race, I sailed over to see what was wrong (a rescue boat had been near all along). He just couldn't right it - but he was a flyweight and well knackered by then so I assumed that was the issue and jumped in to do it while he sailed my boat back. Now normally, I'd right it in no time. It took ages just to get to 90deg. Once there, no amount of hanging, leaning, rigging righting line, grunting or jumping about would do it. Eventually a 13 stone rescue guy jumped in and two of us had enough weight to do the job - Cue massive jets of water from small holes around the base of the mast. It was full of water - and being 'sealed' it took ages to drain. It later transpired that it wasn't properly sealed at the top, and had filled quite quickly. So in my opinion, sealed is hugely important - especially at the top.
Happy sailing.


Edited by Hector - 24 Apr 12 at 7:02pm
Keith
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RS200 968
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gbrspratt View Drop Down
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Post Options Post Options   Quote gbrspratt Quote  Post ReplyReply Direct Link To This Post Posted: 24 Apr 12 at 6:52pm
You could just take the sail to a sailmakers and ask them to put a pocket at the head of the sail with a custom shaped bit of high density foam in it. once your out sailing I bet very few people would notice it was there and you could take it out when you feel confident.
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Post Options Post Options   Quote rogue Quote  Post ReplyReply Direct Link To This Post Posted: 24 Apr 12 at 6:27pm
Yep, although not sure how he'd launch it off the beach!

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Post Options Post Options   Quote andy101 Quote  Post ReplyReply Direct Link To This Post Posted: 24 Apr 12 at 6:24pm
Pop a keel on it & launch from the harbour - inversion problem 99% over & once the rig is sorted you will have a ball!
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Post Options Post Options   Quote fab100 Quote  Post ReplyReply Direct Link To This Post Posted: 24 Apr 12 at 5:54pm
Turning back to masthead floats for a mo, as well as the balloon type that gets attached to the main halyard and flaps about in the breeze, there is always the Hobie solution...



Whether a whippy 700 mast will take the strain in the way a cat tree-trunk-mast would is an interesting thought of course. When i was a boy, many decades ago, cats had floats that were more like disks/Streetlights than Zeppelins, but I cannot find any pics of those.

Regards not falling in in the first place, I agree with many of the other comments here Graeme. The rig tension needs to be far higher and, no offence, but I think you should sit down with the boat and someone who fits out dinghies regularly (an Int Canoe or even, arf, a Merlin guru) and completely review the controls. You have lavished huge effort into the hull, but you also need to get the rig and controls sorted. In these days of SMODs, this is a skill many of us have lost, if we ever had it in the first place.

Look at ICs for the jib controls but beyond all else, ensure jib and mainsheet tails are spliced, sewn or otherwise irrevocably connected to each other.

If you get all the controls working 100% of the time, 100% perfectly, you could potentially eliminate a fair proportion of swims in the first place - this thing was never going to be easy if you dropped it in - the trip to and from the plate looks a 5.9 on the difficulty scale when the much maligned laser is about a 0.8




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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 24 Apr 12 at 5:48pm
Originally posted by oldarn

Regarding inversion, it is best to minimise the likelihoohy of this happening,


Only if you like being an almost invisible head in the water watching a boat on its side being blown downwind faster than you can swim...

Personally, if there's no-one on board, I want my boat to invert whilst it's still within swimming distance. A large mast with small holes at the top isn't a bad solution to this since it will float for a while, but such masts aren't great when you don't chuck it in these days.
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