Author Topic: Who dunnit?  (Read 34073 times)

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Michael Rogers

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Re: Who dunnit?
« Reply #15 on: 22 Dec 2014, 10:43 »
Peter, I'm not sure what, or where, a gz curve is: and it might be different for the 'big' Swallow boats, though I rather doubt it. I have a CF mast, 15ft long (for a 12 ft hull) and weighing about 2 1/2 kilos. It should have been sealed but wasn't (now definitely is!), and after 2 hours of inversion was pretty full of water. However the leaks were very small, and the inversion happened within about 2 minutes of the capsize. I don't believe a significant amount of theoretical mast buoyancy could possibly have been lost in that time. (Once the boat was upside down, I suppose the extra pressure 15 ft down might have squirted water a bit more quickly into the mast cavity?)

So, whatever the theory, I'm sceptical that a CF mast would prevent, or even delay by very much,  the inversion of a super buoyant and therefore inversion-prone boat.

Graham W

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Re: Who dunnit?
« Reply #16 on: 22 Dec 2014, 11:42 »

So, whatever the theory, I'm sceptical that a CF mast would prevent, or even delay by very much,  the inversion of a super buoyant and therefore inversion-prone boat.

Which suggests that in unusually risky situations, having a Secumar or similar run up the mast or strapped to the top of the yard (on a gunter version of the BR20) could be quite a good idea.

Incidentally, although it was discussed on the Drascombe forum, I don't think the risks of inversion by buoyant boats was supposed to be a problem for Drascombes.  From what I remember (and I can't find it any more), it was a dyspeptic reaction (one of many) to someone daring to suggest that the Swallow Boats deliberate capsize videos indicated that said boats were in any way superior to a Drascombe.
Graham
Gunter-rigged GRP BR20 #59 Turaco III

Peter Taylor

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Re: Who dunnit?
« Reply #17 on: 22 Dec 2014, 14:43 »
Peter, I'm not sure what, or where, a gz curve is: and it might be different for the 'big' Swallow boats, though I rather doubt it.

The gz curve for the BC20 attached) was published in PBO's review (Practical Boat Owner, 526, p39-42, September 2010). A positive number means the boat tries to stay upright, negative means it likes it upside down! It shows that with the ballast tanks full the BC20 has a reasonable self-righting moment even if knocked down flat.  With the tanks empty there might be enough righting moment as the mast dips under at 100 degrees to delay an inversion. But gz curves relate to flat water and calm conditions which is why I used the term "theoretical"! What I think the curves show is that for a BC20, if in doubt, have the tanks full!

With much smaller boats like my 15' Seafly dinghy, righting the boat from a complete inversion is not a problem if the water is deep. However where I sail, getting the mast stuck in the River Itchen mud would be an embarrassing problem! Thats why I fitted a masthead float. The same might be true for some of the smaller SB's in inland or inshore areas.

Peter
Peter Taylor
BayCruiser 20 "Seatern" (009)
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David Hudson

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Re: Who dunnit?
« Reply #18 on: 22 Dec 2014, 18:45 »
I.14 Kirby v, upside down quicker than Reliant Robin?

Expectations or the Alan Clarke's  "actualites"?
David H.
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Michael Rogers

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Re: Who dunnit?
« Reply #19 on: 22 Dec 2014, 18:51 »
Thanks, Peter. Now I can't plead ignorance!

I know Graham brought up that Secumar link for illustration purposes. I haven't looked all that exhaustively but have already found it elsewhere quite a bit cheaper (not sure if that's good grammar). So, as always, it's obviously worth shopping around.

(What an amazing thing this internet 'shopping' is! - applies just as much, if not more, to chandlery-type items.)

Julian Swindell

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Re: Who dunnit?
« Reply #20 on: 22 Dec 2014, 22:02 »
Hobie cats often fit a blimp shaped mast float to the top of the mast. They rotate in the wind, so are meant to be aerodynamic. They look fairly daft, but on a catamaran they make sense.
Like Michael, I have found that my CF mast is not water tight and actually part fills with rain water on the mooring, which is a bit weird. I think you would need to fill it with foam if you wanted reliable buoyancy, but that would increase the mast weight significantly. I keep my tanks full. That plus a very large helping of cowardice has kept me upright for quite a few years so far.
Julian Swindell
BayCruiser 20 Daisy Grace
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Graham W

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Re: Who dunnit?
« Reply #21 on: 07 Mar 2015, 09:20 »
There's currently vigorous speculation on the Drascombe Forum about whether a lack of mainsail boom (or possibly having a mizzen set) contributed to a Lugger's accidental gybe and fatal capsize off Ireland last August. The official accident report is believed to be due shortly. See 'Sad news' in the general section of their forum http://www.drascombe-association.org.uk
Graham
Gunter-rigged GRP BR20 #59 Turaco III

david

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Re: Who dunnit?
« Reply #22 on: 07 Mar 2015, 16:01 »
Hi, I purchased one of the smallest Hobie floats, a few years ago to put on top of of my boat/ 16' dingy. (Prior to my BayRaider). I was surprised at how heavy it was. I ended up not using it and just fitting a regular fender to the mast top with a loop around the mast at the bottom of the fender to keep it tidy on the mast. It looked a little strange without the bottom secured as the fender would flyout when heeling!
Good news was that I never "went turtle" again! Capsize yes, but never completely over again!
David

Ex - BR 20 - Nomad

Peter Taylor

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Re: Who dunnit?
« Reply #23 on: 07 Mar 2015, 18:24 »
Here's a photo of my Seafly with the masthead float I use with the alloy mast... it's a 9l Crewsaver one ( http://www.crewsaver.com/Leisure/p/98/mast-head-float-9l )
and worked on the one occasion I've tested it by accident.  They do do a bulky 40l one which the sailing school uses on their Wayfarers, but 9l that high up on the mast is quite a lot of moment to prevent turtling.
Peter Taylor
BayCruiser 20 "Seatern" (009)
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Michael Rogers

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Re: Who dunnit?
« Reply #24 on: 07 Mar 2015, 20:30 »
Thanks for the picture (nice one!), Peter. Very helpful to see what the smaller Crewsaver mast float looks like in action/situ. I think stretched along the yard up to the peak would be best on my boat.

Tony

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Re: Who dunnit?
« Reply #25 on: 17 Mar 2015, 23:20 »
Old news (2007) but since you asked...... broached my unballasted Cardigan Bay Lugger off the top of a breaking wave. Next big wave rolled us over to 180.  (Sails pushed under by wind on hull? Perhaps, but wave pressure enormous.) Pulled nearest bilge board back out, heaved a little and up she came - totally swamped as cabin hatches were open (!). Dropped main, sheeted in mizzen so sitting head to wind and waves and, if the lockers had been closed (!!) and the bailer  tied on (!!!) could have sailed away without problems. (As it was, things got messy - but that's a much longer story.)

Things to remember.
1 Don't believe dinghy sailors that say they know what to do with a mizzen.
2 Don't trust 'more experienced' sailors who say "It'll be ok. Stop worrying!" It's your boat, not his!
3 At sea, stay with the capsized boat. (My "experienced" helm swam off after his shoulder bag, despite myself and the other crew shouting to him not to. He was out of sight in a minute as the boat blew downwind. He was picked up by a passing cruiser but I didn't find that out until 2hours after we got to shore. I thought he was a goner. )
4 if you are going to capsize in an F6 do it in the Ionian in August. The water's nice and warm.

When running in strong winds, furling the mizzen is a good option and in view of what has been discussed here, I will also consider running a fender up the jib halyard, whatever it looks like.

Graham W

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Re: Who dunnit?
« Reply #26 on: 01 Jun 2015, 21:56 »
There's currently vigorous speculation on the Drascombe Forum about whether a lack of mainsail boom (or possibly having a mizzen set) contributed to a Lugger's accidental gybe and fatal capsize off Ireland last August. The official accident report is believed to be due shortly. See 'Sad news' in the general section of their forum http://www.drascombe-association.org.uk

As far as I know, the Irish report hasn't been issued yet.  Here's another incident at the weekend with a much happier outcome http://www.dailymail.co.uk/news/article-3105635/Pleased-getting-dry-land-Moment-pet-dog-rescued-lifeboat-crew-owner-s-boat-swamped-capsized-Poole-Harbour.html.

It would be interesting to know what caused this one, apart from the weather, obviously.  The RNLI reported that their original salvage pump wasn't big enough to pump the boat out and they had to call for a larger one from another lifeboat that happened to be nearby.  Something similar (without the dog) happened to Webb Chiles when he crossed the Pacific in his Lugger 'Chidiock Tichborne'.  In the photo below the centreboard slot can clearly be seen well below the waterline.  I think this may explain why the RNLI needed to call for a larger pump, to bail out the Poole boat faster than water gushed up through the slot.

It's currently gusting F8 straight up Lake Bala.  Paperwork for me tomorrow.
Graham
Gunter-rigged GRP BR20 #59 Turaco III

Julian Swindell

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Re: Who dunnit?
« Reply #27 on: 01 Jun 2015, 22:07 »
I think the photographs in that article tell me why I feels safer in a Swallow Boat than in a Drascombe. I used to have a Drascombe Dabber, which I loved, but I dreaded ever swamping it as I knew it could barely float and was impossible to bail out. Happily the event never happened.
Julian Swindell
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Peter Taylor

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Re: Who dunnit?
« Reply #28 on: 02 Jun 2015, 06:58 »
The dinghy sailor in me would class that boat as unseaworthy. If you can't bail it out in Poole Harbour, what would you do on the sea?
Peter Taylor
BayCruiser 20 "Seatern" (009)
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Jonathan Stuart

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Re: Who dunnit?
« Reply #29 on: 02 Jun 2015, 08:44 »
I seem to remember an erstwhile prolific forum contributor had strong views, which he shared here and on the Drascombe forum, on Drascombes' buoyancy and he questioned the changes made to achieve RCD compliance. Unfortunately I think he had a good point and this incident and others support that.
Jonathan

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