bas 0 Posted February 2, 2012 Share Posted February 2, 2012 Viking can fit at Low water Since her mast was extended, Viking can only get under on a very low spring tide. Link to post Share on other sites
wheels 543 Posted February 2, 2012 Share Posted February 2, 2012 Could you imagine the carnage on the motorway if suddenly they spied a Woman levetating at road level at the side of the bridge. Link to post Share on other sites
Nate 2 Posted February 2, 2012 Share Posted February 2, 2012 I have it on reasonable authority that Greenhithe bridge has 20m clearance at 1.0m tide. We will be testing that next week to within a couple hundred mm so will find out for sure... Link to post Share on other sites
wheels 543 Posted February 2, 2012 Share Posted February 2, 2012 Annnnnd there ya see. Another differing report on the height. Good luck on that Nate. Link to post Share on other sites
rigger 47 Posted February 3, 2012 Author Share Posted February 3, 2012 I have it on reasonable authority that Greenhithe bridge has 20m clearance at 1.0m tide. We will be testing that next week to within a couple hundred mm so will find out for sure... MHWS 3.32m your low tide 1.0m your height + your low tide = height from chart datum = 21m 17m (charted height) + 3.22 (MHWS) = height from chart datum = 20.22m NOTE: MHWS has changed over time. Link to post Share on other sites
Nate 2 Posted February 7, 2012 Share Posted February 7, 2012 Our masthead is 20m off the water, and today we went under the Greenhithe bridge with around 80mm to spare 20 min before a low tide of 0.9m. So there you go. Link to post Share on other sites
Guest Posted February 7, 2012 Share Posted February 7, 2012 DId you have someone at the masthead watching? Link to post Share on other sites
rigger 47 Posted February 7, 2012 Author Share Posted February 7, 2012 Have been told the air draft figures all have a small amount of fudge factor to allow a safety factor. Good to know your boat can fit Link to post Share on other sites
wheels 543 Posted February 7, 2012 Share Posted February 7, 2012 80mm, blimey! That must have been slightly nerve racking. You wouldn't want some idiot in a speed boat around. Link to post Share on other sites
ab1974 1 Posted February 7, 2012 Share Posted February 7, 2012 With about 80mm to spare I suspect if you had been at the mast head you would have thought it was going to hit until the exact moment that it didn't! That would be very tricky to judge. Not much room for error there Nate. Well done good to know. Suspect my 13m will be just fine then! Link to post Share on other sites
wheels 543 Posted February 8, 2012 Share Posted February 8, 2012 Sonmethign I discovered last weekend, was that everytime i come back in (heading upstream to Hobsonville) under the Harbour Bridge, all my instruments lock up. Thats GPS, Log and wind. Navman and Northstar. Four units plus the GPS. They lose all the numbers and the needle on the wind instrument goes to 12oclock and they lockup. I have to turn power off to them and back on again. I have had it happen everytime, but never noted where exactly it happened before. Till thistime i went below to the GPS and the screen was still stuck on the chart with boat right under the bridge. Most strange. Link to post Share on other sites
Nate 2 Posted February 8, 2012 Share Posted February 8, 2012 Yes we had someone at the mast head and yes it was nerve-racking! The underside of the bridge is very flat and level transversely, so with the mast head at eye level you were able to judge clearance by whether you were able to see the underside of the bridge or not. Still a big call to make, but on the second 'fly by' the young fella up the rig called it and through we went. Not planning to do it again anytime soon. Link to post Share on other sites
Deep Purple 512 Posted March 4, 2013 Share Posted March 4, 2013 Sonmethign I discovered last weekend, was that everytime i come back in (heading upstream to Hobsonville) under the Harbour Bridge, all my instruments lock up. Thats GPS, Log and wind. Navman and Northstar. Four units plus the GPS. They lose all the numbers and the needle on the wind instrument goes to 12oclock and they lockup. I have to turn power off to them and back on again. I have had it happen everytime, but never noted where exactly it happened before. Till thistime i went below to the GPS and the screen was still stuck on the chart with boat right under the bridge. Most strange. Happened to me Sunday on a little sail up to Herald Island and back. After the harbour bridge, the log stopped working, switched it off and on and working fine again Link to post Share on other sites
Deep Purple 512 Posted March 4, 2013 Share Posted March 4, 2013 How much clearance under the Greenhithe bridge ? Plenty of room for a 930 (about 14m all up) and I've taken my 1020 under there as well Link to post Share on other sites
k88 7 Posted March 4, 2013 Share Posted March 4, 2013 A 80ft tall mast can easily clear a 60ft bridge; http://www.whatsonxiamen.com/health3340.html Link to post Share on other sites
John B 106 Posted March 4, 2013 Share Posted March 4, 2013 We popped through the southern arch at the knights again this year.. thats tense fun, and there's always some swell. Link to post Share on other sites
Guest Posted March 4, 2013 Share Posted March 4, 2013 How big a boat John B?? I was looking tfor the vertical clearance on the bridge earlier this week, should have known Crew.org.nz would hav ethe answer!! My thoughts were that if the America's Cup course went under the bridge and around Ponui, then the boats would be naturally limited on height and drft and there's be no need for any other "rules" on design. Link to post Share on other sites
John B 106 Posted March 4, 2013 Share Posted March 4, 2013 45 ft. There's 90 ft through the arch according to Darcy. But I cheated. I dithered and let me mate go through first ,and that confirmed the spare half mast height or so. Link to post Share on other sites
Guest Posted March 4, 2013 Share Posted March 4, 2013 A quick scan of my sailplan says 16m luff length, so say max 19 to w/l. Still don't feel good about it - maybe if I followed you. Link to post Share on other sites
John B 106 Posted March 4, 2013 Share Posted March 4, 2013 If you believe the 90 ft/27 M ,then you have plenty to spare. Our air draft is around 17 so we had tons of room for error, plus the similar height rig pioneering for us. ' course there's always the swell rise and fall...... Link to post Share on other sites
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