Island Time 1,235 Posted October 8, 2016 Share Posted October 8, 2016 I'm starting to think about tactics etc for the coastal classic. I'd like some tidal flow info for the coast from Auckland to BOI. I've got this info (chart for each hour after high water etc) for cook strait, but surely there is something similar for this area? Who's got something? Also interested in general comments from those who have done this race before ( I haven't)... Thx Quote Link to post Share on other sites
Kevin McCready 83 Posted October 9, 2016 Share Posted October 9, 2016 On the Spirit of NZ, it's the morning job of the cadet under supervision of the Third Mate to calculate daily tidal flows for where the ship will be. I'm sure they'd be happy to share the recipe and adjustments they may make for deviations from predictions. And I'm sure you know about the occasional tidal flow notations on the paper charts. I'm assuming ECDIS systems have the same? Quote Link to post Share on other sites
eruptn 95 Posted October 9, 2016 Share Posted October 9, 2016 IT there are a few science papers around, I'm sure NIWA has lots of info, maybe trawl the web page Here is a 'global' over view; http://www.tandfonline.com/doi/abs/10.1080/00288330.2001.9517023 http://journals.ametsoc.org/doi/full/10.1175/1520-0485%282001%29031%3C2917%3ATDOTEA%3E2.0.CO%3B2 http://www.tandfonline.com/doi/abs/10.1080/00288330.1985.9516077 Bay of Islands; http://www.tandfonline.com/doi/abs/10.1080/00288330.1974.9515537 There must be heaps more out there. Quote Link to post Share on other sites
Island Time 1,235 Posted October 9, 2016 Author Share Posted October 9, 2016 Thanks guys, yeah, got the info from the charts etc and a bit more from online. Still working on it... Quote Link to post Share on other sites
khayyam 68 Posted October 9, 2016 Share Posted October 9, 2016 Have you got these? Quote Link to post Share on other sites
Island Time 1,235 Posted October 9, 2016 Author Share Posted October 9, 2016 Not all of them khayyam, only the first 5 hours after high water Auckland. Do you have the whole set? Thats what i'm looking for... Quote Link to post Share on other sites
Clipper 343 Posted October 9, 2016 Share Posted October 9, 2016 Where do they come from? Id like to see those too... Quote Link to post Share on other sites
Jon 360 Posted October 9, 2016 Share Posted October 9, 2016 What you really need to know is what's happening with the warm current that runs down the east coast. It's often close to cape Brett then runs outside the Hen & Chicks then outside the Mokes then kicks south at the needles The catch is sometimes it runs inside the H&Cs and therefore speeds up so that makes going outside beneficial, but rarely it runs the other way ie south to north. It's usually not that fast at this time of year but speeds up as the warm currents come out of the pacific The other major area of concern is tidal flow at bream head Other than that sail north and turn left at the Cape, but inside or out of Piercy Is ? Quote Link to post Share on other sites
B00B00 310 Posted October 9, 2016 Share Posted October 9, 2016 As far as Auckland tides go, the thing to remember is that the 'sink hole' is actually the firth of Thames not Auckland harbour so the incoming and outgoing tide is relative to that rather than Auckland harbour itself. Therefore the current in Tamaki strait runs the oposite to what you think, ie outgoing tide has current running towards Auckland and incoming tide it runs away from Auckland. 1 Quote Link to post Share on other sites
khayyam 68 Posted October 9, 2016 Share Posted October 9, 2016 Not all of them khayyam, only the first 5 hours after high water Auckland. Do you have the whole set? Thats what i'm looking for... Tidal atlas for the Hauraki Gulf and Greater Cook Straight, ed: R Garrett. I also only have high tide to high tide + 5. I think the idea is to reverse the charts for the incoming cycle? Quote Link to post Share on other sites
Island Time 1,235 Posted October 9, 2016 Author Share Posted October 9, 2016 Tidal atlas for the Hauraki Gulf and Greater Cook Straight, ed: R Garrett. I also only have high tide to high tide + 5. I think the idea is to reverse the charts for the incoming cycle? Yeah, I thought about that. I know the ones for cook strait are not reversals though.... Attached is what I have for Hauraki Gulf Tide Maps Hauraki.pdf Quote Link to post Share on other sites
Magique 3 Posted October 10, 2016 Share Posted October 10, 2016 From about 3 days out the Navionics app will give tidal flows at various locations for all times. Quote Link to post Share on other sites
Island Time 1,235 Posted October 10, 2016 Author Share Posted October 10, 2016 yeah, got that... but no info on stream paths, eddies etc etc, just point data. Quote Link to post Share on other sites
jay 3 Posted October 10, 2016 Share Posted October 10, 2016 These two websites have free ocean current models: https://www.windytv.com/?currents,2016-10-15-21,-35.299,174.375,8 https://windria.net/auckland-nz (click on the "currents" tab) Not sure how reliable they are?? particularly as one gets closer to east coast, but interesting to study. General NZ current diagram - http://calib.qub.ac.uk/marine/currents/NewZealand.html I have observed southerly current approaching 1/2 kt between brett and poor knights. I suspect Jon is right about east auckalnd current not being as strong this time of year. Quote Link to post Share on other sites
Steve Pope 243 Posted October 10, 2016 Share Posted October 10, 2016 I have seen yachts (with I suspect, local knowledge) sailing North between Whangaruru and Cape Brett curve in towards Whangamumu before reversing the curve as they neared the peninsular, heading out to Cape Brett. They literally sailed away from us, we were headed directly for Cape Brett, I didn't check, but it would suggest that the tidal flow was southerly and there is an eddy that rotates inshore of the Cape. Quote Link to post Share on other sites
Jon 360 Posted October 10, 2016 Share Posted October 10, 2016 I have seen yachts (with I suspect, local knowledge) sailing North between Whangaruru and Cape Brett curve in towards Whangamumu before reversing the curve as they neared the peninsular, heading out to Cape Brett. They literally sailed away from us, we were headed directly for Cape Brett, I didn't check, but it would suggest that the tidal flow was southerly and there is an eddy that rotates inshore of the Cape. Most likely Steve But don't stay in too long or you will fall into the wind shadow between Whangamumu and the Cape "Shot the gap" or 'round the out side like a buffalo girl' ????? That's the real question, I've always gone through and said next time I'm going around ???? "The definition of insanity is to keep doing the same thing but expect a different result" Quote Link to post Share on other sites
smithy09 50 Posted October 19, 2016 Share Posted October 19, 2016 Most likely Steve But don't stay in too long or you will fall into the wind shadow between Whangamumu and the Cape "Shot the gap" or 'round the out side like a buffalo girl' ????? That's the real question, I've always gone through and said next time I'm going around ???? "The definition of insanity is to keep doing the same thing but expect a different result" Went around last time the Marshall did it and got killed... Good luck!! Quote Link to post Share on other sites
ScottiE 174 Posted October 19, 2016 Share Posted October 19, 2016 Haven't you lot figured it out yet - it works like this The guy in front will go round - and get it right The guy behind will go through - and also get it right It doesn't matter which way you go - you're guaranteed to f**k it up! Quote Link to post Share on other sites
Sail Rock 28 Posted October 31, 2016 Share Posted October 31, 2016 Here's a tip for the next time you are crossing Bream Bay: check the direction of any anchored ships. They normally lie to the current except around the slack with a strong wind. The current at either end of the Hen and Chicks is generally Northwards on the ebb and southwards on the flood. Quote Link to post Share on other sites
nickt 0 Posted November 16, 2021 Share Posted November 16, 2021 On 9/10/2016 at 9:43 PM, khayyam said: Have you got these? Hi Khayyam, Where did you find these? Exactly what I'm looking for. Quote Link to post Share on other sites
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