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16-10-2017, 02:51
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#1
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Registered User
Join Date: Sep 2008
Location: On the boat, somewhere in Australia.
Boat: Swanson 42 & Kelly Peterson 44
Posts: 9,112
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Navigation challenge - hitting a bullet with a snail?
OK, this may become one of my silliest posts yet... but please, hear me out.
This summer (December in the Southern Hemisphere), the Volvo Ocean Race boats will sail from Cape Town to my old home town, Melbourne.
Let me tell you, as a Melbourne boy, born and raised... I have no idea why they are sailing to Melbourne. But they are. They probably have a good reason.
Anyway, I will be in Adelaide as they sail past to the South of me, and I am wondering if it would be possible to sail out there into Bass Straight and actually watch them sail past. As in, get them in sight at least.
Initially I thought "Not a chance." I mean my boat does 6 knots on a good day, and those things are doing 25 or more.
But... then... I only have to sail North/South, to intercept them... and their location and course are pretty well known in near real time.
What do you navigator types think? Possible?
Oh, and I already know the idea is totally silly, so no need to point that out. I mean it could be dark, the weather could be wrong (though that's a decent time of year for the weather in that area), etc etc. Just trying to figure out if the degree of course variation those boats display makes it possible to get them in sight. And I get a few tries at it, there's what, half a dozen of them or more. (If none have run aground or broken masts by that stage.)
Matt
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16-10-2017, 03:15
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#2
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Moderator and Certifiable Refitter
Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: C.L.O.D.
Posts: 20,242
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Re: Navigation challenge - hitting a bullet with a snail?
Quote:
Originally Posted by GILow
OK, this may become one of my silliest posts yet... but please, hear me out.
This summer (December in the Southern Hemisphere), the Volvo Ocean Race boats will sail from Cape Town to my old home town, Melbourne.
Let me tell you, as a Melbourne boy, born and raised... I have no idea why they are sailing to Melbourne. But they are. They probably have a good reason.
Anyway, I will be in Adelaide as they sail past to the South of me, and I am wondering if it would be possible to sail out there into Bass Straight and actually watch them sail past. As in, get them in sight at least.
Initially I thought "Not a chance." I mean my boat does 6 knots on a good day, and those things are doing 25 or more.
But... then... I only have to sail North/South, to intercept them... and their location and course are pretty well known in near real time.
What do you navigator types think? Possible?
Oh, and I already know the idea is totally silly, so no need to point that out. I mean it could be dark, the weather could be wrong (though that's a decent time of year for the weather in that area), etc etc. Just trying to figure out if the degree of course variation those boats display makes it possible to get them in sight. And I get a few tries at it, there's what, half a dozen of them or more. (If none have run aground or broken masts by that stage.)
Matt
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Well if you are going as far as Bass Strait, jill around Cape Otway and you are sure see a couple of them; if not, nip up to Point Lonsdale.
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
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16-10-2017, 03:17
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#3
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Registered User
Join Date: Sep 2008
Location: On the boat, somewhere in Australia.
Boat: Swanson 42 & Kelly Peterson 44
Posts: 9,112
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Re: Navigation challenge - hitting a bullet with a snail?
Quote:
Originally Posted by Wotname
Well if you are going as far as Bass Strait, jill around Cape Otway and you are sure see a couple of them; if not, nip up to Point Lonsdale.
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Yeah, getting a bit close to Melbourne for my taste. I am currently stuck here in Melbourne, have been for a while. Totally can't wait to get home. Certainly not keen to sail back.
I made the mistake of smiling at dad's neighbour today. I swear she looked at me like I was about to expose myself and I am sure she was reaching for the pepper spray. I ran back inside the house and hid for a while.
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16-10-2017, 03:18
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#4
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Registered User
Join Date: Sep 2008
Location: On the boat, somewhere in Australia.
Boat: Swanson 42 & Kelly Peterson 44
Posts: 9,112
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Re: Navigation challenge - hitting a bullet with a snail?
Quote:
Originally Posted by Wotname
Well if you are going as far as Bass Strait, jill around Cape Otway and you are sure see a couple of them; if not, nip up to Point Lonsdale.
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More importantly, there'd be something really special about seeing them out in the open ocean.
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16-10-2017, 03:20
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#5
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Registered User
Join Date: Sep 2008
Location: On the boat, somewhere in Australia.
Boat: Swanson 42 & Kelly Peterson 44
Posts: 9,112
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Re: Navigation challenge - hitting a bullet with a snail?
If they are navigating the Rip, I wonder if they'll wait for the tides...
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16-10-2017, 08:54
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#6
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Registered User
Join Date: Sep 2014
Location: Manila, California
Boat: Cape George pilothouse 36 and a Cape Dory 25
Posts: 608
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Re: Navigation challenge - hitting a bullet with a snail?
Just your brand of boat pretty much guarantees success.
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16-10-2017, 09:09
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#7
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Registered User
Join Date: Feb 2014
Location: richards Bay, South Africa
Boat: voyage Mayotte 50 ft cat
Posts: 165
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Re: Navigation challenge - hitting a bullet with a snail?
Not a silly idea at all. There is an enjoyable interception navigational calculation that you can do to intercept them. You require their track and speed as well as your starting point and speed. The arc will give you an exact intersection point. see OIC-NW Reviewer Blog: Course To Intercept Vessel
Regards
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16-10-2017, 09:14
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#8
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Registered User
Join Date: Feb 2013
Location: Bumping around the Caribbean
Boat: Valiant 40
Posts: 4,625
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Re: Navigation challenge - hitting a bullet with a snail?
How long will it take you to reach an intercept point? Their track and ETA will be relatively easy to forecast given the accuracy of the tracker; put that together with a weather forecast and it comes down to whether you want to go or not and how long you need to leave in order to get there. Yes you may be bobbing around for a few hours but if it's daylight and the weather is acceptable then it all comes down to whether it's worth the trouble to you. Would be interesting for sure.
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16-10-2017, 10:42
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#9
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Registered User
Join Date: Mar 2011
Location: fl- various marinas
Boat: morgan O/I 33' sloop
Posts: 1,447
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Re: Navigation challenge - hitting a bullet with a snail?
It's not rocket science. Pick the closest point that is on their course. Calculate when they will reach it. Using the distance to the selected interception point and your average speed calculate a departure time. Subtract a few hours for errors and you have your departure time, course and speed.
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16-10-2017, 11:00
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#10
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Registered User
Join Date: Mar 2007
Location: Santa Cruz
Boat: SAnta Cruz 27
Posts: 6,683
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Re: Navigation challenge - hitting a bullet with a snail?
I'm pretty sure the racers are going to be broadcasting AIS, which should simplify the intercept.
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16-10-2017, 11:19
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#11
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Registered User
Join Date: Sep 2008
Location: On the boat, somewhere in Australia.
Boat: Swanson 42 & Kelly Peterson 44
Posts: 9,112
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Re: Navigation challenge - hitting a bullet with a snail?
Well, nobody thinks I'm mad, or they are too polite to say so, which is nice.
But, watching these boats I am just no so sure about the whole course thing. They seem to weave about a bit. Sure their overall course is reasonably steady but is it really likely I can get within a half mile of them, which I think would be the maximum distance you'd want to make it worthwhile.
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16-10-2017, 11:20
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#12
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Registered User
Join Date: Sep 2008
Location: On the boat, somewhere in Australia.
Boat: Swanson 42 & Kelly Peterson 44
Posts: 9,112
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Re: Navigation challenge - hitting a bullet with a snail?
Quote:
Originally Posted by YPSILANTI
Not a silly idea at all. There is an enjoyable interception navigational calculation that you can do to intercept them. You require their track and speed as well as your starting point and speed. The arc will give you an exact intersection point. see OIC-NW Reviewer Blog: Course To Intercept Vessel
Regards
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Good stuff!
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16-10-2017, 14:41
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#13
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Registered User
Join Date: Dec 2012
Location: Mannum, Australia
Boat: Houseboat, 60ft.
Posts: 290
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Re: Navigation challenge - hitting a bullet with a snail?
Pretty sure most sail a long way South, go below tassie & head up the East coast to Sydney. Not sure about destination Melbourne though.
I know Jessica Watson went way South so there was much less chance of hitting ships at night on auto pilot.
Might be more favourable winds more South too perhaps?
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16-10-2017, 14:50
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#14
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Moderator
Join Date: Nov 2011
Location: aboard, cruising in Australia
Boat: Sayer 46' Solent rig sloop
Posts: 28,400
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Re: Navigation challenge - hitting a bullet with a snail?
Quote:
Originally Posted by GILow
If they are navigating the Rip, I wonder if they'll wait for the tides...
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Depends where the finish line for the leg is located, and that's probably on their website.
Anyhow, I don't think pepper spray is legal in Oz. Instant antipathy is hard to take.
Ann
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Who scorns the calm has forgotten the storm.
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16-10-2017, 15:15
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#15
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Registered User
Join Date: Sep 2008
Location: On the boat, somewhere in Australia.
Boat: Swanson 42 & Kelly Peterson 44
Posts: 9,112
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Re: Navigation challenge - hitting a bullet with a snail?
They are going to stop over in Melbourne so that means they'll go North of Tassie unless all the navigators trained on Vestas Wind. :^)
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