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-   -   Can't get there from here!! (http://www.sailnet.com/forums/seamanship-navigation/76999-cant-get-there-here.html)

davidpm 07-31-2011 12:18 AM

Can't get there from here!!
 
1 Attachment(s)
This picture show today's trip.
This is Long Island Sound.
The trip was leg 1 almost due south.
Then we had to return.
Leg 2 started off pretty good but as you can see I angled west as I neared land.
Leg 3 started ok also but again I angled east after a while.
Leg 4 was motoring the last mile.

My question is why do legs 2 and 3 start off good then angle off.
I was heading up as much as I could during the whole exercise
Current was from the west at about 1.5 and wind was from the north at about 15.
I was reefed and the boat was handling well. Good control no drama. Catalina 25 with worn sail and no traveler.
The ? marks label the segment of the track on leg 3 and leg 4 where I lost about 20 degrees which is my puzzle.
There is another unlabeled track from a previous day, please ignore.

I want to blame it on the current but is it really reasonable that the current will get worse I get closer to land?

acunningham 07-31-2011 08:21 PM

Were you "headed" by the wind changing direction more towards your bow?

davidpm 07-31-2011 08:27 PM

That would be a good theory but if so I've the worst luck ever as it happened twice in the opposite direction.
I had the problem on leg 3 and leg 4.

acunningham 07-31-2011 08:36 PM

Was it perhaps a gusty day, with variable wind directions? If so, you may just have been unlucky.

davidpm 07-31-2011 09:13 PM

Quote:

Originally Posted by acunningham (Post 756986)
Was it perhaps a gusty day, with variable wind directions? If so, you may just have been unlucky.

Wow you are a nice guy, haven't been around long have you. :)

It could be just bad luck but my current theory is that I was pinching it so much that my speed slowed to the point where the current was having its way with me.
I'm going to review the track log again and check my speed. I remember checking the gps and if I remember correctly I was doing at least 3knots.
That may not help my theory though.

HPLou 07-31-2011 09:20 PM

It could be the current was picking up speed when you got out of the lee of Faulkner Island. With the pinching, the boat will lose forward speed and the current will have more of an impact on the boats direction.

CalebD 07-31-2011 09:43 PM

David,
If I know you and I think I do, you were not popping open beers the whole way but paying attention to your course.
I'm pretty sure that HPLou is on to something with the current building to the east (ebb) and moving around Faulkner Isl.
Is your Cal 25' the fixed keel or center board variety?
My best.
Caleb

davidpm 08-01-2011 08:17 AM

fixed keel

davidpm 08-01-2011 01:17 PM

OK that's a good theory eb current around Falkners but leg three is still a puzzle to me.

Leg three started out great. But as you can see I had to veer west for the last few hundred yards. Why? If the current was comming from west to east it should have curved me to the west especialy if I was slowing down pinching too much.

Unless it is the kind of thing where the current was right on the nose and if it got just to starboard of the boat it would push me west.
The good thing is that I've got the track so can obsess over this untill I figure it out.

I'm going to check the current directions for that area and see just how variable the directions are. I usually think of the current as more or less following the coast but maybe not. Obviously when it gets to inlets it has to change direction radacally to go up the inlet. This must cause local direction changes the closer you get to the shore.

Part of my problem is that leg 3 started out just the way I planned it. If it started wrong I would just have accepted that I misjudged the wind and/or current. What bothers me is that it started exactly as I planned but I veered off west the last bit.

The other half of the problem is that I had exactly the same issue with leg 4. Started off great then I veered off but east this time. This actually make sense as the current was going east.
But why did I get hurt both ways?

I've got my speed and location's on the whole track so I'm thinking I can plot out whole thing and maybe I can find a current speed and direction that would explain the behaviour.
Copping out and calling it a wind shift sounds too unplausable to me.

CalebD 08-01-2011 07:27 PM

David,
Two things.
While the current does essentially follow the coast line there are eddies and counter currents closer to shore and around obstacles like Faulkner Island. This is true even in the Hudson River which may have stronger currents then the LI Sound.

The other thing is a question about the track you uploaded. Should I assume it is from your GPS? We use our Garmin GPS during races and it saves many of our previous tracks. I'm wondering if this is where the leg you marked with a "?" came from. There are also moderate wind shifts that occur which would help explain the not so 'erratic' course you show.

I applaud your attempt at figuring out how this deviation may have happened as it may help you navigate more precisely in the future. It also may not as the conditions vary from day to day. One thing you can do is to monitor your GPS and heading to see when you are getting 'headed' and tack to the other point of sail.


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