# Racing in current



## Sailormon6 (May 9, 2002)

I need help coping with currents, in particular, on the Chesapeake Bay. What websites do you use before a race to plan for currents? 

What is the best way to enter a river in a rising and in an ebbing tide? In the center? Along the shore? Tack back and forth across the current? Sail straight against the current, if the wind direction permits? A couple of times, I had to tack back and forth to enter the river, and the current carried the boat so far down current that I couldn't make headway. 

I always raced where there were no currents, and the currents on the Bay are killing me. Please help with all your best tips!


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## sharkbait (Jun 3, 2003)

In SF Bay we used tide books that were free at marinas


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## Faster (Sep 13, 2005)

There used to be such a publication.. maybe you can scare up a used copy.

Chesapeake Bay Tidal Atlas


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## paulk (Jun 2, 2000)

Lots of rules of thumb about current. It tends to run fastest where it's deepest. Slower by the shore. Local geography (bottom & shore contours) will play a part in the directions it takes going in and out. Long-term wind patterns can also boost current by pushing water so that it piles up higher at high tide (so that it runs faster when it goes out because there's more water to go out) or reduce current by pushing against it and reducing the amount of water that piles up. Plenty of stuff happening all the time with current. Just wait until you get to the Gulf Stream.


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## RobGallagher (Aug 22, 2001)

Eldridge. At least in New England the Old Captain was as smart as any new application. Probably smarter.


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## RichH (Jul 10, 2000)

Faster said:


> There used to be such a publication.. maybe you can scare up a used copy.
> 
> Chesapeake Bay Tidal Atlas


This was originally published by the Maryland Dept. of Nat. Resources and was included in Maryland's "Chesapeake Chart Booklet". Has not been published since the ~mid 90s.

The tidal current pages (2 to 4 ?) graphically (vectors) listed historical current speeds in 'hourly intervals' between high & low and from low to high tide MLW to MHW and the reverse (and from actual hydraulic survey) in the 'flats', shallows, river entrances, 'lumps', narrows, in proximity to the few islands, etc. etc. etc., also including the main shipping channels and anyplace there was a robust change in the bottom contour/depth --- ALL the Maryland portion of the Chesapeake and including the Potomac, Patuxent, Patapsco, Chester Rivers.

Ask your fellow racers or long term neighboring Ches. cruisers if they still have a copy. You may find an old copy in one of the local small town libraries.


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## jsaronson (Dec 13, 2011)

OpenCPN Nobeltec and others show currents at multiple points in the bay at any time in the future.


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## SVAuspicious (Oct 31, 2006)

Sailormon6 said:


> I need help coping with currents, in particular, on the Chesapeake Bay. What websites do you use before a race to plan for currents?


First, good for you to understand that tides and currents are different out-of-phase things.

The bad news is that there isn't really anything you can do for sure to predict things without spending a lot of things.

The best data available is from NOAA ( NOAA Current Predictions - Current Predictions ). The problem is that water moves around in the Chesapeake driven by wind more than driven by lunar tides. If predictions are for .5 kt N current but the wind has been blowing hard from the North for a day or so (water still blowing out of the Bay and inertia building) you might see .5 kt S current. Just to make things more interesting, if it's been raining hard in Pennsylvania for a week and the dams up the Susquehanna are dumping water then everything is going to be moving South. Water flow in tributaries like the Severn and Potomac will increase as it is sucked out into the flow from the Bay.

You can use current predictions from NOAA as a base and pay attention to wind over time (going back a week is fine) and rainfall (same) and make some assessments. That may be enough to at least tell you which side of the Bay to favor.



paulk said:


> Lots of rules of thumb about current. It tends to run fastest where it's deepest. Slower by the shore. Local geography (bottom & shore contours) will play a part in the directions it takes going in and out. Long-term wind patterns can also boost current by pushing water so that it piles up higher at high tide (so that it runs faster when it goes out because there's more water to go out) or reduce current by pushing against it and reducing the amount of water that piles up. Plenty of stuff happening all the time with current. Just wait until you get to the Gulf Stream.


All true. Much more complicated though.

The good news is in most cases the whole fleet is subject to the same conditions. Watch who does well and compare where they go to the conditions. Someone in the after guard can take notes for later review. You can also pick the winners brains afterwards in the bar while they are high on endorphins.


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## MarkofSeaLife (Nov 7, 2010)

There will be some old dude who is 97 in the slowest boat but wins every race. That's the old guy who knows where every current deflecting rock is.
So get your hourly tidal charts and go talk to him - if he will talk. If he won't then get him drunk


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## Stu Jackson (Jul 28, 2001)

Good question. The basic answer, embedded in the answers so far, is basically: learn to use them to your advantage.

This, like sailing itself, is a PROCESS, and does not come overnight.

I've sailed on SF Bay for 35 years, and it took me many, many years to learn how things work around here.

Read, read, read. Even the basic books, like Chapmans and Duttons, include great articles on "current sailing." 

Even more important is to go out and practice. Until you get the hang of what happens in your neck of the woods when it ebbs and when it floods, all the reading will not help you at all.

Learn how to use the VMG function of your GPS for both true wind and next waypoint indications.

Good luck.


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## Hudsonian (Apr 3, 2008)

One way to gain insight into currents is to watch the way boats swing on their moorings. Generally current changes first near the shore and the change works its way out to the middle. 

There is a tidal atlas similar to the Chesapeake atlas referenced above. Frequently you can use the atlas to estimate how far off shore is optimal.


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## FSMike (Jan 15, 2010)

Google the "rule of twelfths".


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## killarney_sailor (May 4, 2006)

You start with published guides after that it becomes a matter of the vaunted 'local knowledge' and that can take years to acquire. Many years ago we did the Nonsuch 'Worlds' off Martha's Vineyard. Coming from the Great Lakes we knew next to nothing about sailing with tides and currents. After a couple of races we noticed two older gentlemen who were doing really well in a fleet of 50 Nonsuch 30s. We started to what they did including anchoring for an hour in the middle of a race in light air. We actually gained a few hundred yards on the boats that get sailing. Turns out they were locals who had been medalists in sailing in the '52 Olympics so a deadly combination of great sailors and local knowledge. They won the regatta we came fourth. If we started emulating them earlier we would have been second.


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## Ulladh (Jul 12, 2007)

Navionics has current speed and direction predictions, but you still need to learn local conditions where bottom and edge conditions will speed, slow or reverse. Predictions don't include effects of pressure change, wind and rain driven river flood, and seasonal changes in sand or mud shoals.


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## hellosailor (Apr 11, 2006)

Any book about sailboat racing, as a whole, not just "racing trim" or "racing tactics", should have a section covering currents and how to deal with them. How to figure for offsets, how to determine where current will be strongest. And regardless of the rules about current, "local knowledge" often is the most important part.

The "E6B Flight computer" used by aircraft navigators to compensate for crosswinds, looks like two plastic discs set on a pivot. Still used, and also sold in marine versions by Weems & Plath, I think. There are also applets that do the same job. I mention that because it is still the basis of compensating for any type of current, it factors in the offset, and that tells you the direction you "really" want to go in, in the simplest most graphic way.


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## SchockT (May 21, 2012)

While looking at current charts and other publications can't hurt, there really is no substitute for local knowledge. Charts aren't going to show every little eddy and current river that happens in specific conditions, but you can bet that the experienced racers have figured a lot of them out! Watch where the front runners go, and where they DON'T go! If they tack away when they are on a lift, there is probably a good reason for it! 

I have always relied on my own eyes more than current and tide charts. I care more about the wake I see on a crab trap float than I care what a current table says "should" be happening. Flotsam accumulations can show you where there is an eddy or current transition. Watch your GPS VMG when you cross tide lines, and if the number goes up, keep going, if it goes down, get back to the other side of the line again!


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## Faster (Sep 13, 2005)

Another good hint is to watch (closely) the tow boat operators. Tugs towing booms and heavy scows and barges will also know where the 'fast' and 'slow' waters are at any given time.. for them its $$$$ and schedules to keep.

One of the best tactical sailors I ever raced with was a tow boat skipper.


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## Sailormon6 (May 9, 2002)

I knew I'd get good ideas from you guys. Thanks! 

I've bookmarked the websites you recommended, re-read some of my old "How to Race" books, and will check Annapolis area used bookstores and Goodwills for the out-of-print publications. I also need to start using the VMG function on my chartplotter.


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