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Catalina/Capri 25/250 Sailor's Forums

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Shinnecock Locks question

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jerlim
Master Marine Consultant

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USA
1484 Posts

Initially Posted - 08/14/2009 : 09:56:22

I'm planning on going through the locks and have read a warning to "...be aware of possible very swift moving currents while transiting the Locks and Canal area..."

We've got an 8hp OB and I'm concerned that won't be enough power through...of course the 'swift moving currents' are not defined in terms of speed. Does anyone have any experience transiting the Shinnecock Locks...any thoughts on the adequacy of our OB?
MANY THANKS!!

Jerry

Edited by - jerlim on 08/14/2009 09:56:50

Voyager
Master Marine Consultant

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5376 Posts

Response Posted - 08/14/2009 : 18:49:18

If you have a dinghy that you can strap the engine to, give the canal a try using the dink. That will give you an idea of the strength of the currents.

If you go in concert with the tides, the current will push you through the canal. Once the lock fills, the current stops. Remember that if you reverse your engine, prop-walk will make the boat move to the side, so put your fenders out on both sides.

Make sure to test with the dink when the currents are majorly strong. You can chart these times using your favorite tidal current website, or check the tide charts for extremely high & low tides. This usually occurs a day or two +/- around the time of the new moon, with lesser tidal ranges around the full moon. This weekend is ideal, because tidal currents are much lower around the time of 1st quarter and last quarter (now).

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Dave Bristle
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Djibouti
10005 Posts

Response Posted - 08/14/2009 : 19:20:30

I've heard that in some tide state, they leave the lock open and the current in the canal is five knots or greater. I'd find out about that--my boat could handle it--yours could have a problem.

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Voyager
Master Marine Consultant

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Response Posted - 08/15/2009 : 21:10:31

Five knots opposing a C-25 will make it go full speed ahead, but you'll be going in reverse!

When I'm in peak current in the Housatonic at 4 knots, I barely make any headway with an 8 HP at full throttle. Forward progress is painfully slow.

On the other hand, if you're going <i>with</i> the tides and need to stop, you may not be able to, especially in full reverse. I've done a bit of practicing in reverse with buoys out in the river, and it ain't easy to control and it's not pretty!

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Voyager
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5376 Posts

Response Posted - 08/16/2009 : 09:19:20

I have been looking at charts, and tide and current information related to Great Peconic Bay versus Shinnecock Bay, and I'm finding that time of LOW tide is about 2 hours different (Shinnecock Bay is earlier than Great Peconic Bay) and time of HIGH tide is about 3 hours different.

Tide heights are around 3 feet between them, which gives rise to a tremendous amount of water trying to move north or south through the canal when the tides oppose.

One thing a sailor can do is transit the canal when the heights of the two bodies of water are approximately equal, which should more or less coincide with the time of slack current. With the information I've dug up so far, slack should be about 1.5-2.5 hours after high tide or low tide in the Peconic Bay, however I can't determine the length of time you have at slack.

According to Wikipedia, the canal is 4700 feet long or approx 3/4 of a nautical mile. With no current, at 4 kts, you should be able to transit the canal in less than 15 minutes.

If you were traveling south from Peconic Bay, you'd want to arrive after high tide just before slack while current was just about finished flowing north through the canal. As you transit the canal, the current should go slack, then as you exited, the current would start to flow south giving you an assist.

Timing is crucial on any such move, so it's always best to ask the locals. There are a few marinas in the area who you could check with.

Now, coming back from south to north, things would be a little different. You'd have to wait until well after high tide in the Shinnecock Bay for tides to equalize between an ebbing tide in Shinnecock and the beginning of flood in the Peconic.

So, you could spend about 4-5 hours in the Shinnecock Bay before you had to return (or you could wait for the next cycle 17 hours later)

Lastly, going out to the Atlantic Ocean from the Shinnecock Bay through the Shinnecock Inlet has its own current timing. My guess is since the Inlet is much wider than the Canal, currents shouldn't be as strong.

For this discussion, I used two NOAA websites:
http://tidesandcurrents.noaa.gov/
http://www.charts.noaa.gov/OnLineViewer/12353.shtml

Edited by - on

tinob
Master Marine Consultant

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USA
1883 Posts

Response Posted - 08/16/2009 : 10:43:06

Hi Jerry,

You can plan your trip at slack water and go without events or contact the lock master and request the suggested time for your boat. I've gone through at slack water with no event, and at a time when the boat that I was transiting on had to tie up and pay out line as the lock emptied. I seem to remember a drop of several feet. I never took my sail boat through though.
What do you intend to do about your mast? There are cranes available ( two of them ) one at either end of the bridges requiriing that you drop your mast. Are you aware of the bridge heights involved?

Val on Calista # 3936, Patchogue, N.Y.

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jerlim
Master Marine Consultant

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USA
1484 Posts

Response Posted - 08/16/2009 : 20:03:37

Bruce - many thanks for the research and for the links, I'm appreciative of your effort and information, I'm totally going to dig deeper, you've given me great details already!

Val - I don't have all the info yet, but have read that the bridge is 55' clear, so I believe I'm OK, but have not completely investigated the entire route, thanks for your insights!

As I understand things at this time, the current is only an issue when both gates are open...seems I'd be best to simply avoid those windows and traverse when the locks are operating...more to come...

As always - WHAT A GREAT SITE THIS IS

Edited by - on

Voyager
Master Marine Consultant

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USA
5376 Posts

Response Posted - 08/16/2009 : 20:34:33

Jerry
According to NOAA chart 12358, there are three bridges whose vertical clearance are each insufficient for the C25.

1. First provides a vertical clearance of 23 feet with overhead power cables at 38 feet,
2. Number two provides 22 feet of vertical clearance and
3. Finally number three offers 26 feet vertical clearance with overhead wires at 34 feet.

So, what Val says about removing your mast is true - if you want to pass through the canal, removal of your mast is required.

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jerlim
Master Marine Consultant

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USA
1484 Posts

Response Posted - 08/17/2009 : 07:39:10

Bruce/Val - just got to sussing the chart...all true...many thanks for the info!

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Rich P
1st Mate

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USA
77 Posts

Response Posted - 08/19/2009 : 19:14:00

Jerry, there is no way a C25 would make it through with the tide running. You would have to drop the mast to clear the bridges. There are lots of changing currents through there with the tide running and the last thing you want to do is get caught in there.
Why do you want to go through anyway? The other side is quite shallow unless you know where you are going.

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jerlim
Master Marine Consultant

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1484 Posts

Response Posted - 08/21/2009 : 10:07:09

The thought was to get out into the big pond w/o going past Montauk.

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tinob
Master Marine Consultant

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USA
1883 Posts

Response Posted - 08/21/2009 : 10:25:51

Jerry, I was at the locks yesterday and the current in the lock was moving slightly while the water an either side of the lock was seemingly still. Why don't you drive your car down NY27 and visit the locks. Can't be but a twenty minute ride for you...draw your own conclusion. Great restaurant right at the lock on the eastern shore with docksidedeck service.

Val on Calista # 3936, Patchogue, N.Y.

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