Tidal Currents Can Be Strong in Bays and Inlets and Rivers

[Steadman Uhlich]

Originally Posted by valhalla360

My comment wasn't so much about going in and out of inlets (though definitely an issue at times).

My point is the ICW channel often runs thru the backwaters and will be impacted by nearby inlets but which inlet changes as you cover distance and also changes over time (state of the tide). Not at all unusual to be surprised by a tidal current going a different way than you expected.

OK.
Understood.

[NRbar]

Mike

I was anchored on the Halifax River at Ponce Inlet FL and my full keel boat would move against the anchor chain. Odd to see bottom paint on my anchor bridle.

rob

[Steadman Uhlich]

Originally Posted by deblen

Saint John R. Bay of Fundy Reversing Rapids / Len



https://www.dropbox.com/sh/4ed0ay1fn...hdA1_ARra?dl=0

I was hoping you would post about the Bay of Fundy.

That is something I have wanted to see since I was a boy. Perhaps someday.

Here is the photo you linked, posted here to make viewing quick, without going to Dropbox. Hope that is OK. Impressive sight!

[a64pilot]

Originally Posted by Mike OReilly

This really screwed with my head for a while, but I finally figured out it was due to our full keel was acting as a big wing. It was generating lift in the strong current; enough to drive us forward.

My full keel will do that to, next time it does I plan on tossing in a bucket as a drogue to see if that will pull it back, cause going forward like that it’s not steady, it yaws around to.

[buzzstar]

There was good reason for the common line in marine literature: "We sail with the morning tide."

[Mike OReilly]

Originally Posted by a64pilot

My full keel will do that to, next time it does I plan on tossing in a bucket as a drogue to see if that will pull it back, cause going forward like that it’s not steady, it yaws around to.

Hmmm, that’s a good idea. I'll try that next time . Luckily my boat never moves much at anchor, but my chain rubs a bit against the hull. I extended my snubbers to make sure only rope came in contact, but I really don’t like it. Feels wrong...

[rbk]

We spend lots of time in and around Glacier Bay Ak There are three very substantial rips within 20 nm of each other and can create large standing (square) waves and large breaking waves when the conditions are right. If you look at a map or image of Glacier Bay you can see that when the tide goes out Icy straights waters leave via Chatham and out to the pacific; Inian Pass (N&S) restrict the water from flowing west towards the pacific. As GB empties (slower than Icy straight can as it gets restricted at Gustavus point) it creates a 7knt current that bends east to make it around Point Adolphus and head towards Chatham. This can create 4-5 ft rips on either side as it passes Gustavus Point and 8-10 steep breaking if there is opposing winds. At Point Adolphus the waves will stand straight up 3ft (square/haystacks as we call them) on a calm day, worse again 4-6ft if winds/waves are present. But the real current is at South Inian Pass where currents can reach 14knt and with a mild Pacific west swell (1-2m) the opposing currents can stack up waves in excess of 10ft on a otherwise relatively calm day as they crash into each other. The rip along the islands rival some of the biggest white water rivers and if there is a storm with full west swell and waves it can turn extremely dangerous very quick with multiple large breaking waves with no way to go back unless in a large power boat.

[Steadman Uhlich]

Originally Posted by rbk

We spend lots of time in and around Glacier Bay Ak There are three very substantial rips within 20 nm of each other and can create large standing (square) waves and large breaking waves when the conditions are right. If you look at a map or image of Glacier Bay you can see that when the tide goes out Icy straights waters leave via Chatham and out to the pacific; Inian Pass (N&S) restrict the water from flowing west towards the pacific. As GB empties (slower than Icy straight can as it gets restricted at Gustavus point) it creates a 7knt current that bends east to make it around Point Adolphus and head towards Chatham. This can create 4-5 ft rips on either side as it passes Gustavus Point and 8-10 steep breaking if there is opposing winds. At Point Adolphus the waves will stand straight up 3ft (square/haystacks as we call them) on a calm day, worse again 4-6ft if winds/waves are present. But the real current is at South Inian Pass where currents can reach 14knt and with a mild Pacific west swell (1-2m) the opposing currents can stack up waves in excess of 10ft on a otherwise relatively calm day as they crash into each other. The rip along the islands rival some of the biggest white water rivers and if there is a storm with full west swell and waves it can turn extremely dangerous very quick with multiple large breaking waves with no way to go back unless in a large power boat.

WOW!

That is impressive, and does sound dangerous.

Thanks for writing in good detail.

[charliegrau]

Interesting topic. I just completed a trip from Key West to Norfolk, mostly in the AICW. Currents are strong, and a planning factor along much of the way. In many St Augustine Marinas, it is common to wait until slack current to enter/leave a slip...even when slips are in line with the current. At the municipal marina they even advise you which way the current is running so you can decide if you want to go bow, or stern to the current. Most folks (including me) are not used to dealing with 2-3kts you can see. With practice it gets better. One of the "tricks" is to learn to counter the current with you engine(s) precisely so you become motionless "over ground" or with respect to the pier. You can often then move you boat side to side without moving fore and aft to approach pier or slip.

Most people seem to like maneuvering bow into the current, but that can be risky. If your bow gets too much to one side or another the current can sping you 180deg pretty quickly. On the other hand, stern to the current is pretty stable..you just end up driving like you are backing rather than going forward.
Strong currents persist all the way from Fl through NC. There are so many inlets in NC that I have found myself fighting the current until I pass an inlet, and then riding it on the other side...or vice versa.

There is a website deepzoom.com that provides current info. A great tool...esp in certain sections where there aren't a lot of inlets..like St Augustine to St John's River...you definitiely want to run that with favorable current if you can.

[Steadman Uhlich]

Originally Posted by charliegrau

Interesting topic. I just completed a trip from Key West to Norfolk, mostly in the AICW. Currents are strong, and a planning factor along much of the way. In many St Augustine Marinas, it is common to wait until slack current to enter/leave a slip...even when slips are in line with the current. At the municipal marina they even advise you which way the current is running so you can decide if you want to go bow, or stern to the current. Most folks (including me) are not used to dealing with 2-3kts you can see. With practice it gets better. One of the "tricks" is to learn to counter the current with you engine(s) precisely so you become motionless "over ground" or with respect to the pier. You can often then move you boat side to side without moving fore and aft to approach pier or slip.

Most people seem to like maneuvering bow into the current, but that can be risky. If your bow gets too much to one side or another the current can sping you 180deg pretty quickly. On the other hand, stern to the current is pretty stable..you just end up driving like you are backing rather than going forward.
Strong currents persist all the way from Fl through NC. There are so many inlets in NC that I have found myself fighting the current until I pass an inlet, and then riding it on the other side...or vice versa.

There is a website deepzoom.com that provides current info. A great tool...esp in certain sections where there aren't a lot of inlets..like St Augustine to St John's River...you definitiely want to run that with favorable current if you can.

Thanks for adding that interesting comment and your tips.

[sailorman7225]

Ft Pierce inlet in Florida can be a challenge. Had to go into the city marina crabbing sideways at near full throttle! That was some years ago.
Something interesting happened last year on a mooring ball at Ft Meyers Beach (also Florida). The mooring ball was stuck under the boat. I hired a diver to untangle and correct the situation. He came up and said “you’re sailing”. Say what? Nothing was tangled; the boat was free and sitting perfectly still! Can someone explain this?

[44'cruisingcat]

Sunda strait, Vanuatu. 5 knots boatspeed, 11 knots over the ground.

[44'cruisingcat]

Originally Posted by Suijin

I think it's important to point out that current is not necessarily directly correlated to tide (i.e. that the strongest current is not mid-tide). Geography and topography can alter the relationship significantly.

Good point! An example is the Swansea channel into Lake Macquarie. A fairly large lake with a narrow channel entrance. The level in the lake is hardly altered by the tides, and remains at more or less mid tide level.

So in the channel, slack tide is mid tide. High and low tides are the times of maximum flow.

[rbk]

Originally Posted by Steadman Uhlich

WOW!

That is impressive, and does sound dangerous.

Thanks for writing in good detail.

Another good one is Petersburg AK, which is essentially in a tidal river (Wrangell narrows), and the mile of docks, piers and breaks does not stem the flow at all and can see 3-4 knts at the dock with whirlpools coming off the pilings. Heading out into Stephens passage on the ebb with opposing winds creates a short but steep wave train.

[Dsanduril]

The PNW has all kinds of spectacular points, but my favorite is Ford's Terror in SE Alaska. A very narrow boulder-bank drains a pretty large fiord. You can enter at high water slack with no drama, but at low tide it is a waterfall. In between the more adventurous surf the standing waves (6+ ft/2m). Pretty cool to watch people surfing and not going anywhere. We've been through a couple of times.

The upstream entry is pretty easy, you hang out in the bay outside and wait until you see slack water (which isn't always quite when predicted). Outgoing is, to me, a little scarier. You're coming down a narrow fiord, can't see around the corner to the Terror, and trying to time things just right so you don't get there too early or too late.

https://www.youtube.com/watch?v=q7qKyZItk_Y