How should standing waves be handled?

[jsc7]

I have been been warned by other boaters that at the outlet of the Cape Code Canal there can form something called a "standing wave" or "square wave" which can be dangerous. Supposedly driving into a standing wave can disable a motor boat by lifting its prop out of the water and then the boat becomes helpless and this can lead to dangerous outcomes because the channel is narrow and lined with rocks.

Nowhere have I seen any written information about this danger. How do I handle such waves and where can I find more information?

[rbk]

We get them all over in SE Alaska. They are tidally influenced and other than avoiding them, usually off points due to converging currents or in calmer waters with ripping tides close by. This affect can be seen in rivers on eddy lines. No good way to navigate through them other than to just push through them uncomfortably. Best to know when to expect them and avoid by going around or waiting for favourable tide. Once you figure out how they form it’s easier to spot them. Good thing is they are generally isolated to an area and in some cases gonright up to them and go right back out and then work out a way around.

[Pelagic]

Standing waves simply means a natural wind produced wave and/or swell that encounters the resistance of an opposing current, causing them to slow down and stack up or shorten in length, while increasing in height. Not unlike when a wave approaches a shoreline and starts to rise in height and break.

All vessels have a critical wave period of around one ship length from crest to crest, so to artificially lengthen that interaction, you do a zig zag course to try and lengthen the space, allowing vessel to recover as well as adjusting speed to avoid slamming.

In river bar conditions, waiting for a flood tide at entrance helps to negate the effects.

https://www.sva-potsdam.de/en/ship/#seakeeping

https://www.sva-potsdam.de/en/ship/#slamming

https://youtu.be/_8sCbQt8iMk

[Chachere]

Originally Posted by jsc7

I have been been warned by other boaters that at the outlet of the Cape Code Canal there can form something called a "standing wave" or "square wave" which can be dangerous. Supposedly driving into a standing wave can disable a motor boat by lifting its prop out of the water and then the boat becomes helpless and this can lead to dangerous outcomes because the channel is narrow and lined with rocks.

Nowhere have I seen any written information about this danger. How do I handle such waves and where can I find more information?

Yup. Coming out of the canal into Buzzards is -- at least from the half dozen times we've done it -- always an adventure. The currents in the canal run quite strong, and since sailboats are kinda slow under power (can't sail in the canal) you generally need to transit the canal going with the current. Thing is, Buzzards Bay tends to have nice SW winds, and with the somewhat triangular shape of the bay, the effect is to funnel the waves into that very corner, where they run smack into the outflowing current from the canal, and voila, nice big standing waves. We've had our 36' boat tossed like a small dingy (oh, and make sure you've dogged down tight your forepeak hatch -- don't ask how we know!).
However, as Pelagic said, you can try to zig zag a bit (although it gets tricky because at that point it can be narrow and a lot of traffic). Generally, just take it slow. One alternative if things get too rough, however, is to bail out once you get abeam of Mashnee Island on your port side (just past the R18 bell) and head east over to can 9, then turn south again from there. You'll be basically in the old channel of the canal (left over from when the canal was realigned in 1928), and no only subject to the current/wave conflict (and thus no square waves).

[boatman61]

River entrances are pretty straight forwards.. wait till slack water or enter/leave on the ebb when river and tide run the same way if your engine has the omphh for the entry.. tide rips off headlands can be pretty dodgy as well if you get caught in them.. Durlston Head near Swanage and the Seven Sisters off Portland spring to mind.. seen boats being tossed around a few times when they got it wrong.. pass very close in to shore or stand well out.
Cape Lookout NC has some biggies in a Northerly.. n that's a fact..

[belizesailor]

Have transitted Cape Cod Canal a few times. Fortunately with experienced local skippers. The least stressful way is simply to work with nature, look up tide and wind state and go when it aint bumpy.

[George DuBose]

If the winds are from the SouthWest, I would fight the slight north-bound current at the south end of the CCC and there shouldn't be any standing waves.

If you can time your passage so your arrival at the south end of the CCC is when the tide turns north, you should be OK.

I have never seen waves larger than 3-4 feet in this area, but I never tried to pass the canal in a gale either.

Timing is everything.

I heard there are 20 foot standing waves at the Race between Fisher's Island and Little Gull lsland where the Long Island Sound flows into Block Island Sound, but I have never seen them.

Also at the south end of the Chesapeake-Delaware Canal there are standing waves.

[a64pilot]

The ones I have experience with are tidal, meaning you can wait them out.
So I do.

[gwbull]

Yup. Been there, done that many times. All local sailors know to go with the tide, not against it. And if the SW wind is up, as it tends to be in the afternoon -- hi teens to lo 20s-- and the current runs against that, don't be a jerk. We've seen 8 ft steep seas less than a 41ft boat length apart... just west of the Maritime Academy still IN the canal. Never did that again. You'll see a lot of early to mid morning transiting when wind is gentler and the current is right. We have learned to plan our cruising around that. However the question is posed by a 31 ft Whaler owner. And frankly most of the time these guys can just bulldoze thru it all... moistly.

[Paul Elliott]

Originally Posted by Pelagic

Standing waves simply means a natural wind produced wave and/or swell that encounters the resistance of an opposing current, causing them to slow down and stack up or shorten in length, while increasing in height.

There are also standing waves caused by "hydraulic jump" where a fast current flows into a slower-speed area. You can see these where a river or channel current meets the ocean. No wind is required and the wave is trulu stationary. A tidal bore is a related phenomenon. We also see standing waves in rivers where the bottom is uneven -- kaykers will sometimes "surf" these spots. Here's a wikipedia article about hydraulic jump waves: https://en.wikipedia.org/wiki/Hydraulic_jump

Of course wind against current can indeed be a big factor.

[Suijin]

It's all about wave period, and they are not always "standing" either. Sometimes it's a moving train of them that are so closely spaced that they have the same effect. I think they are generally more dangerous in a powerboat than a sail boat for the simple fact that if a power boat stuffs the bow into the wave it's probably going to swamp and roll. A sail boat can crab sideways to get out of it and while it won't be pleasant you're not going to get rolled. With a power boat if the wave period is just wrong for your boat there is no way you're going to navigate that wave...can't climb the wave without stuffing the bow, so you really have to look for a way around it, or even bail and wait for conditions to change.

I think one of the biggest dangers is that often you don't see standing waves, or see how bad they are, until you're right in one or a set.

Here's a good example. This is not a small boat...looks like a 25-30' or something. The guy was basically hosed trying to stay perpendicular and not being on the back of the front wave. Only option when stuck in the trough is to escape out the side, going diagonal and throwing in some power, but it would basically be the nautical equivalent of bull riding:

https://www.youtube.com/watch?v=OHqmpM8Wnio

[a64pilot]

What got this guy was it was a “Bay” Boat, a center console meant for fishing the bays and has no freeboard to speak of and as you can see can’t take any real water.
The are sort of big bass boats, and have as much business in rough water as a bass boat.
But they way way cheaper than a regular CC of the same size

[Pelagic]

Interesting video Suijin.
From the tide line on rocks it
looks like he tried at low tide with too much speed and did not stay at the back of one wave....But that was definitely the wrong time to try.

[Scotty Kiwi]

There's different types of "standing wave". The ones I know of:

Standing waves at bar crossings from sea into a river system - incoming tide, swell, or wind wave against outgoing river current or tide. Avoid peak flow, try to avoid and tidal flow, try slack tide, if outbound pick your time, power off a little as you hit to wave straight on, inbound stay powered up on the back of a wave.

Standing waves in a current at sea - well locals will know of these areas, and basically avoid them in the wrong conditions. Local to me, Cook Strait off Karori, peak tidal flow 7 knots to the north west, wind 40 knots to south East, NW swell 2 meters, wind wave 3 meters. I expect there'll be many many know areas around the world like it. Off Karori there can often be about a 400 meter square area of 3 - 4 meter standing waves - meaning apparently standing still, but forming, breaking and re-forming. We were pushing the tide at about 3 knots SOG, 8 - 10 knots on the log, with a strong wind behind us. I set a course to pass it by but get a good close view, but the area seems to suck a boat in. In my one experience, in these conditions in this area, in seconds I appeared to have been sucked into the middle of the area. The tender on davits 2.5 meters above normal water line entirely disappeared under a wave with the boat on an reasonably even keel (not up at the bow). Was motor sailing with 40 knots of wind following a bit on port quarter, a few turns in the Genoa and a well reefed main centred hard to reduce the roll, so we had plenty of power. The boat just seemed to stall as the sea rose up in wave hillocks all around us. Log speed began to vary between 2 and 12 knots. That was a 68 foot 30 tonne ocean vessel with 1.5 meter freeboard. We pushed through, plenty of deep blueys over the decks, heart in mouths, cockpit stayed unflooded, but I wouldn't do that again if a had a choice.

[Pelagic]

Hi Scotty, Yes there are a variety of types, with the only common denominator being opposing forces that "stand up" an ordinary wave.
Many are marked on charts as rough waters, usually with hidden causes like joining currents at two Seas (common in the Philippines)
Severe upwellings from bottom profiles at offshore Seamounts and the typical Bar crossing.

I often wonder if.... when someone reports a Rogue Wave in the middle of the night, that they just happened to encounter a standing wave situation