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Real chance of capsizing?

srimes

.
Jun 9, 2020
149
Macgregor 26D Brookings
Here's a short clip of yesterday's sailing. Was using the heavy air jib and 2 reefs in the main as there was a gale warning. Overall went pretty smoothly, but got hit with a breaking swell and had this exciting moment. Seemed pretty much OK at the time but we were surfing sideways so was there any real chance of rolling? How do you know when things have gone past "exciting" or "uncomfortable" to dangerous?

Edit: added slow-mo replay!

 
Last edited:
May 17, 2004
2,675
Beneteau Oceanis 37 LE Havre de Grace
Looks to me like you were still in the exciting category, not moved to dangerous. I’ve read things like a wave height needing to be 30% of a boat’s length, or higher than the boat is wide to roll it, in the worst case. Cameras don’t do a good job of showing wave height but it didn’t look that bad to me.

You might want to consider keeping the boards secured in the companionway on the especially sporty days. If the boat does get knocked down water can flood in there and make matters worse. Probably not as bad on the MacGregor with the raised bridge deck as it is on some others where the companionway goes all the way to the floor, but still a best practice.
 
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Joe

.
Jun 1, 2004
7,106
Catalina 27 Mission Bay, San Diego
Even with the reef in the main, it still looks too full. I'd work on trimming out that excessive draft. The other comment comes from my experience sailing lightweight center/dagger board boats.... keep the tiller in one hand and the traveller or mainsheet in other. I never cleated the main when I was sailing in those type of conditions. You can feel the extra pressure and respond immediately. You can definitely get knocked down by a breaking wave if you're overpowered by a gust. Otherwise, it looked like you were having fun..nothing was flying around the cockpit and the dog stayed onboard.:biggrin:
 
Jan 11, 2014
5,930
Sabre 362 113 Fair Haven, NY
Seemed pretty much OK at the time but we were surfing sideways so was there any real chance of rolling?
That was rounding up, had it kept going it would have been a broach, and not the kind your mother wore to church on Sundays.

Assuming the boat is properly ballasted, it is very difficult to capsize a keel boat. The wave has to be sufficiently large to lift the boat up and then allow it to turn more than about 120° to face of the wave. These are ocean swells breaking at 20 feet or higher.

As the boat heels over the heeling force is reduced because the exposed sail area is reduced. When the boat is up right 100% of the sail area is exposed to the wind, at 90° heel, 0% of the sail area is exposed the the wind, the wind is blowing parallel to the surface of the sail. At this point the keel forces the bottom of the boat back down and the mast starts to come upright. Typically this happens as the boat rounds up and heads towards the wind, again reducing the sail area directly exposed to wind. The boat will head up and go into irons reducing all heeling force.

To capsize, the boat has to be at 90° heel and ridding up the face of a wave so high and steep that the weight of the mast pressing down exceeds the weight of the keel pressing down. A breaking wave will give the boat that little extra momentum to go all the way over.

When the boat starts to round up, drop the traveller or release the mainsheet, this takes pressure off the sail and allows the keel to do its job easier. I used to sail with a dog, he never made a good mainsail trimmer, so I would leave him ashore on robust days. ;)
 
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Jan 1, 2006
5,014
Slickcraft 26 Greenport, NY
I don't think you were in the dangerous area. I don't know how to replay the video but it seemed OK. I didn't see any risk of rolling. The suggestion of putting the hatch boards in is good advice. The big danger of rounding up or broaching is water coming over the cockpit comings and ingress into the cabin - which is a sinkable situation. Also make sure the lazarette cockpit hatches are dogged down. Usually there is no or weak barriers from water flowing from the lazarette to the main cabin/bilge. Also a danger of sinking.
 
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srimes

.
Jun 9, 2020
149
Macgregor 26D Brookings
Yeah I wasn't really worried, just wondering how to know when I should be :).

Dog was tethered to the boat as was I. Reported waves were 7-8 ft at 6 seconds. I've read that breaking waves as tall as the beam can roll a boat. That's what got me thinking.

That was all wave action lifting and turning the boat, not wind. I think of rounding up as when the wind lays the boat over and then the boat turns into the wind. Here the wave lifted and carried the stern until the boat was beam to the wave, then carried the boat a bit more. I updated the video and added a slo-mo replay. Skip to 0:50.

How would I reduce sail draft? Reef line was tight, would I need to move the mounting points? I don't have a vang but it's on the list.

The laz latch is missing. Replacement should be here soon.
 
Oct 22, 2014
12,809
CAL 35 Cruiser Portland OR, moored EVERETT WA
No one has a hold of the mainsheet. No control of the sail trim. Release the main sheet boat stops healing.

When you get to the top of a wave I like to head down the wave rather than to take it on the beam. Think of the way surfers tame a wave. Heading down those waves and releasing the main a bit will keep you in control and the rudder in the water tracking. When you let the rudder get out of the water like on a heel you loose control and open your self up to a broach opportunity.

Use the waves to your advantage. In waves my course is more like a skiers salomon than a straight line. Near the bottom of a wave I aim at an angle to climb the next crest avoiding as I go the white water.

I think you can judge the conditions by the way the dog reacted. When he felt you had control he was calmly laying down. Then he got up!

It was kind of a give away when you look at the nervous smile on the crews face.
 
Oct 19, 2017
6,426
O'Day 19 Littleton, NH
You looked fine, not even close, but I'm sure you had to give your stomach a moment to stop back into place.

-Will (Dragonfly)
 

Joe

.
Jun 1, 2004
7,106
Catalina 27 Mission Bay, San Diego
Sail the boat like a dinghy. Keep the sheet uncleated and in your off hand. Or give it to the crew. Steer an S shaped course through waves, always keep your eyes to windward for peaking waves. Either head straight up the wave's face and fall off at the peak to keep from slamming the rig silly before heading up again once you're in the trough. Or... if the wave is on the quarter.. bear off and ease out the main to ride down the face diagonally...then heading back on course diagonally up the face... Remember.... S motion. This type of sailing is exciting and makes you thankfull you have a tiller steered sailboat that allows you to feel.
 
Jan 13, 2020
18
Hunter H-31 Southport
I have always heard when the height of the waves is equal to or greater than a beam of a boat you have a chances of broaching Are greater
 
Nov 8, 2007
1,317
Hunter 27_75-84 Sandusky Harbor Marina, Ohio
The danger zone is breaking waves greater than the beam of the boat. This is one of the results of extensive tank testing after the Fastnet Race disaster. If a breaking wave higher than the beam hits you on the beam, it will roll the boat over. If you are in those conditions, trimming the sails, secured against flooding, and helming the boat as described above are all critical.

Because it takes hours of time and hundreds of miles of fetch to build waves to build such waves, we find it easy to avoid them. We just get to port and stay there. With 6 footers, if we are not pounding into them, we just enjoy the ride.
 
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Oct 19, 2017
6,426
O'Day 19 Littleton, NH
A critical element is in the depth of the keel. Deep fin keels can be held still or even swept in a counter flow to the oncoming wave. As the wave picks the hull up, gravity is surfing that hull back down the wave while the keel is actually being dragged back against the direction of the wave's movement. The reverse can be true on the back side of the wave, where the hull falls into the trough faster than the keel. Keeping some sail on, goes a long way towards stabilizing this action. Sailboats that get dismasted are in more danger of rolling from tripping the keel, even though they have a greater righting moment, because the rigging aloft is a dampener to the pendulum movement.

A shallower full keel is often more sea-kindly because of this. It might make sense to bring a center board half way up where there is a beam sea. Maybe, just thinking out loud here.

-Will (Dragonfly)
 
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srimes

.
Jun 9, 2020
149
Macgregor 26D Brookings
The danger zone is breaking waves greater than the beam of the boat. This is one of the results of extensive tank testing after the Fastnet Race disaster. If a breaking wave higher than the beam hits you on the beam, it will roll the boat over. If you are in those conditions, trimming the sails, secured against flooding, and helming the boat as described above are all critical.

Because it takes hours of time and hundreds of miles of fetch to build waves to build such waves, we find it easy to avoid them. We just get to port and stay there. With 6 footers, if we are not pounding into them, we just enjoy the ride.
These waves were right about the size of my beam, and "spilling" some. What do open-water breakers look like? Just the same as on the beach?
 
Oct 19, 2017
6,426
O'Day 19 Littleton, NH
These waves were right about the size of my beam, and "spilling" some. What do open-water breakers look like? Just the same as on the beach?
No, they are sporadic and sudden. They typically occur when two waves converge and their heights add to each other. They become steep and the wind helps knock them over. They can appear to lift straight up and crash before bubbling back down to nothing as the energy from each converging wave compounds the other, then they move on as divergent waves. Sometimes they are different wave systems crossing paths, sometimes there are wave's that simply move faster or slower than the other waves and you get two waves following each other that merge into a single big wave, travel a short distance together, before separating again.

It is hard to tell and it is often just chance that you happen to be in the same spot that one lifts and crashes.

-Will (Dragonfly)
 
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Jan 11, 2014
5,930
Sabre 362 113 Fair Haven, NY
The waves @Will Gilmore describes are often referred to as Rogue waves. There has been a lot of research on them over the past few years and they are more common than was thought. They have been found to occur all over the ocean and at varying sizes, measured in a few feet to tens of feet. The waves are often square and steep sided. We get them a lot on Lake Ontario due to shifting wind patterns as fronts roll through. A wave pattern gets started, the wind shifts and starts a new pattern before the old pattern has subsided and square waves pop up.

One way boats capsize is surfing down a large wave, the bow buries in the trough which stops the front of the boat while the back of the boat continues forward, this causes an abrupt turn and places the boat broadsides to the wave into a broach. The boat then rides up the wave sideways down the backside of the wave, unless the wave is about to break. If it is tall enough and steep enough the vertical lift can roll the boat past the point of vanishing stability, at which point the boat will capsize.

Perhaps more important than wave size is hull shape. Some shapes are better at recovering from a broach or capsize and others are not. The worst boats are catamarans, they are a stable upside down as they are right side up, so it is difficult to right them. Boats with broad flat decks can be more stable inverted. Search for information on the Wing Nutz accident in the Chicago Mac race a few years ago.

Boats with flat bottoms, sharp corners at the chines, and vertical sides offer a lot of initial stability, they don't heel very much at first. However, once they approach the point of vanishing stability they quickly become unstable and will flip. A good example of this are the old aluminum canoes made by Grumman and popular in camps. Step in the canoe and it feels stable and solid, however, lean it over too far and you are swimming, there is very little room or forgiveness. Other canoes, like the Mad River Tripper were very tippy at first, they had a low initial stability, however, they could be heeled over and the gunwale placed on the water and the boat would become very stable. A boat with a rounder or V-shaped bottom will be more resistant to capsizing than a boat with a flatter bottom and more vertical sides. One of the Mac 26s that double as a power boat are good example of a boat with high initial stability and low final stability. Boats like Bob Perry's Valiant 40 and various Pacific Seacraft design have rounder bottoms and softer chines, these boats have good offshore reputations, they heel quickly, but become more stable as the heeling increases.

I guess the point of this rambling is to answer the OPs question, "Real Chance of Capsizing?" with a big "well it depends" on wave size, wave pattern winds, hull form, and crew skill. In general I'd be much more concerned about getting pooped with the companion way open and filling the boat with water, breaking some critical piece of rigging, or blowing out a sail than capsizing.

EDIT: Forgot to add a link to this article on stability. Boat Stability