Is a Mac Knock Down fact or Fiction?

[delevi]

My second day out on San Francisco Bay on my new '05 , we were hit with 30+ mph winds which came out of nowhere. Up to that point, it was a mild, sunny day. It took maybe 5 minutes to build up and blaamoh, I was sailing in a gale. A strong gust hit and the boat was knocked down on its side with the boom in the water. I released the main sheet but it only came back up a bit. I made my way to the jib sheet, hanging on for dear life, and managed to release it. The boat came back up and rounded up into the wind. I spent the next day practicing reefing while on the trailer and bought a VHF radio so I can hear the marine forecast. That being said, I don't believe 45 degrees would define a knockdown. I sometimes hit 40-45 degrees and keep going, though this is my roundup threshold. Before taking out the mast rake, it was around 30-35 degrees.

[kmclemore]

Not bragging, but I rarely get knocked down in any boat, even small ones, and I think it all comes down to careful observation and being attentive at all times.

Way back when I learned to sail (age 8 ) I was taught by a fellow who's first task it was not to tell me how to sail, but instead how to watch the clouds and the water's surface for clues to the weather and any upcoming winds. The sailing skills came later.

Carefully watching the water will tell you all about any near-term winds that are about to arrive... if you look far across the water, all around you, you can see color changes in the water brought about by the wind's disturbance of the surface... and the color of the water will tell you both the strength and direction of the wind above it, as well as the speed of the wind's arrival (and thereby the strength).

Also, watching the clouds carefully will help tell you the type of weather you're having and about to have, too, although the effects from that judgement are less immediate. Both of these are something that takes careful observation over time, and after a while it becomes almost instinctive. However, the most important point is to be aware of your environment at all times when you're piloting a vessel, becoming one with the wind and the water, and in turn, your ship.

[Moe]

I agree with Kevin that learning to avoid, or at the least EXPECT, knockdowns is the best approach, but I also realize I'm prone to human error, so I agree with Scott that you need to work up to some serious heel when you DO expect it, so that when it happens accidentally, its a place you've been before and know what to do.

Barb got us over 45 degrees or so by either falling off a close reach or not following a wind shift quickly enough (I don't know, I was just coming out of the head). She burned her hand popping the mainsheet to get us back upright.

I took us back over the same course, tightly closed hauled and steered off enough to bring us over to 45 degrees or so (inclinometer all the way over). I intended to show her the boat would round up and come out of that heel angle by itself. But it didn't. It just chugged merrily across the lake at 45 degrees, and I felt I could take it over further, but didn't want to scare her. At least I got to show her the boat would stand up if she headed up. She'd already discovered that even releasing the mainsheet won't bring it back up very far if the jib is still sheeted in tightly.

That was a lesson not only for her, but for me. I had ASSUMED the boat would round up and it didn't. I'd like to work up to taking it as far over as it will go... at least to 60 degrees.

Bottom line is that I don't think 45 degrees or more has to be "dangerous."

[Zoran]

Very interesting posts. I wanted to knock my boat. It was nice windy day and we are sailing at 7.6 per GPS close hauled heeling about 30 deg and I suggested to turn and knock her over. My friend didn't want to do it, he was scared that he might get wet and it was late fall and water was really cold and day was not good for swimming.
It happened to me several times that I was overpowered when single handed and I decided to hold on and not to reef and what I noticed is that as soon as I am over 35 degrees the boat will round up even when I was on broad reach. This happens even when I am heeling due to the wakes and not to the wind power. However, one of Mac fellows claims that his X will not round up since he installed genoa, and it was rounding with the jib even he did nothing to the rigging.
So what is the conclusion is the knock over point 45, I always thought it is 90?

Zoran

[richandlori]

I guess 90 is the official knock down, I was just thinking that 45 is as much as anyone would ever what to be without taking corrective action. I haven't come close to being knocked down, which is a good thing. I created this thread because based on my experiences, I was thinking that it was almost impossible to get knocked down and I was getting complacent at the helm. These experiences have definitely made me reevaluate my complacency and I will keep my guard up, especially with the kids and admiral on board.

Rich

[Catigale]

However, one of Mac fellows claims that his X will not round up since he installed genoa

I can assure you the genoa rounds up quite nicely. It might induce less heel than the jib, which could just be the effect of the sheets being mounted lower on the boat (cockpit coaming rather than up on the companionway)

Evidence of this
1 Conjecture
B When we heel under full sail of main and 150 genny, popping the main sheet stands us right back on our feet -
(iii) We dont heel at all genny only
sqrt(16) YMMV

[Zoran]

I can assure you the genoa rounds up quite nicely. It might induce less heel than the jib, which could just be the effect of the sheets being mounted lower on the boat (cockpit coming rather than up on the companionway)

Confused again. More sail area and less heel? Genoa is not seating significantly lower than jib, same furler system is used only sheet blocks were moved aft and sitting lower but sail itself is pretty much the same.
This conversation between me and my Mac fellow came up after discussion of single handling the boat and none of us has auto helm. He is actually worried because if the wind shift and I am bellow my boat will round up and he is worrying his will not. He had her over 35 and she was steady on course.

Zoran

[Miami]

Theoretically, the center of pressure for the genny is more towards aft compared to the jib. Thus, it should round up more easily than the jib in a gust.

I suspect variations that we see may be a function of how each has set the depth of their centerboard, or sea conditions working on the centerboard.

[norbert]

i did not vote. i had one time a knock down but did not consider it as dangerous nor was the boat out of control.

the knock down happened some years ago on an inland lahe. there was a medium but gusty wind, we had raised full main and genoa. 6 people in the cockpit, a girl on the helm with almost no sailing experience. me sitting on the edge, the main sheet in the hand. when we rounded a cap suddenly a heavy gust hit us and the boat leaned over. i pulled on the main sheet but did not get it out of the cleat! i sat too high on the mid rail and the angle was so that the sheet did not get out of the cleat.

the boat healed over, don't know how many degrees, but the main and genoa were in the water, and water spilled outside the cabin windows. all crew was clambed on the rails and lifelines. a few seconds later i managed to release the main sheet, and the boat popped back upright. it was more fun than thrill, nobody had the feeling of beeing unsafe. no water in the cockpit. some mess in the cabin although...

i think the only risk is to have a knock down on the open sea with higher waves coming abeam. imho only this could cause the boat to turtle (as any sailboat). shure that water ballast is always full on the sea. this summer i was surprised ( "surprise" is my boats name) by a very sudden thunderstorm on a bright day, we had gales force 8 and not even the time to lower the sails. with main and jib up, i released the sheets, let the sails flogg, the boat heeled a bit but nothing serious. 10 minutes later the storm was over, we swept the hailstones out of the cockpit and sailed away...

[baldbaby2000]

Accidently submitted twice so ignore this.

BB

[baldbaby2000]

I've had the boat heel over 45 degrees more times than I can count. We call it "washing the windows!" Usually it rounds or if I get right on it I can keep it from rounding. Just today I saw it hit over 45 degrees (max on my inclinometer) 2 or 3 times. Not that I liked it but I was single handing and was caught with an unreefed main when the wind came up; about 20 knots gusting to 30+. I didn't consider it dangerous at all but I finally got sick of dealing with it and took the time to reef. If I was in big waves I might think otherwise but most of the lakes I sail on don't get very big waves.

I voted no because the Captain didn't consider it a dangerous situation.

BB

[Frank C]

As far as knockdown ... is 45 deg the official point of knocking down??
They tend to round up before then.

Agreeing w/Scott and others, I'd judge a knockdown as 90 deg. instead of 45. I've had the boat heeled to 45 several times but it's nearly impossible to maintain for more than a few seconds or so in gusty conditions. At that heeling angle the water line of waves can overwash the coaming and the side windows.

Any added push from the wind will push down on the mainsail leech, dragging an aft-quarter and levering the bow up and into the wind .... safely rounding-up. Seems to me that another mechanical reason for the rounding-up is failure of lift as the rudder achieves that extreme angle.

IMO, a knockdown would have the mainsail in the water. I've never even approached that point. Witness Roger's video demo with mast horizontal ... waterline doesn't reach the horizontal lip of companionway.

[davidpage]

Auto pilot nearly did me in. Second or third time I used it.

I lake sail and get a lot of strong gusts. I was inside making coffee when I felt a heavy gust start to take me over. Wasn't concerned because I knew the boat would turn in to the wind. But suddenly I was looking through the gally ports down to the water. I looked up at the wheel, and saw the sportpilot spinning the wheel to keep me on course and away from the wind.

Rest is a blur as I raced up the steps and grabbed the wheel. Ended up with a great bruise on my arm but I don't remember hitting anything.

Sure did scare me.

[waternwaves]

Frank, in real conditions with lots of waves...........it was pretty wet wet from wind and wave spray, tho none came inside the boat (companion way was closed), and wind and breaking waves was mess.........

Only a really avid and spirited salesman lays a boat on its side in flat water and implies it stays totally dry.......

But my own stupidity was the sole cause..........not reading the depth on the charts and realizing there was no place for those rollers to go..

But I felt a hull of a lot safer at 90 with the mac..........than I ever did in a 25 capri at 55 degrees of lean............that boat always felt like it was going way way over....

P.S. And david............

I'm impressed,,,, If I had had sail up....... I would have gone for the sheets instead of the helm and probably still be wet...


P.P.S BB lets go sailing ............your my kind of dunnkem', splashem' testem' kind of sailor

[Tony D-26X_SusieQ]

I haven't tested it yet but according to Jeff Stag, "Speedyrigger.com" if the Mac heels more than 50* she will go over. Less than that...Have fun.