Keep the jib to maintain stability in higher winds?

[JimInPB]

... a guy mentioned he found the boat was more stable with the jib out but loose. He had furled the jib and went over.

Can someone explain why? What is happening?
...

A lot of people got into this pretty deep. I'm going to try to give a slightly more simple answer to the original question.

With just the main up & not reefed, in windy conditions, your sail plan is VERY unbalanced. In this situation, there is a lot of force behind the centerboard & not much in front of it. This gives you a LOT of weather helm & makes you pull hard on the tiller to head off, which makes you run with the rudder not in line with the centerboard, which creates a lot of drag in the water. It also gives you poor dexterity in maintaining your point of sail angle. This is true on both my 170 & my 212. An experienced keel boat sailor had trouble handling my 212 with just the main in 15-20 knots of breeze about a week ago. I grabbed the tiller & had no problems sailing her, as long as I spilled enough pressure & took enough luff. When the other person tried to use the rudder to gain a full sail, the rudder eventually dragged sideways in the water & the boat rounded up anyway. This is how badly out of balance the sail pressure is when you have no jib on one of those boats.

With the jib up you have a more balanced sail plan. With the jib sheet left loose, your center of effort moves back, but not as far back as if you had no jib at all. That is the difference.

With all main & no jib in heavy weather, you are more likely to flip the boat because you have poor control of your point of sail angle. Once you are over, your chances of going turtle are equal with both sails up & sheets loose compared with just having the main up & no jib. The jib does not appreciably prevent the boat from going mast down once the boat is over. The jib makes it easier for you to not flip in the first place. That is all. A jib sheet or main sheet pulled tight will slow the rate at which a boat goes turtle, but that will also prevent you from righting the boat, so it is not recommended.

I have sailed the 170 in very gusty conditions, right under the flight path of landing 737s & A320s. I had full canvas up at the time. She bounced around a lot, but never went over. As long as you sail it like a small boat, spilling excess air as needed & nobody grabs the boom to steady themselves while your are heavily healed, I would not expect the boat to flip.

 

[Crazy Dave Condon]

I taught my customers never to heal over 12-14 degrees using sail control. Heeling further created an unsafe situation in many cases. Further if the main has no reef points, pay and have that done for sailing in heavy air. I did that for my customers to also include a mainsail cover and other gear.

 

[BobbyFunn]

Here's a sail from a few weeks back. It demostrates exactly what JimInPb says.

The goal was to sail from the ramp to the back side of the Ringly museum then to the Dry Dock Restaraunt for lunch. I had never sailed to the Dry Dock. I looked at a nautical chart and it looked like it was next to a deep channel with a shallow area in front. I checked google maps and the shallows looked to me like they might have mangroves on them. I set in my mind that i was looking for an entrance to a channel behind mangroves. Find mangroves, then follow the maze with my left hand until i find the opening. Motor down the channel.

Theres no mangroves. The google images is just sand and some vegetation showing through.

The sailing was great. I got a max speed of 6.7kt (34% over hull speed) and tried out some new telltales in what i think are the best locations for the sail controls i have. It was cool to get a view of the Ca' d'Zan from the bay and have a plane fly a couple hundred feet over us on aporoach to SRQ. You know there was some person looking out the window and is now hooked on sailing watching us livin the dream .

Were on the other side of the bay now, all on the lookout for the entrance to the channel when the centerboard starts bouncing. We unclip the bungee and raise the board to 1/4 (motoring) depth. Its getting calm out and were almost on downwind safety run so no problem with that. The rudder starts dragging too now. Im totally confused because there is no mangrove sandbar. We look around and there's the dry dock just a little bit more downwind.

At this point the rudder is dragging too so that is pulled up. It's still in water so i can steer a little, but trying to be careful so it doesnt snap. The water is like 6-9 inches deep and we are going about 2-3 knots over it.

Realizing that the dry dock is much closer than expected the call is made to furl the jib so its not a hassle later and its easy to shield as we are heading downwind.

Within moments i realize furling the jib was a bad decision. With just a 5kt wind and not enough leading edge of rudder i am not able to keep the bow downwind towards the restaurant. No heel, we are level. The rudder is sticking straight out with the tiller off to the side and making a huge spashing sound as it churns the water while i fight to stay downwind. Rudder is 100% stalled with severe weather helm. Soon we are over the sandbar and on top of a gorgeous clear section of water about 2-3 feet deep with some lush green flowery plants growing at the bottom. We're all lost looking down as we ghost over it. We are almost nose to the wind now and drifting downwind.

The main comes down and the jib is unfurled. Im hesitant to drop the rudder over the grassy section but the jib pulls us nicely past the dock for our motor to the dock. In deeper water of the channel i should have lowered the rudder.

How we run the trolling motor with the rudder straight out while pushing the bow upwind is another post, but we did get to enjoy the Dry Dock.

Ive sailed just the main most of the time, but always with a correctly positioned rudder. Without a jib the rudder has to make up the difference. I knew that before, but it did not feel obvious. It was a chaotic experience with just minimal wind downwind with just a main, over 6 inches of water and no rudder. I lost control. If there was more wind it would gave led to a more interesting experience.

Poor balance leads to chaos, which leads to mistakes.

 

[Kermit]

I tried reading this thread but had to stop after the 3rd or 4th reply. All this technical discussion... Sheesh!
https://youtube.com/watch?v=f5cL-h3Pj1o

 

[Crazy Dave Condon]

Yup too much fer me too you old frog

 

[Shorefun]

I understood it, makes sense to me. But I have been accused of being a bit odd by others.

 

[Crazy Dave Condon]

anytime I see or hear someone is trying to sail in shallow waters, I shake my head in disbelief knowing what can and will happen. Good example the centerboard is up but still protruding downward hitting an underwater object or one such incident hitting a cotton mouth snake trying to shake that snake off and so on. It is not worth it due to damage and injury or even death. I will not speak anymore on this subject but needed to advise avoiding in too shallow waters for which any sailboat is not designed for.

 

[Kermit]

...but needed to advise avoiding in too shallow waters for which any sailboat is not designed for.

Talk about a deep subject!

 

[Crazy Dave Condon]

Hey Kermit. may I call ya