it wants to round up hard in a strong wind...why?

[weinie]

Yesterday, I took my wife and three year old girl for a nice Mother's day cruise...the first time for them on my boat. Blowing between 10 and 15 knots, the wind was a bit stronger than I hoped for on their initiation into sailing.

But I unfurled my 150 genoa out only about 70%, kept the traveler on the main eased slightly, and pinched the wind while sailing close hauled when the wind gusted. While we didn't hit warp speed, my wife was probably much more comfortable than otherwise, and it certainly made for a very pleasant sail!

Now, sailing by myself or with friends, I normally would have tried to coax out every possible knot.

What this has do with the original post, I'm not really sure, but I think what I'm trying to get at is that sometimes, we learn a lot about how our boats handle by trying to get it to respond to how we want it to sail and not how we let it overpower our ability to control it.

 

[RichH]

I always thought it depended on the hull, and that for most cruising boats, as the boat heels, the center of lateral resistance moves forward. To have a balanced helm at both 15 degrees heel and 45 degree heel seems unlikely, no?

Construct a right triangle with the longest side approximating the keel bottom. Hold the triangle in front of you on a left to right orientation. Now 'rotate' the triangle about the left to right horizontal axis ... does the ratio the left to right change, no the overall size (ratio) becomes larger or smaller as you rotate the triangle ..... the ratio of CLR stays the same, the CLR stays in the SAME place, on the rotating triangle. ;-)

When the triangle become 'very small' the boat (triangle) diminishes the projected area (lateral resistance) and the boat/triangle as begins to skid to leeward, this sideways motion is 'felt' on the hinged rudder as increasing pressure ... and is mostly and erroneously considered 'weather helm'.

Its VERY easy to confuse a 'skid to leeward' with so called 'weather helm' .... the only visual clue will be: is the stern wake (rudder/keel turbulence) coming almost 'straight' off the stern (weather helm) or at an angle greater than about 3-4° (leeward skid).

 

[kpgraci]

As we say in programming..."That's a feature, not a bug".

The Oday 22 was advertised to be 'safe', that is, it will round up when heeled over more than 15*. A side effect of the shoal keel and stern hung rudder, the designers did not 'add' that feature, they just left it in.

When I get that much pressure on the rudder I always imagine it going 'crack', so I try to avoid that when possible.

 

[CarlN]

There are many factors that affect weather helm but the most common is that more heal causes more weather helm (because the leeward side of the bow submerges "steering" the bow to windward).

You can (and should) adjust the sails and rigging to balance the boat but this balance will change as the angle of heal changes.

Most boats (including an Oday 22) sail faster "sailed on their feet". Reef early to keep heal at 20 degrees or less. You'll have less weather helm, make less leeway, have less drag from a turned rudder, and a happier crew.

One of the frequent complaints you hear from women as to why they don't like sailing is that they don't like healing. I think that's because women just have a better feel for good boat speed than guys who like to put the rail in the water.

Carl

Carl

 

[JohnS]

Rich, that example works well to describe the keel's contribution to CLR, but the hull is not a 2 dimensional planar surface. As it heels, the waterline increases, and depending on the shape of the hull, may increase more toward the bow than toward the stern.

In the end, there are multiple factors, and a skid to leeward will indeed apply pressure to the rudder which will feel just like weather helm. To the extremes Centerline was pushing it, he was probably making very little headway, so it may very well have been all skid pressure.

I guess the point is, there's an optimal heel angle for your boat, and exceeding it, while providing an exciting ride, results in increased drag which actually slows you down. If you don't have weather helm at normal heeling angles, don't worry about it.

 

[RobertLangdirect]

From my Avitar you can see that I too probably spent more time on the side or rounded up than going forward. But that was then.

Sail shape has as much to do with turning up as does sail area. If you control one but not the other, you can still round up but I offer, shaping is easier than reefing on my boat. For others, reefing is the only answer.

 

[RichH]

John -
The 'projected area' that is moving sideways or resisting the sideways movement IS the 'lateral resistance'.

A boat that is laying on its side will have very little lateral resistance (depth X cos 90 = depth X 0), a boat standing straight up will have its lateral resistance at a maximum (depth X cos 0 = depth X 1= depth).

A skidding boat will have have 'side pressure' on the rudder .... usually 'perceived' as 'weather helm'. A well set-up boat (proper rig tension, proper sail *shape*) will have the minimum of rudder side force and minimum skid - my first post in this thread.

As an illustration - At 30% heel will only lose 14% of 'projected' area of lateral resistance (+ some increase of topside projected area submerged). A boat that is 45° over will only lose 29% of its lateral resistance (below the water line) and will increase (some) lateral resistance due to the portion of the topside of the hull that is now submerged (due to the new submerged topside area projected in/to the vertical plane). At 60° heel, will lose 50% of Lateral Resistance (below the water line) and will have cos 60° = .5X of the submerged topside surface added to the LR.

All just very simple trigonometry.

 

[centerline]

All because you won't, can't, don't know how to reef and reduce sail; (Assuming a Mac21 has reef points) as a center boarder, you could have broached and been in trouble, could have lost the mast, could have broken the tiller and or rudder. A gybe slapping the mast over hard could have ripped the mainsheet out of the boat too.. or worse.. now that you know what not to do... (consider yourself scolded LOL)

Your boat at least had the good "sense" to round up! she was basically yelling reduce sail! glad you had fun and came back safe.

Denise, the mac21 does have reef points in the main.
and your right, I dont know the proper way to reef.... and I wont do it until I learn how and then I need to learn when to do it.
and yes, my boat probably does have more sense than I do, LOL...
the mac21 has a weighted swing keel.... and I had the keeper bolt in it. if it didnt, I would definitely have been knocked down....

I do know the risks I was taking, so even though i dont know all about the personality of my boat in different winds, im not afraid to go beyond the limits of my personal experience to find out.... and now after the weekend my personal experience is a little bit broader..... in all due respect to my little boat, which I really like, when im done with her she will either be wrecked, or her and I will know each other intimately...... I am hoping for the latter. I have put a lot of time and effort/love into her and although im sure the old sails are too far out of shape for optimum trim, they will still allow me to learn the limits of the boat and what works and what doesnt. I am fairly careful and not in the habit of making mistakes, but it happens sometimes..... like when the mainsheet came loose. I am always looking for the "why" in the way things work and in searching for the answers I do take things to the limit and sometimes beyond... I dont think im abusing her, I think im giving her a good workout.....

So i'll take my scolding like any kid with a new toy has have to sometimes, but as soon as your not watching, Im going to be doing it again, LOL....

I appreciate all the advice I have gotten and it has given me several ideas to reduce the weather helm effect..... thank you.

 

[Bill Roosa]

As the boat heels over the rudder and keel act at an increasing angle. they are intended to supply the lateral force to counteract the force from the sails but if they are horizontal...... not much chance of them doing their job in that configuration. The manufacturer has designed for extreme heel and the boat did what it should have, headed up into the wind (safe response to user miss use) due to the rudder being less effective at providing lateral resistance when heeled way over. Less lateral resistance at the stern results in turning into the wind as the stern of the boat no longer can resist the turning moment of the sail's CE against the keel/rudder combo. The same thing happens when you loose a rudder due to mechanical failure.
Reef or depower the main (same thing actually). If you try to balance the rig by powering up the jib you will only heel more and make the problem worse.

 

[Bill Roosa]

for the record, if you can get the toe rail in the water you have more than enough power to drive the boat at hull speed. Depowering the sails will not make the boat go slower. You can't get much over hull speed no matter how much power you supply due to hydrodynamics.
Sailing is more fun when sailing with the boat "standing up" and the crew/first mate will appreciate it.

 

[shemandr]

Why are you trying to have a knock down? To see what happens? Well you'll be uncomfortable and in danger of breaking the boat The art of sailing is to learn how not to have knock downs It's an old saw but you can't defy nature - you can live within her will

 

[DeniseO30]

this should help
http://youtu.be/ddyB9GwAkI8

http://youtu.be/7Ay4tyvObtQ

 

[centerline]

so what I have learned from all the wisdom that has been bestowed upon me, is that i was heeling too far and skidding.... that better describes what i was experiencing. and it is all more understandable now.
and without pushing the envelope, I would never have learned this.... and would always have been afraid of the dreaded "knock down" which seems very difficult to achieve in this boat with the keel pinned in the down position.

and now..... onto learning about the death roll, LOL....

 

[okawbow]

I had a Mac 25 that would round up much like your 22. It's mostly the design of the boat, but you can get more out of the Macs by tuning the rig, using newer, well cut sails, and replacing or modifying the rudder, with a more balanced rudder. Make sure your rudder and keel are down and locked in higher winds.

After my Mac 25, I sail a Bristol 24 that can sail rail down in heavy wind, with two fingers on the tiller under complete control. I still have to balance the sails and tune the rig for best performance, but the B24 is so much easier than the Mac25 when the wind pipes up.

 

[higgs]

You want your boat to round up before you take a knockdown. Be happy it does that. I would not want a boat that did not do that. Turning into the wind is your safety switch. Without it you stay pinned down and your cockpit - and then your cabin - fills with water and you sink.

 

[DeniseO30]

It' really not hard to reef a main even without the lines. the hard part is getting someone to understand they are not less of person or a wimp when they reef. So try it sometime, just hook the reef at the boom front and tie down and back at the end of the boom. and have some keech while your relaxing! in 20 mph wind!

 

[Joe]

A violent rounding up action is called a broach

A knockdown is when the boat lays over so far that the mast is almost in the water.. a sailboat's heavy keel will help itself recover from a knockdown. Boats without a counterbalancing keel will most likely need help form the crew to recover from a knockdown. (centerboarders, daggerboarders, asymetric hulls, etc)

It's hard to knockdown a keelboat without some strong wave forces on the beam... so rounding up may actually prevent a knockdown.

In it's simplest form, though, a boat will broach when the aerodynamic force on the rig greatly exceeds the hydrodynamic force on the hull.

In other words, the forces above the waterline overpower those below it,

When the boat heels over the mast acts like a big lever.... increasing the round up force. Picture a pencil stuck in a piece of floating cork ... with your finger on the eraser's head... if the pencil stays vertical pushing the eraser moves the cork and the pencil as one unit through the water.... however... with the pencil leaning, now on the side rather than the top of the cork, pushing the eraser moves the pencil horizontally...around the cork center.... like a big lever.... or rounding up the cork platform.

So... my advice to you is this. You don't have to die in order to know that it is advisable to avoid death. Take the time to study some basic sailing instructional books and videos. Then you will learn that the essence of sailing is balance....and that overpowering your rig is not only poor seamanship, but dangerous.

 

[SchwarckT]

Upgrading your rudder will give you more control in windy conditions. My O-Day 22 developed severe weather helm when heeled until I got a new rudder for it from IdaSailor. Now the helm stays balanced regardless of the degree of heeling. My other two boats also had the same problem as yours, so I made new rudder blades for them and got similar results.

 

[finding41]

Here is my modified rudder. Its wood wrapped with fiberglass. Being home made it has a airfoil design approx 0018. I wanted 0012 but was working with what I had.

 

[kenn]

Good on ya!

Hi centerline, thanks for sharing your experience. We went through similar (albeit accidental ) in our first two years with our boat.

Plain and simple, you had strong weather helm and rounding up because you had too much sail for the conditions.

I dont know the proper way to reef.... and I wont do it until I learn how and then I need to learn when to do it.

Reefing is easy. With some reading and a half-hour's practice at the dock on a light-wind day, you'll know all you need to.

On this forum and elsewhere the conventional wisdom is that on the water, it's much easier to let a reef out then to put one in. Ditto for changing headsails. From advice and experience, we now know that if the expected wind is likely to be at or over X knots, we will start with one reef and the smaller headsail. (for our little boat, X is about 12 kt).

When you have the right amount of sail for the conditions, properly trimmed, the boat will handle nicely, without excessive heel or weather helm. You'll still be moving at hull speed, except the boat won't be the bucking bronco you experienced. Brains over brawn.

While we admire your courage, there are many mistakes you don't need to repeat . I presume you're not going to deliberately go agrouind on the rocks for the experience... :naughty: