The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.
The comment about kayakers not using rudders but steering by leaning their craft caught my attention. Also, the use of the term “rocker” which may be the equivelant to a sailboats center of lateral resistance as it’s the pivot point for the forces of the wind on the hull. If they have aft Rocker (a center of buoyancy aft), they experience weather helm with a cross wind blowing the stern to leeward.
This may relate to my concern for some time that sailors may be looking at the helm issue from within a box. The issue of fore and aft balance or center of buoyancy is not mentioned as having an effect upon weather helm in The Annapolis Book of Seamanship but there is simple mention that the turn characteristic of heeling is a contributor to weather helm.
It seems to me, that we may not fully credit the various forces that may be contributors to weather helm. Very often, the discussion is all about the “lead” and relationship of CE to CLR. How strong are turning forces caused by heeling? If a C250 were without center board, rudder or sails… and were heeled to 35 degrees… what would be the turning force? Remembered is a problem I had when the beaching rudder was not working well. The hold down system had worn and allowed the unbalanced rudder to tilt back an additional couple of inches. If the boat experienced a rudder lock turn with much speed on… it was very difficult to pull out of the turn do to severe rudder torque. The problem was corrected by balancing the rudder and adding some skeg. Was this an indication of the turning force of the boat while heeled? That heel angle was only 10-15 degrees…
Some time back, someone described their ordeal of trying to helm the C250 without a rudder. They first tried steering with the outboard… but were unable to hold a course. They were then taken in tow… at which the boat wanted to veer off making the tow very difficult. Why didn’t the boat track under motor or towing conditions? Was it experiencing significant turning forces from slight amounts of heeling that were strong enough to preclude steering by the outboard? Does aft buoyancy leave the boat vulnerable to yaw and this tendency was magnified by not having the rudder in place?
If either is true, then what specific responses could be made to deal with either of these two contributors? Of course, a lengthened lead by a more forward CE or a more aft CLR will yield a corresponding resistance to a stern wanting to yaw. But, those techniques while overcoming…don’t specifically address either issue.
Sand bags do. They will have the effect of moving the center of buoyancy forward thus reducing or balancing leeway. They also make the bow a little finer or deeper which has a known decreasing effect upon weather helm. They also deepen the draft of the vessel and make it less tender, both of which are criteria understood to lessen weather helm.
The turning forces resulting from heeling a wide hulled boat are likely the main cause of adverse weather helm and likely are the hardest to counter. The best technique of course is to limit the boats heeling but that leaves a boat without a forgiveness zone. To gain forgiveness, increased resistance to yaw has to be provided. This has been addressed in part by the high lift rudder. Beyond normal boat balance issues of sail trim, use of the traveler, jib cars aft, flattening of sails, raking the center board aft, etc. there are other things that can be done.
Other suggestions from the reading sources are to add skeg, move the jib tack to a bow sprit, move the mast forward, shorten the mainsail foot, lower the mainsail, reduce the mainsail roach, add to aft section of keel. All these involve significant effort.
A skeg would likely be the easiest change to make (likely a bolt on item). It would reduce the yaw tendency associated with the heeling characteristic as well as add additional latteral resistance aft to assist with boat balance caused by leeway. This is something I have suggested for some time. A skeg of course has some undesirable traits. It adds wetted surface and reduces the effectiveness of the rudder but at slow speeds this likely wouldn’t be an issue as many C250 skippers augment the rudder with motor steering when docking.
I’ve had a small skeg on my boat the last several years and recently when fitting the 3rd generation rudder removed the most significant amount of it. Test with the 3rd generation rudder indicated some wandering. Having experienced very good tracking with the 2nd generation rudder and the skeg, I am not willing to compromise good tracking. Plans are to return to the 2nd generation rudder as it has superior lift to the 3rd or perhaps the skeg was assisting the 2nd generation rudder considerably. If the boat wander stops… then the 2nd generation rudder will get the credit…if not…then I will certainly redesign and add the skeg back.
Arlyn, Do you have finite knowlege or aware of some distinguishing visual appearance of what the 2nd generation beaching rudder looks like compared to the previous or original rudders on the C 250 WB ? Thanx in advance "Bear" on Brandy C 250 WB "089
I'm not much on physics or theory, but I can definatively tell you greater heel causes greater weather helm. Any boat sailed flat will experience less weather helm and any boat will turn (all other things being equal) in the opposite direction of heel. I think all of your conclusions are correct. The easiest thing for us to do is "Sail It Flat" (Sunfish primer by the same name) and move all possible ballast forward.
You are right that the turning forces are affected by heeling. If you have ever experienced a knockdown (who hasn't?) then you have seen this in its most extreme form. The C250 will round-up wildly when it reaches a point that all steering is lost because the boat heels so much that there is little or no water passing over the rudder.
Every sailboat will experience weatherhelm in certain conditions. Our boats just get it quicker than some. We have traded less weatherhelm for more interior space. High freeboard, flat bottom, large sail area - compared to older more traditional designs, limited keel, all increase the on-set of weatherhelm. The wing keel has slight advantage here in certain conditions, which is why raising the swing keel half-way up in heavy air will help on the WB. (Although that has greater effect on speed than weatherhelm)
Reducing weatherhelm can be effected by several adjustments. The most important -sail flat. Having lots of crew to hang off the high side is one. Raising the keel, reducing sail, tightening the outhaul, easing the vang, will all have some effect on weatherhelm. But things that reduce the lateral forces are the most effective. That's why a traveler is so helpful. By dropping the traveler leeward, more air will be spilled out the top of the mainsail and lateral forces are reduced.
Adding a skeg would reduce weatherhelm by converting lateral force to forward, driving force. But the increase in wetted surface and increased turbulance (right in front of the rudder) should have a real negative effect on boat speed. The real enemies of boat speed are wetted surface and turbulance. That another reason why adding sandbags is a bad idea - it sinks the boat deeper - more wetted surface, more turbulance from a flat bottom. Having crew is a better idea. Crew can be moved forward-aft, in-out to adjust to ever changing conditions and different points of sail
<BLOCKQUOTE id=quote><font size=1 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>The wing keel has slight advantage here in certain conditions, which is why raising the swing keel half-way up in heavy air will help on the WB. (Although that has greater effect on speed than weatherhelm)<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>
Responding to your thoughts... I’ve been on record suggesting that the center board likely had a bit of advantage over the wing regarding a sensitivity to weather helm. Perhaps before proceeding… I ought to say, the basis for that conclusion is somewhat skimpy and therefore falls into the realm of speculation.
I would rather were based on actual sailing comparisons… rather than on what others have reported over the years. Basically that is that the center board boat with 2nd generation rudder and center board raked aft somewhat, can heel to 40 degrees and sail there without undo rudder turbulence and drag slowing the boat and causing a round up. I've not heard those kinds of numbers from wing owners. In fact...they more often suggest no forgivness zone exist much beyond 25 degrees. Hopefully someday I’ll get some time on a wing keeled boat to make that comparison. Here are some thoughts anyway…. And I’ll continue to take the stand until proven otherwise that a center board boat has a bit of advantage when coping with weather helm.
A wing keel when heeled, theoretically doesn't lose lateral resistance as the losses on the vertical plane are offset by the gains on the wing plane, whereas a centerboard loses both laminar flow and lateral resistance with a diminishing vertical plane. So, leeway resistance will likely be greater on the wing keel at greater heel angles and combined with a greater amount of sail area due to the larger jib and more freeboard, more heeling forces will exist on the wing keel boat. However, as the center board model is more tender do to less righting arm… they probably wash.
The big difference is that when the yawing effect becomes strong… the centerboard can be raked aft which has a great effect at overcoming the yaw by having shifted the center of lateral resistance considerably aft whereas the wing keel CLR has no similar compensation ability. I’d point out that a shift of the CLR is done within the hydro medium rather than air and thus has a much more dramatic affect… a corresponding shift of the CE is not an equal.
Reading one account recently… a sailboat designer in an effort to balance a new design…first tried adding a bow sprit and moving the headstay more than two feet forward and when failing to accomplish relief…added a few inches aft on the keel.
Arlyn quote: -------------------------------------------------------------------------------- "centerboard can be raked aft which has a great effect at overcoming the yaw by having shifted the center of lateral resistance considerably aft whereas the wing keel CLR has no similar compensation ability" --------------------------------------------------------------------------------
But isn't the CE and CLR much different for the WB because of the W in the bilge? Without the ability to rake the keel, the WB would be at a distinct disadvantage to the wing keel.
However, in light air, the superior tracking and lower CLR of the fully extended centerboard will give the WB a distinct advantage. I have experienced that many times in my Oday 25 swing keel which I use to race. I had a distinct advantage in light air against winged keels and fixed keels but lost it as the wind increased.
1. The increase of weather helm at extreme heel can be explained when you think about what way the rudder is actually trying to turn the boat. As heel increases, and as you turn the rudder to leeward to offset weather helm, there is a vertical component to the force on the heeling rudder that is trying to lift the transom and drive the bow down, not just turn the boat. Since aft end of a 4-6000 lb. boat isn't that easy to lift and the bow doesn't want to dive, the rudder resists the turn considerably more than when the boat is flat and the forces on the rudder are virtually horizontal--merely turning the boat).
2. The wandering under tow is probably the same effect as sailing around a mooring... The "CE" of the boat under bare poles is forward of the CLR, largely affected by the mast and the high freeboard at the bow. That pushes the bow off to one side or the other until the angle of the tow or mooring line is so great that it pulls the bow over and the boat "sails" the opposite way. A riding sail moves the CE aft, and might help under tow as much as on the mooring. I've seen racers leave the main up under tow--probably for just that reason.
Under power with no rudder, I can attest that tracking is very poor. I think it's because you're pushing from the extreme aft end while the boat tries to rotate on the axis that is the centerboard well forward. I've tried that, and it's very touchy. Think of the CE being at the transom (or behind it on a C-25).
I hope not to test the theory on towing... <img src=icon_smile_cool.gif border=0 align=middle>
Dave Bristle, 1985 C-25 #5032 "Passage" SR/FK/Dinette/Honda in SW CT
Leonard, I think we may be viewing the CE & CLR in differing planes… while their centers do change vertical positions which come into play in regard to heeling… it is the horizontal positions that play upon boat balance (helm balance) and the boats ability to track without undo yaw to windward or leeward.
It is the horizontal that I was thinking of when commenting that the centerboard as it’s raked aft… has the effect of shifting the CLR aft, which increases the leverage of lateral resistance forces to counter yawing to weather.
1. Huh?... weather helm or yaw to windward would become severe at greater angles of heel whether there was a rudder attached or not. Don't think the rudder is a player in the cause...albeit it is a major player in the overcoming.
It's my belief that the major player is the turning forces caused by a lowered gunnel and the smaller the length to width ratio...the greater the effect.
2. I agree with your comparison that at tow may be similar to at anchor or mooring... though I'm more a believer that lifting forces of the hull foil are more a part of sailing at anchor than the push effect. At any rate, these forces are opposite to the tracking forces of a boat under sail. Under sail, the stern is trying to yaw... and under tow or at mooring, the bow is trying to yaw so the opposite CE is needed to enable tracking so....your right... increased aft CE should help greatly.
Will have to remove the rudder and try to motor the c250 sometime. I do remember doing this on my C22 once and had no problems. Arrived at the lake once to spend the night to find very high winds and a skidish crew so didn't raise the mast, drop the center board or install the rudder. Motored to an anchorage without any steerage problems.
As in depth and erudite as your discussion might be, I'm afraid you might be losing most of the readership that sails out there for some fresh air and a tan, and just wants to keep the long thin thing up, and the short heavy flat thing down......<img src=icon_smile_big.gif border=0 align=middle> Let me put forth the analogy of two musicians. The concert pianist, schooled in chords, keys timbres and progressions, and then the jazz or blues musician who closes his eyes and just plays. (Fats Waller could not read music....). Most of our sailors are more on the latter than the former end of the technology/seat of the pants continuum. Although I was taught how to read music, I was dumped in a sailing dinghy and shoved off at age six, with no more than a "be careful", and figured it out for myself. Even though I have since been taught the priciples of aero/aqua dynamics, I sail by the seat of my pants, and not with a protractor in hand. <img src=icon_smile_wink.gif border=0 align=middle> From that perspective, and having just spent about 60+ NM on the Chesapeake in 10 to 25 knot winds getting a first real taste of Lady Kay, let me put in my five cents for the other folks trying to figure this boat out..... Yep, she's touchy (sporting?). If it starts picking up, have the mainsheet in hand. If the wind is at, say 10 knots and you start getting puffs, pull it out of the cleat (the mainsheet).....If you feel she's heading for, say, 15 degrees of heel, with energy for more, start dumping the main.....don't hesitate to let it go all the way.(Limited forgiveness zone) Let her come back past level, this helps with getting her nose back to where you were going in the first place. (The yaw-heel theorem....)Try not to get the rudder sideways, it really slows her down. When dumping the main isn't enough anymore, and she keeps wanting to bark at the wind, reef. When it heads for 20-25, put in the second reef, on top of the first. (That way the first is still there if you decide that the second was a bit panicky....) Indeed, you need to keep this baby flat. Looking at the fish through the port holes, and still maintaining course ain't gonna happen. Following the above strategy, I spent the entire time in the 5-6.5 knot regime, outrunning a Santana 2023-C which has a very similar PHRF rating. Adding parts and pieces below might make sense on paper, but takes away from sailing time, and money for, say a reacher drifter.....boy does that make her go in 10+knots..... Keeping the heavy stuff forward will help 'r from walking on her heels-keeping the bow in the water is always a good idea. If not for directional stability, then at least to keep the speed up...(Induced drag.) In summary, treat her like a big Laser, and she'll go like hell....especially in light air. If she wasn't so big you could even rock her downwind in light air.......
Please do continue the dissertations......I am learning here <img src=icon_smile_wink.gif border=0 align=middle>
_____________________________________ Dave B. wrote: "there is a vertical component to the force on the heeling rudder that is trying to lift the transom and drive the bow down, not just turn the boat." _____________________________________
At a certain point, I agree that the rudder would have a downward force on the bow when the boat is heeled greatly but the turning forces have not yet take control. I have experienced this in a knockdown when the bow would dig down but the boat will round-up wildly. These two actions would seem to be opposite but I think the bow going down actually speeds up the loss of control in a knockdown. When the boat heels sufficiently to lose rudder control the hull shape takes over which forces the boat to windward. It could be hull shape causing the bow downward but I would think the curve of the hull would force the bow up - so the conclusion would be the rudder postion (trying to move the boat to leeward) would be causing or at least adding to the downward force on the bow.
Arlyn, I'm not sure the hull to lenght ratio affects whether or not there are turning forces to windward at extreme heel. A larger boat will round-up also, although probably not as fast as the C250. Hull shape would seem to influence the speed of on-set of these turning forces and indeed may affect their strenght...which sounds like I just agreed with you.
_________________________________ Arlyn wrote: Leonard, I think we may be viewing the CE & CLR in differing planes… while their centers do change vertical positions which come into play in regard to heeling… it is the horizontal positions that play upon boat balance (helm balance) and the boats ability to track without undo yaw to windward or leeward. _________________________________
One factor we are omitting in this discussion is the righting moment which is affected mostly by ballast, which neither the WK or the WB have much. The CE and CLR are very different on Dave's fixed keel. While CE & CLR can be adjusted slightly, it would seem that hull shape and lack of ballast has more to do with the heavy weatherhelm and the abrupt windward rounding-up incurred with excessive heel (the turn characteristic of heeling). Which would follow your thoughts of the early rudders, are not the newer rudders longer, thus giving more control at increasing angles of heel - which you discussed in your first post. If you could attach 200 pounds to the bottom of you swing keel I would think you could keep it lower in higher wind having a positive impact on CE, CLR and RM. Knowing you like to engineer modifications to your boat - see if you can figure out how to do that. (Or add Bubba to the windward rail)
Excellent discussion, BTW. You have sent me to my dictionary a couple of times just to be sure I was following your thoughts correctly.
This discussion does bring up the humorous first experience I had with a C250.
A friend of mine bought one of the early 250. Being extremely proud of his new boat he entered the local spring regatta just a week after taking delivery of the boat. He asked me to crew for him in his new boat and since I did not have enough crew, I joined him for the regatta. At the start of the day, winds were 18 - 20, gusts to 25. By early afternoon the winds began to increase dramatically. A weather tracking unit on shore registered 28 - 32 with gust to 38.
You can imagine what happened to the 250. There were several knockdowns that caused us to do a 360. At one point we were knocked-down FOUR straight times. As soon as we would complete a 360, get the boat headed on course again, we would immediately go over again - the boat would round wildly to windward and just keep going - crew and gear flying. We did that four times in a row. Amusement park designers could not have created a wilder ride.
My friend, who ego is significantly larger than the boat, was nothing short of total embarassment by his lack of control. The next week he called his dealer and immediately traded the 250 for a 28 MkIII. We later learned the rudder deficency was a source of much of the problem
<BLOCKQUOTE id=quote><font size=1 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote> 1. Huh?... weather helm or yaw to windward would become severe at greater angles of heel whether there was a rudder attached or not. Don't think the rudder is a player in the cause...albeit it is a major player in the overcoming. <hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote> Arlyn:
I'll try again...
First, I have to believe the rudder is a component of the CLR, albeit a variable one, unless it is left entirely free and is 100% unbalanced.
But my theory had to do with the angle of the rudder at heel, assuming it still has some purchase. If the rudder is at 30 degrees from vertical, turning it no longer simply pushes the stern in horizontally in one direction or the other--it also tries to lift or lower the stern. If the rudder is vertical, only the boat's resistence to turning or desire to turn (as with weather helm) is going to create force on the tiller. As the boat heels, the rudder's "turning" forces are no longer strictly horizontal. Thus, it takes a greater turning angle to compensate for weather helm (CE aft of CLR), and part of that turning angle will be trying to lift the stern and drive the bow down--think of it as trying to turn the boat on its own plane, rather than the plane of the surface of the water.
Oh hell, I give up! <img src=icon_smile_dead.gif border=0 align=middle>
Moving on to motoring without the rudder... If the centerboard is raised, motoring should work more like a powerboat--a little change in the motor direction will not affect the boat as greatly. But with the board down (or a fin keel), the boat will slide very little, and the slightest turn of the motor creates an exagerated turn of the boat as the board does its thing. Powerboaters wish they had this effect when they're trying to back into a slip, but they surely don't want it at speed! It would be like backing a car at 50 mph--very touchy! Centerboard sailers with no rudder will ride more easily under power by lifting the centeboard--until they get to a dock or slip where they want the precise tracking.
You don't need to remove the rudder to test this--just let it go free and steer with the motor--board up and board down. I've done it with a smaller centerboarder, but not with a C-250.
Dave Bristle, 1985 C-25 #5032 "Passage" SR/FK/Dinette/Honda in SW CT
Dave....you gave up just as I got the point... and your explanation makes sense. Certainly the effectiveness of the rudder to counter yaw decreases with heeling, when its needed more... and I agree that the attempted impossible turn of the hull into the depths might be adding to the yaw problem.
And... yes, the rudder is certainly a part of the boats lateral resistance. A significant part in fact because its fartherest aft and has the greater lever.
And... I agree with your thinking on the center board when motoring...will test the turn characteristics while motoring with center board down and up. Up... it will likely act like a skeg and enhance tracking. And your right, a loose rudder will likely follow the turn.
When I had the problem with Catalina's hold down system allowing the rudder to rake aft a couple of inches... it was very difficult to pull out of a rudder lock turn do to the forces holding the rudder over. The autopilot couldn't begin to cope with it. Only after adding some skeg and balancing the rudder some was that problem cured.
Your story has been a familiar one... though yours is one of the most humorous. When confidence in the skipper is in question during these roundups... the moments aren't as funny as the later accounting.
I remember my first response when looking back and seeing the rudder dragging sideways and the boat rounding up and thinking...Holy Smokes!
The efforts over the years which were given a proper label as "taming the beast" however have been successful.
Yes, the first rudder had inadequate lift. The second had adequate lift but presented severe torque. The third is between the two...having fair lift without torque problems.
I've said before, IMHO the best rudder so far has been the 2nd in the beaching configuration. Though the blade and beaching were essentially the same, the ability to modify the beaching head and balance the rudder was a big plus. However, the strains upon it are evidently strong as several of us using it have reported gel coat cracking just below the beaching head... I've installed the 3rd which is the current production rudder but it doesn't have the lift of the 2nd. It is however a very well balanced rudder and thus has no torque issues.
A future project is to add carbon fiber to the stress areas of my 2nd as it's my favorite.
Your right, righting moment hasn't been a part of this discussion which dealt with coping abilities once significant heeling had caused severe weather helm. Increased righting moment (stiffer boat) certainly is a big player in avoiding severe heeling. As you point out, neither of the two models are stiff but the wing is more so than the center board. It is interesting to point out here that Catalina evidently had intial thoughts that the wing ought to considerably stiffer than the center board. When the wing was introduced... it was released in a tall version with 150% genoa but soon these were dropped as the boat was overpowered.
Why was Catalina caught by surprize in this? I think because there wasn't enough understanding of the c250 hull form characteristic. IMHO, I think Catalina's thought process may have gone something like this. Gosh, if a 900 lb wing is added 30 inches under the hull of the c250, it combined with the righting form built into the c250 (flat beamy hull) ought to stiffen it up a lot.
Remember...initial sales of the c250 had been good... but reviews of the c250 hadn't been. Stories such as were just told were circulating and water ballast was getting a bad rap. Remember, the C250 was conceived as a water ballast design meant for easy trailering. When sales and acceptance wained, Catalina I believe reacted to their belief in the virtues of the design and decided to produce the boat in a wing keel version.
The hull form characteristic that likely has been the issue is the square bilges which were necessary to internal ballast. I wish I could find the article that I read several years ago...it was from a yacht design journal and paraphrasing what was said, "its been long understood that a wider beam with square bilges is much more given to weather helm issues".
So, the information was out there... but its extremes hadn't been fully appreciated. It should be remembered that modern design attempts to provide answers to current needs which were perceived in the early '90s to be a family cruiser capable of easy towing and launch. Remember, good used boats were plentiful...new boat sales had to be to a niche that used boats didn't fill.
Where am I going with this... first, to understand the c250 these points are important. They are the reason for a boat with square bilges and wide beam which are a trade as you said for lesser weather helm.
The challenge as always...now what. Do we accept limitations of historical truths or find work arounds? Certainly the c250 has taken the design envelope to the limit and produced a sporty yet coastal cruising capable design with the caveat... keep it flat. What I have attempted to say all along is that flat is ok...but the nature of sailing really requires a forgivness zone...and if there's a way to have it... then the effort is worthwhile. I've found it... and doing so has turned my c250 from an ok boat to a good one.
Notice: The advice given on this site is based upon individual or quoted experience, yours may differ. The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.