Unbalanced Lines Sought

For a continuing research project into balance in sailing hull design, I am looking for some bad examples. Any size, any class, any era: the only criteria is a consensus opinion that it was a difficult boat to steer. The worse the better, for my purposes I need lines sufficient to construct a model of the hull; sailplan is not required.

Cheers,

Earl

 

Bad yacht designs? How many do you need? I'll start drawing now and have a dozen sent your way by the end of the night. If I run out of inspiration I'll just look to the MacGregor website. Or to the Cruising Log of the Murrelet, the mother lode of bad sailboat design concepts.

 

when you say research, what exactly are you doing?

Does it revolve around model-testing or computational work?

Tim B.

 

Ah, thanks -- but I just want ones that experience shows are bad in a specific way; ugly, cramped, wet, etc. doesn't count. If the people on the helm have to battle the wheel until they drop from fatigue, that's what I want. Example: Crowninshield's giant scow "Independence," which supposedly was so unbalanced she flung her helmsman overboard as he fought to control her

Cheers,

Earl

 

Model testing first to validate anecdotal evidence, then computational work if interesting correlations arise.

Cheers,

Earl

 

Unbalanced boats

Try a J24 for starters, they appear well behaved initially due to the balanced rudder, but this belies an unbalanced hull which develops so much weather helm the boat can round up out of control and even tack without warning in gusts if you do not drop the main. 11m one designs are also pretty bad!

I have previously conducted a discussion on the reverse of your quest, ie:looking for ways to design a balanced boat, but with little success.

Wardi

 

"Balance" in a sailing vessel is always a function of the interrelationship between the canoe hull, the keel, the rudder/skeg, and the rig. How are you going to isolate these elements in your (theoretically) badly balanced boat? And how will you "know" that a specific hull is unbalanced if you don't look at the rig as well?

Tad

 

I've successfully raced J24s in all conditions including gusts up to 30 knots (SF Bay) and have never seen one round up or tack while sailing upwind.

In fact, the design of the J24 is off in the opposite direction. The boats don't have enough weather helm. If you want to race in a competitive fleet you have to move your keel as far forward as allowed under the rule, and also use the max allowable length headstay to get the maximum rake.

The rudder doesn't have enough counter balance, which requires a lot of helm input when sailing upwind in waves.

Sailing dead downwind with the kite up in big breezes they are very unstable. The crew needs to constantly and quickly move body weight to change trim or the helm cannot stop the roundup/down. The wipeouts begin at very low heel angles, so the balance of the hull shape (tendency to pitch nose down as the boat heels) is not the issue there. Neither is balance between the aerodynamic/hydrodynamic centers (tendency for lee helm or weather helm).

 

I'm trying to isolate the effect of the hull and appendages from the rig. I have enough full-sized and (especially) free sailing model designs that are reported/observed to demonstrate balance in practice. I'm looking for full sized designs that are reported/observed to be the opposite. So far I have only three "notorious" boats: Satanita, Whirlwind, and Independence. Hence the question.

Cheers,

Earl

 

Earl;
Your line of reasoning is legitimate to the extent that one must analyze the problem before it can be fixed. Much of scientific inquiry is based on that premise.

Tad is spot on when he says you must address the rig. We need to quantify the degree of unbalance to begin meaningful analysis. A badly cut or bagged out set of sails will often render a good boat piggish in terms of balance. A flat cut suit may do that in the opposite direction. We have a mess of variables that complicate things beyond mere geometry.

Another factor is that boats behave differently at different angles of heel. For a simple case consider the traditional Sharpie. At 5 degrees of heel it is very likely to have weather helm. Increase the heel incrementally and it goes to neutral helm, then to lee helm. Many boats behave somewhat similarly or sometimes oppositely. That does not make them bad boats.

If you will allow me to refer to the ridiculous, then consider this one. The fun loving boys at the TSCA chapter in Bradenton Florida wanted to build the worlds cheapest sailboat. They called it Corky. It consists of an inner tube from a truck tire, a piece of plywood cut round to match the tube. The Mast was first attached to the rudder head because that part was already conveniently there. The boat, I reckon you would call it an RIB, would actually sail. But it refused to go to windward. They moved the mast to the front of the contraption and now it does go to windward (sort of). Those boys were just funnin' around and not interested in research. However they made the boat work simply by rearranging the parts a bit. Independance could surely have been made manageable by fiddling with the force vectors. I submit that almost any floating object can be made to balance well enough to become functional though perhaps not hydrodynamicly efficient.

 

I owned a '77 7 meter S2. I would have to say the boat was very poorly balanced (sorry old girl)---------- which made for a very tough weather helm as the wind piped up. In addition, the boat was a handful running in a following sea, requiring as much as 60 degree (constant) swings of the rudder to stay on course--- a real workout.
Yet... yet, I put a 3 ft bowsprit on her, a jib on the end of that (kept the original stays'l, making her a cutter), made an adjustable draft half-wishbone self-tending spar for the stays'l, and went on to make consistent 6.9 knot (gps confirmed) two-way beam reaches, often keeping up with boats with far more than my meager 18 1/2' waterline.
The boat had always managed 6.2 kts max before, but as said, the weather helm was horrible as designed.
The cutter rig was not a good close-hauled set-up, but I could always douse the jib and go with stays'l or genny and do okay. A lot of work.
Okay meant a lot of leeway, or full and by amounting to (I'm sure) no better than 55 degrees off the wind.
I don't know where one could find sections of that boat, but you could try.
Few were built.
I attribute the boat's characteristics to extremely unbalanced sections---- a wide stern and a narrow bow, which really had a major effect when she heeled. Even after my changes, there was a lee helm penalty at low wind speeds, enough to prevent ghosting to weather, though the boat felt perfectly balanced and safe when the wind piped up.
Bottom line, the helm difference was never fixable. I had only changed the nature of a comprimise.
Neither was the modified boat safe in following seas when running. The broad stern was determined to slew around a bow that dug in.
You cannot fix a bad hull with any kind of rig. You can only shiff the problem somewhere else. As it was, the modified boat was extremely fast on a beam reach, which suited my sailing at the time, which mostly consisted of trips at right angles to the prevailing summer wind. Otherwise, no fun.

A.

 

I'm afraid I haven't made myself clear. It's not enough that the boat sail to windward at all, it's that it do so with minimum input at the helm, as described by Phillips-Birt:

"A yacht is balanced if she shows a natural desire to steer straight when
heeled. A well-balanced yacht, like a good model, will sail herself under normal conditions with the rudder amidships; variations in the angle of heel will have no effect on the steering, while under the worst conditions she will be light on the helm and show no tendency to run wild."

The models he refers to are free-sailing models, which are what I sail and what got me interested in this subject in the first place. I must also admit that I am far from convinced of the primacy of rig as a factor in this property. I can cite three examples that support this opinion:

1. The balanced cruising designs of Butler, Symonds, and Welch were reported to be balanced whether they were sailing with full cutter rig in moderate air or under storm trysail in a blow.

2. The J boat Yankee underwent several major changes in rig over her lifetime, from a three-headsail rig in 1930 to a mammoth genoa with movement of mast position for the 1937 Defender's trials. There is no report that at any time she lost her light and balanced helm -- acknowledging that absence of evidence is not evidence of absence.

3. In the realm of personal experience, I designed and sailed in competition a free sail (vane steered) boat with a sliding rig; that is, the whole sailplan could be moved fore and aft over a range of about 15% of the LWL. The rig position, like other elements of trim, is set before launch and cannot be changed when underway. The hull was "balanced" under the simplified criteria that the LCB did not move under heel. The boat was a dog. There was no adjustment of sail or rig position under any strength of wind that would keep it from heading up sharply in a gust. I then built a hull that was balanced according to the criteria of Turner (not, I might add, that I believe his explanation of why this criteria works) and mounted the same rig on it. The boat is a delight, tracking through puffs and gusts like she was on rails. My working hypothesis is that the rig factors govern how the boat points and foots and hull shape governs how she reacts to gusts. This is not a new observation; Phillips-Birt made it in an article printed in 1947. The topic is discussed in (perhaps excessive) detail in the following thread:

http://www.rcsailing.net/forum1/showthread.php?t=3436

and is organized and summarized in a paper I gave at the last CSYS:

www.csysonline.com

The paper is only available from SNAME. In a day or so I will put my slides and notes to the talk up on the USVMYG web site and post the URL here.

The evidence, as I have said, is anecdotal, unscientific, and devoid of observation in controlled circumstances. My next step is to try and validate supposed correlation of Turner's criteria and behavior by recording the tracks of self-propelled free sailing hulls under artificially induced changes of heel. Nothing earth-shaking, just an old geezer messing about with toy boats

Cheers,

Earl

 

I'm with Tad - trying to find an unbalanced sailing hull without looking at the rig and foils is like trying to find a tyre (tire to the US) that doesn't steer well without looking at the car it is attached to.
Steve

 

I assume, Earl, you're saying consistency of helm throughout the range of heeling angles/speed is a product of balanced lines, something I completely agree with.
Further, you appear to be saying that the "proper hull" does not induce change of helm if the CE is shifted within 15% of fore/aft range when close hauled.
Does beam/length ratio factor into this in terms of maximum beam, and if so, how practical would the ideal hull be scaled to less than say, twenty feet LWL?

A.

 

Yes, exactly.

Er, no. The rig is moved to keep the boat pointing with the desired helm under conditions of changing mean wind velocity (averaging out the puffs). Maybe an example would make it clearer. Free sailing regattas consist of round robin match races. At the first race of an afternoon the wind was at about 8 kts and my boat would do the length of the pond on a beat in 2 1/2 tacks. At the last race, about 4 hrs later, the wind had tailed off to about 4 knots. At each race I moved my rig back a bit. By the end of the afternoon the rig was set about 5 % of the LWL aft of where it had started, and she was still doing the length of the pond in 2 1/2 tacks. Boats with fixed rigs were sailing much lower by this time.

Beam/length ratio is not a factor in Turner's ideas. The first full-size boat designed using his "system," Frank Welch's Fidelis, was about that size, as were many of Harrison Butler's designs. Fidelis was built in 1931, and evidently was a very successful ocean racer in the 1960's, although I do not know if this was an artifact of the boat or the rating rules of the time.

Again, I want emphasize that I do not believe Turner's explanation of why his method yields balanced hulls; it is a happy coincidence that bears further investigation. The one consistent thing is that if you go through all his folderol you end up with a hull whose LCF sits right at its LCB through all angles of heel to rail down. Even if that is all there is to it, we are still left with the mystery of why a hydrostatic property should be predictive of hydrodynamic behavior.

Cheers,

Earl