Check This Out

[henkmeuzelaar]

Fun picture to analyze, Rick!

First of all, you are clearly making good boat speed with modest wind speed and minimum heel. So you must be doing a lot of things right. Secondly, I am not a racer who constantly twiddles everything. With Rivendel I am already happy if she doesn't flutter, slat, chatter, burp or whistle and I get positively ecstatic if she happens to look good on top of that!However, you are inviting our comments; so here goes: According to the wavelets the true surface wind direction must be about 10 degrees abaft the beam. Combined with the boat speed and wind speed info you just provided that must put the apparent wind some 10-20 degrees forward of the beam and shows the angle of attack to be just right for the main but probably a bit too large for the genoa (by enlarging the image the belly of the genoa can be seen to protrude forward of the headstay).Considering the modest wind strength, the foot of the main could perhaps be slackened a bit and the vang tightened to reduce twist and bring the upper batten in to line up more with the boom.The puzzling "knick" in the foot of the genoa might be connected with the large angle of attack (perhaps the point were the inside airflow reattaches?) and the copious amount of twist aloft. I would first have brought the angle of attack in line with that of the main by taking one or two wraps on the genoa sheet winch. If the remaining twist in the top of the genoa was then still on the large side I would probably have moved the traveler forward as well.By now, however, the boat would have started to heel more (because of the reduced twist in main and genoa), resulting in more weather helm and a dragging rudder. During a race this could then have triggered a power struggle over who was willing to be RAIL MEAT. If I would have lost that struggle I might well have decided that a bit more twist was not such a bad thing after all....However, I would probably have stuck with the genoas reduced angle of attack. Fair winds,Flying Dutchman

 

[Franklin]

helm?

Helm is caused by unbalanced sails, not heeling, correct? Isn't this a bit hard to tell that your adjustments would cause weather helm by the picture? You suggested triming improvements for both the main and genoa. If his sails were balanced before the adjustments, wouldn't they still be after (both sails improving)?

 

[henkmeuzelaar]

Heeling-induced weather helm

There are at least half a dozen factors that affect (weather vs lee) helm. In the final analysis it boils down to the relative position of the Center of Effort (COE) versus the Center of Lateral Resistance (CLR) and to the direction and strength of the force vectors through each of these two points. The position of the COE is indeed mostly affected by the sailplan. The more the COE moves aft relative to the CLR (e.g. by sailing on the main only or by raking the mast aft) the more pronounced the weather helm, and vice versa.When a vessel heels, however, the COE (situated high above the waterline) moves to leeward and the CLR (situated well below the waterline) moves to windward. As the COE is still being pushed forward (and sideways) by the aerodynamic forces acting on the sails and the CLR being pushed back (and sideways) by the hydrodynamic resistance of the water, the resultant rotational force in the horizontal plane tries to round up the vessel (thus creating weather helm).In most finkeelers with beamy hull designs (i.e. most Hunters) this effect tends to be quite pronounced. Not all hull designs show a marked heeling-induced weather helm effect, however. If the hull design is such that heeling causes a strong increase in wetted surface (i.e. friction drag) on the lee side combined with a decrease in friction drag on the windward side, the resulting heeling-induced rotational force may counteract -- and perhaps cancel out -- the rotating force created by the lateral separation between COE and CLR.Hope I got this right (no time to hit the books tonight). If not, the students of naval architecture on this board can be counted on to straighten me out.Flying Dutchman

 

[Franklin]

Under Gusts

I guess I somehow missed that point when reading about COE which leads me to another question then. If I am just using the genoa at a slight broad reach which of course gives me a lot of Lee helm, when a gust comes, I get a lot of weather helm. Is this because of the heel or because of the rudder fighting the lee helm? I read some place that when fighting a Lee helm and a gust comes that it will produce a weather helm and confuse rookies like me.I have a furling main and genoa and figured with practice I could eventually find the perfect balance between the two without making any rigging changes but now I starting to think that my understand of helm was a little mislead. I read somewhere that if you have perfect balance, you can go straight without a rudder and when a gust comes you will just heel and not turn. I guess that was wrong. Well...time to go practice now.

 

[Franklin]

Forgot to say

that I was just using my genoa that day because the main got jammed from rolling it up in the dark the night before. I found a trick to un-jam it at the doc the following week but it sure took a lot of effort to figure that out On a side note: that day I was out, I noticed about 80% of the other sailors were only using their genoa's too and they weren't running either. I don't know what to think of that.

 

[r.w.landau]

Rick, Where do you get people

to take aerial photos of your boat?r.w.landau

 

[RichH]

Thats a NICE boat ........

Rick - Your boat seems to be set up and laid-out VERY nicely .... all the controls very easly in reach. More importantly she's a "pretty" boat!For what its worth: a few years ago I switched over to rigid vangs .. and although they are WONDERFUL, I find that when keeping sail shape up, I have to keep fiddling with these vangs ALL THE TIME to keep the shape I want. On my big boat the boom is so heavy and the sailcloth weight so heavy that in light air (like what I see in the pic) I usually find that I have to release the spring tension so much until the leech becomes unstable (flops) so that the r-vang FORCES the boom UP ... and only then I can tweak 'down' with the vang. If I simply release the rigid vang to shape the twist I usually get less twist than I desire until I start to let the upward force of the rigid vang start to actually LIFT the boom. This doesnt happen on light weight booms on small boats - but is quite important on large boats, especially when there is no topping lift. In the pic I see the lowest draft stripe hooking to weather slightly at the leech .... and this acts like an air-brake. I think your rigid vang was simply left too tight - r-vangs simply dont have the 'stretchy-ness' that a block and tackle vang has. On my big boat I have to tweak the rigid vang almost as much as the mainsheet when racing and on a reach. Maybe this is too 'high-falutin' for such a discussion .... I dont believe that one shouldn't even consider what the very top/peak of a triangular sail is showing on the tell tales .... as there is a 'rotor' (like a slow speed horizontal tornado) streaming off the tip of the triangle and may confuse what you see in the tell tales. I simply put my 'top' tell tales further down (1/4 of the luff down) and completely ignore what is happeining higher. You never will see a bird wing or aircraft wing that comes to a point! and most of the super speed catamarans, etc. now simply cut away everything above the highest batten. For chafe when the main is up against the shrouds & spreaders .... I simply use stick-on insignia cloth (the stuff they make sail numbers and adhesive sail repair tape) and apply several layers. At the end of the season or when this sacrificial patching begins to chafe through, I simply peel it off the sail and reapply new. If the adhesive gets 'messy' I use a product called "Goo-Gone" to remove it. My boat has intermediate aft shrouds so its either lay the sail onto the shrouds or have a rotten angle of attack. For long distance racing and so that I dont turn the trimmers arms to pulp by constantly grinding on the winches when on a reach, I apply a long row of teeney 'steering' tell tales to the genoa - running about half the cord length from the luff back to the middle, 2" long and spaced about every 12" and that row about 10 ft. off the deck. This row will keep the steering *perfect* and if I gain a 'few inches" per minute .... over 20 hours will add-up to *incredible* distance gained. This way I can alternate between holding a bee-line course (with the trimmers working like hell) and 'scalloping' to the steering tails (trimmers taking a well deserved rest). Long distance sailboat racing is a game of constantly gaining - 'inches'. A full set of tell-tales (luff and leech) and a row of steering tell tales will put you further towards the front of the pack.best regardsRichH

 

[Rick D]

Couple of Answers

First, the race committee contracts with an aerial photog for the big races. I think any local aerial photog would do the same. Here's a suggestion: get a couple of YC's or just guys on the dock to get one. Guarantee a set fee (if necessary), offset by all photography sales. As you can tell, you can learn a lot from an overhead shot and they are pretty. An 8 by 10 runs about $80 as I recall.Second, thanks for the comments on the vang and telltales. I haven't used a soft vang in 15 years, so I had forgotten that they were perhaps more forgiving in light air. In this boat, it is my experience, like yours, that the spring is marginal in light air and sometimes needs some help to raise the boom. The genny has three teltales in windows, but I am going to add more. All the main telltails are on the leech (at each batten end). I always had some also in the draft and miss them. I will add some there also since I think it is a bit more easy to both over and under trim a full-batten main in my experience.One other thing: altho the PO put some very nice Harken cars on the jib tracks, I find this genny to have a very finicky sweet spot and will soon put an adjustable car system on.Rick D.

 

[Tom2909]

This it?

Here is a H34 from the Hunter forum area...

 

[Don Guillette]

Tom; That's the one I was looking at.

 

[r.w.landau]

Don,

It looks like this is a loose footed main. It looks like the clew should be tightened and the boom released to just leeward of the centerline.The genoa car need to be moved foreward and the jib trimmed to try to shape the jib to move air past the main instead of into the main. Never mind the car, just trimming the jib might do itI am done. someone else go from there.r.w.landau

 

[Ken Juul]

H34

Draft of the main looks to be aft of mid boom. also top of main is twisted open. Additional outhaul will move draft forward and help reduce the twist. Adjust outhaul then adjust mainsheet, if heel becomes an issue, drop the traveler a bit. The head sail has a loose foot and a bit of a twist, tighten the sheet.A larger picture sure would be nice.