Rig changes for improved 26X/M genoa performance

[Murv Barry]

Normo I didn't modify the genoa when I shortened the spreaders a couple of years ago and still use the original sail with the car fw'd on the track. I'm not sure if VMG is better. I think it is but next years racing season will give me more info. The 26Ds walk away from any X however I get a good idea during the first leg as to the performance of the X.
Spreaders are well tested. As I said earlier, I've had the rail down to the water and could hold it there just to test it (mainly the enlarged rudders) and it all performs well (so far anyway). A friend of mine cut his spreaders before I did and neither of us have faced any problems. The sailmaker went so far as to say that the rig may not even need spreaders. Not so sure about that.

Good sailing, Murv

[Frank C]

Could the curved shroud be the result of a wide angle lens?

Nah, Tom - the rig was a slack, so the picture shows the wind & gravity effects on that lee shroud. The Genoa photos are striking though. After seeing them, I'm probably going to attach a padeye down near the rubrail under the galley window. I'll use it to anchor a barberhauler that might yank that leech straighter. If that brings it too close to the spreader - well that's an easy fix too.

Since day-one with this Genoa, we've noted that the Genny track is too high to trim the sail. I think the tack angle needs to be closed a little tighter. I need to decide if I'm going to work with it, or just ask UK to adjust the sail. It's a beautiful sail for light air days but it becomes a handful when the wind is up. Unfortunately, the tapedrive construction would really complicate the change.

[Jeff S]

This thread is excellent. I am planning on purchasing a new genoa before this spring and haven't decided which way to go, I am leaning toward Cruising Direct. It seems it might be easier to get slightly better pointing, less weather helm, and maybe a tad less heel with something less than a 150 and still get good performance in light winds- 130-140 range.

Frank, was your 65 degrees off the wind relative or true?

Has anyone moved the Genoa track forward, or installed a longer one? Would this help, or would the shrouds still be the limiting factor for sheeting angle? I haven't sailed with a Genny on my boat so am unfamiliar with the interaction there. The boat sails nicely with a jib as long as there is at least 10 knots of wind, otherwise it is not enough sail.

Jeff S

[Moe]

The boat sails nicely with a jib as long as there is at least 10 knots of wind, otherwise it is not enough sail.

Wow, that much? That's interresting, since we only have the jib... and a motor, of course. We're thinking of sticking with that, and just adding a cruising spinnaker later. Sounds like it may have to be sooner.

--
Moe

[Frank C]

Yep, the boat just barely moves with the std jib in 10 knots or less. Double the wind and that jib is your friend. I like the size of the 135, but a 125 might be just as good where I mostly sail. The 135 is still a nice compromise to have aboard for trailing to other locations.

The 65 degrees is measured to apparent wind, the only measurement on a boat unless you hook up the GPS and so the computer can calculate true. Look under Mac Mods "Sailing" category to see a picture of the wind instrument from that mild winter day with winds @ 11kn. The page title is "instruments & Genoa." That instrument panel is now hinged to the lip of the sliding hatch.

[Jeff S]

Thanks for the info Frank. Winds here seem to average around 8 knots- that is just my observation. There are plenty of days when the jib is nice, but I think I would be more thankful for the Genny on the RF than the jib overall.


Moe- it is true about the wind and the jib- I thought I could just stay with the jib, but it isn't enough. I thought about the spinnaker too, but I think I would get more out of a Genny for my money, and then maybe go with a spinnaker the following year as my sailing skills improve (and that of my crew!) and I get used to the nuances and balance of the boat with a Genny. I think the Genny has far wider range of wind conditions to where it would be suited on this boat than my current jib.

Now I am curious to hear some results of those who reduced their spreader length. When I get my Genny hooked up I will have to check out the issues first hand and see how much pointing ability I lose and what I might be able to do about it. I think Frank is on to something with the barberhauler idea, but I will have to see how everything interacts with the sail I finally decide upon.

Jeff S

[Moe]

Hmmm.... for all practical purposes, the second mod picture is a reach, and with a genoa yet! So is it safe to say that with a jib, best speed in 8-10 knot winds might be 2.0-2.5 mph?

Putting this in perspective:

In [a recent study published in the Journal of Aging and Physical Activity], the walking speeds of a group of elderly men and women, aged 77 to 89, were measured over an indoor course and across a typical suburban street of the same length. The speeds were measured under four conditions and produced the following results.

indoor at a preferred pace: result, average walking speed = 2.1 mph;

indoor as fast as possible: result, average walking speed = 2.7 mph;

outdoor at a preferred pace: result, average walking speed = 1.7 mph;

outdoor as fast as possible: result, average walking speed = 2.0 mph.

--
Moe

[craiglaforce]

Not at all. The boat sails nicely with a standard jib (and mainsail of course) in under 10 knot winds. You just have to pay a lot more attention to sail trim and at some point sit on the leeward side to induce enough heel to keep the sails set.

But on a reach or downind a Genoa would of course be faster.

pointing 65 degrees to Apparent wind is rather poor. This means an even larger angle to true wind. It is easy to get the angle to true wind. Just sail as high as possible and tack to sail as high as possible on the new tack. Take the total number of degrees you have tacked through and divide by 2. WIth a jib you should be able to tack around 100 degrees or maybe a tad more (50 degrees to true wind).

[Dimitri-2000X-Tampa]

I went sailing today with 8-12 kn winds on the nose. Per somebody's suggestion here, I rigged up a second light set of sheets from the Genoa clew to the jib cars to see how that would work beating upwind. With the Genoa partially rolled up and the forward sheets pulling it into a good shape, it seemed like I could point 20 degrees higher than when I went back to the normal genoa sheets and unfurled it all the way. Unfortunately, there was not enough sail up to go more than about 3kn with the fairly light wind.. With the full genoa, I had to bear off about 20 degrees but my speed went up to about 5kn. Anybody want to do the trigonometry? When I download my GPS track, I'll see how high I was pointing. Probably tacking through 120-130 degrees with the Genny I'd predict.

I think with a bit stronger wind, the forward sheets would have worked real well, but I wanted the extra couple knots of speed with the full Genny today. Didn't have any opportunity to do any good reaching due to the restricted course. Had a couple huge dophins come up right next to the boat (maybe 1 foot from the boat) and scare the bejeezus out of the wife though. After that, it was a big thrill since the kids got to see them closer than they had before. When we went out to the gulf at Thanksgiving, we saw some dolphins jumping (a few feet out of the water) repeatedly..first time we ever saw that outside of Sea World!

[waternwaves]

Dimitri

Was anyone lucky enough to get a camera on the dolphins?? sounds like a great trip..

I am going to have to try the second sheet idea..lol but with my 150... its gonna be terrible sail shape from what I have been told.....

[Dimitri-2000X-Tampa]

I only have a camera on board about 50% of the time...and of course, today was a non camera day. Now that I think about it though, I did have my cell phone which has a dinky camera built in...but I didn't think of it at the time.

We see dophins out in the bay/gulf probably about half the time we go out typically. This is just the first time that one has come so close to the Mac. I've had 'em come that close before on my former sailboat though. If you happen to be on the low side of a heel and one of those big suckers sneaks up a foot away from you and then clears their blow hole...it will definitely get your attention! I suppose they do it on purpose to "scare the humans"

[Jeff S]

With the Genoa partially rolled up and the forward sheets pulling it into a good shape, it seemed like I could point 20 degrees higher than when I went back to the normal genoa sheets and unfurled it all the way. Unfortunately, there was not enough sail up to go more than about 3kn with the fairly light wind.. With the full genoa, I had to bear off about 20 degrees but my speed went up to about 5kn. Anybody want to do the trigonometry?

NP, I believe you were doing better VMG with the Genny at 5 knots. Here is a chart I whipped up real quick with MS Excel. (The top row is boat speed in knots, the left column is degrees off course- the intersection is VMG to the destination):

0.0 2.000 2.500 3.000 3.500 4.000 4.500 5.000 5.500 6.000 6.500 7.000 7.500
30 1.732 2.165 2.598 3.031 3.464 3.897 4.330 4.763 5.196 5.629 6.062 6.495
35 1.638 2.048 2.457 2.867 3.277 3.686 4.096 4.505 4.915 5.324 5.734 6.144
40 1.532 1.915 2.298 2.681 3.064 3.447 3.830 4.213 4.596 4.979 5.362 5.745
45 1.414 1.768 2.121 2.475 2.828 3.182 3.536 3.889 4.243 4.596 4.950 5.303
50 1.286 1.607 1.928 2.250 2.571 2.893 3.214 3.535 3.857 4.178 4.500 4.821
55 1.147 1.434 1.721 2.008 2.294 2.581 2.868 3.155 3.441 3.728 4.015 4.302
60 1.000 1.250 1.500 1.750 2.000 2.250 2.500 2.750 3.000 3.250 3.500 3.750
65 0.845 1.057 1.268 1.479 1.690 1.902 2.113 2.324 2.536 2.747 2.958 3.170
70 0.684 0.855 1.026 1.197 1.368 1.539 1.710 1.881 2.052 2.223 2.394 2.565


Therefore if you were pointing at 40 deg with the jib cars at 3 knots you have a 2.298 VMG, and if you were 60 deg off with the full Genny at 5 knots you have 2.500 VMG so you have a slight (.202) advantage in VMG 20 off in this case. It is a larger advantage if you are sailing 35 off at 5 and 55 off at 3 (a .411 knot VMG advantage to sail 55 off at 3) so it does depend a bit.

Jeff S

[Moe]

I understand VMG, but doesn't it have to be based on the actual track of the boat (i.e. from the GPS), accounting for leeway, rather than just the pointing angle away from the true wind?

--
Moe

[Jeff S]

I understand VMG, but doesn't it have to be based on the actual track of the boat (i.e. from the GPS), accounting for leeway, rather than just the pointing angle away from the true wind?

Yes. The numbers above are for simplistic comparison. The numbers also assume the wind is coming directly from the direction to which you are sailing. If the goal was to reach a certain distance upwind, but not a specific point or area, then degrees off the true wind in this case would be easy to compare per the chart. If you are sailing to a specific point in the case you mentioned, a boat sailing more off the wind would have to tack more often. If you assume that a boat does not lose any speed in a tack (an incorrect assumption) then the numbers would be close if done perfectly to minimize leeway.

There are many factors to consider - so VMG is a bit of a misnomer on those numbers, they are simply a simplistic way to reference net headway against true wind- when to tack, how often, etc. makes it much more problematic and is where racers compete in strategy. And since I can do Trig, but since I am not a racer, nor an experieced sailor, I'll leave it to those who are to apply the strategery.

Jeff S

[Dimitri-2000X-Tampa]

Nice table Jeff, really emphasizes the point that usually you are better off going as straight to the upwind mark as possible.

Moe, I think you are technically correct but we are in effect making some assumptions here in order to keep some variables constant. What really makes things tricky is currents, which can be extremely strong near bridges and other passes. As for my experiments yesterday, since the wind wasn't too strong, I had my CB all the way down and the boat tracks pretty straight like that. Regardless of the somewhat moderate wind, there is still apparently too much weather helm indicated by my rudders which seem to have to always have at least 20 degrees of deflection to stay on that straight upwind course.

I looked at my GPS track last night and there are a few corrections based on my actual track. First, the difference between the forward sheeting (jib cars) and aft sheeting (genoa cars) was 15 degrees, not 20. Also, my tacking was not quite as bad as I initially thought. The wind varied a bit and when it was a bit weaker, perhaps 8-10, I tacked through 116 degrees (58 degrees away from the wind) but during my second tack, the wind picked up a bit, perhaps 10-12 and I tacked through 107 degrees (53.5 degrees each side). Although this isn't exactly top performance stats compared to a racing boat, its not quite as bad as I thought the Mac was doing with main and full 150 Genoa sheeted outside of the shrouds. I suppose a racing boat would still be getting that 5 kn of speed at 35-40 degrees into the wind.

This brings out a couple more questions:

1. How would I have done with the full jib instead of the furled genoa? My guess is due to the much better shape, I would have picked up that extra half knot in speed that would have made it quicker to stay 40 degrees from the wind at 3.5 kn. I would like to try this experiment again with the jib in similar conditions to be able to prove that.

2. How does my stock forestay affect this? We went back and forth with this in a different thread and although there were some conflicting theories out on the net, people who had shortened forestay on the 26X thought that pointing was reduced. Can this be validated by comparing your results with what I just posted? I'm figuring I have 3-4 degrees of rake with my stock rigging (turnbuckle all the way tightened). Would I lose 5 degrees of pointing with a vertical mast? Comments appreciated.