Tuning tips??

[DanBerger]

Looking for a little help. I sailed my SC15 this weekend in the first distance race and had mixed results. The boat has a standard main with a self-tacking jib.

My rigging was not tight, but if I would have gone down one more hole on each of the sidestays, it would have been very tight.

On starboard tack, upwind, I had very strong weather helm, but I felt that I was going faster than on Port tack. My rudders are at the same angle, but I may need to work on the toe. My mast isn't bent and my rigging was in the same hole on the sidestay and bridle adjusters. Any idea why?

Downwind, I was dead even with a Hobie 16. The guy has great boat speed, but is new to racing. I lead the entire non-spin fleet, so I felt like I was fast. Upwind, I could out point him, but he couldn't keep the hull down and I couldn't fly mine. I mean, it was skimming, so it was 'fast', but the boat seemed sluggish to me. I could out point him by trapping between the sidestay and the front beam and just driving the boat. It seemed that he was having difficulty controling his boat and the big hulls on the 15 made it very smooth for me.

Unfortunately, I found that the single-hand righting system works very well--about 50 yards from the finish line.

[Eric2101]

Did you take in any water in the hulls?

[Matt Haberman]

Dan,

A couple of things to check.
Adjust the forestay so you have 5 degrees of mast rake, this is the angle between the front of the mast and the deck of the hull measured just forward of the main cross beam.
Next adjust the side stays so you can rotate the mast 160-180 degrees. Ie: The sail track should be able or almost able to point at the ends of the beam when rotated without the sails up.
Weather helm on one tack but not the other could be attributed to a couple of things, but I would guess that one side of your rudders are not symetrical with the other side, in fact I would guess that the starboard side of your rudders might be concave. It could also be that the pivot hole in the rudder(s) is worn out so one rudders is not raked as far forward as the other.

[DanBerger]

Thanks for the help.

I didn't take a drop of water in the hulls, they actually had positive preassure when I pulled the plugs.

I'll step the mast in the back yard and measure the rake. I think I may have a little more than 5%. I felt really fast down wind, and I could out point the Hobie 16s as well as hang with them, but it just didn't feel fast.

I'll check the blades, too. they are interchangeable, right? I mean, I thought they were symetrical, so neither side was concave. I also want to check the toe, because I swapped out the tiller connectors with a different style.

Talking to some other locals, we thought maybe I had some grass on the port blade or maybe it was the angle of the tack and that the waves were coming at a different angle, so it was smoother on starboard. I need more time on the boat...

[Matt Haberman]

Dan,

There should be a small vent hole in each hull right above the upper gudgeon, approx. 1/16" in diameter. Please make sure this hole is there and is open to vent the hull, positive pressure is not a good thing.

The rudders are interchangeable, but sometimes they become distorted and non-symmetrical. Your thoughts on weeds on the rudders and wave direction could also be a cause.

[DanBerger]

I made some changes to the rig, but I still think there is more to it.

I shortened the sidestays and lengthened the bridles so the mast is between 4 and 5 degrees. It takes a little effort to close the hayfield lever on the second sidestay, but the mast rotates freely up to 180 degrees. The wind was light at first and I had no problem with rotation. I cut and reswaged the sidestays because the rig was really loose if I just loosened the bridles. I have the self-tacking kit and there are 10 hole adjusters at each of the bow tangs, so that is how I loosened them. I have an adjuster at the forestay/bridle connection, but the forestay reaches the top hole, so no adjustment there.

Upwind, I was pretty fast and the boat handled well. I could really point well, too--better than before. However, a Hobie 16 walked right through me downwind where before, I was dead even with them. I still had pretty strong weather helm, too, but no worse than before.

A few questions:

Loosening the rig by extending the bridles moves the jib up higher from the hulls. Good thing? or should I keep the compression pole lower (by extending the forestay instead)??

On the downwind sailing thing, how about if I loosened the rig by loosening the hayfield lever on one or both sides? That would move the rig forward, but I'm thinking it would kill the shape of the jib. If i had the boat rigged uni, I would be all over loosening them, but the jib throws a kink into it.