Questions on speed

I have a few quick questions regarding speed. Does anyone want to chime in?

1) Besides pointing ability, can mast rake have any effect on speed, whether pinching, reaching, or running?

2) Rudders parallel versus slight toe-in -- which is better for speed? My current cat's manual says to make them parallel, but my Prindle recommended toe-in. Are both right for their own boat, or is one wrong? Or is toe-in really more to control weather helm (which isn't an issue for my boat)?

3) Typically speaking, which should be faster on a reach: hiked out and flat on the water with both hulls sharing the load, or flying one hull slightly over the water?

4) In moderate wind, what is the basic correlation of downhaul to speed (assuming one isn't overpowered by conditions)? Would you say, for instance, that more downhaul on a reach will typically = more speed? What about upwind and downwind?

Thanks!
Kevin
Trac 14 (and don't say to just buy a bigger boat! <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />)

1. Mast rake can have dramatic effect on some boats. You need to balance rake to crew weight and wind strength.

2. Toe-in, meaning the trailing edges are farther apart than the leading edges, is commonly recommended for the H16. I've always run at the recommended toe-in for my H16 (1/8 inch), so I can't tell you how much difference it makes if they're parallel.

3. On any point of sail, and especially a reach, boat speed should be fastest with the windward hull just touching the water. This isn't necessarily the same as VMG, however.

4. In any wind strength other than nuclear, all sail controls (downhaul, outhaul, etc.) are optimized when they are set just tight enough to remove the wrinkles from the sail. In high wind, you want to crank it tight to reduce power. Some people want their sails to be baggy if it gets really light, but that's another story...

Hope this helps.

Mike

You want to be specific as to what type of sails you have. I have just changed boats and went from a mylar square-top to an old pinhead design (Dart 18). I discovered that this pinhead gets FULLER when I downhaul. To depower I RELEASE the downhaul, just the opposite of the fat head.

Every boat is different, every sail is different, every sailor is different, every tack is different, every day is a new day. Whatever you try, it probably isn't the best so keep tweaking it. "Faster" is only relative to the boat beside you.

And get a bigger boat.

David,

Sounds like you have a very odd Dart 18 sail. All mine flattened with more DH.

I hear that from others but on our beach where we have quite a fleet of D18s we pretty much agree that downhaul adds fullness. Maybe its the Florida weather or warm water. Colder UK/European/Canadian climates and Darts act normally. Warm 'em up and they get weird.

OK, it's just a theory.... <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Make sure you have telltales coming off the leech of the main, otherwise you'll be guessing on the sheet/traveler settings.
As for mast rake while running,don't run, it'll be faster to reach out a little and do some gybes...

How hard are you pulling? I would stand on the rope to get it on tight; the mainsail would be pulled down to the top of the poening in the mast at the foot!

Hi there,

1) if you have a boomless design, it has an effect. More rake = flatter sail = strong wind trim. With boom, effect is smaller or disappears.
2) I guess the reason why H16 use toe in is the non symmetric wake of the H16 hulls, which are as well not symmetric. If you have symmetric hulls, I don't see a reason for toe in.
3) in most cases: one hull just kissing the water
4) no rule of thumb available, nut let all your tell tales fly could be a good starting point.

Cheers,

Klaus

My Dart 18 sail is 14 years old and pulling the downhaul makes it flat. You can change the the downhaul from 2:1 to 3:1 within the Dart 18 rules. You must pull hard, I mean really hard, so you should see a significant bent in the mast. Maybe your battens are too tight??

Cheers,

Klaus

Oh yes, forgot about the telltales. Keep in mind, those are also affected by your steering and sheeting.

So, the basic rule of thumb is, adjust outhaul and downhaul so that there are no wrinkles in the sails, then steer and sheet so the telltales fly. If you can't get the telltales to fly, consider tweaking the outhaul and downhaul, but usually you're more focused at other things (steering, sheeting, racing, etc.).

Mike

Actually, in my case faster = higher speed on GPS. I typically cruise a distance run with no boats around me, but still enjoy trying to get the max out of the top end of the boat's capabilities.

Regrarding a bigger boat--been there, done that. My P18 definitely had its advantages, but a 14' fits my lifestyle much better at the moment. At 190 lbs fully rigged, it's a cinch to rig and move around solo.

I have two sets of telltales toward the luff, but not the leach. How far from the actual edge should leech telltales be placed, and how many sets would you recommend? Also, how should they behave when the airflow is optimal?

They should be right at the leech, like where the battens poke out, maybe 5 of them. You want them on the luff of the jib too, but they are key for setting the twist on the main. The top ones should be flowing about 90% of the time, but flipping behind the main every now and then. The combo of sheet tension/traveler setting it takes to achieve that keeps changing with windspeed and point of sail...if the top ones are flowing fulltime. you could maybe travel out and sheet in to drive the top of the sail harder, i.e. less twist. If you are already sort of overpowered, you might want to travel in and sheet out,getting them flowing, showing a power shedding, twisty shape.

I know, I know it's a mono, but it shows the idea..