We are new at sailing a 20 footer, and are having a great time. One thing (there are more :-))we are wondering about is how to operate the downhaul, and what to expect of it.
We have tried to use it to keep the boat under control during windgusts, but we do not seem to be able to really affect boat trim. We have a alu mast.

The questions we have:
- how much distance (inches/cm) does the downhaul travel when applied? Does it travel more with a mast that is not rotated?
- how does the mast rotation come into effect? We currently use it faily simple, full power (max rotation), half power en no power (min rotation), and we do not change it much, other than moving to full power when using the spinaker to protect the mast (and tension up the mainsheet)
- Does one use the traveler instead to deal with windgusts? Do people not find that difficult operating the traveler from trapeze?
- Is there a completely different way to deal with gusts when sailing closehauled?

(Additional non-related question: what website(s) are you planning to use to follow the olympic sailing events?)

I realise I might have not expressed myself clearly, but all commenst/help etc is welcome. Please do not hesite to correct me when wrong or unclear.


Regards,
Martijn

First off I have no experience with an aluminum mast. All of this comes from having a carbon mast. My understanding was that the carbon masts are stiffer though.

My Downhaul travels about 16 CM from where I set it to start the day to fully downhauled on a windy day. This flattens the main and makes the boat drive great upwind.

Mast rotation is very important. I set it about at the shrouds for most conditions (upwind and downwind). When I'm max downhauled and need to depower more I rotate in a little at a time not going past pointing at the rear beam.

I use the main to handle wind gusts. If I'm already max downhauled and rotated in then I start to travel down to depower more. If I'm constantly letting mainsheet out and in then I travel down. I don't like to travel down more than about a foot. This depends on your teams weight.

Deal with wind gusts by heading up and sheeting out. Sheet right back in within seconds of letting it out to accelerate.

Mike Hill
N20 #1005

Forgot to mention.

If you are having trouble putting on the downhaul you can add diamond wire tension. The more tension you have the easier it is to downhaul.

Also you need to make sure that you have some spreader rake. Somewhere between 4-7 CM of spreader rake depending on your weight. More spreader rake the heavier the crew weight. More spreader rake also helps you downhaul the main easier.

Edit: Chris is right Less spreader rake with a heavier crew. Sorry for the mistype.

Mike Hill
N20 #1005

Mike,

I agree with almost everything you have written. I was thinking less spreader rake for heavier teams?

Hi Chris

I would say set the spreader rake (with min down haul lots of wrinkels) to match the luff curve of your sail = max power from that particular sail. Hopefully, the sail is cut well so the shape is constant above and below the diamonds.
Wh

Charlie Ogletree (US Silver medalist on Tornado last games) told me to think of downhaul as a course sail trim adjustment and the main sheet as the fine trim adjustment. Leave downhaul loose (no wrinkles in main) until both crew are trapezing and the hull is popping out too fast to handle with about 1 arm length of mainsheet easing. Then start putitng more and more downhaul on, inch by inch, until you reach a point where you can mange the gusts using an arm's length ease/re-sheet on the mainsheet (the crew should be handling the mainsheet from the trapeze...skipper's one arm is not strong enough).

Once you're at this point, crew will ease in puffs to control hull popping high...but must aim to keep the hull out of the water at all times...so re-sheet the sail again BEFORE the hull starts to fall back down. When you get this right, the boat should surge forward with each gust, not pop out the water. It takes practise, concentration and quick responses from the crew.

If the winds are so high that you're still needing too much mainsheet movement with each gust (downhaul at maximum...we use a 16:1 system!...rotation aft of shrouds), start feathering the helm up to weather as gusts approach. This is preferable to travelling out when doing a windward leg...as you don't loose so much ground windward.

One point to watch out for...as you start applying downhaul...if you go too far too soon, you'll find you need to steer further off wind to get the hull out the water. Then as gusts hit, you will still pop-up because the angle to the wind is quite large...so you'll put more downhaul on...this can continue until your boat is sailing flat and slow, far off the wind with your main sail looking like a piece of plywood! So, make sure you are always at the minimum amount of downhaul needed and no more!

Mike.

Did the I20 ever have an Al mast???

Don't forget the boards as a powerful tool for adjusting power.

Just a small digression Mark: I would think the lower third of the sail would have less draft with max draft further aft to compensate for the airflow over the jib?




Yes please <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />


The way we sailed our Tornado the last years (not the I20, sorry), we used the downhaul, mast rotation and traveller as coarse adjustments. Then we ran the boat with just the mainsheet going to windward. If the conditions changed or the wind was very offset to the waves, we would re-trim as needed so the crew did not have to sheet more than an armlength in puffs/lulls. We trained mostly on a fjord surrounded by largish hills and mountains. With a northerly wind we often had severe gusts. In those conditions I (as helm) held on to the traveller line as an emergency release. Operating the traveller from trapeze while helming is just another skill <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

Mark
Is it not best to set the spreaders/diamond tension so that the mast in this shape with MAX downhaul. Otherwise what is the point of increasing downhaul if the mast already matches the luff curve of the sail?

I think it does now.

Does it really or is this just more of the same wild rumor tha's been going on for a year now? I know I asked Jim Young a/b it in Oct and he said, "no, we'll never do it...". Then I've heard side rumors since then.... but I've not seen a boat with one yet.

Thank you all for much information on how to sail the boat, very much info, thank again.

Will_R made a comment on using the boards. Currently I am using simple formulas:

going up: all down, lots of wind 30 cm up.
broad reach: 50 cm up
going downwind: 50 - 70 cm up.

I believed that raising the boards made it easier to allow the boat/beam "slip away" and that by raising the boards going up with lots of wind is a defence against the board creating lift as the other hull lifts (to far) out of the water.

Is making the boat "slip away" the power regulator that Will refers to or am I completely lost here?


Tx again for great info, hope more follows ;-)!


Martijn

Will, the boat we are sailing is fairly new, and as we understood it alu or carbon mast is an option.

Martijn.

It's not necessarily "slipping way" (or giving leeway). As you move faster through the water, you require less daggerboard to provide the resistance to keep the boat from sliding sideways.

Trying to explain this clearly; if your daggerboards are extended all the way down, the center of the sideways force they generate is further down in the water - roughly in the center of the board that is exposed below the hull. The further away this center of force is, the more tipping leverage is applied to the boat (wants to fly a hull sooner). When you are going faster, and since you don't need as much daggerboard to get traction in the water, you can raise the board and raise this center of force closer to the hull and the surface of the water. What you are after is to have enough daggerboard in the water to keep the boat going in a straight line but just barely enough so that the boat is much more controllable and not too tippy.

If you watch the wake coming off the stern of the boat, it will tell you how much, if any, side slip you have. the outside wake will roll over on itself when you slip sideways ... this tells you that you do not have enough daggerboard in the water. Try sailing with the daggerboards in different positions and watch the effect it has on the trail in the water...you will see.

we call it "tripping". The lift goes up as the square of the velocity. when you're sailing in med+ breeze you need less board (as jake said) b/c of the speed. Essentially by shortening board you decrease the leverage that the boards have on the boat. (Sorry if I repeated what Jake said but I didn't read the whole post)

You said it much more simply.

Will_R, Jake,

Just a quick message to inform you that we have indeed an carbon mast and that no there are no alu masts for the I20.

Feel (a bit?) stupid about it, but there it is. We have a carbon mast.


Kind regards.

Martijn

Not a problem!!

One thing you will feel with this boat and the downhaul/cunningham is that there is not much "stretch" in it. The stiffness of the carbon mast causes it to just kinda stop when you hit a certain point. An Al mast gets gradually stiffer unlike an I20.

The reason I was wondering about the use of the downhaul is because I was told that is was used to open the top as as you sail into a gust.
Following the advice I obtained here has worked much better however. We do chache the setting while we sail along, but we deal with the gusts differently, as described, major settings (downhaul, rotation & boards) and minor/dynamic settings (Mainsheet, luffing & traveler).

We did go over last tuesday as we crashed while double trapping with the spin up. (It was great of course, and if you do crash you might as well do it fast). We did break our boom, got a replacement yesterday.

What troubled us a little was how quickly we went "turtle", that has never happened before sailing my Inter17. As we got our mast stuk in the mud approx. 30 cm, we needed some help to get back up again. Apart from the boom, no additional damage. We did find quite a lot of water in the hulls, I suppose that got in there through the airholes in the inspection hatched while upsite down.

Maybe a separate thread, but how does the guy steering the boat manages to get of the boat backwards? I think I might have been hanging around to long on the upper hull trying not to hit the boom or sail, and by doing so pushed the boat turtle. I could no however get off the other side, and slid down onto the boom.

Anyway, we had a great sail, and we are full on the learning curve in getting this I20 experience under control ;-). It is amazing how much fun it is even after sailing the I17 for the last 4years. (Don't get me wrong: I still sail and love the I17 as it gives me the freedom to sail whenever I feel like it, and i enjoy it immensely)

Take care! Martijn

Whether or not it goes turtle depends largely on the angle at which it capsized. If you go over with the spinnaker up, there is a good chance that it will go turtle as you usually turtle because the wind is immediately pushing on the bottom of the trampoline. If you can quickly get someone out on the daggerboard you can usually avoid the turtle.

Getting off the high side of the boat? Swan Dive off the stern (be sure to be unhooked from the trapeze). If you are swinging somewhere between, you can step on the boom but try to do it near one of the ends where it is supported by the mainsheet or the gooseneck. It is weakest in the center of the span between the two.

We DO use our downhaul for gust response in moderate breezes...if you've got just enough wind to trapeze normally, then use the downhaul to manage the power. If you are starting to get the downhaul to the maximum setting frequently, you should set it at an average setting - about 80 to 85% and use the main. If the wind is really high, crank the downhaul on fully and work the mainsheet. If that's not enough, drop the mainsheet traveler down a couple of inches and work the mainsheet. If that's not enough, drop the traveler down a foot and work the mainsheet. If that's not enough, just enjoy the ride, do what you can and hope you don't need to reach!