I'm currently sailing a Hobie 17 and would appreciate input on a few issues related to optimizing shroud adjustment:

1) I currently sail with the shrouds fairly loose, ie, very non-restrictive mast rotation to 90+ degrees. This does mean that the lazy shroud is fairly floppy. I've assumed this is a good way to rig a unirig since I don't need to worry about jib luff sag and I get better mast rotation for downwind sailing. Do most people set up unirigs this way? What is the case for tighter shrouds?

2) I'm curious what shroud hole setting most people use for the H17? The manual says to use hole #4 from the top on side and bridle adjusters. I recently bought new standing rigging from Murrays and the shrouds were WAY too loose when I did that. I'm currently on hole #7 from the top on all adjusters (still with fairly loose rigging as stated above). Are my shrouds just longer than the factory shrouds? What holes do other H17 sailors use?

3) When I bought my boat, the previous owner had it set up (for racing) with a very raked mast. The mast on the H17 is fairly raked to begin with using the baseline setup. When I first sailed the boat that way the amount of weather helm was significant - ie, if I let go of the tiller on a beam reach I was head to wind within just a few seconds. I can't imagine it was faster than a less raked setup. My current setup has only a mild weather helm. So why did he have it set up that way? Do most people have an exaggerated rake on on the H17 like they do on H16s? If so, is that for all conditions or just for heavier air? Even in heavy air, is it really worth it - I'd think the weather helm would be hard to manage in those conditions.

Thanks for the input,

Jerry

Most H-17 sailors have the rig loose enough to allow the mast to rotate freely to about 10 degrees past the beam. As for rake, Attach a tape measure to your halyard shackle, run it up the mast and hook the ring at the top. Then measure to the top of the traveler track in the middle. Most sailors rake so this dimension is about 27'. I suspect this is about what you originally had.

The amount of mast rake effects the degree to which the rudders are loaded. More rake results in more loading on the rudders. However by raking the rudders forward you can reduce the load transmitted through the tiller to your hand.As a starting point if you place a batten flat against your transom and let it extend down along the side of the rudder the front edge of your rudder should be about an inch in front of the transom line at its maximium point. This should result in a very light helm. Opinions differ slightly on these measurements but this is how my boat is set up.

Dan,

Thanks for the feedback on H17 setup.

I've got my shroud tension about where you suggest so I guess Murrays shrouds just run long compared with the factory ones.

I'll measure my mast rake and rudder rake as you suggest. I was familiar with how to overcome the sensation of weather helm by adding forward rudder rake but I didn't do this because it's been my impression that loading the rudders with excessive mast rake and hiding that with rudder rake isn't fast. How can it be fast to load the rudders? So why do it?

Thanks!

Jerry

As you change the load on your rudders, you also change, ever so slightly, the angle of attack of the daggerboards and hulls through the water. The proper angle of attack of the daggerboards will help generate proper lift to windward with minimal drag. With the proper amount of pressure applied to the underwater foils, leeway will be virtually eliminated allowing the hulls to track straight, and more efficiently, through the water.

In addition, a swept back wing profile is more efficient through the wind providing less forward drag...hence raking the mast back works a little better for speed but at the expense of a little power. A straighter wing profile will provide better lift (more power) so less rake is better for lighter airs.

Jake, thanks for the input.

Most sailing days on my local lake only give me 10-12 (often even less) with occasional 15 MPH days. In this scenario, wouldn't less mast rake be better than more?

I'm curious if people go to the trouble to setup less rake for lighter days and more rake for windy days, and if they do, whether they also change rudder rake at the same time. If they do this, what generally is the cutoff between low vs high rake - approx 15 mph?

Thanks again,

Jerry

Yes - we change our rake for different expected wind strengths. We don't generally do much with the rudders because, at least in my case, my rudders are so neutrally balanced that the rake really doesn't affect them - I pretty much have no helm (but am working to put a little weather helm back in it). Even if I feel more or less helm, it has very little affect on boat performance so we don't mess with the rudder rake all that often.

Jerry...I agree with Jake. Once you get the rudder rake where the helm is light, changing the mast rake does not affect it much. I don't usually change the rake for different wind strengths but I probably should. The typical weight forward bows down attitude we use in light air has the same effect as raking the mast forward and the weight back bows up high wind attitude has the same effect as raking back.
Dan

Remember that a well designed sloop rig boat will push the stern toward the lee side anytime the boat is tuned to sail on an 'even keel', that is with a minimal mismatch between the center of lift of the sail rig, and the center of lateral resistance determined by the hull's and/or daggerboard's centers of lateral resistance. Since a little weather helm is generally regarded as a good thing, it is intentionally designed into the boat by the placement of the daggers/max hull draft, etc. in conjunction with the sailplan.

Unbalanced rudderrs (rudders with the pivoting axis in front of the rudder's center of lift) have the ability to feedback the amount of lift they create back through the tiller; the greater lift they create (the angle of deflection) the greater the push on the tiller. This type of rudder will always self adjust to the angle of least resistance when the tiller is released. Since the boat naturally wants to steer to weather when correctly trimmed the unbalanced rudders give you the feel of weather helm. Virtually all beach cats have unbalanced rudders.

Note that the conditions which causes weather helm have nothing to do with rudders at all; it's just that unbalanced rudders allow you to feel it. This is not necesarily a bad thing because the feel of the helm can be regarded as a tuning tool allowing the skipper to adjust the center of lift of the sailpan (traveler position/cunningham tension) until the helm is light. The boat sails faster when the rudders are not fighting the daggers. This is sailing on an 'even keel'

You could adjust the rudder overhang to make the rudders more balanced, and this will reduce the sensation of weather helm, but the forces acting on the hulls and rig are still present, and you still need the same rudder deflection angle to overcome these forces and steer your intended course. With balanced rudders it just takes less muscle power to do so.

Anything you do which moves the center of lift of the sailplan aft will cause or increase weather helm. Loose downhaul tension increases the sail draft and moves the point of max draft aft, thereby moving the center of lift aft. The opposite is true for increased downhaul tension. Centering the traveler moves the cener of lift aft while traveling out moves it forward. Rear mast rake moves it aft also, so rear mast rake definitely will increase weather helm. Despite this, some boats will sail faster with pronounced aft mast rake despite the increased drag caused by the increased rudder deflection. This has to do with lowering the center of lift thereby reducing heel angle, among other things.

So if you have a 'stock' boat with excessive weather helm, don't immediately look to modify the boat to correct this. Check for the factory settings first and if they are OK, try to move the center of lift forward (traveler position, proper downhaul tension, mast rake) and then go from there.

I'm not trying to be too technical here, just want everybody to understand what's really happening.

Jimbo

It's probably not much more than terminology but you do actually want the rudders to fight the daggerboards ever-so-slightly. This gives the daggerboards a slight angle of attack resulting in lift to windward countering the side drift introduced by the sail force ... it's all semantics really though.

Jake, as you are changing mast rake according to the conditions, do you also change your spreader angle and diamond tension?

I am asking becouse we dont bother to change mast rake (perhaps we should), but we do change our spreader angle and tension if crew weight changes and we want to be really competitive.
Also, I was wondering if you feel that mast rake really is that important to change? Can you actually feel a change in power while beating with less rake?

I haven't been changing the spreader rake and/or diamond wire tension very often but only because Chris has been sailing with me steadily - our crew weight has remained consistent. With regards to the spreader rake, my feeling is that once it is setup to match the shape and reaction of the sail, it shouldn't be changed. I expect that the spreader rake specifications should come from the sailmaker. Diamond wire tension, however, helps to control the initial power setting (and keep the mast from inverting with the chute up!). So I would expect to make minor changes to this somewhat with changes in crew weight and wind/water conditions.

Having sailed in a pretty tight and reasonably populated F18 class for the last year, I have had opportunity to witness how important mast rake is. I've ended up without enough mast rake in some of the windier regattas and suffered pretty dramatically. Pointing ability suffered as did our speed because we were pretty overpowered (in some cases we probably we did not have enough downhaul cranked). Because we are a heavier team, my thought was to stand our rig up a little more than everyone else - but that has not proven successful.

Thanks for answering Jake, good to know what you think.

I am with you on the spreader angle and diamond tension, but I think it's important to get it right for your crew weight. Heavier teams need more power (less angle and tension), and I guess having them out on trapeze helps bending the mast a little bit. We are talking small differences here, but still a difference (we still have a alu mast, and they also differ a bit in stiffness, so the sailmakers numbers aren't neccesarily the best, even we amateurs have figured that out )

We also tried raking the rig less, to gain power, with the result that we lost windward ability. Now we sail with one rake in all conditions, and are pretty pleased with it.
If you sail with your 'high-wind' rake setting in a light wind race, do you get killed off due to lack of power?

I am just trying to find out how important adjusting mast-rake to the conditions really is on a high-performance cat, as we have more or less found a setting we are pleased with. Ricks book discusses it, but my own experience or rather lack of experience perhaps, is that once it's dialled in, adjustments aren't really needed.

We have yet to experiment much with light wind...usually, around here, when it's light it's also very spotty so it's difficult to determine whether or not you got better breeze or had a better setup. In the next couple of weeks we are planning a small two or three boat tuning session to experiement first on settings like mast rake and diamond wire tension that are difficult to set on the water. It should be interesting because we will probably have at least one Hobie F18 tuning with a Nacra or two.

Would really like to hear about your experiences on mast rake (or whatever else you find out that you want to share) after your tuning session!

I have seen several tuning guides for the T, but it looks like mast rake is more or less set (which suits us fine)?!?

I guess you will change settings on one of the Nacra's and use the the other twos as scratch boats?

Jimbo, Jake, Dan - thanks for the valuable input.

Jimbo - are you saying you don't think I should re-rake the rudders, even if the mast rake gives promiment weather helm? Beside the needed muscle power I really don't like significant weather helm, especially on a singlehander, since if you drop the tiller you're in irons before you know it and it make tacking tricker.

The recommended facory setting for the shouds (rake) is 4th hole from the top all the way around. I'm on 7th hole from the top (I assume my shrouds are just long) now with only mild weather helm but the prior guy who raced had it raked way back from that setting.

Remeber this is a unirig - I get the feeling that raking the mast on a unirig has a greater effect on weather helm than sloop rigged boats.

Thanks,

Jerry

Jerry, couple of insights for you from my H17:

1. Lay out your old shrouds along side the new ones and you will quickly have an answer on the length question. I replaced mine this spring. The new ones were very slightly shorter than those replaced. I can rotate to 100-110 degrees downwind.

2. Confirm the new shrouds are matched to each other in overall length. You do not want mismatched sets.

3. I will try to put my hands on a couple of H17 tuning guides that I could email to you. One was published in the Hobie Hotline probably around 1989. In 2 issues..Sweet 17 and then Sweet 17 revisited. I believe Bob Curry may have written one also that is emailable. They discuss mast rake, rudder rack, helm, etc.

4. I will confirm but I believe I am at the 3rd or 4th forestay hole from the top. I sail with light to moderate helm with the rudders raked all of the way forward. Nothing I need to fight with.

5. Where are you in terms of rudder rake adjustment?

Sail on, Tom G

Jerry,
It's going to come down to an evaluation of just what you are getting out of all that mast rake. Some boats point significanyly higher with pronounced aft mast rake. Also, some boats heel less since the center of effort of the sailplan is lower. This may make the boat faster generally. I know that the mast rake mod works well for the H16, and there may be other boats where it is applicable as well. But it is not likely universally applicable. I'm not knowledgable about the H17 so can't comment on the applicability of this mod to that boat. If you race around buoys these sorts of mods do make sense, since they help you win and you are not fighting the helm all that long.

But if you do mostly distances races or usually just like to cruise around, then that prominent weather helm has got to be fatiguing. Fatigue loses distance races.

If you decide to keep the rake, then it does make sense to mitigate the weather helm as best you can with rudder balance. Don't expect miracles here; the rudders will still be unbalanced rudders, just a little bit less unbalanced.

This whole dilemna might be just the thing you need to help you decide to add a jib No more getting stuck in the irons, either. And sloops definitely point higher than unas.

Jimbo

Jake,

We run our Tiger with the rig raked well back and leave it set - along with the spreader rake and diamond tension, regardless of wind conditions. Seems to do OK even in the light stuff so I don't think rake is too critical. Our crew weight is 328lb

My theory: Raking the mast forwards kills pointing upwind and makes little difference downwind with the chute. On the Hobie 18 without a chute it was a different matter - we used to rake forward in the light stuff and back in a blow.

Chris.

Tom,

Thanks for the input. Yes, I'd really appreciate the H17 tuning guides!

It's been a while since I measured the rudder rake so I need to re-do that.

My shrouds must be longer than spec since I have 110 deg all at hole 7. If I put the bridles to hole 4 then I may run out of room on the side shroud adjusters...

Thanks,

Jerry

Jimbo,

Thanks for the great feedback and additional clarifications.

Interesting my H17 points amazingly well, even not overly raked. In fact, I can out point H16's sailed sloop rigged by a huge margin.

Jerry