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PostPosted: Sat Jul 12, 2008 7:37 am 
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Another sailing report, finally! :) Our power went out twice in the last couple of days with serious storms, but fortunately at 6:00 this morning, the weather was just right!

I set up the outfitter with the jib and set the sidekicks to the highest position. I had the boombat in the main. I sailed solo with my rock set in front, just like the picture in a previous post. The wind was 10-12 mph, with an occasional gust reaching around 15. It is a little tricky managing the rudder, the jib, the main, and the wind meter, while reading the GPS on my wrist all at once, but I think I managed it enough to get some reasonable data.
I averaged 4.5 mph, and was able to hit 5 mph with 12 mph wind. :D It really handled nice and really felt more like sailing than when just using the main. It's a rush in an outfitter going that fast, as the barge of the Hobie mirage fleet gets loud, pushing water, when it goes over 4. I would be really interested to see what a narrower, lighter yak would do with a jib.
When running, I could get 4 mph, sailing at an angle to fill both sails.

Lessons Learned:
1) With these higher winds, it's not ideal to attach the jib to the shrouds. For one thing, I was using the figure 9s in a way they weren't designed to be used, with a line coming in from the side, and it was a hassle to get the jib secured to them, as the figure 9s would twist with the extra force. It also makes the tension on the shrouds difficult to balance, as the off wind shroud does loosen a little with high winds, which is the shroud that the jib was attached to, so then the jib loosens. Next time I will bring the jib lines back to the seat eyelets and use their own figure 9s. (a cam cleat may soon be in order).
2) I liked the boombat. It could still be a little less stiff, as I think it may keep the main sail too straight to be optimum. But when I was messing with the jib, I could let the main go, and it wouldn't ripple and crack like a whip, which happens without the boombat. Because of the jib attach issue I had with the shrouds, I needed to spend 20 seconds or so adjusting it when tacking. But once the jib was in place, and the main was tightened again, the yak really took off! You can feel the force when the jib fills.
3) It's extremely important to have shrouds with the jib in 10+ mph winds. There was a lot of pressure on the mast, and I think the shrouds help a lot to reduce the pressure and the bottom of the mast. I think the height of the attachment area I have on the sail is about right, as it allows the tip of the sail during gusts to flex and spill the air, preventing damage. The last mod I did, attaching a line from the strap to the top of the mast was a success, as there was no damage in the strap area even with the higher forces. The jib was also acting as a forestay, so that also helped keep the mast in position.

4)I think it helped to have the sidekicks at their top position so that it did allow the gusts to spill without flexing the mast too much. But I haven't tried them in the other positions, which I usually use when only using the main.

5)At the end of my trip, I had trouble turning right. The last time that happened, one of the stow-n-go lines needed to be tightened to keep the rudder in the slot when down. If the rudder has any play and gets out of the slot, the rudder will rotate up a little when trying to turn right while sailing. I'll need to check that out again. I'm tempted to put a pin in the rudder to keep that from happening. Has anyone else had that trouble with the sailing rudder?

Future sailing:
1) To go any faster than 5 mph, I think the boombat may need to flex more, and possibly the sidekicks would need to be set lower, or I would need to lean more to keep the sail angle more upright. I felt in control the whole time, like there was some margin for adjustments.
In previous journeys, when I didn't have the jib, didn't have the boombat, and had the sidekicks set to the medium position, and had shrouds attached to the top of the mast, under higher winds (15-20?) I have been able to push it to 5.3 mph, but the main sail was begging for mercy.

2) I had the jib just tied to the strap on the mast, but I might need to be able hoist it instead. If the winds got stronger, I don't think it could just wrap it in front of the mast...I would need to take it down.

In summary, this was the most fun I have had sailing my outfitter, and it started to feel more like a sailing vessel than a wind-aided pedaling yak. :D

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PostPosted: Sat Jul 12, 2008 1:01 pm 
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Great report Tracker, how fast do you guess you would have been going in the same wind with main only ?


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PostPosted: Sat Jul 12, 2008 2:19 pm 
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It's my last day of vacation, and the wind is 30 mph, so no more sailing today, and probably not again for another month. :(
Some questions that would be nice to have answered from someone with some experiece, as I have essentially none!
1) Would a jib that is too cupped in the front make it difficult to sail close hauled? It seemed like I lost some angle on my sailing with the jib, but it was hard to tell.
2) Did this jib have too big a gap between the jib and the main, or is it acceptable? It would be interesting to try a genoa and see how it performs (It looks like a genoa was used for the modern sail theory article I referenced.)
My jib seemed to perform OK, but this is the first sail I've ever built, so I'm sure it's not ideal. Likewise, I don't have any data to reference from other people's jibs...maybe it didn't perform well at all. Hopefully someone who really knows their sailing can use this information and take it to the next level. At the very least I hope other people try making jibs of their own, since it doesn't cost much to build and doesn't take a lot of time or skill (doesn't even require sewing).

Cheers,
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PostPosted: Sat Jul 12, 2008 2:56 pm 
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instigator:
I tried once to release the jib to compare, but it flapped around in the higher wind (I had the same problem running, so I really needed to be able to take the jib down to get an accurate comparison. From sailing for the last year without a jib, I would guess I would sail solo around 3 mph in a 10 mph wind (I didn't have a wind meter until this week, so I'm guessing a little on the wind speed). I could feel a dramatic drop in force when the jib was released. There is definately a turbo-type feeling with the jib that really makes the yak get-up-and-go when the jib is filled and then the main is put on line, a feeling that I haven't experienced with just the main.
I don't know if the hull of the outfitter is really made to go faster than 5 mph. When two people are pedaling hard with the turbo fins, the hull pushes water in the front at around 4.5-5 mph...you would not sneak up on anyone on a calm day. So the narrower non-barge yaks might be able to benefit more from the use of a jib. I would think the adventure would really benefit, as some people have posted 7+ mph in that yak with only a main.
Kepnutz mentioned he would not sail without his boombat. I would have to say that I'll always take a jib with me. :)
I will be sailing the outfitter with an adult in front in a month (weather permitting) in Lake Superior. I'll post what the extra weight does to the sailing performance.

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 Post subject: Rudder pop-up issues
PostPosted: Sat Jul 12, 2008 11:15 pm 
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Kepnutz,
Back to the rudder and winglets...

First, I saw that there are two different sailing rudders...apparently upgraded in June of 2007?

http://www.hobiecat.com/community/viewtopic.php?t=6403
Roadrunner:
NOTE: 06-12-07 HOBIE IS NOW PRODUCING THE BALANCED RUDDER, MAKING THIS MODIFICATION UNNECESSARY. THE HOBIE VERSION GIVES AN EXCELLENT RESULT AND HAS THE ADDITIONAL STRENGTH OF ALL SIX SCREWS.

My outfitter (purchased in July 2007) has the old unbalanced sailing rudder...should I have the ability to request the new rudder, as I probably received an old stock rudder....or did they only give AIs the balanced rudder? If I spend the time adding a winglet, I want to do it on the proper rudder!


Now back to winglets...
I've done some forum mining on winglets, and this looks like a complicated engineering task. The outcomes on the Hobie forum suggest that the winglet solves the rudder pop-up problem, as well as improve performance (more response with less rudder turn). Thank you Roadrunner, Kepnutz, Yakaholic, and others for the info. 8)


winglet
http://www.hobiecat.com/community/viewt ... 0080#30080
http://kfs.infopop.cc/eve/forums/a/tpc/ ... 090753/p/1


Other sources seem to be mixed on winglets though:

One thing that wasn't clear to me is how it was decided how large the winglet should be. On airplanes, the winglets are very small compared to the area of the main wing.
I found one reference to winglets on yacht keels:
http://www.oossanen.nl/download/peterva ... yachts.pdf
which states that "as relative spans of wings (or keels) become smaller, the size of these winglets need to increase to obtain their full benefit. This is the reason why winglets fitted to keels are relatively larger in size than those fitted to aircraft."
It also states that "when winglets are placed aft along the bottom chord of the rudder, however, the required rudder torque is excessive, demanding large steering gear, unless the balance of the rudder is adjusted."

Did adding the winglet change the balance of the rudder?

Here's an interesting opinion from the America's Cup Forum:

http://www.northsails.com/americascup/S ... letts2.htm

which states:

Question:
As a follow up on the winglets on the square top sail - on a normal pointy top mainsail, would there be an advantage to adding winglets to the top of the mast to reduce induced drag? How about the same on the bottom of the rudder? Versus the added drag from the extra surface area...

Brett
--------------------------------------------------------------------------------

Answer:
Any device that can help reduce induced drag will probably be of assistance, except as you point out if the added form drag outweighs the benefit. The problem with winglets for the mainsail, and also for the rudder case, is that the amount of lift the foil generates varies a lot with time, so it would be a very difficult design problem to solve to get an optimal winglet design for the range of mainsail trims (or in the case of the rudder different rudder angles).

Rudder winglets have been tried in a few cases in the past, and I guess you can summise that they were not of great benefit, as they have not become a common feature on ACC yachts.

Note that the winglets in the keels are only of benefit when sailing upwind (note also that the keel sees a pretty contant flow field, not changing angle a lot with time), and definately slow the boat when sailing downwind. Note that I am not professing to know a lot about appendage design here!!

Written by Burns Fallow
Emirates Team New Zealand

>>>>>>>>>>>>>>>>>>..
I have read this as well, that winglets are optimized to a specific flow, so on airplanes they are optimized to cruising speed. I'm not sure how this translates to water rudders. But, it seems that if they worked to well, that they would be used everywhere, especially in America's Cup yachting, where there is money to spend.


So are the winglets solving problems that other sailing vessels don't have?
If the rudder didn't pop out of its slot, would the winglet still be useful?

In the short term (besides looking into getting a balanced rudder), I was thinking of just adding a little more pressure on locking the rudder down by adding a bungee cord wrap around it. My intent would be that if the rudder grounded, it would still be able to pop up, but it would take more force and will hold the rudder down when sailing. I might have to tie the bungee cord together with a line that I could pull for a quick release in case I needed to get the rudder up.

Image

Thoughts?

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PostPosted: Sun Jul 13, 2008 7:32 pm 
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Hey Tracker


Last edited by kepnutz on Tue Sep 16, 2008 3:39 pm, edited 1 time in total.

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PostPosted: Sun Jul 13, 2008 10:24 pm 
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Hi Kepnutz!

It's hard to question the experience that you and others have had with winglets. Maybe the winglets help with the slower and smaller form-factors we have in the yaks compared to the larger vessels. From your picture, you have a huge rudder as well as winglets.
All I know is that I've had trouble with the stock "Stow-n-Whoa" rudder, as it just wouldn't turn starboard for me at the end of my sailing, and the shore got a little close before I reached back and pushed it down by hand. Looks like people have been using winglets for about a year now, and the only trouble seemed to be with KayakingBob, breaking two rudders (that had the balancing mod done also). I wonder in Bob's case with the 4-5 foot waves that the winglets pointed up while sailing fast through a wave, and the rudder wanted to push forward and up, causing enough force to break it? :? That's one concern I have and I'm trying to search around for the science behind the winglets as to how big the winglets should be. If I can't find anything I'll stick with roadrunner's design. The references from Yakaholic that the winglets make the bow stick up from the water more seems like there would be some new stress points on the rudder, especially for a two person yak....but getting the bow up is something that's needed on a outfitter :) Maybe I should add winglets to the back turbo fins! 8)
If I need to swing an extra $20 for a new balanced rudder, I probably will put the winglets on the new one and keep my old one for a backup in case I have trouble. I'd hate to be in the middle of my August Apostle Island adventure and bust a rudder.

7.4 mph...the Oasis is much faster than the Outfitter... or was with the windpaddle spinnaker? Were you sailing with two, as your pictures suggest? Looking forward to the windpaddle report! :wink:

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PostPosted: Mon Jul 14, 2008 12:53 am 
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PostPosted: Thu Jul 17, 2008 7:31 pm 
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I found out some more things to watch for when using/designing a jib...information from a co-worker who sails standard sailing vessels. Some of this might be pretty basic for some, but as a novice trying to help out others who may be in my position, I'll list some of the things he told me. He listed many difficulties with having a finely tuned job on this yak, but he was willing to help :) Hopefully I don't mess up the lingo too badly :? And if I stated something wrong hopefully some else can correct me.

1) Looking at the pictures, he thought that the jib might be too far away from the main to create a good slot effect. Kepnutz in another post mentioned the same thing. The way to fix that would be to either make the jib bigger or to attach the jib more aft (the latter suggested by both my source and Kepnutz).

2) He also asked how balanced the boat was...did it lee helm with the jib? Now that I think about it, I think it had a strong lee helm. This is likely because the jib size is large compared to the size of the main. Also, he said that if the mast does flex and spill air, it will further the problem as the main acts even smaller. He said ideally you want a slight weather helm. I have never tried to test to see how balanced it is even without the jib. Since Hobie uses the same sail for all types of yaks, I'm assuming that the sail isn't perfectly balanced for all of the yaks. He said balancing is a little complicated because it is speed dependent...but to decrease the tendency to sail leeward, I was told you need to either increase the size of the main, attach the mast more aft, or decrease the size of the jib.

3) He also said the luff should be really tight, which is difficult to maintain with a flexible mast. I thought the front edge stayed reasonably tight, so I'm not quite so worried about that one. Also that's a problem that would be hard to fix further, as I already stiffened the mast a little and added shrouds.

4) He also mentioned that you need to watch the angle that you attach the line to the clew. He said you want it at an angle that, when luffing, the air causes the sail to ripple evenly across the sail. I hadn't tested that either.

Looking at this info, I'm planning to move the front edge of the jib more aft. I'm not quite sure where I should attach the jib yet. I could try the hook for the front bungee, but that may not be enough. Maybe I could attach it from a line that goes between the two hex screws that hold in the front mirage drive? I don't want to modify the yak until I figure out what works best. Unfortunately attaching the jib to anything but the bow would make the jib solo sailing only. (It may be already...depending how tolerant the person in front is having a sail blocking their view on one side and having to move it when tacking.)

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PostPosted: Thu Jul 17, 2008 9:00 pm 
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Kepnutz


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 Post subject:
PostPosted: Fri Jul 18, 2008 5:46 am 
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Kepnutz,
I'm guessing that I'll end up with two jib configurations, one for solo sailing and one with two aboard. Even though the jib attached to the bow has some issues, it still sailed faster than without a jib in winds up to 12 mph. Also, I haven't sailed with a jib with someone in the front seat or with the Mirage drive inserted in the front, so I don't know how that will impact the balance. I'll continue to play around with the setups and post what I find out.

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PostPosted: Sun Aug 31, 2008 10:14 am 
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Sailing report:

Finally got the yak out on the lake this morning. :D I started with my tapered boombat in the sail and the jib attached near the Outfitter front mirage drive hole, in an attempt to reduce the lee helm of the configuration. (The below picture was taken afterwards with my stiffer boombat inside.)


Image

Image

When sailing, the jib was controlled by attaching the line to the either seat eyelet.

I had a pulley attached to the main sail for the jib so that I could take the jib down while sailing:

Image

All of the readings below were taken with GPS and a handheld windmeter.

The wind wasn't ideal for testing/comparing configurations, as it was gusty. I started in 6-8 mph with 12 mph gusts. I was going 2.5 to 3.5 mph, so the performance wasn't noticeably different than when I had the jib tied to the front eyelet. It still had a significant lee helm. I'm wondering if adding a centerboard in the front mirage drive hole would help?

As the winds picked up (10-12 mph with 16 mph gusts), the stress on the mast got to the point where I was ready to take the jib down. The shrouds prevented any damage, and the main was good about spilling the air over the top of the main without mast damage, so that was good news. :) I got up to 4.3-4.5 mph a few times.

I tried both my stiffer boombat and the tapered boombat (from the whip core mentioned earlier). The shape of the sail looked better with the tapered in the light winds, but when the winds hit 12+ there was some wrinkling in the center of the main. When I put the stiffer uniform boombat in with the stronger winds, the sail stayed more uniform. My tapered is about 2 feet too long, so I'm going to cut the smaller end off and try it again.

After I took the jib down, the winds increased to 12-15 mph and I recorded several 20+ gusts, one at 27 mph gust. The main with the side shrouds performed well, no damage. I had the sidekicks set to the highest position, which probably helps spill gusts like that. I hit 5 mph a couple times.

I had a bungee around the top of the rudder to keep it from popping up when sailing, and that seemed to work well. I used the bungee I took out of the mast when I added the extra tube inside the top section.

Image

Although I didn't need to, if you need to pop up the rudder after sailing, you can slip the bungee off of the hinge that secures it to the yak and the rudder can rotate up.

This Summer's Summary of importance for modifications:
1) The boombat is the easiest and most important improvement. It keeps the sail shape better and keeps the sail from whipping in the wind if you have to release it.

2) Adding a strap to the main and attaching side shrouds greatly improves performance and durability in higher winds (15 mph+). I will likely use a stay to the front eyelet on the yak when not using a jib, just to give the mast some additional support.

3) Doing something to the sailing rudder to prevent the twist and stow mechanism from causing the rudder to pop up when sailing is important. The bungee method I did seems to work...the winglet others have done seems to work well too.

4) The jib is an interesting experiment, but (at least with the size/shape of jib I used) you trade off increased speed in low winds for poorer handling. Maybe somebody else can figure out the handling issue :wink:. The jib also adds a lot of fiddle-factor when sailing (extra lines everywhere!), and prevents a front passenger from riding in a tandem. It makes you appreciate the "keep it simple" approach with only having a main. But...when the winds are light and you want to sail, it's a good option.


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PostPosted: Mon Sep 01, 2008 11:24 am 
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Got out one more time this weekend, this time with my 7 year old son in front. Nice wind, varying from 12-20 mph, with gusts higher that I didn't catch on the windmeter. We started without a front stay, but the mast was bending too much, so we went back and put one on. The front stay helped, and the mast/sail seemed very stable, although in the higher winds the sail was still spilling over the top, but no damage with the stay and shrouds in place. We had lots of fun crashing through boat waves as we routinely hit 5 mph and set a PR for our boat of 6.2 mph :)

Image

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PostPosted: Mon Sep 01, 2008 6:26 pm 
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PostPosted: Fri Oct 03, 2008 10:53 pm 
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Now that I've read through some other posts, I want to try putting the front mirage drive in while sailing solo with the jib (with the locking pin in drive to keep the fins straight) and see if that helps the upwind sailing angle. It would be interested to test this with the back fins both down and up to see how the steering is impacted.

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P.S. clarification: The 6.2 mph PR was without pedaling.


Last edited by tracker on Sun Oct 05, 2008 9:36 pm, edited 1 time in total.

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