Yuloh oar?

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Yuloh oar?

Postby Dirtybug » Sat Nov 26, 2022 8:24 pm

Looking for alternative propulsion, considered an electric motor but deciding to avoid having to deal with charging batteries and having one more thing to load and unload. My local lake is electric only so can't do gas and that would have same issues of transporting it etc. The couple times I've been out with zero wind gave me a chance to paddle with the rudder which worked better than the short paddle I had on board but a better option that's not so hard on things is needed.
I've thrown together a yuloh from some wood I had laying around, still need to mount an oar notch on the transom and wait for spring to try it out. If it works a way to fold it or make it two piece will be figured out.
Has anyone ever tried one on their daysailer before? I'd love to hear how effective it was compared to rudder paddling.

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Re: Yuloh oar?

Postby GreenLake » Sun Nov 27, 2022 12:30 am

i think you'll have to be the pioneer here and tell us how it works for you. I've always been intrigued by the idea, but never tried to put anything into action.

How big is your lake?
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Re: Yuloh oar?

Postby Dirtybug » Sun Nov 27, 2022 9:58 am

I've seen a few short videos of a yuloh being used with good results so I'm hopeful avoiding a motor will be possible.
Currently sail on a 500+ acre reservoir but hope to get into some bigger water and possibly the bay next season.
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Re: Yuloh oar?

Postby GreenLake » Mon Nov 28, 2022 2:01 am

Paddling for over 1/0th of a mile is definitely a no-go with a DS. I don't know whether it's just the non-ideal paddling position or also the fact that the DS hull isn't as easily driven as a kayak or row boat. There are several people who have experimented with oars. They are challenging to stow for anyone who doesn't have one of the '60s DS 1s, because the bulkhead (or in the oldest models the transom tank) limit the maximum length that can be stored in the cockpit.

I've sailed on a friends DSII that was fitted out with oars. I used them inside a marina, once. It worked, but I don't recall looking forward to longer distances. But, as he would have admitted himself, his were a foot or two too short, because of the need to stow them when not in use. So, longer oars might have made the experience a bit more efficient. Who knows.

But that's a reason I'm curious to learn how this works out for you. Is the DS hull inherently limited for human powered propulsion, or is it just a matter of finding the right technique.

PS: one thing I've had reason to try recently is paddling with motor assist. Like an e-bike :). We had an ambitious itinerary (over 8nm point to point) and we ran into repeated calm patches. We had a young eager crew that hated sitting around, so we let them have the paddles. At the same time, we put the motor on some low power setting. That combination worked really well. It was easy to keep the boat at a speed where paddling was efficient, and the paddling helped extend the range. Already, the motor has much longer range at lower speeds, so we could have kept that up well beyond our typical 3 or 4nm of motoring range. (Or until the first crew strike)
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Re: Yuloh oar?

Postby tomodda » Tue Nov 29, 2022 11:42 pm

GL! You've de-spammed the forum, thank you! I was waiting to comment on Yulohs till that little unpleasantness was over.

So... wow, what an idea using a Yuloh on the DS. I've sculled before and always been yuloh-curious, seems so much easier than my muddled attempts with an oar. On a dinghy with a proper sculling notch, that is, never tried to scull the DS.

Two thoughts:

1: Most of the examples of Yuloh that I've seen - online only - have the "bent oar" set up off to one side, so the helmsman/yuloh-er can stand near the centerline. Smaller boats even have the Yuloh "pivot point" on an outrigger. @DirtyBug, you may want to do the same, rig a plank right at the aft bulkhead (rear of cockpit), extending off to port a big (I think that's correct for right-handers). And maybe do it in a way that you can unship the outrigger when sailing? Dunno, something to try, better than cutting a notch in your transom!

2: I'm wondering about your fore-aft balance. All the Yuloh examples online appear to be on keelboats. Our DS's do not have such a pronounced keel, especially if your weight is aft, leaving the boat bow-up and floating on her broad aft-section. Essentially a saucer.. great for going downwind, but I fear that you'd just waggle around if you tired to scull her while aft-down, bow-up. Suggest you rig your yuloh oar so that you're standing near the centerboard, and put the board at least partway down.

Last quick suggestion, as the yuloh oar is nicely bent, store it on deck, forward of the cockpit, along the gunwale. In other words, put the handle up near the bow and the blade should reach back to the gunwale right around the side stays somewhere. You could even bungee it to the forestay and sidestays.... Anyway, that's how I'd do it in a DS2 or 3. for a DS1 could go in the cuddy.

Let us know how the experiments turn out!

Best,

Tom
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Re: Yuloh oar?

Postby GreenLake » Wed Nov 30, 2022 1:00 pm

I second Tom's suggestion for storage on deck. A clip or shoe forward to capture the tip of the blade and using the sidestay to keep the handle in board. A quick lashing at that point would be all that's needed to keep the oar secured. I sometimes store paddles on the side decks by wedging their tips between cuddy and stay. Mostly for brief periods, when they are wet, but they aren't in the way.

About fore-aft balance. I ran tests with a small motor at around 3 knots and found that fore-aft balance could add almost 1/2 knot to the boat speed at constant power. Sitting on the cuddy gave the best result, but that's not practical. However, you might benefit from setting things up so you can operate while standing in the forward part of the cabin. You can put the tiller on a tiller tamer, preferably the kind that uses friction, so you can nudge it into a new position w/o having a hand free to disengage.
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Re: Yuloh oar?

Postby Dirtybug » Wed Nov 30, 2022 8:45 pm

Great suggestions from all!
At least for my initial testing I plan to make the oar notch on a scrap 1x that I can bolt to the transom through some holes that used to be for an adjustable motor mount. This is port of center so I should be standing center-ish, I do think I’ll be too far aft for perfection but time will tell.
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Re: Yuloh oar?

Postby tomodda » Thu Dec 01, 2022 4:52 pm

Just out of curiosity, how will you secure the lanyard? Drill into the side of the seat tanks? or???
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Re: Yuloh oar?

Postby Dirtybug » Fri Dec 02, 2022 9:40 pm

I will have to see how the balance is but I hope not to need the typical lanyard. There is a handle built into my oar to accomplish the movement the lanyard would produce. If the balance is unmanageable a short tether at the oar notch may help.
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Re: Yuloh oar?

Postby Bandit » Sun Dec 04, 2022 12:05 pm

I use an adjustable paddleboard paddle when the wind shuts off. You can stand in the middle of the boat with the tiller between your legs and just paddle along with sails up ready to catch the slightest breeze.
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Re: Yuloh oar?

Postby GreenLake » Sun Dec 04, 2022 9:35 pm

Clever.
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Re: Yuloh oar?

Postby Dirtybug » Thu May 18, 2023 9:46 pm

I was finally able to get out on the water to test the yuloh. It was a success with some tweaks needed. I found it to be more about rhythm than speed or effort to get the best results and with my current setup if I changed or lost rhythm abruptly the oar would jump out from the oar notch so that will need to be addressed. On the calm lake with little wind my tracking app showed a top speed of 9.9kn but that can’t be accurate, the boat was certainly moving along quickly but not speeding.
Overall the Yuloh proved to be faster and more efficient than paddling with a single short oar over the side or the rudder which always felt abusive to the equipment.
Figuring out the oar notch and making the Yuloh two piece for easier storage are top of mind.
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Re: Yuloh oar?

Postby GreenLake » Fri May 19, 2023 7:33 pm

Interesting. Thanks for reporting results. Do you have a picture of your setup and any notes on technique?

On another subject, your tracking app needs some serious calibration :) The theoretical hull speed of a DS is 5.4kn (nautical miles / hour, in mph the figure would be 15% higher). As long as you stay in displacement mode, the energy needed rises sharply as you approach hull speed. The DS can be put on a plane, but that needs full sails, good wind from the best angle and perhaps even an assist from surfing down a wave. Definitely not something you can achieve with manual propulsion.

At some point past 4kn, your boat will have a significant wake, and as you go faster it will look more like what you might be used to from a motorboat.

I strongly suspect you were much slower, but since my 0.3HP electric motor can get the DS up to around 3 kn, I'm not ruling out that you might have reached 2.9kn. I know that when I rowed a friend's boat across a marina, it never felt faster than 1.9 kn, possibly slower.

If you have a stretch of known length over which you could measure time, that might be more accurate than the app. Many people might be interested in seeing that figure.
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Re: Yuloh oar?

Postby Dirtybug » Sat May 20, 2023 10:25 pm

I’ll try to get some pics of my oar notch, it’s basically a 1x6 cedar board mounted on the transom port of center. (Used some existing holes from a removed motor mount) there’s a “U” cut into the top for the oar to sit in. I had a small cleat on the board facing into the cockpit to in theory lash the oar so it didn’t hop out or go overboard, in reality when I wasn’t actually sculling smoothly the oar wanted to ride up in the water so the cleat should be on the other side pulling into the water.
Technique is something like straddling the tiller and steering with the legs, right hand on the vertical oar grip changing the angle 45 degrees back and forth pushing and pulling. Left hand shoulder width away helping. When the rhythm was just right it felt natural and moved the boat along nicely. If I lost rhythm or when trying different techniques the force of the water would lift the oar out of the water and it would jump the notch. There was another type of sculling oar whose name escapes me that had the blade vertical in the water at rest, I may make one of those to test at some point.
The boom caused some interference at times, I had it held up by the topping lift and tied off to a cleat on the port side so I occasionally bumped it with the oar handle. I will have to try releasing the topping lift and securing the boom end low at the cleat or on the starboard.
Digging into my gps app it looks like 1kt was the average speed, not sure how much can be taken from that considering the pauses to reset the oar or attempt different styles and the absurd max speed of near 10kt which I can only assume was the phone sliding on the bench or falling off it though I didn’t see that happen.
If I get the technique just right I may have to find a way to get a video of it in action.
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Interpreting GPS data

Postby GreenLake » Sun May 21, 2023 2:23 am

With respect to interpreting GPS data. I have a dedicated GPS and that means I download the data into a freestanding desktop app after my trip where I can look at all the data in some detail.

I learned a couple of things. One is that the momentary speed display does not match what the app computes as speed between waypoints. I may be seeing some value on the display and later can't find that in the track data. I think the main effect here is that the saved track tries to economize on storage by coalescing adjacent points that don't differ too much in speed and direction. I even get the sense that this is adaptive: if you try to capture more data, the device will more aggressively throw out existing intermediate data points to make room for the new track data.

That said, I never use any "maximum speed" settings from the device itself, but for bragging rights, I will scan the track for sections that are colored as fast and then look up the speed values. I've never caught anything more than, I think 6.3 knots (or perhaps not even that much). That would represent a speed that is in excess of the hull speed (which is 5.4kn for a DS) but below true planing speeds. Some people call that "forced mode". Thehull speed corresponds to the wave speed of a wake that is so long that the boat always climbs uphill. (As described in the linked post). Now, with the DS hull shape, you can push it a bit faster, into forced mode, and I've seen that happen for long enough stretches that even after averaging out the track point a speed above 5.4 knots shows up.

When you are not sailing in flat water, you can also get that when surfing down waves, because in that case the water also surges forward and your speed over ground will exceed the hull speed for that reason.

The other thing I do is to mount my GPS in a fixed holder, and to not turn it on when not in the holder. That way, I don't get any false readings from moving the GPS inside the boat. If you have visual track data, where you see at what point you record such high speeds, my prediction would be that you would find one very short leg that gives you the peak value, not two or three legs each building to that speed (like you would get when a gust hits).
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