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Discussion Starter #1
I don't think the hard-core folks here would call what I'm doing "rafting", but I'm looking for a particular accessory and figured you guys would know.

I got a "six-person" inflatable boat which in practice holds about 3 people:
Solstice Voyager 6-Person Inflatable Boat Pool Toys & Inflatables
because I can't afford (and can't practically transport around) a boat for 3 people, unless it's the inflatable kind. And, I like paddling it with a kayak paddle instead of the oars that come with it, since the kayak paddle takes less energy and I can see where I'm going. However, since the raft sits on the surface of the water, it swings quite a bit to the right and left each time I'm paddling with the kayak paddle on either side. (I assume this doesn't happen with a canoe because the hull cuts further into the water.)

It seems like the raft would swing side to side a lot less when I'm paddling, if I could attach a rudder (which wouldn't even have to be moveable for steering, just a flat piece submerged in the water to stop so much back-and-forth swinging), or simply something that could be folded out and mounted on the front of the raft to make a pointy end like the front of a canoe. This guy says he saw a huge performance improvement after attaching a homemade rudder:
Rudder Design for Inflatable Boat
Does anything off-the-shelf like that exist, which could be attached to an inflatable boat?
 

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A raft has a very different shape than a hard shell kayak or inflatable kayak and behaves differently. In simple terms you are using the wrong tool to push your boat. A raft is going to row best with oars. Adding a rudder won't make it track like a canoe.

If you like to paddle it with a kayak paddle then go have fun but don't expect it to work well. While you can propel a raft with a single paddle you really can't spin the boat or ferry very well, and that is what the raft does best!

Point number 2. Take a good look at the text in the link for your boat. Notice the words 'pool toy' it is in there for a reason. There is a very big difference between a 'pool toy' and a whitewater raft. The boat pictured is not safe for moving water and I would be very careful about what lakes I put it on. That rig is just one sharp stick away from a swim.
 

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Discussion Starter #3
Well the guy who posted this:
Rudder Design for Inflatable Boat
said "You can't believe the improvement in steering of the boat you have with a rudder mounted on the boat" which is why I thought it would make a big difference, and he was also using an inflatable boat. But I can't build it myself like he did, so I hoped it was an off-the-shelf part. Is there any particular reason why it wouldn't work? Sure seems to make sense that a vertical flat piece of stiff material would stop the end of his boat from sliding right to left.

If not, then what about inflatable kayaks and inflatable canoes like this one:
http://www.amazon.com/Intex-Explorer-K2-Kayak-Yellow/dp/B00A7EXF4C/
You get a lot less space than for spending the equivalent money on an inflatable raft, but can they at least truly be paddled with a kayak paddle, without swinging right to left too much? Or does being inflatable mean it will be floating too high out of the water so that it won't track like a real kayak or canoe.

All I'm looking for is something that (1) is inflatable (for ease of transportation and storage), (2) can hold 3 or more people, and (3) can be paddled with a kayak paddle, or some other forward-facing motion not requiring constantly leaning back and forth. I'd only use it for lakes and very calm rivers and not for whitewater rafting.
 

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Based on the breakdown of that guy's physics diagrams he's mostly concerned with the use of a rudder while paddling upstream in a river, or in completely stagnant water which rarely even happens in Louisiana, and while most of it checks out there's a couple mistakes (the direction of the boat flotation would be the buoyant force which would be coming out of the page not to the right of the page, the direction of the boat against the current would be the intended/applied force on the boat by the person in the boat). If you were using a rudder while traveling downstream in a river there would likely be a more significant amount of turbulent water flows at a number of different angles, which would result in a loss of control pretty quickly if you get bumped in a strange orientation and pop into a strong laminar flow at that angle. You also have the added consequence of rocks near the surface of a river that would damage the submerged rudder and affect the intended downstream angle of the boat. If you're taking it on a lake you might be better served looking into sailboat rudders and how they operate. It'll be different for you, though, because the forward direction of a sailboat is the result of wind on a sail, a much greater force than one person paddling. You might also find someone who is into Stand Up Paddleboarding (SUPing), as many of them run rivers and some boards have small straight rudders similar to surfboards. If I were you I'd explore small lakes with what you have, always wear a PFD, and start to looking into putting a few hundred dollars into a rowboat or a downstream boat that's designed for such use.


UNC has a pretty cool .gif of the changes in water pressure and torque response to a rudder for a sailboat: The Physics of Sailing
 

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Discussion Starter #5
Regarding "looking at" sailboat rudders and stand-up paddleboards, I'm not clear what you're suggesting that I could actually *do* -- I can "look at" those rudders and understand how they work, but it's no good to me unless I can attach them to the boat that I have :)

A non-inflatable boat that can hold three people looks like it costs over $1,000, and even if I wanted to spend that, I have nowhere to store it (I live in a condo where we can't store boats in our parking spots, and I wouldn't be able to get it into my unit). That's why I probably need an inflatable one, if I want a 3-person boat.

So either (1) has anyone found whether inflatable kayaks are reasonably easy to control with a kayak paddle without swinging right and left like my raft does, or (2) has anyone found a way to attach a detachable, non-steering "rudder" to an inflatable raft after it's in the water, to prevent the right-to-left swinging, or (3) is there some third possibility?
 

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The third possibility is to get paddles. One person on either side of the boat paddling. You could even be the rudder man with a third paddle sitting on the back of the boat. Look for pictures or video of commercial rafting trips and apply what they do to your situation.

I doubt you will be able to find anything off the shelf for adding a rudder to an inflatable, and a DIY solution probably isn't worth your time or money. Rafts just aren't made to have rudders.

Inflatable kayaks will track better, at least the good ones will.

Good luck!
 

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I was going to suggest the skeg at the bottom that bosco suggested. I think it will provide some, albeit minimal, "swing" control for your tube. I installed one on an inflatable kayak and the guy says it tracks like a dream now. I would imagine you would have less than those results but it would help as long as it was installed correctly.

3 people would generally be considered overloaded for an inflatable kayak.
 

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Discussion Starter #9
OK, *skeg*, that's the word I was looking for. (Not "rudder", apparently.)

However the glue-on skeg page description at:
Fin Kit for pvc inflatable kayaks, removable skeg
says that gluing to PVC is quite difficult, is that true? Besides, if the inflatable craft still doesn't track well after gluing the skeg to it, I can't return it after the skeg is attached. ($150-$200 for a raft or inflatable kayak isn't a lot, but I was hoping to return it if it didn't work.)

Feathercraft makes a strap-on one:
Feathercraft — Skeg, universal
but the straps are only 22" long (not enough to wrap around the raft, but I could try extending them somehow) and it might not hold straight against the soft bottom of a raft instead of the hard shell of a kayak.

Is there no tie-on or strap-on skeg for rafts? It just seems surprising that there wouldn't be a product like this already, because paddling a raft seems like the cheapest, most convenient (in terms of deflating and storing your craft), and most energy-efficient way to go exploring calm lakes and rivers (plus, unlike rowing, you can face the direction you're going) -- but *only* if you have a little piece of plastic tied on to the raft and sticking down a few inches into the water to stop the swinging back and forth.
 

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I imagine a strap on skeg on a raft would have to much flex to be of much use. Gluing on PVC is not difficult. The main thing is to make sure that you glue it with perfect orientation or you will track sideways. You would not be able to return the skeg once glued should it not perform as you had hoped.
 

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If you plan to eventually take it back and get your money back.......go back over to Wally World and get you an electric trolling motor. Problem solved.

You could strap and/or duct tape a paddle or piece of plywood to the back end as a rudder.
 

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Another thought is to go back to the oars. It's true that when you see a picture of a guy rowing a boat he's usually facing backwards. He's doing this because the pulling motion when rowing is stronger than a pushing motion when you're facing forwards. In the whitewater world most of us face forwards and push our oars in the direction we want to go. That's because we need to see the obstacles in front of us. If we have a hard move to make we'll revert back to the pulling stroke. Using this boat with canoe paddles would also be a good alternative. The boat is a little wide to effectively use a kayak paddle.
 
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