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Discussion Starter #1
I've been thinking about getting a smaller raft for doing low water tech runs down the Middle fork and Selway rivers. It seems that high water years are going the way of the buffalo and this might be a good way to extend my season. I've been looking at the Aire 13D, 13E, and the Puma series. I have been watching some videos of Jon Barker doing low water Bruneau and Owyhee with the 13E and it looks very capable. The added .5" on the tubes on the E series could be nice to have in low water, but the D have a smaller waterline albeit slightly smaller tubes. I have rowed a superpuma down the MFS top end @500cfs before and it was a breeze. I remember wishing that it was a little more stable for some of the bigger drops, but it was pretty sweet. But I would like to put on a little more gear for multi day. The super duper looks nice but the long waterline has me wondering if it would be difficult to spin and turn on a dime.

Thoughts?
 

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All would be good options for low water floating. I think that the Puma series are particularly nice for really narrow rivers or getting through narrow slots. I have also run a super puma down the top end of the MFS and it was an absolute pleasure, especially in places like Sulfur and the Chutes. But I agree that they are small and a slightly larger yet still very nimble raft would be better for multiday and still being able to sneak thru the gnarly rocky shoals of low water. I think I know what videos you are talking about, I've seen one where Jon Barker runs Owyhee falls in a 13E. It looks like he is running a scaled down 4 bay frame with captains boxes and all, looks like a very sweet setup.
 

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If you looking at doing multi day in low water I would avoid the E series. The Puma would be great because they will distribute the weight, so will the D series but the E series would actually be counter productive because it is a white water design and will sit lower in the water due to shorter waterline. JMO
 

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Discussion Starter #4
Interesting...however, looking at the Aire site. The 13D has a waterline of 91" and the 13E has a waterline of 93". So the E actually has a larger waterline and larger tubes than the D series. Wouldn't this actually make the E series float higher in the water with multiday gear? I'm pretty much torn between the Super Duper Puma, 13E and 13D. Interestingly enough, the SDP has the longest waterline at 98", but would this make it hard to turn when loaded?
 

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From a boyancy perspective, I'd avoid the narrow superpuma and go with a more traditional design for larger surface area. is 8" really going to make a difference on where you fit or is the extra capacity going to keep you from sticking in the shallows? In my experience more draft is king, you really want to maximize surface area for boyancy (I know it's more complicated than that, but area is the biggest factor). That or go longer to the SDP - has more surface area but fits in narrower spaces.

I know this is all a balancing act, but the bigger the boat, the higher it floats (with the same load) so it comes down to what's more important, draft higher or fit in smaller spaces.
 

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Just to think outside the drybox - have you considered a radical leap to a Fat cat, Cutthroat, or even packraft? I have used each of those and much prefer them to a small raft under the conditions you describe. A cutthroat even looks, rows, and hauls a little like a raft
 

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Discussion Starter #7
Just to think outside the drybox - have you considered a radical leap to a Fat cat, Cutthroat, or even packraft? I have used each of those and much prefer them to a small raft under the conditions you describe. A cutthroat even looks, rows, and hauls a little like a raft
I'm definitely looking for a small raft. I want to be able to haul a cooler and a couple boxes. I have an IK for backpacker style trips if I want to go that route, but I would like to be able to bring more stuff and eat better and drink beer. I am not a fan of cats in low water, rafts work much better and I am highly skilled and proficient at rowing large rafts through really shallow rocky rivers. I would just prefer to have a smaller one for myself. I really like the setup on these boats in the video below.

https://www.youtube.com/watch?v=6QuGS9Qq2nk
 

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That's a cool video I'm assuming those are 130E. Which I'm not sure why they would choose over a D.

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Spider will haul more than a puma with less draft. I miss mine but she's in good hands these days. Shes now running low water multis in OR with people and gear or padding up to 7!!!! People. Amazing boat, just a bit flippy when running solo. New owner just did dechutes, rogue and umpuque running 3 up with gear. She is the Jeep of boats..
 

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Interesting...however, looking at the Aire site. The 13D has a waterline of 91" and the 13E has a waterline of 93". So the E actually has a larger waterline and larger tubes than the D series. Wouldn't this actually make the E series float higher in the water with multiday gear? I'm pretty much torn between the Super Duper Puma, 13E and 13D. Interestingly enough, the SDP has the longest waterline at 98", but would this make it hard to turn when loaded?
I shouldn't have said waterline. I should have said weight capacity. the E will have some. The D will have more and the R will have the most but it's wide. I'm not sure how the puma series fits in that line.
 

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Displacement is your friend. Longest waterline with the biggest tubes equals shallow draft. All the boats in this class will spin very easily- but the less you hang up, the better. I haven't studied the specs, but I second the vote for the Spider.

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I shouldn't have said waterline. I should have said weight capacity. the E will have some. The D will have more and the R will have the most but it's wide. I'm not sure how the puma series fits in that line.
Puma series are roughly the same length but 8" narrower. Way less boyancy between similar lengths.
 

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Displacement is your friend. Longest waterline with the biggest tubes equals shallow draft. All the boats in this class will spin very easily- but the less you hang up, the better. I haven't studied the specs, but I second the vote for the Spider.

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I agree displacement is our friend but displacement is purely a volume measurement. As long as the tubes are bigger than the draft, tube diameter has little to do with it. Tube diameter comes into play by giving you more potential draft i.e. more displacement with more submergence, but if your thinking of minimizing draft; surface area is king. I'm not saying that large tubes are bad, or useless, they just aren't always better.
 

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Look into "displacement". Submerging a bigger tube gives you exponentially more displacement- requiring less submergence for the same load. Larger tubes effectively make your hull wider.

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Yep, I agree too. I don't know the specs of the spider. I'm an Aire driver so maybe going with the smallest "R" series boat would be the ticket. Lot's of capacity and the 13' should still be good between the rocks during low water = smaller and shallow. The Spider might have the same properties. I'm sure other manufacturers have the equivalent speced boats as well.

Another thing to consider is the way you pack. The term "multiday" can be very subjective. I can do five days out of a 25lb drybag with dehydrated meals and filtered water from the river. The only luxury I would bring is a camp chair. Then I could do a multi day trip in an IK. Obviously the lighter you pack the shallower you will run and the smaller boat you can go with. Maybe even something like a mini-me or mini-max.
 

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Look into "displacement". Submerging a bigger tube gives you exponentially more displacement- requiring less submergence for the same load. Larger tubes effectively make your hull wider.

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That's true of a cylinder but not necessarily true of compound shape. Below are some quick calcs. It is based on a simple 72" wide (overall width) boat and then the calcs are expanded for 90" of straight tube with no bow or stern tubes to simplify things.

displacement calcs.jpg

In the end what it shows is that for a given submergence (we're talking displacement at a given depth) a 20" tubed boat has a displacement of 605 lbs while a 24" tubed boat will displace 576 lbs. The 20" boat displaces ~29 lbs more weight at 3". Therefore at the same load, the 20" tubed boat will float higher than the 24" boat. At 6" its a 48lb difference. It's not a huge difference but it's pretty clear that bigger tubes do not necessarily displace more than smaller tubes. Particularly with light (3") to moderate (6" drafts).

You'll note that 24" tubes do displace more in and of themselves, but in this case the width gained center to center of the tubes overrides the tube displacement. That's 4"x3"x 90" of volume = 1080 CI or 0.625 CF. The difference in tube diameters totals 278 CI or 0.16 CF. As submergence increases there is a tipping point, where the large tubes displace more. But that's not what this thread is about.
 

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I have only rowed a 14 ft. Sotar SL (diminishing tube) so I can't speak to the others that have been mentioned. I have done one late season, low water MFS trip and this raft is perfect for my needs. I was coming from being a long time (15+ years) catarafter, and I found that I liked the Sotar SL better than my cataraft. It maneuvered, spun, and moved better with far less hang-ups. I was hoping to try it on a low water Main Salmon this week, but had to abort the trip due to a medical emergency with a trip member.

I've looked at the specs on the rafts that have been mentioned, and they have a little bit of a range as far as width and tube dimensions. I'm bummed that the AIRE website no longer has it's wireframe drawings of its rafts. Those drawings gave a lot more info on their boat designs. Now they only list one tube diameter for their diminishing tube rafts. The Super Puma and Maravia Spider are the narrower two at 5'8" for the Super Puma and 5"9" for the Spider. The Spider lists 20.5/14 diameter tubes, but the Super Puma just lists 18.5 for tube diameter. On the wider end are the AIRE 13D at 6'4" wide & 19 tubes, and the Sotar SL 13 at 6'6" wide and 21/16 tubes.

Based on the OPs desire for a nimble craft, but one that could carry more multi-day gear, and the OPs wish for a bit more width/stability than the Super Puma that he has rowed on the MFS in the past, I'd say the AIRE 13D or Sotar SL 13 might be good choices. I know that I'm very happy with my Sotar diminishing tube raft.
 

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That's true of a cylinder but not necessarily true of compound shape. Below are some quick calcs. It is based on a simple 72" wide (overall width) boat and then the calcs are expanded for 90" of straight tube with no bow or stern tubes to simplify things.

View attachment 10534

In the end what it shows is that for a given submergence (we're talking displacement at a given depth) a 20" tubed boat has a displacement of 605 lbs while a 24" tubed boat will displace 576 lbs. The 20" boat displaces ~29 lbs more weight at 3". Therefore at the same load, the 20" tubed boat will float higher than the 24" boat. At 6" its a 48lb difference. It's not a huge difference but it's pretty clear that bigger tubes do not necessarily displace more than smaller tubes. Particularly with light (3") to moderate (6" drafts).

You'll note that 24" tubes do displace more in and of themselves, but in this case the width gained center to center of the tubes overrides the tube displacement. That's 4"x3"x 90" of volume = 1080 CI or 0.625 CF. The difference in tube diameters totals 278 CI or 0.16 CF. As submergence increases there is a tipping point, where the large tubes displace more. But that's not what this thread is about.
They answer is, they will displace the same, because that is determined by the load. The larger diameter tubes will require less submergence to accomplish the same displacement, because they have more surface area for every submerged inch. That means you hang up less- which is the goal for this application.

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They answer is, they will displace the same, because that is determined by the load. The larger diameter tubes will require less submergence to accomplish the same displacement, because they have more surface area for every submerged inch. That means you hang up less- which is the goal for this application.

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Look at the calculations. Then review your post.
 
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