How raft tube diameter and rise affect handling - Mountain Buzz
 

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Old 12-07-2018   #1
 
Augusta, Maine
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How raft tube diameter and rise affect handling

As I look at rafts and the myriad of configurations available I am a bit perplexed. Could someone please explain when different tube diameter and rise compared between two similar length rafts become noticeable. What are the effects? Thanks.

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Old 12-07-2018   #2
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Well, I'll at least start ya out.
The main difference with tube diameter, is how much displacement you get. The more the displacement of water, the more weight a boat can carry, and keep the same amount of Draft, or how low in the water it will sit. Boats that sit higher, tend to be more manueverable, and float over more of the rocks in the river bed. They also will get surfed easier, catch more air currents and head wind.
When tube diameter becomes noticeable is a little hard to say, there are other variables, if it is a raft, then the width is one of those, since that to, affects displacement. It is basically a percent of the load capacity that would be noticed. On something like a 16' cat, I think you would notice the difference between 25 and 28" tubes in a big way, from what I've seen of friends that have them.
I will let others chime in on rise affect.
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Old 12-07-2018   #3
 
Augusta, Maine
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Thank you Mattman for your response. As I look at boats I am wondering how differently say a 14' boat with 22 inch tubes and 25 inches of rise will handle compared to a 14' boat with 19 inch tubes and 20 inches of rise. Then there are different types of floors to contend with as well.
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Old 12-07-2018   #4
 
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Tell us what you plan to use your new raft for and maybe that will give some insight into what type of boat would best suit your needs!
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Old 12-07-2018   #5
 
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Tube size and the rise are just two factors. Where the "kick" starts, the rocker profile and a bunch of other aspects of a raft make a huge difference in how it handles (plus width and such too). Add in diminishing tubes and there are A LOT of different options.

Honestly...the rocker profile of a raft probably makes the most difference in regards to how it handles and how much weight it will carry. The tube diameter won't really come into play until it gets loaded down quite a bit.

Generally, something with continuous rocker (the bottom has a constant curve) will be quicker and more maneuverable but may not carry its speed for as long, won't track as well, and won't carry as much weight as a raft with a flat rocker profile.

The Aire D series compared the Aire DD series is a good comparison between these. They both have diminshing tubes, but the DD (double diminishing) tends to keep the same profile as the R series rafts on the outside edge and the D series does both sides. The D series has continuous rocker and the DD has a flat bottom. They both can do double duty, but the D series rafts generally are used for paddle rafting or lighter gear boats and excell when you need speed and the ability to spin easily. The DD series, especially the 136DD and 160DD have very long and flat bottoms. For its size, the 136DD can carry a ton of weight but after a season and a half of using mine I find that its a bit slower and more prone catching waves then punching them.

So yeah...obviously you can get in really deep with this stuff. I think the important thing to note is that most of the times its gonna be personal preference and that rafts of a similar size will all be able to do similar stuff...they will just have small differences. To your most recent question...I think the difference between a 22 inch tube and a 20 inch tube will be minimal. The Rise (or kick) of the raft may be more significant, but will only really make a difference in how dry the ride is, how well it will ride over waves, and how much wind it catches. As I said already, other aspects of the rafts design will make a bigger difference.

I agree with Curtis...in order for us to help you the most it would help to get a description of what your intended use for the raft is and maybe a few specific models of raft you are looking at.
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Old 12-08-2018   #6
 
Hood River, Oregon
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Thank you for asking the question. I've been thinking about this quite a bit and have been testing a few things lately. Here are some generalizations I've come up with for discussion:

1. For performance - bigger tubes are better. I'd like to see more 22" and 23" tubes. There probably isn't any problem with bigger tubes other than maybe air resistance.

2. The most expensive part of a boat is the fabric. I have a conspiracy theory that suggests that raft manufacturers like smaller tubes and diminishing tube boats to use less fabric for the same length of a boat.

3. One downside of larger tubes is that you have less interior room if the outer dimensions stay the same.

I'd also like to hear what you're planning to use your raft for.
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Old 12-10-2018   #7
 
Augusta, Maine
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I plan on using the boat for flyfishing on the rivers in Maine. There is some good whitewater on the Kennebec and Dead Rivers,but the big rapids can be skirted. I need a boat that will carry three people comfortably, but will mostly be myself and teen son. Perhaps an occassional overnighter, but mostly day trips. I am 6'4 with a wingspan of Kareem Abdul -Jabar. A lot of the rivers in Maine are pretty shallow. Hope this helps. What is the reasoning for diminished tubes?
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Old 12-10-2018   #8
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It might be wrong for fishing( don't fish, so don't really know) but I tend to think something 16' or 14' range, seems more comfortable for a big guy, with two other people. It would float higher in shallow water, and more room for overnights. If you are planning on a used boat, there are lot's of 16's in that neck of the woods, since that's the standard outfitter boat up there, or at least what I have seen on the Penobscot. Fishermen will have better info, however.

Zach, I agree with you on tube size, I would love to see larger sized tubes in more models, especially for boats that are meant for gear hauling. About 98% percent of my river time anymore, as a private boater, is multi day, and I really like having flotation, especially in Cats. I don't want a boat to ride low, punch into features instead of riding over, be sluggish, soak me in every wave on cold, winter time grand canyon trips.
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Old 12-12-2018   #9
 
Augusta, Maine
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I found this site that I found helpful in describing how boat design affects function.
https://triadrivertours.com/river-re...rison-shootout
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Old 12-12-2018   #10
 
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I highly recommend sticking to a raft in the 13 to 14 foot size range. 19 to 21 inch tubes will suit you well. Too big of a tube diameter makes it hard to get back in if your swimming. Rocker profile is not such a big deal, unless you plan to run steep drops, surf or R6+.

You’ll have to carry or drag your raft at most Maine put ins and takeouts. A big heavy 16 footer will be a hassle. Many paths will be narrow more suitable for canoes, and lined with poison ivy. You want a raft you and a buddy can carry into the good fishing spots. 13 foot rafts handle Dead or Kennebec River high water just fine.

I live in Massachusetts and have been rafting privately and commercially since 2006. I have an Aire Super Puma and a 13 foot Momentum (similar to NRS Otter 13 specs), a bucket boat, and formerly a mini max. With your long legs , a Super Puma will feel cramped.

If you got the cash , go Hyside Pro 13 or 14, or NRS Otter 142, maybe Super Duper Puma 14 or 143D.
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