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Thread: Thwarts?

  1. #1
    Member Scottsum's Avatar
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    Default Thwarts?

    Maybe this is a stupid question, but I don't know much about physics and weight distribution in rafts. My question is this:
    Will adding a couple of strategically placed thwarts add load capacity to a self bailing raft with a rowing frame?

    It seems like the more floatation you have the more weight you should be able to carry...

    I realize of course that every space filled by a thwart reduces the amount of space available, but just a thought.

    Thanks in advance.

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    Member danattherock's Avatar
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    I would say that it would add to the rigidity of the raft, but not sure how it would increase floatation. Seems the main tube/tubes will be doing all the work here since they are what is in direct contact with the water. My guess is you would just be adding 7-9 pounds of weight and cutting into your precious cargo room. I would be interested to hear what the more experienced guys have to say though. Interesting thought for sure.
    The two loudest sounds known to man: a gun that goes bang when it is supposed to go click and a gun that goes click when it is supposed to go bang.

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    Moderator Alaskacanoe's Avatar
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    Default Displacement

    adding twarts as Dan mentioned only adds a place to sit if you have no frame, and helps keep the rafts shape during extreme white water.
    I pull my twarts out and do not use them if I am using a rowing frame.
    They just take up space and weigh a little extra in the plane.
    For paddle rafting they are nice to sit on though,,
    Max
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  4. #4
    Member danattherock's Avatar
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    Yeah, my raft did not even come with a rear thwart, or the attachment for it. Made to be rowed and lightweight. Just came with a front thwart for this reason.

    The two loudest sounds known to man: a gun that goes bang when it is supposed to go click and a gun that goes click when it is supposed to go bang.

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    A thwart can only add to weight capacity if you're so loaded that the floor is submerged and the thwart is providing lift. I have done that, but the boat handles like a pig, and your feet are always cold.

    I usually leave my thwarts installed, but deflated, laying on the floor with coolers suspended over them. In my old Aire self bailer removing and reinstalling takes too much effort, so there they lie. When the frame comes off for paddle power, the thwarts get pumped up for seat space and "structural" rigidity.

    BTW, In an emergency a thwart can be used to replace a blown bladder in an Aire raft. You have to be desperate to do it, but I know a local commercial outfit that brings them along for that reason alone. This would also work in conventional raft designs, but you have to rip the tube open enough to push the thwart through. Desperate for sure.

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    Default Buoyant force and displacement...

    Buoyancy, which in rafting means the amount of weight you can carry, should be a function of a raft's displacement.

    There's plenty I don't know about rafts and maybe there's more to it, but buoyancy, the force acting upward to float the raft, can be calculated and basically equals the weight of the water the raft displaces. Because the thwarts are inside the raft, they wouldn't add any displacement or buoyant force.

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    Member Scottsum's Avatar
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    Default That's about what I thought.

    Thanks guys, that's kind of what I figured, but I hoped it wouldn't be so. I knew some of you more experienced boaters would know the answer for sure.

    Wow Jim, I hope I never have to row my raft when it's "so loaded that the floor is submerged and the thwart is providing lift." That doesn't even sound like a fun trip; Sounds like trying to row a swamped skiff!

    Scott

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    Thumbs up THWARTS... Wuddar they good for?

    Quote Originally Posted by Scottsum View Post
    Maybe this is a stupid question, but I don't know much about physics and weight distribution in rafts. My question is this:
    Will adding a couple of strategically placed thwarts add load capacity to a self bailing raft with a rowing frame?

    It seems like the more floatation you have the more weight you should be able to carry...

    I realize of course that every space filled by a thwart reduces the amount of space available, but just a thought.

    Thanks in advance.
    Hey Scott -

    Not a stupid question at all...

    With all the present-day self-bailers, thwarts give a person well-situated inflatable seating. Thwarts additionally provide safer seating, improved weight distribution, and an advantageous paddling position (keeping legs/body parts and center of gravity inside the boat).

    Thwarts are not just for seating. They create helpful foothold stability that offers spacing, balance, and leverage for paddle rafting.

    Some thwarts come permanently fixed yet many nowadays are removable. Either way if you use them, you should make sure they are in working order and that the connections, hardware, and fabrics are in good condition.

    Thwarts can be accessorized with D-rings, rope holds, and add-on carry handles that serve as handholds. They also make bags, fishing rod holders, including a whole assortment of other stuff. It’s possible to makeshift airbags, duffels, outriggers, outdoor games, outdoor showers, and water carriers with the removable ones.

    One of the best applications of thwarts on non-bailers (but also self-bailers and even rigid hull boats) is water displacement inside the boat when it’s coming in to fast to bodily bail or self bail.

    Extra air chambers in the event of an unintended deflation can be a means to stay afloat and retain some control. In rigid boats like kayaks and canoes they’ll maybe keep it afloat!

    Maintaining structural integrity is yet another function. By keeping the boat geometry… in return you obtain its top performance, stability, rigidity and strength. A major pinning, broaching, or impacting situation can flex a boat like a clam-shell. Have this same event occur simultaneously with significant keeper reversals, potent eddy-lines, deep ledge-drops, or powerful hydraulics/holes and a boat can torque into a hazardous bend and twist combination. Tho’ rare, people have died in this escape proof sort of coil effect entrapment --- even in rigid boats!!!

    CatRafts use them for structure like some of Jack’s Plastics very innovative boats.

    I had a thwart from my AIRE 156E used on top of my old AIRE WildCat & welded frame for descending spring runoff on mountain Jacuzzi. It was originally intended as a fifth air chamber that perched one active passenger in a position to perform fast and very effectual high-siding. It provided dynamic padding in a flip situation from the frame itself…. conceptually a roll-cage pillow that may provide self-rescue leverage in the form of self-righting assistance if flipped in a canyon with no way out. Only used it twice, however never had to baptize my inspiration. I noticed maybe a year ago or so that some river rats down south were experimenting with a variation on my theme.

    Some will inquire… If using a well constructed frame do I need thwarts?

    On non-bailers I’d say… better to use two, but at least one for sure directly under the rower’s seated position. Many raft manufacturers and designs (new & old) place two chambers up front with only one in the stern.

    For most applications I’d say NO on Self Bailers and Cats… particularly if you are on multi-day expeditions attempting to maximize all square footage of the boat. I’ve not used them in most Self Bailers or Cats in years while using high-quality frames on representative whitewater of the Sixmile canyons or big waters down the Newhalen River Gorge.

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    Lightbulb Nice boat but....

    Quote Originally Posted by danattherock View Post
    Yeah, my raft did not even come with a rear thwart, or the attachment for it. Made to be rowed and lightweight. Just came with a front thwart for this reason.

    Dan nice light bucket-bailer boat... HOWEVER - Thwart-wise it is architecturally flawed as a more demanding whitewater boat or a properly equipped gear hauler.

    I cannot precisely tell you if the boat pictured is symmetrical geometry bow and stern. In other words the bow and stern are identical and it makes no difference which way is forward or backward, but it doesn't look that way to me.

    While having a convenient & good removable inflatable seat for the front --- the installed d-ring hardware is simply in the wrong spot in terms of safety utilizing 1 thwart for this boat... and for where it appears your main chambers & valving are located.

    The easy fix is to put additional d-rings for 1 more aft thwart and use the one thwart you have under your frame beneath the rower's station. Get a second one if you can.


    My first commercial 15.5' raft (non-bailer) had a fixed front thwart and a removable rear thwart... not a good combo for river rafting and both showed different signs of wear and tear over the years.

    If you removed the rear thwart the boat would flex more. If lots of water inundated the boat there was less time to deal with it, the boat got heavier, and only one thwart to displace it. In an event like an unanticipated rear chamber deflation, it opened your whole back-side up to dropping out from under you, the non-bailer floor grabbing/constricting your feet, and having water rush in, meanwhile negating any last minute back-stoking ferry angle option. The concept with that good ol' boat tho' was the ability to install a main section of rigid wooden floorboard when using a motor or while towed across flat water so that the bow would ride up and flex as the larger surface area of the hull could plane.

    Hope this helps out --- like I said great boat, but re-think the thwart concept and use.

  10. #10
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    The thwart is in the front and I have a 22 lb frame for the back. While I appreciate your thoughts, I don't see any issues. But I will not be doing very heavy whitewater either. I got this raft for some float trips in Gates of the Arctic and ANWR mostly. Class I/II for the most part with small canyon sections of class III. That is about it. Doubt I will have any problems with the raft with my intended usage. Main thing I needed was a raft that flies well. Commercial air from NC to Alaska makes challenges for rafting gear. This one fit the bill perfectly at 93 lbs.
    The two loudest sounds known to man: a gun that goes bang when it is supposed to go click and a gun that goes click when it is supposed to go bang.

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    Smile Lightweight and simple...

    Quote Originally Posted by danattherock View Post
    The thwart is in the front and I have a 22 lb frame for the back. While I appreciate your thoughts, I don't see any issues. But I will not be doing very heavy whitewater either. I got this raft for some float trips in Gates of the Arctic and ANWR mostly. Class I/II for the most part with small canyon sections of class III. That is about it. Doubt I will have any problems with the raft with my intended usage. Main thing I needed was a raft that flies well. Commercial air from NC to Alaska makes challenges for rafting gear. This one fit the bill perfectly at 93 lbs.
    Yep Dan... that's a long haul up from NC. Lightweight, simple as possible, durable fabric, compact, with the fewest items for airlines to damage or loose en route is the name of the long distance, multi-logistical game.

    The SOTAR boats are fortunately some of the toughest, stiffest rafts manufactured and handle very well. For the easier class rivers you described I'm know your boat will perform just fine even when leaving thwarts at home. As you probably know, I was talking more from an utmost safety perspective with thwarts on non-bailer rafts.

    If the boat is symmetrical... of course you could strap the frame in facing the other way for longer stretches of more demanding whitewater canyon until you get the safer two thwart set up that really would not increase the weight by much.

  12. #12
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    Thanks for the insights Brian. I appreciate it.
    The two loudest sounds known to man: a gun that goes bang when it is supposed to go click and a gun that goes click when it is supposed to go bang.

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    Wink Rafts!

    Dan your correct that the frame will do the work and the Thwart is not needed. But I like having on in with my 14-foot rafts even with a frame. I feel it helps with the rigidly and placement of the frame. There is a trade off with cargo room but an average 14 foot fart will hold 1,100-1,300 pounds of meat or??? A little more room is only needed when you have bulky items. I don’t like the self-bailers because when you really add the additional wt. You can force cold wet water up into your feet and gear. We only float class 1-2 water up hers so Bailers are not needed.

    On another note… I need a thwart for a 14-15 footer if you guys have one for sale I am looking!


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    Dan: Did you look at Flyfisherman this month yet? Just came out.

  14. #14
    Member danattherock's Avatar
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    Quote Originally Posted by northwestalska View Post

    Dan: Did you look at Flyfisherman this month yet? Just came out.

    Been out of town and don't have internet access. Was in a book store here in NC last week but the current Flyfisherman was to be on the stands till Feb 4th and it was Feb 3rd

    I live in a small rural town, but will be going out looking for the issue you told me about soon. Thanks for the heads up man. You know I like my dollies

    Thanks man!
    The two loudest sounds known to man: a gun that goes bang when it is supposed to go click and a gun that goes click when it is supposed to go bang.

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