Do I really need that thwart?

Spring is almost here and I am just now starting my winter project boat.

I got a RX Penobscot with vinyl gunwales. It has three seats and two thwarts. I am removing the center seat and adding a yoke (I ended up getting a shadow yoke from slipstream yokes). I think I am also going to remove one or both of the thwarts.

The two seats and yoke should stiffen the canoe up enough. The only reason I could see leave a thwart in would be to hold onto while portaging. Then I might install the yoke backwards and leave the rear thwart in.

Opinions? Will it make it not stiff enough?

if you get swamped
and pinned, then you’ll find out. Not offering any advice, you’ll get plenty I’m sure. I would say it depends on what water you’re paddling, lakes vs. cl.3 granite strewn rivers. I’d bet your seats have drops, which isn’t as strong as a straight thwart.

On the other hand, a few guys I pole with who have specialty poling boats have no seats and 2 thwarts. They do have 10’ of airbags though to keep the canoe high if it swamps. Couple times I’ve been glad for the 4 thwarts in my OC-1 and the 2 seats, 2 thwarts plus portage thwart in my poler. I note a lot more flex at the seats and kneeling thwart due to the drops.

Which size?
The Penobscott 16 is standard with one thwart and yoke while the 17 is standard with two thwarts and a yoke. The thwarts do help a bunch for stiffness in rough conditions. Bell always uses a thwart immediately behind the bow seat because the seat on drops do not supply enough lateral stiffness for the hull.

Seats don’t offer much “thwarting”

– Last Updated: Feb-25-09 9:03 PM EST –

The normal ways of mounting a seat do not strengthen the boat. Typically, the seat hangs below the gunwales on wood or metal hangers. There is no tensile or compressive strength between opposite seat hangers at gunwale height. Apply stress there and the junction of the hanger with the seat or the gunwale will bend (metal hanger) or break (wooden hanger). If you are only talking about compressive strength, the other thing that can happen is that the joints will fail and the ends of the seat will be jammed into the sides of the hull (that's not a good way to reinforce the hull). You could mount your seats directly to the gunwales and then you would get the same strength as with thwarts, but they would be too high to sit on.

On that note, if the seats are mounted for kneeling (high and sloping forward), perhaps the back rail of the seat will be almost as high as the gunwale. In that case, you will get "some" reinforcement from one side to the other, but if there's any kind of hanger between the seat rail and the gunwale, that will still be a flexible (and failure-prone) joint.

Not arguing for regarding seats as
thwarts, but hanging seats can be firmed up somewhat by installing minicell between the seats, seat hangers, and the side of the boat.

Thwarts don’t weigh that much. My MR whitewater boat came with four ash thwarts. I replaced them with four spruce thwarts, but I only saved about a pound of weight. Considering the relatively light weight of a thwart, it isn’t worth removing them unless they are in the way.

Old Town Seat hanging hardware
3/16 x 6" bolts through unconnected dowells, do not do much to strengthen the boat if it gets pinned. The yoke will help but at minimum I would keep, the thward behind the front seat, provided it was going to be used loaded. If it was going to be used empty most of the time, I would keep the rear one too.

Old Town "solution"
I’ve noticed that Old Town builds the 14’ Osprey with no thwart and a third (solo) seat. The center seat has metal reinforcing brackets that angle between the gunn’l and the inner seat frame - sort of a truss. Probably not as strong as a thwart, but maybe a good compromise for moderate use?

Thanks for the responses. Its a Penob 16. It will get some mixed flat, river uses. But almost never with a load other then out 3yo and 1yo, we have other boats for that.

I think I am going to remove the fore thwart and move the aft to a good place for holding on to while portaging (but keep it in reach for thwart bags). The thwart right behind the bow seat gets in the way of paddling the boat backwards. I will also mount the yoke backwards so I can hold on to the thwart.

Y’know - if you leave in that center seat, the thwart behind the front seat won’t be a problem. You could rig a removable yoke just ahead of the center seat. The yoke you have can be set up that way easily. Just a thought. Have a look, and read especially the post titled “QD yoke”…

Three Thwarts
hen I was at Bell, ans specing tandems, we always installed three thwarts. First tight behind the bow seat to keep it from flexing the hull. Center carry thwart for obvious reasons, dpoiuble machine screwed, and a third, which could be exchanged for a kneeling thwart far enough forward to allow the stern paddler some leg room but far enough aft of the carry thwart to allow a solo paddler to kneel.

That Royalite is way floppier than Bell’s BlackGold, so you’re removing that thwart at your own peril. Hulls need all thge stiffness they can get.