Since I’m replacing all wood on a 2001 Royalex Bell Northwind with vinyl
gunwales anyway, I would also like to replace the metal seat hangers. They
don’t allow raising the low-mounted seat easily, and they act like side-to-side
swings, bumping the seat frame into the hull with each wave or hard paddling. I
bought some “arc” wooden hangers from Ed’s as replacements, hopefully
eliminating both problems.
The metal hangers are attached with rivets to the vinyl inwales and hull. How
do I uninstall them and reinstall the gunwale? I know you can drill out rivets
somehow, but have no experience. Are there special precautions to take with the
vinyl gunwales and ABS hull? Do you need to put in larger rivets afterwards
because you drilled out a larger hole? What kind of rivets? Solid or pop
rivets? What’s a good way to go about this?
Since I’m replacing all wood on a 2001 Royalex Bell Northwind with vinyl
Use pop rivets
Aluminum pop rivets will work fine and you can use the same size. Pop rivets come in different diameters but also different “reaches”. You will want a rivet the right depth for the combined thickness of your Royalex hull and gunwale.
To drill out a pop rivet just drill off the large head which should be the part that is exposed. You do not need to drill out the entire shaft of the rivet (usually). Use a bit a little smaller in diameter than the exposed rivet head. The goal is to drill the head off of the rivet shaft without enlarging the hole in the gunwale or the hull that the shaft goes through, and it is usually fairly easily done with the right sized bit and with care.
Once you drill the head off the rivet you can drive the shaft out of the hole (assuming there is sufficient clearance on the other side of the gunwale) with a punch or drift. On boats in which the rivets go through both sides of the gunwales this is a simple matter. On Bell and some other boats the rivets are only visible at the large head end.
Driving the shafts into the interior of the gunwales will leave small pieces of metal inside them which could rattle a little bit. If this is going to bother you, or if there is insufficient clearance on the other gunwale side to drive the shafts free of the hole then you will need to drill out the rivet shafts using progressively larger drill bits.
The gunwales are basically hollow channels that are open at the ends below the deck plates. Conceivably you could get the rivet shafts out by having a couple of people stand that boat vertically one one stem and shake it around. If nothing else, it would make for an entertaining photo op. If you try that (no I never have) first remove all machine screws securing thwarts that go through the gunwales. I rather suspect the loose rivet shafts would tend to get hung up on the ends of the intact rivets, but it might conceivably work and allow the metal pieces to drop out the open ends of the gunwales.
Once you have drilled out the rivets and slid out the seat hangers, you should be able to use a pop riveter to replace the rivet through the existing hole.
If seat swing is a problem on metal
hangers, you can get a suitable size of stick-on minicell foam and put it between each hanger and the hull.
Temper and reinforcing
When replacing pop rivets, be sure to acquire tempered rivets, the Hardware store variety is mild aluminum and wears pretty quickly.
A second concern when replacing pop riveted in seat hangers with wooden trusses is that the vinyl rail is not reinforced with an aluminum plate as is the case in many WW canoes. You'll want to use 10-24 flathead SS rather than 1/4 in, and use SS finish washers to spread the downforce from the seat. This may not be enough, and worse, the machine screw heads and washers are a real issue, pulling divots from wooden rails when doing boat over boat rescues and from hands whenever paddling.
tempered rivets and 10’20 screws
nice insider details that will hopefully help me avoid some mistakes!
When replacing pop rivets, be sure to acquire tempered rivets…
where can I get the tempered aluminum(?) pop rivets if not the hardware store?
…You’ll want to use 10’20 SS rather than 1/4 in,
Unfamiliar with the 10’20 notation—what diameter and length is that? I did
get Ed’s stainless seat hardware kit, but I take it that won’t be sufficient?
and worse, the machine screw heads and washers are a real issue, pulling
divots from wooden rails when doing boat over boat rescues and from hands
that does sound a little concerning. I take it they’re more in the way than
other thwart screws?
It's 10-24, ie size 10, 24 threads per inch, Flathead SS machine screws you want, along with four locknuts and finish washers per seat, two ea per thwart, preferably four on the carry yoke. MacMaster Carr has a fine selection including 6" lengths. I have no explanation for the Phillips drive; why not in square, or better yet, hex or torque drive? E mails to Robertson, the square drive folk, remain unanswered as to longer lengths.
McMaster Carr also has high strength blind rivets and SS finish washers, so one-stop shopping there for you.
#10 machine screws
Number 10 stainless steel machine screws refer to a standard SAE diameter which is smaller than 1/4" diameter. They come in fine thread (32 threads per inch, or tpi) which would be designated 10 x 32, or coarse thread (24 threads per inch) which would be 10 x 24. Either threading will work as long as you have the appropriate stainless steel nuts.
You are likely going to have trouble finding stainless steel machine screws long enough for your seat hangers, though, depending on how much drop you want. Of course, the seat trusses you got from Ed’s can be trimmed. The gunwales are usually an inch in height or so and using a finish washer will put the head of the machine screw a little above the top surface of the gunwale. The thickness of your seat frames is probably 3/4-1" or so and you need to have the end of the machine screw stick out at least 1/4" or so to get a nut on it.
That means for a 4" drop you will need machine screws that are at least 6" in length and they are hard to find. I have bought them from Jamestown Distributors in the past but they might have a minimum order requirement of 25 or so. You can find other online sources but they might have a minimum order requirement too, and might charge you a substantial shipping fee as well.
You might have better luck finding stainless steel carriage bolts in that length. If you are unfamiliar with these they are like machine screws with a somewhat wider rounded head but the head as no slots like a Phillips or standard slotted bolt head. Instead they have a short, squared segment on the bolt shaft just below the head that fits into a square hole and keeps the bolt from turning when you put the nut on. They do work but require you to cut or file a small square hole in the top of your gunwales to fit the carriage bolt into.
As for readily available pop rivets, many hardware stores carry steel pop rivets as well as aluminum, but your hand will get a real workout cutting the steel shafts with a hand pop riveter. It can be done, however. Actually, I have used the aluminum variety readily available in hardware stores and never experienced a problem, but I have only replaced a few rivets at a time, which would be the case in your situation.
If you use a stainless steel machine screw and finish washer the head of the machine screw will stick up a bit from the surface of your gunwale. It can scrape the gunwales of an inverted canoe if you slide it over the top of your boat in a boat-over-boat rescue.
Actually, the great majority of whitewater canoes with vinyl gunwales or vinyl-covered aluminum gunwales were set up this way, and I have never experienced any particular difficulty scraping my hands on the machine screw heads, but other people might have a different experience. Carriage bolt heads stick up a little too but have a lower profile and are rounded so they are a bit less intrusive.
learning more about rivets today
than in all previous days of my life combined, but still
getting lost in that fascinating world. For example, below I list some options
on the McMaster-Carr high-strength aluminum blind rivets (which only come in
“domed for wide thickness ranges”):
Domed for Wide Thickness Ranges—Aluminum
Range Length Dia.
3/16" Dia.—For Hole Size: 0.191"-0.201" (Drill Size #11)
0.062"-0.27" 0.415" 0.385"
0.062"-0.437" 0.572" 0.385"
1/4" Dia.—For Hole Size: 0.261"-0.272" (Drill Size F)
0.08"-0.375" 0.56" 0.525"
0.08"-0.625" 0.81" 0.525"
I assume the material thickness range means the combined (vinyl) inwale and
(Royalex) hull, but I don’t know how much that is, nor do I know what hole size
or length I should choose. Can anyone advise?
For what it’s worth, they also have “Blind Rivets for Soft and Brittle
Materials” for attaching “plastic and fiberglass”—anyone ever used those?
drill out the rivets and find out
I would guess the hole diameter will be 3/16" but after you drill off the rivet head you will see the hole the shaft goes through and can just measure the diameter of it.
As for the depth range, once you have the rivet shaft out of the hole you can make a little depth gauge out of a paper clip wire with a short right angle bend in it, put in through the hole and get a pretty good estimate of the depth.
I’m Currently Refurbishing a Northwind
The gunnels on this one are aluminum, but I have done this with vinyl gunnels on Wenonah and Mohawks.
Looks like you already have expert advice on removing and replacing a few rivets. It's NOT hard, promise. Drill them out, tilt the plate, and wiggle it out. Replace rivets.
Now, I've used these on drilling through vinyl and aluminum gunnels to replace seats in Bell, Wenonah, Esquif, and Mohawk canoes:
The flanged washers "Spread the load" and keep the bolts from pulling through and I'm NOT a little guy. Don't skimp and buy flanged washers from the "Big box" stores or you will find they rust and need replacing. Learn from MY mistakes (LOL)!
I like the "Truss" like seat hangers, but I always trim mine since I like to kneel. They will move around less and provide more support for your seat. I think very highly of Ed's canoes, and get all of my seats, thwarts, truss mounts from them. Here's their link:
It's not that hard to re-do the seats and I highly recommend it. I HATE those cheesy metal seat hangers as do most paddlers; do you hear that Wenonah and Mohawk?
Oh, and IF you do use a skinny washer and have a "Pull through," in the gunnel, even that is easily fixed with a bit of fiberglass work to the gunnel.
Don't sweat it, it's not that hard even for those of us WITHOUT "Handy man" skills!
SS seat hardware from Ed’s?
thanks for the encouragement!
Now, everyone loves Ed’s but it almost seems like people get the SS seat hardware elsewhere. When I ordered their seats and “arc” hangers, I got their SS seat hardware kit with flanged washers, nylon locknuts and long bolts, although I don’t know if they are the recommended 10X24 bolts. Too wimpy?
Is this what you got?
Because Ed’s also sells seat hardware kits using carriage bolts.
The picture looks as if they are #10 size machine screws. You can find out easily enough by either calling Ed’s or going to a hardware store and holding your bolts up against a number 10 machine screw.
It makes no difference if your bolts are coarse thread (24 tpi) or fine thread as long as the nuts fit on. The picture looks like coarse thread.
Yes, the dished washers in the picture are what are called finish washers. The larger flat washers are called fender washers.
that’s what I got. Sufficient? Ed does sell it as a seat hardware kit.
Should be good.
Number 10 machine screws is what the great majority of boat builders use.
Quarter inch hardware is a bit more robust. Ed’s actually drills their seat hangers for 1/4" hardware, but this is more to allow some wiggle room to avoid binding the bolt when placing them through the gunwales, hangers and seat frames.
It is a bit hard to get everything to line up exactly. You have a hole in the top and the bottom of the gunwale, then a 4 inch long channel in the seat hanger, then another channel extending through the seat frame and the straight machine screw has to go through all of them.
You might find that you have to enlarge or even redrill the holes in your seat frames to line up with the holes in the hangers. You might also have to enlarge the channels in the hangers a bit by running a drill bit through them and wiggling it around a bit to allow the machine screws to go through at exactly the right angle.
Ed’s hardware is fine. I order those washers in large ammounts, so that’s where I get them from.
It ain’t the
Robustness of the bolts that we’re worried about. Anyone breaking two 10-24s in tension assuming all weight on one seat bar, is too heavy to get in/out of a canoe.
The consideration is the size hole bored in the inwale. This is particularly the case with wood rails, the inwale normally 3/4 X 3/4 stock with the rabbet removed. A 1/4 hole, bored 17/64 comprises over a third of the inwale. Hence the move to # 10, nominally 3/16 in; leaves more wood and weighs less too.
didn’t think the problem was the bolts breaking, but guessed that maybe pulling the
heads through the gunnels even with the finish washers.
Thank you for clearing that up.
Many manufacturers still hang their seats from the gunnels, don’t they?
Many manufacturers still mount their seats the "Proper" way. Even Wenonah does with their wood gunnels. I've NEVER had a bolt pull through, even with some 300+lb paddlers. I DID, however, have to fix a vinyl gunnel with fiberglass after having a "Seat holding" bolt strip. After many attempts, it was obvious that the only way to remove it was to cut it out. Pblanc suggested I could fix it by 'glassing the gunnel over. Worked like a charm!
my project of replacing the seat hangers, seats and thwarts is finally finished.
It took quite a while with borrowing and reborrowing tools and the varnish took
a long time to cure, but I think it was a big success despite of several smaller
hickups. Maybe a revarnish this summer when outside temperatures don’t make the
varnish gel so quickly and leave incorrectible runs.
A big thanks to everyone who advised me on the hangers, seat angles, machine
screws, riveting, varnishing and much more. I couldn’t have done it without
We’re taking the boat out tomorrow, the first time since the project started!