Oil canning, huh?

If it’s not too much trouble, as I research my way into my first canoe selection, could you blokes give me a 101 on oil-canning? 'Tis a weird sounding term, no doubt. What’s it look/feel like and when do you know you’re doing it? So much to learn, just to get on the water.

Oil canning is…
the term for hull flex while paddling. The water resistance against the hull causes it to flex inward and then outward. Kind of a magic carpet ride, if you will. Not all boats do it. Construction materials and hull design increase or decrease the effect.

Not to be confused with rack dents and such.


the first time I have seen “oilcanning” to describe flex in the hull on the water. Most times, oil canning is used in reference to denting from racks.

No right or wrong. But, yes, just that much more confusion for someone new to the sport.


I was confused when I heard it too
If you remember the little metal machine oil cans for sewing machines and such that you pushed on the metal bottoms and the bottom flexed in and out and the drops came out of the needle like tip, they made a little boink sound when you used them. That movement of the bottom of the oilcan that doesn’t leave any visible change in the hull is what is being refered to here. In kayaking it is used to refer to an unwanted flexiblity of plastic or fiberglass hulls, disconcernting as you paddle thru the water. I had an 18’ fiberglass boat that was very fast and handled well, but oilcanned very badly, although it was a high quality boat, this made it feel like it would fold at any minute.

Hope this helps.


oil canning
Ever poured oil from a quart oil can into a car? the kind you had to puncture with a top, the can would dent inwards then when air went in it would pop into place, We are talking about a denting that usually self-resolves over time. )in the oil cna it forms and resolves every few seconds.

I differ the oil canning can come from anywhere and racks, over-tightening and poor saddles are the biggest culprits.

Let’s think for a moment, if you are not making a hot spot in the boat, (by applying a lot of force to one point) the water is pressing back oh so evenly/ A rack, or padded bars, focuses the pressure on a small number of square inches. A boat that regularly oil cans in the water, will likely have serious trouble on a rack on a bumpy road.

Erl cannin’

– Last Updated: Aug-25-06 7:45 AM EST –

Wha Ho, Pilgrims;

Yup, oil canning be de in an' out flexing of a hull while in de water as previously stated by Holmes. Usually see it on the bottom in a wide Royalex or poly boat. Denting of the hull from too tight tiedowns and/or rack contact is what we in the trade (when ah' was in de trade) call rack rot. Two different thin's.

Fat Elmo

you really don’t
have to worry about it if you see it happening while you are padling, BUT if it starts making the oil can noise ABANDON SHIP (unless you have a tin canoe that is)

Thanks, I stand corrected!
I think :wink:

Around here…
I’ve always heard denting from a rack to cause a ‘wow’ in the hull, and the flexing of a hulls bottom in waves to be called ‘oil canning’. Oil canning is also what happens when say a whiteH2o boats hull gets compressed or squished betweeen a downstream currents force and a hard place, such as a rock, in a pinning.

verb vs. adjective
or, static condition vs. permanent condition

Oilcanning (v.) 1. Hull flexes in & out while gliding through the water. (Not to be confused with “denting” such as if it is an object, not the water stream, that couses the flexing.) While not a desireable hull chacteristic, it’s not a serious concern either, so long as it causes no long term deformity.

A hull that has been strapped down to a rack too long/too tight is dented, not oilcanned.

But what about a hull that has a section which is “wavey” or “rippled,” that is, a series of alternating bulges & dents…could this not be described as “oilcanned?” (adj.) This permanent (or semi-permanent) condition, call it what you will, is caused not by impact but from non-linearity, usually from improper storage in direct sunlight. Can also happen in the cool-down period of the rotomold process, which explains the occassional rippled specimen among the showroom-new-never-been-in-the-sun hulls.

PS: I’ll fix yer flat tire, Merle…

Don’t you get your sweet country-pickin’ fingers

All covered with erl…

One word, two usages
Confusion is easy because the word “oilcanning” is used in two senses:

  1. To denote the flexing of a boat on and off the water (see multiple postings above).

  2. To denote the kind of denting or warping that takes place when a plastic boat is cinched down on a car rack on a hot day (see Sing’s post above).

    In other words, different people use it differently. I suspect that (1) is etymologically “correct”. But I see the word being used by many in the second sense (2) too.

I think you’re right
Oilcanning comes to the boating world from canoeing at about the time Royalex hulls were introduced in the early 70s. It refers to hull flexibility when paddling. Pakboats describes it well on their website: “Oilcanning occurs in boats without stiffened bottoms and is very common in large Royalex canoes. The most annoying characteristic is that the bottom “flaps” when you paddle little waves without a load in the boat.”

It has been used (misused IMO) in the kayaking world to refer to the denting caused by leaving a plastic hull tied on to a rack in the hot sun. Please join my crusade in convincing the kayaking world to call the rack denting thingy a “dent” rather than “oilcanning”. Then we won’t have to see this post repeated every six months or so. Maybe we should encourage Brent to put up a glossary of canoe and kayak terms on the site. Think of the discussion possibilities …


I liked “Rack Rot” for dents… NM

I’m told that the motion of a hull flexing due to oil-canning robs a bit of efficiency, much like a mountain bike suspension takes away some power as the suspension flexes. The physics of this is beyond me and the effect may not really be that noticeable to most paddlers. It’s probably no big deal in most cases except perhaps in a race.

Dents and Oilicanning
Yep, this subject seems to come up pretty often. I am going to keep calling any permenant deformation of the hull a “dent” and not oilcanning. Not only does the term “oilcanning” come from the operation principle of old-fashioned oil cans (an NOT the “glug-glug” flexing of storage cans as they are poured), but the term has been around for a long, long time (talk to any mechanically-talented man who’s in his 80s or 90s and you will find that he has been applying that term to flexible metal objects all his life). Only since the advent of plastic boats has this term been bastardized to refer to dents and other permenant deformations.

So for me, any in-out flexing of the hull is “oilcanning” (in Royalex canoes, this is most obvious when high-centering on submerged logs, but if you look closely you can see it happen as you apply weight to the boat or bounce your weight up and down a bit) and any distortion of a plastic boat is a “dent” or “warpage”.

dent or whatever…
you all may want to call it. I’ve been absorbing all this info on oil canning this week and lo and behold- went out to car top my boat today and, yikes, there was a big dent just a bit forward of the seat. Luckily,after I got to the lake, it popped right out when I pushed on it with my hands before entering the boat. Mine came from storing it bottom side down on a wood pallet. I thought it would be ok to store like that because the weight seemed to be evenly distributed. Guess not!

Thanks for all the info. At least I knew what was going on, no matter what one chooses to call it.

I’m storing it on it’s side now. Does that sound like a better idea?