advantages of "rotomolded" material

I’ve seen alot of threads talking about “oil canning” and material warpage. I’m considering a Current Designs Sirocco and am wondering if the rotomolded material negates any of the oil canning or warpage issues. If not, the second boat on my wish list would likely have to be a hurricane tracer which uses the thermoformed deltron material and doesnt have either issue. Anyone have any experience that can offer advise on what the advantage of the rotomolded boats are?

it’s tough and not as expensive as a composite. “oil canning” is an unfortunate term because it doesn’t describe what happens with plastic. If a plastic hulls becomes deformed from heat and point pressure it can be restored to its original shape with heat and pressure. You can’t do that with a metal can. Keep it stored on it’s side and in the shade. J saddles are a good way to transport a plastic sea kayak, especially if you can’t get a wide bar placement.

Oil cans used to distort indeed
you tapped them with a spout and inverted the can over the crank case. the oil would flow down create a vacuum, and the sides of the can would dimple in, then when the vacuum got too intense the oil flow would reduce, air would flow into the can, and you heard a bwoop bwoop bwoop sound as the can sides flexed their way through this process.


– Last Updated: Jul-09-06 10:00 PM EST –

Never mind.

don’t say 'never’
Blow molded kayaks like Prijon are made from a stiffer plastic but…they still dent.

been there, done that.


cd storm
my CD Storm has the same defect (oil-canning/dent)

My fix is simple but perfect.

Follow along:

1X4X6" on top of said defect

1X2X14" across thigh braces

turnbuckle between the two pieces of wood

crank turnbuckle till dent(defect) is removed.

I store the Storm this way and when I remove the support the dent(defect) stays away all the while I am paddling. However if I am lazy and don’t put the support back after paddling, the dent(defect) reappears. So I just keep the support there and the boat is fine.

Side note: I have measured the Storm’s speed both with the dent(defect) in place and without the dent and there is ZERO performance differance…ZERO…

2nd side note: the whole process takes a grand total of 20-25 seconds to install the support…so anyone wanting a CD with the oil-canning should not fret too much-it’s really not a big deal…

almost every polyethylene kayak is rotomolded. There’s nothing unique about CD’s material.

I had better luck against oil canning

by transporting my Storm upside down.

Oil canning is annoying, more than
anything else. If it doesn’t bother you, and you are not racing, then it’s no big deal. If it bothers your psyche, then it is a big deal.

Warpage is a big and bulging big deal, and if you walk around a mooring area where canoes and kayaks are stored bottom up for the paddling season, you’ll see a great deal of warpage. The warped are all some type of plastic composite. Granted, they are not the upper echelon of paddling craft, but that tells us something about plastic and warpage.

This does not mean that any specific model will warp, as exposure, abuse, and storage factors all contribute.

Fiberglass is still a great material for paddling craft, except for rock bashing. Had to throw that in. Happy paddling!


– Last Updated: Jul-10-06 2:06 PM EST –

We had a surpisingly big discussion about what constitutes oil-canning about a year or so ago.

The term "oil-canning" is directly tracable to the functioning of old-style oil cans used for lubricating machinery, NOT those one-quart automotive oil cans. Old-time oil cans were cylindrical or semi-cylindrical, and had a recessed convex base. You squirted oil out the spout by tipping the can and depressing and releasing that "bulge" on the bottom of the can using pressure applied by your thumb. Each "pop" of the base created a sudden spurt of oil out the spout. The term oil-canning has thus been applied to any bending motion that suddenly goes "pop", in or out, of the sides of a metal container ever since (and yes, this term would and does apply to the flexing of the metal bottom of those old one-quart oil cans as they were drained, unvented and inverted), and this was the standard meaning of the term decades before the first thin-walled composite boat or flexible plastic boat was ever made.

In the last discussion about this, quite a few folks here made the point that a very flexible in-out motion of a hull is "oil-canning", while permanent distortion, or at least any relatively non-reversible bending of a plastic hull due to heat or pressure is simply warpage.

Many have multi-chined hulls which stop the flex, not familiar with the models you listed.

“Oil canning” can be a good thing in the shallows. Bounce off & slide over rocks, leave it laying behind the shed when not in use… Buy another when it wears out, they’re cheap.

Those are the advantanges of rotomold in my case.

A friend of mine
has a Sirocco. I have a Tracer. Sirocco is 70#. Tracer is 47#. Sirocco can store more stuff which is good if you overnite. They both handle about the same in the water. Tracer handles better on land . . . easyer to carry. Oil canning is a fact of life with rotomolded boats but it is no big deal. Because of the weight I chose the tracer.

Resistance to denting/warping is not one of them. But there are things you can do to avoid or minimize denting. Like don’t leave a loaded boat sitting on land with a rock(s) protruding under the midsection–guaranteed denting. Use cradles. Don’t overtighten tiedown straps.

Flexing (oil canning?) while bouncing against rocks/logs in the water IS an advantage. Or at least preferable to breaking.

Main advantages are toughness for low maintenance, and lower price than composites. When there’s ice, you can gaily smash through the thin stuff to make great tinkling sounds. If a big chunk bumps you, you won’t cringe.

I Prefer Plastic
I have fiberglass and kevlar boats, but I prefer plastic. I rack 2-3 boats almost every weekend in summer, and can be less than careful about it, especially after a long weekend on the water. The plastic boats take more abuse.

I have a brand new Sirocco and I am sure it doesn’t weigh 70#. I think it is closer to 60. I find it much easier to carry on my shoulder than my nearly 3-foot shorter Zoar Sport.

I transported mine on foamies with straps and tie-downs on the bow and stern for 8 hours from Minnesota to Upper Michigan and had NO evidence of denting of the hull. Just snug it up; don’t overtighten. By the way, the Sirocco is a sweet boat to paddle!!