Oil Canning

The term “oil canning” is used often here and I realize its the flexing of a thin hull. My yachts exhibit this characteristic and it never concerned me yet I was wondering if the hull depresses when sailing? I figured the contact with the water was distributed evenly and over a large distance, unlike my thumb which pushed in one area, and that the hull doesn’t deflect.


Sit the boat on the table with the weight resting on the keel. Pick it up, slowly. If the Hull/keel joint deforms, you have at least some degree of Coke-canning. Whether you need to do anyting about it, even with your rather large models, is a moot point.

Hope this helps.

If the Hull/keel joint deforms, you have at least some degree of Coke-canning
Thanks, Angus

There never is any flex around the keel, mast(s), chainplates, rudder, or anything where a movement would effect trim, etc. The boat is stiff. But in in large areas of hull…

…is where I can move it with my thumb. Will this deflect under sail or is the pressure dispersed, with the curve of the hull being strong enough to hold it’s shape?


Broadly speaking, you are talkimng about ispersed pressures and there should be no problem. Th expression beer/coke/oil canning originates (so far as I know) with a number of full-size designers (Carter, Peterson, Holland) decided they might go faster if they bolted a lead keewl straight onto a flat-bottomed hull and failed to beef up the structure in the way of the keel and mast. Of course you CAN overload monocoque sructures anywhere you like (see One Australia), but it’s not very common.:zbeer:

I asked this question waaaay back. Read here