I am pretty new to this stuff. I just acquired a used Wenonah Southfork. It has some warping in the bottom (like a section of the bottom sunk while it was stored upside down). I'm wondering if this will significantly affect performance or if it shouldn't be a problem. Also wondering if it is worth trying to fix and how i would do that. Thanks

It sounds like you are describing hog-backing. Generally, there is little to be done about it, but you can try things like gentle heat while set in the correct position. Do you have some photos? That will go a long way toward diagnosis/prognosis.

Sure here is a picture. Primarily, I'm wondering if it affects performance or anything like that.

As Tryin noted this hull is hog backed. The canoe is still functional but just not as efficient when paddled through the water. Not sure if this can be fixed. We have several poly Old Town Discovery canoes at the nature center where I volunteer with the same issue and we just live with it. If you happen to find a possible fix please let us know.

The only fix I have had any success with is supporting the canoe upright with weight applied to the affected area and then heating it with hot water, solar cycles, or VERY gentle use of a heat gun. I have had minor success with this method using direct summer sun exposure for a week.

Be careful not to use too much weight, think about it moving a little every time and not all at once. Also pay attention to your support structure: more is better, too little and you will just end up with new creases.

In the world of whitewater kayaks we call this oil canning. Since the canoe you have is polyethylene, there are a few tricks. Polyethylene is a thermoplastic. It was made by mixing the component resins in the mold and the final chemical reactions and bonds were formed in the mold. What this means for us is that the plastic has a memory. If we give it the right conditions it will tend to go back to it's molded shape.
Too much heat will melt a hole in it, so no torches are bad and even a heat gun is iffy. If the plastic is too hot to touch, you are at risk of ruining it

There are two main methods that are safe and fairly reliable.

The first, and easiest is to get the canoe out in the sun on a hot day, hull up so the sunlight does the warming. Prop some logs or milk crates under it so the dented spots are being pushed up, you should have the milk crates support the full weight of the canoe. Let it be like this for a few days in full sun.

The other method is to support the canoe hull down but not on the ground. Make sure the dent is the low point. You don't want it up high on saw horses, just on a couple of logs, but make sure it's very stable. Don't support it near the dent, you want that to be able to go back down. Heat up a big kettle of boiling water and dump it in. (I have used a turkey fryer). Adjust the position of the boat to make sure the hot water is over the dent. Put a few bricks or cinder blocks on the center of the dent to push it down. You need the full dented area plus a bit of the surrounding are to get hot and stay that way for a while. Let it be until the water cools on it's own.

I've heard of people putting a kayak on sawhorses like this and setting an electric heater under it too, just don't let the plastic get too hot to touch. It needs to stay like this for a good bit of time.

I prefer the sunlight method, and I have used a hair dryer to help. As I noted earlier, I'm gunshy of a real heat gun, but a hair dryer shouldn't melt the plastic. The big goal is to use heat, pressure, and time to let the plastic go back to it's original shape. Don't rush it.

Listen to davemcgov. First of all, he knows to call it oil canning. :-)

The rest of his advice is spot on and matches what I spent a fair amount of time in a past life explaining to the semi-unhappy purchasers of such boats each spring. In between rasslin’ the inventory around out in the boatyard to prevent it (mostly) from happening to the new boats offered for sale.

Signed,
A guy with way too many Pungos on his conscience