It does look like a crack. If it is, you need to pull the boat ASAP and have the valve replaced. If it splits or opens up, the boat will sink or at least fill with water to the gunnels.
Get them all replaced while you are at it.
It does look like a crack. If it is, you need to pull the boat ASAP and have the valve replaced. If it splits or opens up, the boat will sink or at least fill with water to the gunnels.
Get them all replaced while you are at it.