Last summer I blew a head gasket on a used boat I recently purchased. The previous owner said the motor had been recently rebuilt. When we removed the blown gasket we found that an area just outside the cylinder sleeve about 1/4" deep and 1/2" wide of the aluminum was eroded. The cylinder sleeve did not appear damaged but it looked like the hot gasses that leaked past the gasket had just eaten away the aluminum surrounding the sleeve. We were in the middle of nowhere so we just installed a new gasket and the compression was fine. I finished out the week of fishing and the boat was only out twice more last year. Is this something that should/can be repaired? Or should I just keep a spare head gasket handy?