A plug wire may look
good on the outside but may not
still be good on the inside.
Also old insulation may look OK
but it can actually leak and short
out. That can be aggravated by
moisture so your out on the water,
it starts raining, and you cant get you
motor to start. Even at $2.00 a foot
its not something I would consider
not replacing.
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.