That is true, check how your boat is wired. Being an 80's formula, my guess was each ignition had a separate fuse, so two leads going to the two switches. The only place a single hot comes in on my 86 formula is to the fuse block. Do that one and it kills everything controlled by the console to include navigation lights.

Come to think about it, I would find it odd that any twin would not have separately fused ignition leads. One short would kill both motors then. Or are the fuses after the ignition switch or just not fused separately. Got a short in one, don't turn that key on!

Good point to bring up though for future reference. Check your wiring out first!

Brian

Ok, if you look atnthenback of the ignition switch there are many wires and only three positions. Top positions has 1 red wire which I assume is hot, bottom right I have 1 yellow with red line I assume that is going to starter. The bottom left has a bunch of purples going to the gauges.

It makes since to wire the kill switches in on the hot, if I do it to the one going to the gauges that's a cluster as ther is four wires on one side and 5 on the other(fuel gauge).

Can I get by doing just the hot.

Red = 12v
Yellow/Red - Starter
Purple = switched 12V/ignition

You can either do it on the red going into the switch or the purple coming out of the switch. If you do it on the purple coming out of the switch you can still turn the motor over with the ignition turned off, if you pull the lanyard. Say if you wanted to spin the engine over a little bit before it fires to 'pre-lube' the engine.

I wired mine in on the purple side. So it goes switch > lanyard > igntion/gauges/etc.

yes just kill the red wire,,you want to kill everything in the boat just incase you hit shore or rocks so the power still being on wont ignite anything..