87 2001 plug Wires

Had my boat out in the water for the first time a two weeks ago ( we are a travel baseball family and all weekends are tied up traveling for that) and it wouldn't start for the first time in 15 years. I hadn't changed the plugs for about 8 years so thought I should do that (it has always ran great so why change them). Got the OEM recommended plugs from AutoZone and installed them. Got the boat running, but it is missing on a cylinder. Had a car mechanic go out for a ride and he diagnosed it as being a spark plug, or plug wire problem by removing the wire from the distributor while running.to the number one plug. When we unplugged that one there was no change in the engine performance or sound, where as when the others were unplugged you lost power and it sounded worse. I went to AutoZone to get new plug wires but they don't carry a wire that has the same boot size on the distributor side. Any ideas where I can get OEM plug wires from?

Thanks for the advice. AutoZone carried the OEM caled for plugs and is 5 minutes away. I think it's the only time I have had any luck buying anything for the Nautique at a car parts place. When I first got my boat in 2000 it was over heating (got the seller to knock off $1000 bucks cause they couldn't figure it out after attempting to put new two new thermostats in), found out after trying car parts store thermostats and getting the same over heating issues, I learnt through this forum that you have to run OEM thermostats and nothing else.. bingo problem solved.

How bout swap the wires around and see if the no spark follows?

Rod,
Chris is correct that the set isn't marine. Due to getting around the exhaust manifolds, it's the wire lengths that are different but he solved that too.