Spark Plugs and Wires?

We purchased our boat last year and it had 130hrs on it. It now has over 300hrs. How often should you change spark plugs and wires? I called a local dealer and he said to change them when you have problems. No problems, leave them alone. Every car I have owned has a certain millage to change plugs and wires. What "problems" would require changing spark plugs?

Wires should be good for a long time. Plugs- pull a few and look at them. If they're pretty clean, but a little brown, they should be fine. If they're really black and nasty looking, change them.

I just changed the spark plugs on my boat but left the wires. My boat has 325hrs. I was told to change the plugs by my dealer at 300hrs.

I change them every 2 - 3 years, which is about every 300hours. It may be a little more than recommended, but it is easy to do and fairly inexpensive and like the fact that it might get me a little more fuel efficiency.

Rough idle and missing can be signs of plug wires going bad. Also if you look at the motor running in the dark, you might see a little electrical storm going on. IMO plug wires in a boat are more subject to deterioration over time, rather than hours on the motor. I just replaced mine on my 1996 model which had developed a slightly rough idle this season.

Depends on how much you use your boat. If you put 25-50 hours a year on it, I would tune it up every other year. I put over 100 hours a year in my boat, so I tuned it up every season.