Which Spark Plugs?
 

What are the opinions out there on brand of spark plug? My boat currently has AC plugs in it and I don't know when they were changed last so I would like to switch them out as well as cap and rotor. NGK? What about plug wires? What is the recommended change interval on them? My boat is 1995 Barchetta 182.

Also I read in another post in this forum about water pumps. Does the boat not have a built in temperature alarm if the water temp gets too high? I realize if you waited that long then you would be paddling back to shore(if water pump goes) but just wondering if there is a safety mechanism built in? At any rate, if I don't know the history on the water pump I am guessing everyone here would suggest I change it for preventative maintenance? Boat has about 165hrs and can't really tell if it was ever changed?

I can't remember what brand spark plugs I used, but I do remember a requirement to be marine rated (plug wires also).

Yes, your boat has an alarm if the temperature goes too high, but by that point, you'll be paddling home! The water pump and especially the impeller depend heavily on the type of water your boat is in. Sandy, dirty water will require a replacement every year (for peace of mind). Clean water, they can last years. In fact, the water pump can probably last a really long time. But the impeller should be replaced at least every 3-5 years I'd say.

Impeller
 

Mercruiser says every 100 hours, I agree, the problem with the type of rubber it's made of is it will take on the shape of the the housing, if your boat sits for a while this increases the chances, if your in an evironment where you temperature sees both highs and lows that may be a factor as well. The impeller operates on pressure within the housing, over time the impeller softens and bends and loses pressure, you'll start cavitating and lose your flow. It's 40 bucks at a store or 20 something online. It's great insurance and your engine will love you for it.

Semper Fi