My advice....
1) Go through every switch and electrical thingy. Make sure everything works right, and feels right. Do this for the trailer lights and B/U interlock if installed too.
2) Even if you are a seasoned boater, make sure the mechanic/captain/whoever takes you through step-by-step any procedures, checks, etc that should be made. You might be suprised what you take for granted. That goes for not only starting and driving but checks and inspections of the trailer as well.
3) Take it through it's paces. If it is for the wife and kids, take them along. Drive it like you normally would with everyone in the boat. Make sure all the gages are operating in thier "normal" ranges. Write these readings down for later.... just in case something doesn't feel right next season, you have something to look back at. Check the grab-handles... are they tight? Open up every nook and cranny. Look for "spare parts", as well as anything that doesn't belong. If it has a bimini, make sure you can set it up and stow it... On the water! Once everything is stowed, and the wife and kids are safely at the dock... Drive it like you stole it! Make sure everything stays secure (I broke my Fire Ext mount this year!).
4) Safety. Make sure you have all the required safety equipment before you shove off. It helps if you have your local reg's in hand. Check over the engine compartment with a flash light. Look for any wires near anything hot. Look for anything rubbing, or that could rub and cause problems in the future. I purchased mine brand new, and found a bundle of wires just "laying" across the intake manifold. The battery wasn't secure (but was dead anyhow), and the cable run near the CC exhaust. I crawled in and just had them keep handing me zip-ties until I was done! Later in the season my shift cable broke because it was rubbing.
It's not all inclusive, butI hope that helps.
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Walt B
"Debt-Charged"Black '07 H210SS6.2L Bravo One turning a 21P HIFive
Wakeboard Tower with Perfect Pass Stargazer version
Missouri River; Kansas City, Mo.