Does anyone have any advise for me. I purchased my father-in-law's boat after sitting in his garage for3 years. I had the fuel polished (cleaned) along with fuel tank cleaned. Bought new batteries, connected water hose to hose intake and started engine. No problems. It's running great. Launched boat for first time and within 5 minutes of running engine, siren sounds to warn for overheating. Let it cool down (about 20 mins), started engine and siren sounds again within 2 minutes. I took it home and it ran for 20 minutes without a problem. I disconnected all hoses and ran water in both directions to check for clogged hoses or obstructions and I didn't find any. I'm guessing that it's a cooling intake problem but that's as much as I can deduct. Engine is an OMC 115 TurboJet drive. Any ideas or solutions?