1997 Bayliner ciera 2855 ST Sunbridge has quite a bit of fuel in bilge area near the engine. We filled the tank earlier in the day and did some boating. We docked the boat and there was no gas leak at that time. About 6 hours later when we checked the boat we could smell gas. On examination we found gas in bilge area . How do I determine the cause of leak and how do I verify a leaky tank ? What procedure do I use to replace tank and can I have a replacement tank built. My problem is that we are in a small European country. The closest Bayliner dealer is 500 miles away and the have no service or no parts. I am trying to determine the best way to proceed. We pumped out most of the gas (about 300 liters) and cleaned the boat. We left in about 30 liters and there does not seem to be a leak. Help!!

300 liters is a lot of gas to leak out . If you can get a visual of the tank you will se it dripping. If no drips appear examine gas lines the lead from tank to enine.also check tank breathrs as gas expands when temperature rises. Short of that your float valve in carberator is stuck and pissing gas into cylingers which will drain to oil pan. Chek oil for gas contamination.