Loose exhaust flappers will not be a cause for water inside the boat. They keep the water from being forced into the engine.
You can run the heck out of your bilge pump and not drain the battery. Any chance the water is coming in through your cover?
CUSTOM WHEEL & TIRE PACKAGES
$125 LED LIGHT PACKAGE - FREE SHIPPING
REBUILDING HOLLEY MARINE CARBURETORS - $249 DELIVERED
REBUILT COMPLETE MARINE HOLLEY 4160 CARBS - $425 DELIVERED
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