My boat is taking on some water...
 

Went out yesterday and before I even left the dock I noticed a small water spot just below the throttle. Thought nothing of it. As the day continues the water spot expands and as I'm driving actually forms a puddle against my driver's seat. Also noticed it coming from under my sub a little bit. It was nothing too concerning, but I don't really like water in my boat unless I planned for it. The spot never really grew more than the area just around my seat, but it was enough to splash if I stomped down. Any ideas?

Maybe the pitot tube for the speedometer? If you weren't moving prior to the water coming in then I guess it would have to be something else.

If you have a heater, the core might be toast....

Would the heater still work if the core was leaking? my kids were using heater most of day. So I assume if I need to check heater core, I should remove the sub box, then look for leaks at the heater? prob need to do while on the water?

Yeah, the heater could still be somewhat effective if the leak was small. Usually they develop pin holes. You could have it welded up at a radiator shop but it can be cheaper and easier to buy a core from an auto parts store. If it's a Heatercraft heater then they use one from some Ford if I remember correctly. Search a little bit and you should be able to find the vehicle year and model needed to lookup the correct part.

This symptom is almost always a broken/pierced heater core. Unless you really need the heater, just rip it out and put in a $1.50 double hose barb nipple between the 2 hoses.

So does your boat have a paddlewheel or pitot tubes for the speedos?

Is the water your splashing around in by your seat warm? Or cold?

That is my guess.....

paddlewheel i believe

water felt a little warm. I will check the heater core