Weird noise coming from the back of the boat, need some ideas

[joeycamaro]

'67 18ft Aluminum Starcraft. Fished the last half of the day on the dam, my buddy pulls the last fish in the boat, pulled in real close to the plug. After the fish is in the boat, I hear this sound, like either someone slowly opening a 2 liter pop, or sand pouring against the aluminum at the very back of the boat near the transom. Checked the plug, it was good, and not knowing what it was, we sped back to the dock. At the dock, still could hear it, but very faint, and out of the water it was gone. pulled the plug, bone dry. The battery is back there, and while I thought it may be the battery expelling air, it REALLY seemed like the sound was coming from under the floor. Not sure here, any ideas?

 

[Boat Doctor1]

only thing comes to mind is the Battery!! If charging & !! Overcharging!!?? the battery WILL create gases & will vent them! Thats the hissing sound you hear-likely! Id check the battery for water??and have checked for charging too. might be overcharging?

 

[joeycamaro]

Looking back there, I found nothing by the bilge pump that could cause that sound. I did charge the battery before the trip, I charge it allot which is probably not needed. Also looking at the battery I found a loose positive connection (motor to batt), so you may be correct.

 

[airshot]

Some years back I also had an 18' StarCraft and similar to your story we were fishing one day and begin to hear a sound similar to what you describe....long story short we found that something under the water was bubbling up like air escaping from something down below. We have no idea what it was or where it came from but it caused a sort of hissing sound on the hull of our boat as the bubbles came up and hit the bottom of our boat. Perhaps you were over something that was expelling some air...could you see anything around the hull that looked like bubbles?

 

[oldboat1]

maybe an automatic bilge pump with a stuck float?

 

[Watermann]

Do you have a fuel tank in that area? A battery venting sulphuric gas would have stunk pretty badly as would gas fumes escaping.

Speaking of 2 litre pop bottles, I've seen cheap guys who replaced their boat decking and used those empty bottles for flotation underneath. :lol: