Sulfer smell in the boat?

So has anyone ever noticed a sulfer/rotten egg smell in their boat? I have been noticing it the last few times we have used the boat and it was really noticable last night. I have had it before in my old boat and finally tracked it down to one of the batteries going bad. So when i noticed it recently i figured it was the battery but there is no smell at all coming from the battery compartment and absolutely no corrosion. I can smell it when i take the cover off after towing and even when we are out cruising in the boat. After getting home from the lake last night i pulled off the cover and it was really strong until it aired out. I searched everywherre (sniffed actually) and could not find the source. I decided to open the engine cover and remove the storage tray on top and it seemed like there was a stronger sent there. My engine is spottles and no water at all. I can't think of what might be causing the smell in the engine compartment. Any thoughts??????

Bad cats can cause a sulfur smell sometimes. But its in the exhaust stream typically not the engine bay.

Are you sure it's not a battery? If it's doing it after just sitting there under the cover not running, I would say it has to be a battery gassing. Unless you had a bird lay an egg in there somewhere!

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I thought it would be the battery for sure since i had this exact thing happen several years ago and it was the battery. But for the life of me i can't get a wiff of the sulfer smell when i lift of the seat. I guess it is still possible and will probably have to have the batteries checked. They are just less than 2 yrs old so i wouldn't think it is that but who knows. I leave the cover off when it is in the garage and i don't get any smell just sitting in the garage with the cover off. It has been most noticible when the cover is on and i have driven to the lake or come home and then opened the cover. I have a snap cover that does not cover the air intakes in front of the windshild. I kind of wonder if while towing the air comes in from the air intakes and then goes down into the hull and into the engine bay. Thus pushing out the odor. Just a theory.

Could possibly be trapped exhaust from your tow vehicle and a bad catalyst, turbo wastegate??? ( don’t know whether you tow gas or diesel) that only sulfurs under load. You wouldn’t notice it at idle, but could be leaving a cloud of HS2 down the road.


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