I was installing new speakers in my 2005 sporster and I noticed what looks like a large nut in the bilge. I bought this boat towards the end of the season last year and only got to put the boat in the water a handful of times. Seems like a large nut that was missed replacing. the bilge is always oily and I wonder if this is related. Any pointers on what this might be and where I should look would be greatly appreciated.