to me it looks like there is one spot that is a 'bondo' job on the gelcoat. i'd check interior & exterior for damage from an impact. the 'stuff' along the water-line looks like: * staining? if it is, it is likely the mess will come out with the right mix of chemicals and elbow-grease. there was some discussion about 'tannin' staining last year from folks sailing on the east coast's (USA) rivers. - and/or - * some sort of mess caused when the waterline was painted? that water line doesn't look all that straight or professionally done ... no laser level work there ;-0 maybe some sort of paint thinner was used as an attempt to clean up the mess and this left some staining/damage to the gelcoat? worse case is someone did some sanding to fix/clean/prep the hull for painting?! if 'looks' are a long term concern it may be best just to have the entire hull painted. IMO for a '75 one's greatest concern should be integrity of the hull/desks/cabin and the standing/running rigging ... less than 'pristine' gelcoat is to be expected, and can be 'fixed'. dave scobie M15 #288 - SCRED visit Scred's www-site: www.freewebs.com/m15-named-scred Andrei Caldararu <andreic@math.wisc.edu> wrote: Dear members, the boat I am looking at buying (1975 M-17) has a mysterious deposit just above the waterline, see the photo at http://www.math.wisc.edu/~andreic/P6070387.JPG Can anyone guess what it can be? The boat spent most of the last few summers (except for the last one) docked on a fresh water lake in Utah. What is very strange is that the deposit appears to exist only *above* the waterline. Do you think it could be some kind of minerals from the water (e.g., iron, calcium)? How hard would it be to remove such a deposit? Or a mold, that grows on humid gelcoat, but not in the water? Could it have damaged the gelcoat? Despite the fact that the boat has been in storage for the last year and a half, I know from sailing pictures of the former owner that the deposit was there at the end of the last summer when the boat was sailed, two years ago (photo was of the boat in the water, sailing, and one could see the deposit at the bow). Thanks, Andrei.