Obliterating old graphics
Most tape-type adhesives will come off with a generous washing with mineral spirits (paint thinner) or acetone. Gummy masking tape and vinyl stick-on letters are easily rubbed off– unless they are dried and stiff. Then it gets nasty.Finished fibreglass is notoriously durable stuff– forget the chemistry, because in practice it will take plenty of chemical abuse. Beyond acetone comes stuff like methalene choride which is used as a dewaxer after pulling the hull from the mould. This will get a lot of gnarly stuff off. The nastiest of all these noted carcinogens is methyl-ethyl-ketone (MEK), which is the solvent for uncured fibreglass resin. Naturally these will destroy any polished finish you have on the hull, but if the residue from the tape or letters has become part of the hull then this is what you have to do.Also, beware of using this kind of stuff casually. NEVER mix these things– if you can even buy them in the same store, don't use one, give up on it, and directly apply another. And of course don't get it on you. MEK will melt most common plastic or rubber gloves– you'll need the big black chemical-handling kind and they may end up disposable (see your boatyard about how to do that). Acetone and other chemical solvents appear to dissipate or evaporate quickly– probably half of that 'evaporation' is the chemical soaking into your skin. These things are inert and will never leave your system. Enough build-up in your body will facilitate cancer (as with my late father).However as with acetone-based nail-polish remover a little prudent usage will do little to endanger you. Be careful and use only as much of any solvent as you have to. The EPA will not thank you for having torrents of the stuff run down the keel into the ground or water. Common sense dictates that you use eye protection, wear old clothes or a work apron, and not have any children or other innocents around.If all else fails, or if none of these sound inviting, you will have to sand off the gunk. As with chemicals start light and do only as much as you have to. In both cases polish the surface back up using 400 and 600 wet-and-dry and coat it out as soon as possible with a good fibreglass wax (something stronger than Star-Brite) or buffing compound. Otherwise the newly stripped and porous area will go grey with atmospheric dirt and weather, and that will NOT come out easily.As an aside, I recommend VERY careful, sober forethought in naming a yacht and then, if the ICC will accept your net tonnage, getting the boat federally documented. The boat thus becomes permanently known by the name and there won't be any owner-by-owner removals.JC