I have, like many no doubt, been taking advantage of the recent fine weather days, with the prospect of another similar day to follow, to touch up various nasty bits on the boat's superstructure, particularly the roof. In the past couple of years, and in order to try and keep the boat looking its best, I have touched up small areas of paint blemish as and when required. This is something that is done on an ongoing basis to avoid the prospect of one day noticing that the whole boat could do with a re-paint! The paint used on her original finish is Oxford Blue gloss enamel, Oxford Blue matt non-slip, and Azure Blue gloss enamel - all from Craft Master paints. In the past, and probably due to insufficient fine weather two days together, I have just quickly sanded the area to be touched, followed by a quick application of top-coat from the same maker. Several of these areas have now started to 'peel', most likely due to my complete lack of proper surface preparation. The last few days has been spent with a wire brush, varying grades of sandpaper, followed by a proper undercoat - left to dry overnight, then finished by an application of top-coat enamel. The roof now looks much less shabby, and being a matt finish non-slip, has blended in very well.
Narrowboat Hull Maintenance.
I wondered if, when the re-blacking was done, (in bitumen paint on this boat), whether the boatyard actually went to the trouble of undercoating rusty areas in red metal primer before applying the blacking, and if they didn't - could this be the cause of the waterline rust so soon after. Questions at two boatyards, and research in an old Canal Boat magazine this weekend, has now made me aware that, generally, bitumen blacking paint will not adhere to undercoats other than those that possibly might be developed and sold to be used by the brand of paint. If bitumen based blacking is applied in this way, it will simply 'drop off' revealing just the undercoat, within a short time back in the water. This is not the reason we have a rusty waterline, it is just that I found out about this phenomenon before I went to the trouble of undercoating with red oxide on a future hull blacking job, which would have possibly landed me with more problems.
Apparently, it is widely accepted within the trade that, as part of the hull preparation, the hull and waterline should have all loose material removed, before re-coating the bare metal directly with the new paint, allowing an overnight gap before applying a second coat and so on. That method is completely opposite to what is required to properly apply a stable coat of enamel topsides, where undercoats are a requirement.
One local boatyard also suggested that owners of hulls of around 10 years old, should consider grit blasting, before re-painting in whatever type of paint you choose, over clean, bright metal. Sounds expensive!
Being the owner of Blackpool Tower springs to mind!