On 29 Dec 2009, at 10:24, Mr Pengalanty wrote: > I am thinking of a 2-pack system up to and including the gunwales, > cut off point being the bottom of cabin sides - then a matching > finish coat from the cabin sides down to the fist strake, over the 2- > pack system. I believe that single pack can be applied over 2-pack > but not the other way around. > > Your assessment of what you are going to do is of interest to me too > - Let me know please - in due cours ?
Alan, Here is a recent summary text following an off list exchange involving a couple of other former "canals-list stalwarts". I've taken to dealing with serious (and semi-serious) boating topics "off-list" because of recent events, topic creep and general disaffectation with proceedings hereabouts. START >> The product I am looking at is Sigma Cover 300 and it is a 2 pack. I believe it starts off as "eggshell" black and usually weathers to a floury grey. The hull will be sandblasted from gunwale to baseplate. UM has a rubbing strake all around - about 9 inches down from the gunwale. So my plan is to overpaint the Sigma 2 pack in this area, including this upper strake, with matt black paint, probably going up over the sanded gunwales which are currently gloss black. There is a warning in the Sigma tech spec along the lines "When over coated with other paints "tar bleed" will occur" but that doesn't seem to be a problem with what I am proposing. I assume the solvent in the overcoat tends to dissolve some of the bitumen from the 2 pack. So spots or blotches are a possibility. The reason for the matt black overpainting is to enable easier touch up of those contact areas. I do wonder if the immaculate Beeky touched up matt black over the powdering grey 2 pack will look fussy over time. One chum says it works for them, except they are touching up with gloss or satin black and wish they weren't ! I'll no doubt run the matt black around the rising bow line over more than just the top strake - so as to get a line parallel-ish with the water. The objective of all this is to 1) get rid of any mill scale still on the steel, which I am sure has prevented the bitumen sticking nicely 2) have a good 2 pack coverage around and under the water 3) have an easy repair finish on the rubbing/contact surfaces I wonder . . . should I blast and 2 pack the base plate while I'm about it ? Not easy I know, and quite an expensive option ! <<END The topic of anodes is another one full of disparate theories. We replaced our 4 anodes after about 5 years. They weren't completely shot but were part consumed. The cost compared with assumed benefit seemed worthwhile, while the boat was in dry dock. Some folk advocate many more anodes (and these are not anode salesmen) and quote such folklore as "anodes only work if they can see each other". Beeky
