Osmotic blistering

[Bob Noodat]

I was reading a description today of a 1979 A25 that had a recent survey which described its condition as good, but stated that the hull had a high moisture content and signs of osmotic blistering. This boat has been mooored in freshwater for a long time, and only recently hauled out. How serious a problem would that be? I don't recall reading before about Albin hulls blistering or sucking up moisture.

[dkirsop]

The A25 is usually not known to blister but if a previous owner was overly aggressive in sanding the hull before applying anti-fouling then all bets are off.

[nebulatech]

The hull on the A25 isn't that thick either. I don't have any thru hulls out at the moment, but 3/8" I think is about right. Take that back, in a few days I'll remove the exhaust thru hull to glass it in. I'll measure it. Anyway, the point is, there aren't a whole lot of layers. I made a backing block about that thick with 10 layers of glass. My resin to glass ratio was higher that it should be, so maybe there's 12 layers in the A25. If the hull is blistering, the problem doesn't have to be too pervasive to be serious.

I wonder where the blistering is? Like, like is it in the keel, where grounding may have removed the gel coat? If it was limited to the keel, that's not too bad. If there's a good working engine in the boat, that might not be a deal killer if the boat was on a trailer and VERY cheap.

EDIT: I have to say, the title of this thread took me for a loop. One of the reasons I got my boat was because of the reputation of no blisters.

[Plum76]

I just removed some abandoned thru hull transducers, would agree with this assessment, the thickest I saw was on the order of 10mm (which rings a bell from the original literature I think?). I'm patching back with fiberglass and will try out my gelcoat skills, as it'll get covered with anti-foul as well.

My boat came to me without any additional anti-fouling on it, and has no signs of blistering. The gelcoat is/was intact and it lived on a trailer mostly, but all I've done is a scuff job, a couple coats of anti-foul and it was fine for ~4 months on the mooring with no adverse spots showing up.

JP

The hull on the A25 isn't that thick either. I don't have any thru hulls out at the moment, but 3/8" I think is about right. Take that back, in a few days I'll remove the exhaust thru hull to glass it in. I'll measure it. Anyway, the point is, there aren't a whole lot of layers. I made a backing block about that thick with 10 layers of glass. My resin to glass ratio was higher that it should be, so maybe there's 12 layers in the A25. If the hull is blistering, the problem doesn't have to be too pervasive to be serious.

I wonder where the blistering is? Like, like is it in the keel, where grounding may have removed the gel coat? If it was limited to the keel, that's not too bad. If there's a good working engine in the boat, that might not be a deal killer if the boat was on a trailer and VERY cheap.

EDIT: I have to say, the title of this thread took me for a loop. One of the reasons I got my boat was because of the reputation of no blisters.

[Bob Noodat]

The boat is in England, and has been in full freshwater for "many years". It is said to have its gel coat intact still, but the hull looks very matte in pictures. Blistering is described as mainly small with a few larger areas. Interesting that the broker, accustomed to seeing these river-kept boats, reckons the moisture and blistering is not a concern ("as expected" he writes), but needs addressing. The boat has no trailer (very unusual to have a trailer for a boat this size in UK), has an MD17C, and IMHO is not cheap at £12,500 or US$16k.

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I only posted this because I also was surprised to see an A25 with osmotic problems. I guess the lesson is, pay more attention to your hull if your boat is permanently in freshwater. Ours is, and it lends a false sense of security where you feel that without the marine fouling or the severe anodic problems that there is little need to think of hull condition and maintenance.

You can find the listing at thamesbrokerage.co.uk