wrote:
Hi, I have put some pictures he
www.photobucket.com/
Search for images named "sabina113"
try this URL :-)
http://s45.photobucket.com/albums/f87/sabina113/

I find when I take the yacht out of the water each year I have bubbles
in the paint mainly where things have been welded to the inside of the
hull. The bubbles are filled with salt water which is quite strong and
possibly acidy. When the bubbles are opened there is very clean steel
underneath. It doesn't seemed to have corroded the steet alot. The
zincs last a year ok.
I guess this is some sort of electrosis or stray current erosion but
was hopeing for a second opinion.
Also, if anyone looks at the pictures, have you seen a driveshaft
thrust bearing setup like in the picture. There is a small brass bung
on top where the thrust bearing is. Do you put oil in there?
Thanks
asdex


I'd bet the bubbles actually contain an alkaline fluid. Its possible
that you are over-zinked, which is known to cause problems with the
paint like this.

I may not have the answers, but I do have some questions that ought to
be asked.

Are you in a marina with shorepower?
If so do you leave the boat hooked up and is there an isolation
transformer or galvanic isolator? (It may not be YOUR zincs that are
providing most of your protection!)

What primer was used? Then whats on top of that? Did you follow the
paint's instructions ACCURATELY, especially correct thinners,
over-coating interval, temperature and relative humidity limits?

Have you had the hull shot-blasted back to bright metal and fully
repainted at any time or have you been dealing with patches as you go?

Exactly what have you been doing to fix the patches and are the bubbles
coming back in the same places?

Have you consulted with your paint manufacturer's technical guys?

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
[at]=@, [dash]=- & [dot]=. *Warning* HTML & 32K emails -- NUL:
'Stingo' Albacore #1554 - 15' Early 60's, Uffa Fox designed,
All varnished hot moulded wooden racing dinghy.