: Say I have a boat varnished with Detco Crystal and it's time for a new coat
: ... can I sand it a little and lay on a coat of Captain's or Flagship
: without having compatibility problems between the two products? Aren't oil
: based marine varnishes compatible with each other?

: Thanks!

: Ken

On some of my first boats, I used a varnish the was not compatible with my epoxy. Who knew!
There was no mention about possible problems in any of the research I had done. The varnish
never totally cured. They way you know, is that your sandpaper will clog up very quickly, even
wet sandpaper. This varnish never cured properly and cloged sandpaper even after years on the boat.

The compatibility issues aren't as much of a problem between finishes as between epoxy
and finishes. It is very likely you won't have any problems, especially with an old finish that
has totally cured, unless it was incompatible with the epoxy in the first place.

I have now refinished several boats I built and finished using a water based finish. One of the
problems I had with the water based finish was that it dried so quickly I brush strokes all over the surface.
In preparing the surface on this boats I did a quick sanding with 150 grit to remove the brush strokes, then
used 220 wet paper over the surface. Then I varnished with Captain's varnish. This has worked very well.

To insure you won't have problems with your new over old varish, do a test on a section on your hull bottom.
If your old finish is smooth and without brush strokes sand with 220 wet paper then varnish. If you have brush
strokes start with 150 on a ROS, then go to 220 wet paper.

Wait a few days and sand the new varnish with 220 wet sandpaper. If the paper don't clog you should be fine.

All the best,
Rob Macks
Laughing Loon CC&K
www.laughingloon.com