The Gel Coat is Off

South winds have been rare as hens teeth this spring. They were blowing this morning so we got some time on Nellie. Phil had moved the stands and blocks giving us access to the only unfinished areas. After today's work there's just a little bit left around the through hulls to finish.

Among other things the picture shows the boot stripe and the black bottom paint below it. While the hull was being laid up it's pretty clear that the gel coat was applied at several different times because the barrier coat is below the gel coat in the lower part of this photo, and on top of the gel coat in the middle of the photo. Perhaps the white, below-the-waterline gel coat was put on first--but only to just above the waterline.  Then the barrier coat was applied over the gel coat and stopped just a little farther up the hull than where the gel coat stopped.  Finally, gel coat was sprayed the rest of the way up the bulwark.  The straight line of gel coat in the picture shows that they taped off the lower part of the hull before spraying gel coat on the bulwark.

Complete Rough Sanding ... Check!

Another 1:20 hours today and all, we'll almost all, the gel coat is off. Asked Phil to move the stands and blocking so we can get the surfaces under them too. Still need to clean up around thruhulls too.

Dark and oozing blisters are very easy to spot on the sanded fiberglass hull. It's a simple matter to dig out the blister with the 24 grit paper we're using to sand the bottom.

As evidenced by the pictures below it seems seawater is penetrating voids in the shoe and working its way to the iorn ballast.

About a week after sanding the show, rust colored water stains it.

An hour after sanding the stain off, drops of clear water appear.

Grinding, grinding, grinding...

Another two hours grinding on the bottom.  Looks like just one more day grinding and we'll be on to the 'fill and fair' stage.

Bicki Feeling her oats ;-)

Starboard Side Completely Sanded? Check!

There's some progress to report.  After 2:20 grinding on the hull today we finished the rough sanding on the starboard side.  Yahoo!  

Clean starboard side bottom!

It feels good to make progress.

With the end of grinding in sight it's time to start nailing down the products and processes we'll use to barrier coat the bottom  Here's a page doing just that...

A sample piece of the gel coat off the bottom mic's in at .027"

The Grind Continues

Hours on end of grinding gives one plenty of time to consider the layers, one, by one, by one as the angle grinder slowly cuts through them.  The picture below shows: black bottom paint; red bottom paint; white gel coat; the gray is an epoxy barrier coat put on at the yard; and finally the raw fiberglass which is tan.  If all the bottom was as well stuck together as the layers in this picture, grinding would be unnecessary. But...

...as the picture below vividly shows, all the layers aren't sticking together.  In fact, in this picture there's a noticeable gap between the fiberglass and the layers above it.   Interestingly, it isn't the gel coat that's peeling, it's the epoxy barrier coat beneath it!  Perhaps during hull layup the yard let the epoxy set too long before applying the glass over the barrier coat.  Whatever was done wrong, it wasn't totally wrong--because at least half the gel coat is well bonded.

No explanation needed for the picture below, except to say this was taken after only 1:20 of grinding.

Another Day on the Bottom

Some people go to gyms...

We lasted 1:40 grinding on the bottom today.  For the first time we covered ourselves in corn starch, the idea being that it fills the pours so the fiberglass can't.  It really does work.

Corn startch to the resuce!

We're both less itchy after showering.  The 16 grit paper cut right through the bottom paint, gel coat and barrier coat, but it's so coarse it misses as much as it takes off.

We've both gotten good at recognizing blisters in the fiberglass: they're usually a little darker than the surrounding glass; the fibers in the glass are more pronounced--as though the resin had been washed away; and some ooze liquid after being disturbed.  The fix is simple enough, run the edge of the sand paper across the entire blister until the glass is the same color and consistency as the surrounding glass.  None of the blisters have been over 1/8" deep and most are 1/16" or less.  At least 2/3 of the starboard side and 1/2 of the port side is now done.

The Bottom Job Begins

Decided against planing the bottom. I didn't like the idea of pulling good glass off just to remove the gel coat. So, today Bicki and I started grinding the gel coat off. It's a dirty, tiring job. The best tool we've got is persistence. The second best tool is a 7", fiber-backed, 36 grit sanding disk mounted to an 11,000 rpm 4-1/2" angle grinder. Getting through the old bottom paint is almost as bad as removing the gel coat. It's time to switch to ablative paint. Phil Jones (P.L. Jones Boatyard, Hooper Island, MD) recommended an epoxy primer followed by an epoxy filler for the areas where the gel coat has peeled into the bootstripe. Phil also said to leave scratches in the bottom's fiberglass, it'll help the Interlux 2000 grab. Here's some good news, I haven't found a single blister.

The prop had some dings on the end of the blades. Used a 6lb hammer as a bucking bar and with a 2lb hammer hit the prop. They did an amazingly good job. I can't tell at all where the damage was.