[Public-list] Bottom Job

Thu Jan 20 10:26:50 PST 2005

I did a bit of research on this for a few years before deciding to do this
to Infinity #57.
She had developed small blisters or actually surface blisters on the
gelcoat.  Most popped over the time she was out of the water.
In the meantime I had researched the idea of barrier coating & had found
out a few things.
1. Infinity had been barrier coated back in the late 70s or early 80s with
a product that had not lasted.
2. Barrier coats last approximately 10 years. Period!
3. If you want to further prevent blistering take your boat out of the
water annually.

Now I have no idea about this extra level of effort that George is talking
about but I will say this about Infinity's bottom job last year:
Took off years of paint with 23 grit random orbit sander - took 2 months
of 2 day weekends.
Tried 2 techniques for filling blisters instead of doing a peel:
1. coat whole section with epoxy & microballoons-left too may bubbles not
effective.
2. Fill & fair with trowel - much more effective but took longer to fill.
Took less time to sand fair.
Following filling & cure time I faired the hull to 100 grit with random
orbit sander. Then roll & tipped on 6 coats of Interlux Barrier coat
product. Faired this to 100 grit then rolled & tipped 2 coats of
Baltoplate (racing finish) & burnished this first to 300 then to 600 grit.
Nice fast bottom.

As for future blisters -- 10 years I hope!
-- 
C.B. Currier
cbcurrier at spinrx.com
Spin RX
410-990-9855
P.O. Box 5758
Annapolis, MD 21403

George Dinwiddie said:
> I'll second that opinion.  I've known of a couple A30's that had more
> problems after barrier coating than before.  In general, A30's don't
> blister much.  My theory is that the gelcoat is so porous that the
> hydrolyzed resin byproducts pass back out through the gelcoat without
> lifting it.  Also, keeping the bilge dry seems to correlate with lack of
> blistering problems.
>
> In any event, for a small area, I would just grind and fill those
> blisters.  I've never known of an A30 to have blisters to the point of
> threatening the integrity of the hull.
>
> If you do decide to barrier coat, you'll need to really dry out the
> boat, much more than just a winter on the hard.  Maybe a winter of
> vacuum drying or a year of covered storage.  Maybe more.  And I'd
> suggest that you barrier coat the bilge, too, as I think that water
> penetrates just as much from the inside if you let it accumulate in the
> bilge.
>
> I recommend the Drip Less packing described on
> http://www.alberg30.org/maintenance/MechanicalPropulsion/StuffingBox/ so
> that you don't need to let the stuffing box drip.  Store your charts in
> the bilge.
>
>   - George
>
> John Irving wrote:
>> I've been considering an epoxy coat "bottom job" as well because I'll
>> be replacing bottom paint in the next year or so.
>>
>> I got an opinion from a trusted boatbuilder who advised against epoxy
>> barrier coating unless the owner is already making significant blister
>> repairs. He felt that problems can be created by sealing moisture *in*
>> the laminate and blocking its avenue of migration out. He was aware of
>> instances where epoxy coating a hull as a preventative measure
>> actually caused blistering where none existed before.
>>
>> I'd appreciated hearing about the experiences listees have had with
>> epoxy barrier coating.
>>
>> John #284
>>
>> On Thu, 20 Jan 2005 08:41:10 -0800 (PST), Michael Connolly
>> <crufone at sbcglobal.net> wrote:
>>
>>>Roger,
>>>Gougeon Brothers, Inc. publish several booklets that detail procedures
>>> for fiberglass repairs.  One is specific to Gelcoat Blisters.  When I
>>> did a bottom job I found that the Technical folks at Interlux were
>>> superb.  Since you are doing the full Monty I would strongly recommend
>>> applying an epoxy barrier coat of your choice.  I used Interlux products
>>> exclusively and have been very pleased with the results.   Oh yeah..  be
>>> sure to visit Popeyes web site to purchase the final top coat.
>>>Michael
>>>
>>>Roger L Kingsland <rkingsland101 at ksba.com> wrote:
>>>Albergers,
>>>
>>>In asking about "careening ship," I forgot to ask the more important
>>> question. How do I do a bottom job? The deck and topsides are ready for
>>> paint. I have gotten down to the gel coat a few inches below the boot
>>> stripe and discovered a total of about one square foot of blisters. I
>>> don't know if this means I should expect more or the hull is in good
>>> shape. Is it customary to sand blast everything then refinish the hull
>>> or should I take less drastic measures? It was quite a chore getting the
>>> few inches of bottom paint off in the area of the waterline. I used
>>> several coats of stripper and still had to do allot of sanding. I would
>>> appreciate any suggestions, particularly "how to" reference material.
>>>
>>>Thanks
>>>
>>>Roger 148
> --
>   ----------------------------------------------------------------------
>    When I remember bygone days                         George Dinwiddie
>    I think how evening follows morn;            gdinwiddie at alberg30.org
>    So many I loved were not yet dead,           http://www.Alberg30.org
>    So many I love were not yet born.
>                                              'The Middle' by Ogden Nash
>   ----------------------------------------------------------------------
>
>
>
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