Conference unifix::sailing

    I can't speak fro the Pettit paint, but I used Micron CSC last year
    and apart from a little slime and a couple of points where weed
    had attached (paint chipped away by hitting "things"?) there was
    no foul growth at all.
    
    As to the merits of quantities of copper?  It's a poison the same
    as tin, and no doubt one day some-one will prove that copper being
    leeched out of small craft antifouling is causing just as much damage
    as TBT ever did.  Of course, the big boys are still using tin ....
    
    I suppose I'm lucky in one way that my boat is small (less poison
    to leech) and I can haul it easily (break-back trailer etc.) so
    I'm actually thinking of NOT putting antifouling on the boat this
    year at all.  Yes, there's still some old layers left, but their
    usefulness is probably nil except that the bottom will scrape clean
    easily.  My contribution to a cleaner environment?  Possibly, and
    every little helps.
    
    Brian

    Haven't given bottom paint much thought. All I know is it prevents
    growth on the hull and you should(must) use bottom paint if you're
    boat will be in the salt water all the time. My hull will be bottom
    painted by the dealer as part of the contract. I'll need to think
    more about re-coating next season.
    
    My question concerns the use of bottom paint on an aluminum boat
    which I'll be using as my dinghy. Isn't the paint for Alum. the
    stuff that was banned recently...and you really shouldn't use this
    type of paint UNLESS you are using it on alum..? I hear that this
    type of paint (the stuff that was banned for use or unavailable)
    is/was the most affective as compared to what is now generally
    available. Can someone shed a little light on this.?
    
    /MArk

I've got to decide on what bottom paint to use this year.  I have been 
using KL-990 in the past but I don't have enough left for this year.

I've sanded the bottom (not bare) and need a paint that will cover/adhere
to what is left.  As you may know, KL-990 is a "soft" paint and I have heard
that not all others will work with it.

Suggestions please.

bc

    
    I am in the same situation.  I just put on the "cheap" Boat U.S. soft
    copper alcoyd(sp) based bottom paint.  I've been in the water about 4 
    weeks now and none of it has floated off yet.  We'll see how it looks
    later in the season.
    
    Regards,
    
    

    Can someone recommend a good or proper bottom prep method prior to
    adding anit fouling?  Last year wwe took all of the old paint off which
    was considerable and started fresh.  Most of it sprayed off with the
    power wash when hauled.  We are repeating the process but do not wish
    to do this yearly.  I do not think we prepped very well ie using a
    solvent or roughing up enough.  Any tips?  We used Horizons 2 and
    probably will again.  
    
    Brian

    My best recommendation would be NOT to use Horizons 2.  I used it last
    season and it was just AWFUL.  It went on more like honey than paint
    and I couldn't get it smooth at all.  I wrote to PETIT and talked to
    their regional sales manager.  Petit is replacing the bottom paint free
    to anyone who used Horizons and called up an complained.  They'll give
    you any other paint in their line as a replacement.  The salesman said
    that they were trying to come up with some other ablative formula, but
    for now they were stuck with Horizons 2.  
    
    As far as the paint wearing off, it shouldn't really be hit with the
    power wash, although most marinas do it as a matter of course.  The
    directions call for washing it down at the end of the season with
    a garden hose since the ablative nature of the paint readily concedes
    to high pressure water.

    Since you are taking it down to the raw bottom, I would agree that now
    is the time to go to a harder finish.  Our botton paint lasts two years
    at least with scrubs only necessary for racing smoothness.  A power
    wash should not trash your bottom and you would then only have to sand
    lightly before adding another coat the next year.
    
    Dave

    Any suggestions on a harder bottom paint?  We have a gallon of Horizons
    2 left over which may be worth while trying to sell back to Petit
    (exchange).  Any recommendation on any of the others in the Petit line?  
    Our needs are skewed towards cruising and we will do not usually scrub 
    the bottom during the season so maximum growth retardation is desireable. 
    Also, are there preparation tips to follow or just read the label?  By
    the way, the Horizons 2 came from a very strong recommendation from
    another person in the yard last Spring.  They were very happy with it
    and the bottom looked great.  Seeing was believing at the time.  
    
    Thanks for the replies.
    
    Brian  

    Brian:
    
    Why put anything new on at all.  Horizons is supposed to be one of the
    multi-year paints.  I'd suggest touching up the spots where the paint
    has worn thin and then wet sanding the older areas lightly with 400
    grit just before launching.  The light sanding should be enough to
    expose fresh toxicant.  Save yourself a few hundred bucks. 
    
    I'm not sure there's much advantage to putting on a hard paint on a
    cruiser.  They're no more effective and they're brutal to remove.  I
    and others have had good success putting on thick bodied bottom paints
    with airless sprayers.  They are designed for latex paints which have
    about the same consistency as bottom paint.  The advantage over a
    roller is that the paint doesn't have a chance to dry prematurly. 
    Unlike a compressor driven spayer, a high volatility reducer is not
    needed.
    
    If Murphy hasn't written a law on bottom paints, I propose the
    following:  All bottom paints lose their toxicity just as the water
    reaches it's maximum temperature.  This usually occurs on or about
    August 1.
    
    - gene
    
    

    Too late.  The bottom is 99& clean again so we are faced with staring
    all over anyway.  I like the idea of the airless sprayer though.  I had
    forgotten you used one.  Do you thin the paint first?  Should the
    gelcoat be wiped with solvent to clean it first?  Should the gel coat
    be hit with sandpaper first to roughen up the surface?  Is priming
    required?  
    
    Brian

    Whoops.  Too late I guess.  Quite an expensive boat bath last fall!
    
    On roughing up the bottom.  The instructions all say to do this.  OK if
    new bottom paint is going on over old bottom paint.  Not such a good
    idea if you're applying over a bare bottom.  The minute scratches just
    invite osmosis.  I'd just wipe the hull down with acetone using clean
    rags or paper towels.  When it's squeeky clean, you're ready to shoot. 
    I haven't had any adhesion problems doing this.
    
    For airless spraying, use a nozzle intended for latex paint (a large
    diameter one) and try using the paint unthinned.  Set the volume
    adjuster for maximum flow.  If, after the flow has been established,
    the paint comes out in globs, add thinner by the teaspoon, mix, and try
    again.  It takes surprisingly little thinner before the paint starts to
    run as it hits the hull.  Remember to wear a respirator, goggles,
    gloves, and old foul weather gear when doing this.  Can get messy. 
    
    Fine line tape works well getting a crisp waterline.   To protect the
    rest of the boat against overspray, tear a pile of newspapers in half. 
    Then make a circuit of the boat leaving 4 peices of masking tape at 2.5
    foot intervals all the way around.  Make a second pass around with the
    newspapers using the pieces of tape to secure them to the hull.  If you
    pull the part that abuts on the fine line tape tight, it won't be
    necessary to tape the bottom or sides of the newspapers.  The spray
    won't get in.  It's a good idea to spray the overhead surfaces first,
    then the vertical ones.  That way there'll be less sputtering as the
    level of paint falls below the siphon tube intake.
    
    have fun
    
    - gene

    If you try spraying Horizon 2, YOU'LL BE SORRY.  Even the widest
    nozzel made won't do much for paint the consistency of cold honey and
    the thinner just separates out, leaving almost no copper in the little
    pools it forms.  If it were anything else, even Red Hand, I'd shut
    up.
    
    The sad voice of experience
    
    

Since the bottom is bare to the gelcoat, you might consider applying
a 'barrier coat' before the bottom paint.  I helped sand elysium's
bottom last year and the owner, NETMAN::CARTER, put a barrier on before 
proceeding.  The rationale was that barrier helps resist blisters which
cost a bundle to repair and while we were 'that close' why not.

Hope this catches you in time if you decide to think about barriers.

Ray.

    I'm in the market for a barrier coat.  What did the NETMAN use?
    
    - gene

    I'm putting a 19' Cape Cod Knockabout into fresh water, in fact, a
    reservoir in New Hampshire.
    
    What Non Toxic paints may I use?
    
    Frank
    

    Many of us who sail in fresh water do not use bottom paint.
    
    My manufacturer (Hutchinson - Com Pac Yacht) recommends a hard bottom
    paint, but of course he would, as he might be the recipeint of
    claims from any blistering.
    
    I assume that the Cape Cod Knockabout is a fibreglass boat, correct?
    
    Marine growth is MUCH less in fresh water - I brush my bottom off
    a couple of times a sesaon.
    
    Blistering is less of a problem in fresh water and less of a problem
    in cold water.
    
    This is my sixth season of sailing without ever having applied bottom
    paint. (or having had any blisters) I must be about at the break even 
    point at having saved the cost (both in $ and labor) w.r.t. a blister
    repair job. And is is one less messy job in the spring.
    
    Bill
    

    Having just been through this fun job, all I can say is that if bottom
    painting is "optional" in your particular situation, then don't even
    think about exercising that option!!

    The barrier coat which Ray and I put on elysium last year is Interlux. 
    I think the part numbers are 2000 and 2001.  A fun to work with, two
    part epoxy.  The containers specify min and max times between coats. 
    Several coats are required to build up the required thinkness of I thin
    12 mils.  I used four coats, which required two gallons for a C+C
    29-fin keel, spade rudder. 
    
    The stuff comes with two cans, one about quart size.  One gallon size. 
    The gallon can is not filled.  The contents of the small can plus the
    contents of the big can equal a gallon.  But you can't use the whole
    gallon at one time.  It has a limited amount of time in which to use it
    after mixing it.
    
    When I started working on elysium last year, I had no intention of
    using a barrier coat.  I was going to remove all of the bottom paint
    for an area of about a foot near the waterline.  The yard apes at the
    marina mentioned several times that as long as I was going that far, I
    should go all the way and do the barrier coat.  I resisted, but....
    
    Just days after I finished the barrier coat application, Practical
    Sailor came out with their test results of blistering, what causes it,
    and what prevents it.  Also, what happens to bottom paint applied over
    barrier coats which may be incompatable.  Their findings seemed to be,
    a barrier coat probably won't hurt, as long as any gelcoat which is
    exposed and abraded in preparation for the barrier coat application is
    properly coated.  They went on to say that some brands of topsides
    enamael applied below the water line are probably equally as effective
    as most of the barrier coats.
    
    Would I do it again?  Ya, probably.  I don't know the propensity for C+C
    hulls to blister.  I keep the boat is Salem Harbor which tends to be
    very warm, conditions which have been said to have a positive
    correlation with blisters.
    
    
    djc
    

re -.? fresh water

I have an O'Day Javelin that I keep in fresh water. I use automotive paste
wax on the bottom. It doesn't reduce the accumulation of slime, but it makes
it easier to remove. I also brush off the bottom once or twice during the
season with a stiff brush. (This is easy if your lake is warm enough to
swim in.) When the boat comes out of the water, clean the bottom with a stiff
brush WHILE THE BOTTOM IS STILL WET. It's much harder to remove the slime after
it's had a chance to dry. 

--RS

re blisters:

Two of three boats I've had in fresh water have had blistering problems. I'm
not sure whether the paste wax helps resist blisters. I believe it should,
because the wax is inherently water repellent. My Javelin got a few small
blisters before I started using the wax. They haven't gotten worse since I
started using the wax.

--RS

    Something I read a while back led me to believe that boats in fresh
    water were possibly more prone to blistering than boats in salt water.
    I don't rememebr the source.  Practical Sailor and Cruising World are
    two potential sources which spring to mind.
    
    Something about salt water being less viscous, not penetrating the gel
    coat as easily as fresh water.
    
    djc
    

    Note .21 is correct. Boats that blister will blister faster in fresh
    water than salt. It is related to the density of the water as stated.
    

RE: .14,

Alan (with help from crew) put 4 thin epoxy barrier coats on TOWARD 
MORNING a couple years ago.  When he gets back, he'll probably have a few 
comments to offer, and can tell you what brand he used.  

RE: fresh vs. salt in osmotic blistering,

Theoretically a boat in fresh water should blister faster.  Density per se 
isn't the reason, but rather the percentage of dissolved solute.  Osmosis
is the transfer of water, molecule by molecule, from a region of lesser
solute concentration to a region of greater, until the concentration of 
solute in each is equalized, at which point osmosis stops.  The region of
greater concentration is the tiny water-filled bubble under your gelcoat;
the region of lesser concentration is the ocean (or lake).  Since that end
point would require an equally high concentration of solutes in the worlds
oceans, it's unlikely to happen (despite Exxon's attempts to help Alaskan
fishermen reduce their osmotic blistering problem by raising the solute
conentration in Price William Sound last year.)  The more common end point
is the bubble growing until it bursts, at which point the concentration is
immediately equalized, and the ocean can start dissolving the resin
directly. 

As water--even a few molecules--finds a little space under the gelcoat to
form the beginning of a little pool, the concentration of solute inside it
is high, practically infinitely higher than fresh water with almost no
dissolved mineral, and plenty higher than salt at 20-25 ppm around NE, and
32-45 ppm in the tropics.  The rate of transfer is somewhat proportional
(maybe not linearly--I don't know) to the difference in concentrations. 
The unfortunate fact is, if there's *any* difference, and there's any
pathway large enough for single molecules to pass through, then osmosis
will occur. 

The only two solutions to the problem are to A) use materials that won't 
dissolve or B) block the pathways of transmission.  "A" isn't practical, 
though some materials are better than others (vinylester vs polyester 
resins, for instance).  Just about everything dissolves to some degree,
and all it takes is the minutest dissolution to set up the osmotic
imbalance.  Also, the need to meet structural requirements is much more
important.  "B" is the best choice; regular paint doesn't work, because as
the vehicle evaporates (another way of describing paint drying) it leaves
microscopic holes all over--perfect for water molecules to pass through. 
(Otherwise, how would paint ever dry completely?) 

The necessary antidote is to use a two-part epoxy system, which catalyzes 
from a liquid to a solid without opening voids.   The other solution is to 
drysail, which removes the water from the outside before it can collect 
under the gelcoat.  Water would rather evaporate into the air through 
those tiny pores than stay within the hull.  

A relatively non-technical description of a rather technical problem, I hope.

J.

    Our debate was ended for us while we weren't looking!  It appears the
    yard took the liberty of painting the bottom for us "while they were at
    it".  I seems alot of stuff got done "while they were at it".  We have no 
    idea what was used and at the price my partner says he doesn't want to 
    know for fear of what the answer might be.  The new paint seems fairly 
    hard and according to the yard should prove to be quite durable from both 
    anti fouling and wear perspectives.  We shall see how it fairs when given 
    the test of time in the water.  As for speaking with Petit, I think we 
    will persue the exchange or return of our remaining Horizons 2 per an 
    earlier suggestion unless of course someone in here would like to buy 
    it.......
    
    Brian       
    

    Well we took advantage of the beautiful weather on Saturday and wet
    sanded our bottom and looked for touch up areas.  The finish is still
    great.  We used heavy duty nylon scouring pads to burnish the paint.
    I was watching others sanding and painting their whole bottoms and
    thanked goodness I escaped that for one more year.  This will be the
    third year on this paint.  By wet sanding we exposed new toxin and are
    hoping it will do the job.
    
    Dave  

    re .18
    
    Having just laid on 4 coats of West system epoxy/barrier coat, I'm
    curious about what Practical Sailor had to say about this with a VC17
    bottom paint combination.  This seems to be the combination of choice
    at Fay's boatyard on Lake Winny.  It is certainly hassle free to apply.
    
    It is an older boat and though there are no blisters, the gel coat was
    brittle and flaky in places.  Seemed like a barrier coat was a prudent
    way to go.  
    
    The barrier additive is some sort of aluminum powder which is mixed
    with the epoxy before application.  The proportions are seemingly quite
    thin, as several coats only give a very light grey tint.  Does anyone
    have experience with the West System as a barrier coating?
    
    						Ron
    
    
    
    

    Does any of you know what bottom paints are allowed or not allowed on
    boats in NH freshwater?
    
    I've just been given a sailboat by my parents, and it needs a new
    coating of bottom paint.
    
    The boat will live the rest of its life on Lake Winnipesaukee.
    
    Any suggestions, or just the name of a paint *known* to be acceptable
    on that lake will be much appreciated.
    
    Thanks.
    
    John H-C

    John,
    
    Many of us do not paint our bottoms on the Lake. I am on Winnipesuakee
    from early May to mid-November. I brush off my bottom a couple of times 
    a season.
    
    If you didn't already have a painted bottom, I would suggest that it is
    not worth the time and trouble. Since yours already has been painted,
    you might want to repaint it, but it is nowhere as necessary as
    in salt water.
    
    Bill
    

    Thanks for the comments, Bill. The boat just came out of the Gulf of
    Mexico after spending three years there. I believe the bottom paint was
    removed with this season's barnacles, but I'm not sure.
    
    I should be seeing the boat for the first time in a looooong time at
    some point this weekend.
    
    John H-C

    Many of on the lake use VC-17m.  This is a teflon based paint that
    doesn't need to be sanded and so forth each year.  Nothing seems to
    grow on it and the only thing we do is clean along the water line.