Conference unifix::sailing

    The blisters should be opened up now, washed and allowed to sit
    till spring.   If you wait till then to do anything, some of them 
    will be hard to spot.   

    The recommended steps to correcting the problem are to:
    
    1) remove ALL bottom paint.
    2) allow the hull to dry as long as possible (weeks-months). There
       are some moisture measurement systems on the market which will
       tell you when the hull is "dry". I suspect most yards can tell
       you who has one, otherwise btween now and March should be plenty
       of time.
    3) fill and fair all the blisters you opened up in the fall.
    4) apply a barriercoat. This is the stuff sold just for the
       purpose of preventing osmosis.
    5) apply bottom paint. I think it is recommended to use one of
       the non-sanding primers.
    
    There seems to be an article in the sailing mags evry other month
    on this, including what to do about it...you might want to look
    thru some back issues of Sail or Cruising World for details.
    
    According to the articles I have read, sanding gelcoat prior to
    applying bottom paint actually increases the rate of moisture
    absorbtion within the resins. As a rule non-sanding primers are
    supposed to be favored in this regard.
    
    Walt

    Is this a new boat if so check around and see if this is a common
    problem.  If it is then the you may be able to get the builder to
    pay for the repair work.  A new properly laid up hull should not
    BLISTER in one season.
    
    
    Forrest

    Gelcoat blisters normally indicate the beginnings of osmosis in
    my experience. They should certainly be investigated thoroughly
    and the problem resolved before re-launching. There are plenty of
    books on how to repair osmosis damage - so won't go into them here
    - but as in .1 you should certainly open them up and dry out the
    interior then put on a replacement gelcoat that has NO solvents.
    A protective barrier should be applied for security.
    
    Make sure you get them all - and don't skimp the job, it could prove
    VERY expensive in the long run.
    
    While you're at it, check for any delamination.
                      
    Good luck,	Brian

re .0: You have my sympathy and a long, unpleasant task ahead of you. 

Osmosis is only one possible cause of bottom blistering, but it is the
most common. Prevention and cure is either very expensive (you pay
someone to do the work) or very laborious (you do the work). The cure is 
to clean and fill the existing blisters and then coat the bottom with a 
water barrier. Consensus seems to be that water barrier is spelled 
epoxy.

When we hauled our 32' boat in the fall of 1986 there were several areas
of pinhead sized blisters. After a few days of drying, the blisters were
almost unnoticeable. Ah, the temptation to ignore them! After some
thought, though, I decided not to. After only a little more thought, I
chose the laborious solution. 

Having the boat in our front yard made the following work feasible. I
wouldn't have attempted it had the boat been stored in a remote
boatyard. 

I discovered that the eight or more layers of hard bottom paint (Woolsey
Blue Streak) would scrape off fairly easily with a very sharp 2" wood
chisel. I had to resharpen the chisel quite frequently, which was a
blessing since my back and arms would begin to ache horribly rather
quickly. I completed scraping the entire bottom shortly after the boat
arrived home. As an experiment, I initially tried sanding off the bottom
paint. Doing this would have taken many, many, many days to say nothing
of the toxic dust. The scraping took maybe 16 hours and resulted in
large paint chips. 

After scraping, I stabbed the blisters with an ice pick. This usually
chipped a bit of gelcoat away from the underlying laminate. In only a
couple of cases did any liquid come out of the blister. Stabbing
unblistered areas resulted in the same chipping. This seemed to indicate
that the blistering wasn't too serious. I felt better. Unless the
blistering is very widespread and serious, the gelcoat needn't be
removed entirely. 

I spent the winter acquiring and reading manufacturer's literature about
various bottom sealing products. Wheee, such a wealth of conflicting
claims. I finally decided that a solvent-free epoxy coating was the best
solution. You want to apply a coating that is as nearly impervious to
water as possible -- gelcoat is a help, but epoxies are much better. The
coating has to be fairly thick to be effective. Some of the products on
the market result in a fairly thin coating and the makers of these
products tend to recommend only one or two coats. Among the solvent-free
epoxy coatings are WEST epoxy, System 3 epoxy, and SPS Osmogard. 

In the late spring I began sanding the bottom with an orbital electric
sander to remove all of the bottom paint residue. Fortunately, before I
got very far, I was loaned a 4 hp air compressor and a random orbit air
sander. This speeded the sanding immensely and left a very smooth bottom
free of swirl marks. 

After sanding I filled all the blisters with epoxy and microballons and 
again sanded everything smooth.

The next step was to drape heavy polyethylene sheets around and under 
the boat, making a mostly draft-free tent. Inside went two large 
electric heaters (you don't want to know what our electric bill was). 
These kept the boat's bottom quite warm for several days. A dehumidifier 
collected virtually no water, so I assumed that the hull was dry. The 
moisture meters available are expensive and require much experience to 
use effectively.

One Saturday in early May six of us assembled, along with many gallons
of System 3 epoxy, respirators, rollers, etc. Getting the six people
assembled was easy -- the reward was a trip to Bermuda. I decided to use
System 3 because Ross Faneuf finds it quite satisfactory in building his
boat, because he had lots of it, and because he was one of the crew. The
stuff I had originally decided to use was very similar, much more
expensive, and unavailable. In one long day, the six of us rolled on
four coats of epoxy, applying the next coat as soon as the previous coat
had hardened to just slightly tacky. This eliminated the need to sand
between coats. The heaters kept the air temperature around the bottom of
the boat about 80 deg F. If they hadn't, the epoxy wouldn't have hardened
quickly enough to do four coats in one day. The epoxy, by the way,
starts to cure within minutes of mixing. One person mixing and four
rolling on the epoxy worked well. It took 30 to 45 minutes to actually
apply each coat. 

After a week of curing, I lightly sanded the bottom again to smooth off 
the rough spots. Getting a really smooth finish would have required 
sanding off at least one coat of the epoxy. Then Julie and I applied two 
coats of bottom paint. At this point the bottom looked exactly like it 
had every previous spring.

I didn't keep careful track of the hours I spent doing all this, but my 
guess is about eight to ten full days. This doesn't include the help 
from the crew. Materials were $300 to $400. I would guess that a boatyard 
would have charged $3000 to $5000 for this work.

After our boat was hauled a few days ago, I looked at the bottom with
great trepidation, hoping that I wouldn't find more blistering. To my
tremendous relief, there is nary a blister. 

Though epoxy coating your bottom is much, much work, I would recommend 
doing so before launching your boat again. Doing nothing will only make 
the problem more expensive and harder to solve in the future.

Alan

    Thanks .1 and .4 for your feedback and instructions!
    
    I trailered the boat over to the dealer this weekend for their
    opinion as to how serious the problem is.  The dealer basically
    said that if the cosmetic appearance bothered me (they are about
    the size of a pinhead) then have them fixed.  They gave me similar
    directions as .4, but said if I really wanted to do it right to
    have is sandblasted which I suspect is really expensive.
    
    He said if it was his boat, he would leave it alone for another
    season.  I have a good relationship with the dealer.  My only
    underlying thought is that they know I'm hungry for a larger
    boat sometime in the future (family capital appropriations
    committee has yet to approve), and may be ready to trade-up
    in the next couple of years....so big deal as long as the
    problem doesn't get any worse.  Everything I read says fix-em!
    
    Any further comments/suggestions?
    
    Keith

Knowing what is required to repair blistering, would you buy a boat with
blisters? (I would, but only if the price were reduced enough to pay a
competent boatyard to do the repairs.) Will the dealer take your present
(blistered) boat as a trade-in on a larger boat? (I doubt it.) 

Blisters are more than cosmetic. They can, if ignored long enough, 
seriously weaken the hull. The laminate on small boats is thinner than 
that on larger boats, so a blister of a given depth is relatively more 
serious on a smaller boat.

Re sandblasting: This is an extreme measure. The sandblasting leaves a 
rough, uneven surface covered with broken strands of fiberglass. SPS 
makes a special epoxy for sealing a sandblasted laminate. Then you have 
to refair the hull. Then you apply the final coats of epoxy. The cost of 
sandblasting isn't much. The extra labor that follows is a significant 
cost, I suspect. I didn't even consider sandblasting.

Letting the problem go another year will only make the situation worse. 
If the dealer is hoping to sell you another boat (same builder?), he has 
a certain interest in minimizing the seriousness of the problem and the 
cost of repairs. 

Alan

    how old is your boat (.4 .0)?   how long does Fiberglas boat last?
    I read some where in here that the insurance jumps after ten years?
    
    George

My boat was built in 1979. Blistering occurs on boats new and old. The
Coast Guard not too long ago did extensive destructive structural
strength testing of one of their 41' fiberglass utility boats (which are
used and abused far, far more than the average yacht). The boat was ten
years old and the Coast Guard found no significant reduction in hull
strength. 

Perhaps the most important limit on the life of (nonwood) boats is the 
fatigue life of the materials used to build the boat. Many high tech, 
high strength materials have a limited fatigue life -- flex them too 
often and they fail. I have heard reports that some recent racing boats 
reach the end of their fatigue life in only a few years (fewer than 
five). In general, well constructed fiberglass boats built with 
conventional fiberglass and resins probably have a life expectancy that 
exceeds that of their owners.

Insurance rates are higher for boats more than ten years probably 
because of higher failure rates for neglected rigging, plumbing, sails, 
etc. The life expectancy of wire rigging is on the order of 10 years -- 
how many owners replace standing rigging before the mast falls down, for 
example? Besides, don't expect logic from insurance underwriters.

Alan

I couldn't have said it better so borrowing from 664.4 (Alan Berens):

"re .0: You have my sympathy and a long, unpleasant task ahead of you. "


On the other hand, I'm not sure if correction of your problems is as difficult
as some of the above notes may have you fearing. It is time consuming, but not
difficult. Since I corrected a minor problem on my boat this year, so I have
some direct experience with this problem. 

From my experience, these are the steps you will need to follow:

1. Remove the old bottom paint. You can use entirely mechanical means 
(sanding, scraping, etc); but I went the chemical route. I used Interlux 
fiberglass paint remover to soften the paint and (many) plastic putty 
knives/scrapers. Residual paint was removed using more paint remover and steel 
wool. For estimating purpuses, I used a little over 1 gallon of the paint 
remover on a 22 ft boat.

2. Sand the bottom. I did this with a orbital sander and by hand. I forget
the exact grit I used, but your paint instructions should help you with this. 
(1-800-Intrlux can also help, ask them about their technical bulletin on 
blister repair.)

3. Open up any large blisters. (I was lucky, all mine sanded out without 
exposing laminate - in fact, I may have had what the industry calls weeping 
and not full fledged blistering).

		*** At this point you are 90% done ***

4. Patch any exposed laminate. 

5. Let the bottom dry thoroughly. A simple test of whether the bottom is dry 
is to tape a 1 ft square of clear plastic to the hull. If after a day or so 
moisture appears underneath the plastic, then the hull is not dry and is not 
ready to be painted. All you can do is wait and hope the boat is dry before 
warm humid weather arrives.

6. Paint with an epoxy barrierkote paint. This stuff goes on thin. I did at
least 6 coats of Interlux 2000. If your boat's bottom is very bad and you have
exposed laminate all over the place then Interlux has something else (2001 ?)
that goes on first. A number of my friends swear by another brand, VCtar. 

7. Repaint with antifouling paint. I would suggest a copolymer only because I 
fear removing paint build up on top of the barrierkote. 


One year later, I'm happy to report that my boat shows absolutely no evidence 
that the problem is recurring.

Several of the above notes talk about whether correction of this problem is
covered under manufacturers warranties. Generally the answer is no, but the
situation is changing. Catalina (my boat company) offers a warranty, but to
get it you have to buy factory applied barrierkote. I think the same applies
to Ericson. J-boats on the other hand has begun offering a 10-year (or
5-year?) warranty against blistering. 

Good Luck,

Bob

  A recent issue of _Practical Sailor_ (Dec 15, 1987) had a condensed 
  summary of research done by the University of Rhode Island on the 
  causes of gelcoat blistering. The report was funded by the U.S. Coast 
  Guard and the American Boat Builders Association. The project findings 
  were summarized in twelve major points (which I have further condensed 
  and quote without permission).
  
  The Causes of Blistering - A Summary
  
  1. Currently used glass-reinforced polyester laminates are excellent 
  materials for boatbuilding but, under some circumstances, can exhibit 
  blisters.
  
  There is a belief among marina personnel that the problem is more 
  widespread among newer boats than it was ten years ago, however there 
  are no reliable statistics to back up or refute that belief...There is 
  also little scientific evidence to support the belief that warm water 
  is more likely to produce blisters than cold water.
  
  2. All resins contain some water soluble material (WSM). Only if that 
  material is concentrated at a point in the hull will it cause 
  blistering.
  
  Some of the WSMs are dust, dirt, and other impurities that may found in 
  microscopic quantities. Other WSMs are part of the basic materials used 
  in the process such as inhibitors, UV stabilizers, colorants in the 
  gelcoat, the promoter or catalyst, etc...A certain level of WSM is 
  essential to a well designed resin...However if they are concentrated 
  beyond normal limits, or if they are concentrated at a given zone, 
  blistering will result.
  
  3. All blisters are caused by water diffusing into the hull and 
  reacting with water soluble material to form a droplet of solution 
  which, because of osmotic pressure, grows in volume and creates a force 
  which results in a blister.
  
  The resin is semipermeable, meaning that the small molecules of water 
  easily pass through it, but the larger molecules of the WSMs do not. 
  Hence water flows in, pressure builds up, and a bubble or blister 
  results.
  
  4. Three types of blisters are discussed. The first are "water soluble 
  material" concentration blisters, formed from clusters of materials 
  present in the hull when the boat is built. The second are "stress 
  induced" blisters which are formed because WSM is concentrated in a 
  location by water diffusion and stresses. "Long-term" blisters form 
  because of ester hydrolysis of the polyester molecules.
  
  The first kind of blisters can be due to "dirty housekeeping." 
  Microscopic studies of blisters have shown bits of debris and sawdust 
  at gelcoat interfaces. Researchers were able to produce blisters in 
  less than 24 hours by placing red-tinted grains of sorbitol underneath 
  the gelcoat of a test panel.
  
  The stress induced blister may result from stress that develops between 
  layers when the hull is curing, or from slight swelling of the gelcoat 
  when it absorbs water. Small cracks form where WSM move in and begin 
  the blistering process.
  
  There is debate as to whether the third type of blister exists. It is 
  theoretically possible, however they have not produced these in the 
  lab.
  
  5. Other factors being equal, gelcoat thickness determines when 
  blisters will form.
  
  Gelcoat is normally sprayed into a hull mold at a thickness of about 20 
  mils, which shrinks to 14 to 18 mils during curing. If a thicker 
  gelcoat can be achieved, blistering will likely be delayed or 
  prevented. 35 mils is about the maximum that can be achieved.
  
  6. Laminate lay-up and post-cure temperatures did not have a major 
  effect on initiation time or severity, for temperatures between 50 and 
  90 F. Higher temperature post-cure should improve laminate stability. 
  The degree of cross-linking is a critical parameter in determining the 
  properties of resin.
  
  7. Design of the resin rich region between the gelcoat and laminate is 
  important in minimizing blisters.
  
  8. Control of air inhibition during lay-up can improve blister 
  resistance.
  
  The study suggests that many blistering problems can be traced back to 
  the process of keeping air away from the polyester resin while it is 
  curing. Waxes that "float" to the surface can eventually become a WSm, 
  mix with water, and cause a blister.
  
  9. Microscopic examination of blisters indicated the presence of 
  sawdust, disk cracks, promoter, and internal stresses in the blister 
  region. Without such examination, it is impossible to pinpoint the 
  exact cause of blistering in a particular boat.
  
  10. Leaching of material from gelcoats will cause surface crazing of 
  the material.
  
  If WSMs are leached out of the hull as the water moves in you will get 
  no blisters, however crazing will result. This is not a characteristic 
  of newer type gelcoats (although this was seen in earlier boas). This 
  may explain why blistering was not as much of a problem with older 
  boats.
  
  11. The blister initiation time and the severity of the blisters formed 
  during this study were a function of both the laminating resin and the 
  gelcoat used. However, the area affected by the blisters was similar in 
  all cases. The size of the blisters depended on the laminating resin 
  used. The chemistry of the materials is complex, and variations were 
  seen among generic types from different manufacturers.
  
  No single brand of gelcoat or laminating resin came out as obviously 
  superior or inferior.
  
  12. It is recommended that boat manufacturers institute programs of 
  quality control and quality assurance, with specification for their 
  supplies, to minimize the blister problem.
  
  Sloppy conditions and building techniques - resulting in concentrations 
  of WSMs - are probably the main cause of blisters.
  
  
  The Coast Guard is funding a follow-up study to determine how to best 
  repair blisters after they occur.
  
  		Howard Radke - Seattle

    My boat had some small blisters on the hull when I hauled it.  Looks
    like I'll have to take the cure and apply some kind of barrier coat
    next spring.  
    
    How have the various epoxies and off-the-shelf remedies worked for
    those who have dealt with this in the past.  I've heard reports
    of blisters recurring despite very thorough repair attempts.  
    
    From reading my junkmail catalogs, I'm intrigued by Petit All Temp
    barrier coat.  It's supposed to work down to 32 deg F which will
    allow doing the work in April as opposed to June.  Any one have
    experience with this?
    
    - gene

re .11:

See note 664.4 also. Unfortunately, I have had some experience with blisters 
and the repair of them. According to what I've read in Practical Sailor and 
elsewhere, properly repairing blisters and epoxying coating the bottom will 
prevent new blisters for some time (maybe five years or more) but not forever. 
Sigh. We epoxy-coated the bottom of our Valiant in the spring of 1987, and 
after three summers there has been no reoccurrence of blistering (and 
Uniflite-built Valiants are, grumble, grumble, becoming notorious for blister
problems). 

As to the catalog blurb about Pettit All Temp Epoxy Undercoater: Life is only 
that simple in fantasies. The Pettit stuff must be formulated to work over a 
fairly wide temperature range. The cure rate of any epoxy increases very 
quickly with increasing temperature. If the working time (pot life) of the 
uncured epoxy is reasonably long (say 10 minutes) at warm temperatures (say 80 
degrees F), it will be very long (maybe hours) at low temperatures (say 40 
degrees F). Pettit supplies a single hardener. System 3 supplies three 
different hardeners and West two to cover the temperature range from 40 
degrees F up. 

There are two important factors in epoxy coating a bottom: getting the hull 
laminate dry and getting a thick layer of epoxy on the hull. When epoxies 
cure, a component of the epoxy (an amine) forms a slick film on the surface of 
the cured epoxy. Once this film forms, it must be washed off with warm water 
and, ideally, lightly sanded before another coat is applied. However, if the 
epoxy has only cured to the point of being just very slightly tacky, another 
coat can be applied without washing or sanding. 

Now then, regardless of some claims to the contrary, a sufficiently thick 
layer of epoxy requires several coats (4 to 6). We used System 3 with the 
fastest hardener (which will allow a cure down to close to freezing). With 
heavy plastic sheeting around the boat and two electric heaters running to 
keep the air temperate near the hull above 75 to 80 degrees F, we were just 
barely able to apply four coats in one day with each coat becoming just 
slightly tacky before applying the next. If you apply any epoxy in colder 
temperatures, it is unlikely that you'll avoid having to wash and maybe sand 
between coats. The time required for the Pettit to become tacky at low 
temperatures must be several hours. 

One more consideration about applying epoxy in cold temperatures: The surface 
of the hull should be dry when you apply the epoxy. If the hull is cold, 
there is a rather high probability of condensation on the hull both morning 
and evening. Not good. 

Boat/US carries a book (I don't recall the title and author's name) that goes 
into great detail about how to dry a hull, repair the blisters, and apply the 
epoxy. The book's author(s) recommends System 3. The Gougeon Brothers (West 
epoxy) have a book that also describes how to do the job. 

Bottom line: Plan to apply several coats of epoxy in one day. I'd suggest 
using System 3 -- it's cheaper. This isn't a fun task, and the cost will be 
a few hundred dollars. 

    I ended up using West Epoxy for the blistering cure, mostly because
    it was easily available and there seemed to be the fewest complaints
    about it.  A few suggestions for those who may be confronted with this
    problem in the future:
    
    The fast hardener is really fast.  They mean it when they say mix in
    small batches when it's warm out.  Five pumps worth was all I could get
    on without it's starting to harden up if it was over 70 deg out.
    
    Buy lots of rollers.  They only last about 2 hours max before they get
    hard.  I started with two and ended up buying 5 more.  The grey ones
    from the hardware store don't work.  They produce too much bubbling in
    the epoxy.  The official yellow ones work much better.
    
    Cutting up rollers to make smoothing brushes as per the intructions
    really doesn't work that well.  I found cheap bristle brushes produced
    a much smoother finish and lasted longer.  When they started to harden,
    a quick swish in some acetone softened them right up.
    
    The old painter's trick of putting rollers in the freezer to keep them
    soft doesn't work with epoxy.  They hardened anyway.  I guess once the
    reaction starts, it produces enough heat to sustain itself even at 0
    deg.
    
    There may be an optimal time for sanding the finish smooth after the
    requisite number of coats have been applied but I never found it. 
    After a two day cure, the sandpaper still clogged.  After about 8 days
    it was like sanding granite, even with a air driven sander.  120 grit
    seemed the best compromise between cutting ability and smoothness with
    a DA air sander.  I used what I consider inordinate amounts of
    sandpaper.  This took longer than the application.  If it weren't a
    racing boat, I'd have been tempted to be a lot less fussy here.
    
    If it blisters again, I'm going to sand them out of existence and
    forget about 'em.  One Spring wasted on this is enough.
    
    - gene
          

    I also tried cutting up the roller and using it to smooth. Didn't work. 
    
    Probably the worst thing I ever tried: epoxying in a snowstorm in
    March. The result peeled off like rubber chicken skin.
    
    Paul

re .13:

As part of the hardening process, a scum (an amine, whatever that is) 
forms on the surface of the epoxy. This scum is what causes sandpaper 
clogging and it can be easily washed off with water (I add a little 
ammonia). 

    It's been 5 years since a reply was posted on this note.
    
    When I hauled last month, I saw some pin head holes in my gelcoat (ie no
    penentration into the actual glass). On a 20 year old boat, I guess it
    was bound to happen.
    
    So it is time to strip and epoxy the bottom. Anything new on the market
    in the past couple of years I should be aware of? I am looking to
    use West to recoat the bottom once I fair out the tiny holes.
    
    
       thanks
    
        john

    I have most the hull stripped. I have picked up the West Epoxy book
    on blisters (excellant reading) and am starting to plan.
    
    Alan, when you did you bottom, did you go around the stands and do
    them a couple days later, or did you set the boat so there were no
    stands in the way?
    

    John,
    
    When I first got elysium I used the Pettit epoxy barrier coat
    (200/2001?) after stripping all the bottom paint.
    
    For some reason or other, maybe the directions on the cans, I worked
    around the jackstands but moved them after soon the epoxy had set, only a
    matter of hours.  Definately not days.  Did the barrier coat and the
    initial coat of bottom paint on one weekend.
    
    I didn't see a safe way of removing more than a few of the stands at
    one time.
    
    Seven or eight years later, I've had good adhesion of the barrier coat
    and no blistering on the 12 year old hull.
    
    djc

     
    
      re .18 Thanks Dave.
    
    
        I thought I was home free having finished sanding the bottom smooth
    by Friday afternoon. I called Gougen Brothers to see if 100 grit was
    too smooth for the epoxy to set to on the gelcoat. The folks there
    said take the gelcoat off. WHAT???? I replied. They told me chances
    were there was going to be damage under the gelcoat considering how
    many pin holes I had (ie hundreds). They said at least strip off the
    worse areas and take a peek.
    
        So I took I out a section that had sanded out well. Below found a
    set of tiny hollows that sort of looked like termite damage. And some that
    you could see the hollow just under the first layer of glass.
    
        Grinding with commerical duty alumimium oxide 80 grit on a 3/4hp
    grinder is getting everything nice and clean, but it is hard dirty
    work. The gelcoat dulls the grit rather easily as it is very hard
    stuff. I have a shop vac attached to the grinder that gets 60% of the
    dust. I have to stop every 10-15 minutes to clean off as I get covered
    in the white stuff. The only good part is knowing I am saving $42 a day
    by not being able to go skiing ;>(  .
    
        I figure about 24 hours to finish from a nice clean bottom.  I am
    2/3ds of the way done with this. The worse sections will then need an
    additional hour to be ground out with my mototool mini grinder. I can see
    why a boat with blisters gets discounted 40%.
    
        Amazing the damage you see under the gelcoat. I can see where prior
    owners have slammed docks, stress fractures in the glass, and 
    cracks. I will deal with all of these this spring. Luckily everything
    is nice and dry in the laminates. I guess I got to it in time. Any of
    you coming over for the winter confab will be able to see the damage.
    I am also photographing all the stages of work for the future.
    
        Not sure I want to buy an old used boat again after having this
    grief on a hull with only "minor" blemishes. Double that on a boat with
    multiple coats of bottom paint. From the weight of the debris in the
    shopvac, the fix should be actually lighter than original, as the
    gelcoat is quite heavy compared to epoxy. After all this work, I will
    hang onto the boat for 2 more seasons just to get my sweat equity out of
    it.
    
        The folks at Goergen Bro is really nice, and they immediately
    hooked me up with an expert for answering questions. seems like a
    good outfit. 
    
         Regards
    
          john
    
    1 mainsail and I will have rebuilt everything including the hull...

    both of my keelboats were new construction. Both got the bottom
    attacked with 80grit after dewaxing. Then West System on the first, and
    VCTar on the second. Neither has ever blistered. 
    
    You have just justified all that hard prep work at a time when you can
    only think of launching that brandy new go fast....
    
    Thanks for the postings.....
    
    

    
    Hi John,
    
       Jeff redid the hulls of the cat this spring.  Very interestng what
    you find.  There were 1/2" long voids in the glass where the gelcoat
    had worn through dragging it through the sand.  Some were 1/2" deep!
    
       Beach your boat more often and it'll clean the gelcoat right off!
    
         Priscilla
      

    re .21
    
        Don't blame me. I never drove your cat and always picked up my
    corner when moving them around... ;>)  ;>)    
     
        Best thing with beach cats is the coat them with Marine tex. Strong
    as iron when it comes to wear resistance.
    
        Come Saturday, the final quarter gets sanded come sunshine or snow.
    What's a little more white stuff in the air????
    
        Say Hi to Jeff for me.
    
       Regards
    
        john

    Well, the task is now completed. I second Alan's opinion that I would
    discount a boat by the cost to have it repaired and have a pro do it.
    It is a lot of nasty work.
    
    Following the 50 hours to strip the bottom, I went to town with the 
    grinder. I had a hard rubber adapter and this caused some gouging. Make
    sure you buy one of those $25 soft rubber adapters for your grinder.
    
    I made one mistake that DOUBLED my work, maybe more. I filled the 
    larger holes and gouges ok, but only ground down the hundreds of pin holes
    until they were smooth, and all air voids had been removed. BIG MISTAKE. 
    
    When I rolled the 5 coats of epoxy, the holes got worse
    because the epoxy was upside down and wouldn't level, and then the
    amaline blush sat in the center of the hole. Didn't look bad until the
    next day after it had all set (ie it looked fine during the
    application). 
    
    I had to wait a day for the hull to harden, wash and scuff it up
    (actually sanded it down a bit to even it out), and then used a
    squeegie to wet out the surface, followed by an epoxy, alumum. oxide and
    Sillica filler paste to even it all out. This was really messy. Once it
    set, I rolled another coat of epoxy/Barrier coat on top. 
    
    If I had to do again with all these pin holes, I would suggest you wet
    squeegie pure epoxy into the holes followed by a mix of epoxy and
    microballons. Let set, wash, & then sand the hull. You are now ready to
    do the normal coating. It will take you an extra couple of days,
    since you have to let it set, light sand it,and then do the recoating.
    But you will have a perfectly preped hull that will easily sand with
    the microballons. The barrier coat is a bitch to sand because it is
    the same stuff as the sand paper you are using, so it takes a long time
    to sand/fair.
    
    I would also second Alan's recommendation to rent/borrow a commercial
    air sander. My grinder/orbital/palm sanders probably doubled my sanding
    time. We are talking 6-7 hours to sand out 200 sq ft properly.
    
    finally, get a quart of prep-sol (light weight actone) to rub down
    the hull before starting, and to clean on tools. 
    
    The West repair book is good. Much of the info is on the net at:
    http://www.cris.com/~Gougeon/ . 
    
    At 1 point, I had a pump break on a Saturday afternoon and the place I
    was buying them was a 3 hour trip. A lookup of dealers for my state
    found a marine store just 11 miles away, allowing the coating to
    continue. I would suggest you buy 2 sets of pumps just in case. You can
    always return any unused material.
    
    Total cost:
    
    Epoxy (2 gallons plus hardners)     $140
    fillers				$80
    Sandpaper 				$60
    brushes, rollers/frames		$30
    Obital sander			$60
    bottom paint 			$112 (would not have needed
    					      otherwise)
    Total hours				~100
    
    This is the worst job I have had to do on the boat, and I have done
    everything that can be done [swapping out the head was fun compared to 
    this]. Having your arms raised above your head trying to bear down on
    vibrating, noisy sander for 5-6 hours while it is 25 degrees out, or
    black flys are chewing you alive is not a lot of fun. About 3 pm last
    week, I was ready to torch the bastard, except my house was less then 3
    feet away.... ;>(
    
    All is now done, bottom paint is, and she looks pretty nice. Report back at
    end of season.