Fairing method.

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xantipo

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Aug 31, 2009, 5:57:12 PM8/31/09
to F22 Builders
This group for some reason doesn't seem to have caught much interest
from most builders which is too bad since it could be of great help
for all of us.

The subject I bring here today is about fairing techniques.

As I was ready to start fairing the floats I decided to use the stripe
method so widely refered in many blogs. I have however some doubts
about the efficiency of this process.
Firsts it trashes way too much compound and then it takes up a lot of
time and sweat to get those stripes fair. In my case the hulls where
reasonably fair to start with except for some strips along close to
the keel and some minor waves along the hull. All these imperfections
could easely be detected by sight or by passing the hand along the
surface. For those finer imperfections one cannot detect , I doubt the
stripe method will pick them all out and probably a sort of trial and
error process will have to be used to complete the job ( well, that's
my opinion).

Thinking of what's ahead regarding the fairing of the mainhull I would
like to get your reading on this issue namely if it's worth it ( the
stripe method) or if you got good results using a more practical
method. I can imagine using stripes on pre-determined areas could be a
good compromise leaving most of the reasonably faired surface out.

Also about longboards and the discussion about lenght and flexibility.
I simply use different kinds of boards according to the job needed. I
usually start with a short rigid board with heavier sanding paper to
pre-level the stripes than a medium rigid board ( 70 cm) to pre-fair
the stripes and finally a long flexble board ( 130 cm) to smooth out
the shape. So far it has worked fine.


MatosF22 #99

Grant Kinsman

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Aug 31, 2009, 6:15:07 PM8/31/09
to xantipo, F22 Builders
I think I agree in that I found that the stripe method was quite useful in those regions on the floats where there was significant filling to be done.  For me, I found the float decks needed quite a bit of putty to get them flat with a stiff longboard.  On the hulls I ended up applying a thin coat and sanded that down lightly.  The areas that still need filling (not touched by sandpaper) are more reflective or shiny, but I was amazed at the number of cycles (apply putty - sand)  required to get it all fair.
Cheers,
Grant
www.f22build.blogspot.com (still in a pause before the main hull is started)
--
Grant Kinsman

simon

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Aug 31, 2009, 10:25:57 PM8/31/09
to F22 Builders

I am close(ish) to start faring the floats and was going to use the
strip method as well. I have been helping out a mate who is building a
35ft cat over the past couple of years and he used the stripe method
as well. He did this on the advice of his cousin who is a professional
boat builder and he said it saves alot of time.

It seemed to work quite well and once you faired the stripes down it
showed up the areas that reqired more filler than others very well.
This seemed to make it easier to apply close to the right amount of
filler in between the stripes as they act as a depth gauge. It also
seemed to have the advantage that when you are doing the first pass of
faring you are only faring a small amount of the surface area so helps
to make the initial bit of the job go a bit quicker.

However having said all that my mate quite often talks about half of
the filler he has put on seems to end up on the floor as dust! I think
this may just be an unaviodable joy of boat building, guess I will be
finding out soon enough! Just think of all the weight you will be
saving!!

Interesting comments on the long board. I had made up a long board
using an offcut of 9mm plywood, about 1 meter long, but it seemed to
be too flexible. When I was sanding the keels down as one end of the
board went over the edege of the hull the it would bend down and as a
result I would sand more off the end. So I was going to make up a
stiff long board using some 18mm thick pine instead, will be
interesting to see how it goes but may just be a matter of what works
best for you?

Cheers,
Simon
www.simonf22.blogspot.com

Thomas Chrien

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Aug 31, 2009, 11:28:04 PM8/31/09
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Hello-

I am close to fairing my floats as well. I have taken the last 4-5
months off to learn to deal with a nasty rash that may be due to
epoxy sensitivity, but that is another story. In the meantime, I have
been sail training the family on my Catalina 30 with several cruises
this summer.

I made a long board out of a 1/4" plexiglass with a wood handle. I
sized it to be 4.5 x 44" to which I spray mount two sheets of 9x11"
sand paper cut lengthwise. This tool worked great for fairing the
bare foam floats. I have one float covered with glass and the other
ready to be covered.

What fairing compound are builders using? I was thinking of just
mixing up cake frosting from epoxy resin and microballoons. I can mix
about a pint of frosting at a time using my drill press mixer. Is
there something better to use?

BTW, thanks for uptake in interest in making use of the f22-builders
group.

Tom


Grant Kinsman

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Aug 31, 2009, 11:49:29 PM8/31/09
to F22 Builders
I've had good results with System Three's QuickFair and Aeropoxy Light Filler.  Links below.  They are light, consistent and paying for this - made me Spartan in application. 
Grant

http://www.systemthree.com/p_st_quikfair.asp

http://www.ptm-w.com/index.asp?pgid=178


On Mon, Aug 31, 2009 at 11:28 PM, Thomas Chrien <tch...@mac.com> wrote:

What fairing compound are builders using? I was thinking of just
mixing up cake frosting from epoxy resin and microballoons. I can mix
about a pint of frosting at a time using my drill press mixer. Is
there something better to use?







--
Grant Kinsman

Bill Scott

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Sep 1, 2009, 8:47:23 AM9/1/09
to Grant Kinsman, F22 Builders
Well, we are getting a good response on this subject.
I used the strip method on the floats and it worked well. I have started to fair the main hull, actually filling the weave and I am just lathering over everything. I'll lightly sand it and then see what is required next.
I find that running your hand over the hull is about the best indicator of fairness.
I'm using West System 410 with epoxy for fairing. It works very well.
Bill Scott

bu...@terrigal.net.au

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Sep 1, 2009, 8:27:28 PM9/1/09
to F22 Builders
It is important to firstly build the foam strips as fair as possible ,
then to fair them well before applying the laminate . If this is done
very little filler is needed and the filler stripes unnecessary . We
use two rigid boards , one flat underneath , the other with a slight
curve plus a flexible board , all about a metre long . Start with 40
grit and work down . We use SP systems quickfair 600 and it is very
good to sand and easy to apply .Jim Buckland .

Tor

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Sep 2, 2009, 11:11:44 AM9/2/09
to F22 Builders
I advice all builders to have a look at Andrew's posting for February
this year in his blog: http://ballard-f22.blogspot.com/2009/02/february.html
I found this comprehensive evaluation of his fairing and also the
links he put in there to be very useful.

Tor F22R #11
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