Double checking fairing filler quantity

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piperdown
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Double checking fairing filler quantity

Post by piperdown » Sun Jun 02, 2019 10:28 pm

For others that have done a (roughly) 16 ft boat or so how much fairing filler did you guys end up using? Seems like a bag doesn't last that long. Might be I'm making it too thick but it seems like I'm using quite a bit to get to a consistency that won't sag. I've already burned through one bag from BBC and almost the same amount from mixing my own.


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Re: Double checking fairing filler quantity

Post by terrulian » Sun Jun 02, 2019 10:34 pm

Sag is controlled by cabosil. I don't know what mix you're using but I never have found it necessary except on vertical surfaces. You can leave it out for the rest of your fairing. Microballoons work for most stuff and are the easiest to sand. I always made my own I don't know how big a BBC bag is so can't judge.
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piperdown
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Re: Double checking fairing filler quantity

Post by piperdown » Sun Jun 02, 2019 11:33 pm

terrulian wrote:
Sun Jun 02, 2019 10:34 pm
Sag is controlled by cabosil. I don't know what mix you're using but I never have found it necessary except on vertical surfaces. You can leave it out for the rest of your fairing. Microballoons work for most stuff and are the easiest to sand. I always made my own I don't know how big a BBC bag is so can't judge.
BBC is 8oz, which doesn't sound like a lot but filled up a fairly big bag.
I'm working on the sides and transoms so it is vertical. I guessed on the mix I made myself but still used a lot of both microballons and silica.
Eric (aka, piperdown)

"Give an Irishman lager for a month and he's a dead man. An Irishman's stomach is lined with copper, and the beer corrodes it. But whiskey polishes the copper and is the saving of him." --> Mark Twain

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Re: Double checking fairing filler quantity

Post by TomW1 » Sun Jun 02, 2019 11:56 pm

Eric there is a couple of things to be careful of when applying fairing material. First if you are using the premixed balloons and cabosil from here make sure that the cabosil is broken up, it tends to clump. 2. Use a wide drywall trowel to apply your mixture. A 10" one is about perfect. It lets you apply a lot of your mixture with a good amount of pressure so you are not leaving a heavy layer of fairing material. You only want a thin layer each time you apply it. It will take you about 3 or 4 passes to have a perfect bottom. After the second coat do a guide coat find your lows and highs and fill your lows.

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Re: Double checking fairing filler quantity

Post by fallguy1000 » Mon Jun 03, 2019 2:51 am

I bought at least 30 pounds of cabosil to date for my build.

I have used some of my balloons, but probably have 20 pounds ready to go.

8 oz seems like not too much
My boat build is here -------->

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Re: Double checking fairing filler quantity

Post by Capt UB » Mon Jun 03, 2019 6:07 am

Just wandering if more or better sanding of the cloth/tape needs to be done?

Like sanding the tape edges and overlap better?

Of course all of this before fairing.
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Re: Double checking fairing filler quantity

Post by OrangeQuest » Mon Jun 03, 2019 7:51 am

Capt UB wrote:
Mon Jun 03, 2019 6:07 am
Just wandering if more or better sanding of the cloth/tape needs to be done?

Like sanding the tape edges and overlap better?

Of course all of this before fairing.
I would think your answer is correct. I have yet to get to the point of much fairing but I have been wondering the same as Piperdown on how much. That day is coming for me soon. 8O
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Re: Double checking fairing filler quantity

Post by piperdown » Mon Jun 03, 2019 10:10 am

Capt UB wrote:
Mon Jun 03, 2019 6:07 am
Just wandering if more or better sanding of the cloth/tape needs to be done?

Like sanding the tape edges and overlap better?

Of course all of this before fairing.
Oh, I agree. Probably could have done a better job tapering the fg seams and removing excess epoxy.
I'm just trying to get an idea how much fairing filler is needed on average. Then, for my build, I'll add 50% extra :lol:
OrangeQuest wrote:
Mon Jun 03, 2019 7:51 am
Capt UB wrote:
Mon Jun 03, 2019 6:07 am
Just wandering if more or better sanding of the cloth/tape needs to be done?

Like sanding the tape edges and overlap better?

Of course all of this before fairing.
I would think your answer is correct. I have yet to get to the point of much fairing but I have been wondering the same as Piperdown on how much. That day is coming for me soon. 8O
Yeah, I spent some time this weekend on the forum to see if there was anyone who listed how much fairing filler they ended up using. Lots of talk about how much epoxy and some on wood filler but nothing that said "I used 2lbs of fairing filler".

Some references that seemed to indicate boats bigger than my size might have used 2 2 quart kits of system 3 Quik Fair, but that was after a couple rounds of fairing with other materials.

So far, on my GF16, I've used just over a pound and have covered the front transom to the point it's probably ready for primer, the rear transom has 2 coats and needs more, the starboard side has 3 coats and probably needs just a little more. Have not done anything to the bottom or port side yet.
I'm estimating, based on what I've done so far (and I'm probably wasting more than needed), I'll end up using about 2-3lbs of fairing filler.
Eric (aka, piperdown)

"Give an Irishman lager for a month and he's a dead man. An Irishman's stomach is lined with copper, and the beer corrodes it. But whiskey polishes the copper and is the saving of him." --> Mark Twain

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Re: Double checking fairing filler quantity

Post by OrangeQuest » Mon Jun 03, 2019 10:39 am

Some have advised to use the wood flour to get close to fair and then final fair with fairing mixtures that are easier to sand. I am trying to save most of my fairing sanding for the year I will spend saving for the motor.
"that it isn't just an ordinary sort of boat. Sometimes it's a Boat, and sometimes it's more of an Accident. It all depends." "Depends on what?" "On whether I'm on the top of it or underneath it."
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Re: Double checking fairing filler quantity

Post by Dougster » Mon Jun 03, 2019 11:59 am

For vertical surfaces I'd just go to Quickfair from the get go. Then apply the way TomW1 posted. For horizontal surfaces I like Cracker Larry's advice to make a loose mix first ( I used Bateaus's fairing mix for that), then on to Quickfair for the finish. I've never used woodflour for fairing, don't want to make sanding any harder than it is. I would use it if a really deep low spot needed filling. I get tired of fairing though and guess I generally lean toward "the heck with the $$ and buy a bunch of Quickfair" :lol: It's really nice stuff, though nothing makes fairing really easy for me.

Dougster

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