View Full Version : Tried System 3 fairing method

Dale R. Hamilton
08-02-2005, 08:41 AM
System Three poblishes a "Epoxy Book" cramed with various directions and hints as to how to use their products. Normally, I just ignore instructions as I'm sure most of you guys do. But this book recommends a "slick trick" for fairing large areas with minimal sanding- like the bottom of my runabout. You mix up a big batch of goop with microbaloons and use a notched trowel to spread it all over the bottom. Let dry- and sand. I used first a little hustler- a pneumatic body file, then switched to a monster belt sander. The idea is you fair the ridges- only about 1/4 the surface area. When fair you trowel on more goop this time with a drywall knife- filling in the valleys between the ridges. Then its just minimal sanding to get a pretty good surface. Anybody elde do it this way?

08-02-2005, 08:44 AM
Sounds like a neat way for system three to sell more goop.

I have never been a big fan of slathering thick layers of slop over a hull. It has a tendency to get brittle with age and fall off in chunks. The aging space shuttle is an example.

08-02-2005, 08:56 AM
I purchased the small white plastic notched trowel made by West Systems to apply fairing compound to the diagonally laid plywood on the Rascal runabout. As you mentioned, it significantly reduces the amount of fairing compound required and is way easier to sand. I then used a long board with 80 grit paper to sand the ridges down. I then installed the final layer of 1/4" Honduran mahogany planking on top of the faired plywood. It worked!


08-02-2005, 09:51 AM
This method saves a lot of effort and a lot of bog.
The WEST notched spreaders are nice, and for larger jobs, there are cheap plastic spreaders intended for tile mastic. The depth of their notches can be adjusted with a belt sander.
The other key tool is #36 sandpaper on a longboard.

[ 08-02-2005, 10:52 AM: Message edited by: JimConlin ]

Todd Bradshaw
08-02-2005, 10:57 AM
It's actually an old technique that's been used for years and works quite well. Back when 12-Metres had aluminum hulls they required a lot of filling and fairing to get a smooth shape and it was one of the better ways to do some of it. More recently, it's been used on strip-planked multihulls, especially those built with Dura-core strips (balsa with veneer on both sides) where fairing needs to be done on top of the core material without cutting or sanding through the veneer skin. The most critical step is getting the filler mix right. You need to be certain that it won't sag or flow out ten minutes after you comb it or you lose the ridges you're trying to create. With most resins, this means using a lot of microballoons and not an awful lot of resin. Make a test batch or two to try on scrap wood and keep track of the mixture ratio until you get one that works and doesn't sag. Then you can make bigger batches as needed, mixed to the same ratio. It's also a good idea to overcoat the faired surface with plain resin prior to painting as sanded microballoons aren't a very good surface to paint over.

08-02-2005, 11:10 AM
There was a WB article on hull fairing recently that described this method in a sidebar, I think.

I used this method on my deck. Despite what seems to be an extra step, I'm convinced that it's a real time/labor saver. I don't think you use any more or less epoxy.

ion barnes
08-02-2005, 09:27 PM
I think its refered to as 'noodeling'.

08-04-2005, 02:14 PM
Originally posted by Nelson:
Sounds like a neat way for system three to sell more goop.

I have never been a big fan of slathering thick layers of slop over a hull. It has a tendency to get brittle with age and fall off in chunks. The aging space shuttle is an example.I would have to agree. I attempt to construct as fair as possible so goop will not be needed. It's kinda like the whole "Bondo" thing with hotrods, it's easy and looks OK but only for a short time.

08-07-2005, 12:36 PM
Nelson and Chub- Of course we all try to build as fair as possible but fairing out a hull by filling, sanding, and repeating is, as some would phrase it, a neccessary evil. Applying huge thicknesses of "goop" to fill huge voids is not the purpose of the task. Any hull, including those !@#$%glass monstrosities they pop out of molds where I work, are not perfectly fair and, if you want a very fast hull, require some work. The use of various types of fairing compounds has been in use since long before you or I hit the ways. As has the long board and the use of sandpaper in increasing grit count. The purpose of this thread was to propose a more efficient method of performing the task. Your proposal of ignoring the task insures that your boat will remain in my wake.

08-07-2005, 01:30 PM
Something I rediscover now and then- A large pot of bog kicks quickly because the bubbles are good insulators and exothermic heat can't escape. So, unless i figure out a faster way to mix it, a half pound is about as big a batch as i dare in summer temperatures, even with slow hardener.

Today's discovery is that a Gougeon spreader after an overnight soak in the acetone bucket is 'al dente'. Wish they made 'em of the same material as the #804 mix-scrape sticks.

[ 08-07-2005, 09:44 PM: Message edited by: JimConlin ]