Marshall's FS17

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MarshallTX
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Fairing questions

Post by MarshallTX »

Finally started the first fairing layer using the blended filler and epoxy (will move to QuickFair next). A few basic questions: - For sanding, is an orbital sander with fine grit too aggressive? What's a good sanding solution? Also, I made my first attempt at applying fairing using a plastic spreader-blade. Seemed OK, but wondering if there is a better tool? I've looked around on the Forum and see a lot of different ideas and wanted to post to get some input. Thanks!

fallguy1000
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Re: Marshall's FS17

Post by fallguy1000 »

Fairing tools need to be stiff.

I use a 6" drywall knife to apply, but almost never to pull.

I bought 12-14" concrete trowels and used them.

I bought aluminum angle irons about 1x1x1/8" and screwed 1x4 or 1x6 handles to each one. They are long enough to cover the greatest fill spans.

I have a 21" flexitool and a 34" flexi trowel and a 39" flexisander for a torture board. It has a bar in it you can remove for contours. But you can save your money and get a piece of very flat wood and make it so you can put hook and loop papers on.

I start torture work at 40 or 60 grit, being careful to not sand down into glass much.

After the basic shapes look good, I fill again and hit it all with 80 grit. It was really hard on me.

Once I pass the 80 grit flat tool sanding, I fill with a colored compound that is quikfair. It is pinkish. Then I sand with a festool rts400 and the passes are all vertical half laps. The festool uses 80-120 grit first pass. I like to get to 180 grit before any paint goes on. For paint, a dust coat from spray cans or single primer coat helps you not lose your mind in layers and feathering. I don't like the spray, so I used epoxy primer. Once you prime, you can scuff and fair some more if needed. The epoxy primer is damn hard. My festool sander is all I used at the end. I had a 8" oscillating sander I spent a fortune on, but it was air powered and my air was too damp and the thing made ice in like the first 60 seconds of use. The festool papers last like 2-4 square feet only on the primer and less on the 2 paks. These paints are super hard.

Let me know if you are confused. I sort of have it down to a science.
My boat build is here -------->

viewtopic.php?f=12&t=62495

MarshallTX
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Re: Marshall's FS17

Post by MarshallTX »

Fallguy - Again, great advice. Makes more sense as I move into the project. You mentioned earlier that this is not like sheet rock (at least at the corners). Is it fair to say it is similar at some of the relief cuts? So far, it does remind me a bit of drywall mud when trying to level/smooth ridges. - Again, many thanks - Marshall

fallguy1000
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Re: Marshall's FS17

Post by fallguy1000 »

It is just a bit thicker than rock mud. So thin trowels tend to float over it or hog into it.

Wall guys try to make walls look okay. Boat guys try to make the boat look fair. Fair is a step above okay.
My boat build is here -------->

viewtopic.php?f=12&t=62495

MarshallTX
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Re: Marshall's FS17

Post by MarshallTX »

A bit thicker than rock mud? Thanks! That tidbit does help. My approach has been a bit thicker (relative) for seams, overlaps, imperfections and a bit thinner (relative) for the smooth open areas of glass. Not sure if that's a good approach...

fallguy1000
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Re: Marshall's FS17

Post by fallguy1000 »

Mix it the same all the time, by weight.

My batches are 75/25 sil32 balloons to cabosil. 100g

Or 80/20

And 543g mixed resins or something like that. 380g resin and 163g hardener

Every now and then I go a little less dry stuff, but like a gram.

It is a big batch, cut in half or quarters.
My boat build is here -------->

viewtopic.php?f=12&t=62495

MarshallTX
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Re: Marshall's FS17

Post by MarshallTX »

Thanks; walking out to the garage now for a few hours of work...

MarshallTX
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Skeg

Post by MarshallTX »

The TX historic heat wave may have passed and my garage has gone from oven-like temps to something more reasonable for boat building. I'm finishing now with the blended filler and sanding with Skeg design on the near horizon. The plans call for a single 2"X2"X7' skeg along the aft keel-line. I see some builds that use twin-skegs offset from the keel (seems maybe easier). Are both concepts effective? Is one design better than the other? What's a good material to use in construction? Any inputs would be greatly appreciated. Thanks - Marshall
Last edited by MarshallTX on Thu Sep 08, 2022 9:47 pm, edited 1 time in total.

TomW1
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Re: Marshall's FS17

Post by TomW1 »

You only need the single skeg as designed by Jacques. Why vary from the designer? The two are also less effective than the one., believe it or not. If Jacques felt that two were better, he would have designed her that way. :D

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

fallguy1000
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Re: Marshall's FS17

Post by fallguy1000 »

The role of the skeg is key.

If you plan to pull up on sand, a couple three might be nicer.

But for normal purposes of preventing sideways slip, I hardly see a benefit for two further up unless an inch if draft, etc.

Really need to know the purpose..
My boat build is here -------->

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