Stupid newb question #163 - lightweight filler application

Hey folks,

I am getting ready to glass the deck of my boat tomorrow (3/8/15). My intent is to apply lightweight filler while the glass is green.

What is your favorite technique for applying an even coat of filler? Do you apply just enough to fill the low spots of weave? Is it best to apply two thin coats - one to fill the weave and a second as meat for the longboard sander?

Or do you apply a thicker coat right off the bat? If so, how do you best maintain an even thickness coat to make the smoothing process...smoother?

Or am I just over-thinking it?

Thanks!

Curtis

 

You're probably over thinking it, but there are two schools of thought, one is a whole coat, sometimes with a notched trowel, the other is where you know you'll need it. I'm the second type, but have done the whole shebang route too. The whole shebang method has you coat every square inch and sand away 80% of it, which is a waste of fairing compound, if you ask me, though can be easier for the novice, particularly with a notched trowel. I identify the lows and highs, before the fairing compound goes on, unless the hull is a real mess and apply only where I need it.

Squeegees and large drywall knifes are preferred tools on large areas, plastic applicators and smaller squeegees on smaller areas. When 'glassing an area, the surface should be pretty fair, before the glass goes on. This lets the 'glass lay on a smooth, fair surface and buries the fairing compound under fabric and goo, which holds better, then if it's applied topically. Of course, you still need to fill the weave, which is simply done with a light filler mix over everything, with the idea of leaving no fabric pattern visible, until you start sanding.

 

Thanks, Paul.

Yes, this will be weave fill. I made sure the structure was very fair before applying any epoxy; no structural mismatch or bumps, fastener fills or bondo more than a couple thousandths, so that is good. Though I will probably need to fair under the hull fabric when overlaying at the sheer when I flip the boat. I'll have to determine how best to approach that when I get there.

Just to be clear, the notched trowel is to get a uniform, measured amount of material on the surface, and then that is smoothed with the appropriate tool, correct? I'm sure that is what you meant, as it would take a LOT of primer to fill those grooves That sounds like a sensible approach between getting at least a sixteenth to an eighth of filler to work with while sanding.

Thanks, again!

C

 

The notched trowel idea is to supposedly half the amount of filling you need to do. The idea is to trowel out everywhere, then take a long board to it, marking the highs and lows. You knock down the highs and fill the grooves in the lows. I've found this works, but you do the same job twice, so unless I'm working on something that's way out of whack, I simply ID the lows with a long board after a dusting of primer, then fill the areas I need to. Plywood boat tend to be more fair then other types of builds, except around seams, butt joints, chines, etc. Compared to roughly done strip plank, a lot fairer to start with.

 

I see, yes, that makes perfect sense. As well as the comment about the inherent fair of ply boats. In grazing finishing process info on the web I was perplexed by the nearly constant reference to smooth with fairing compound in view of the fact that the darn thing was already pretty smooth to begin with.

So, a very light weave fill, primer & sand (and fill if primer can't deal with smoothing issues alone) sounds much more appropriate for my situation.

Thanks, Paul, always good & helpful info

 

Smoothing and fairing aren't the same thing. Smooth is what you feel if you run your hand over a surface. A 40 grit surface isn't particularly smooth, though a 1,200 grit surface is very smooth. Fair is what you see. A car door with a dent in it, isn't fair, but if polished with 1,200 grit, can be smooth in spite.

 

Put the first coat of primer on the deck today.

You were right, Paul, about not using too much hardening or bonding additives in the fairing compound... At one point I have to use the nuclear option: A belt sander! But, lesson learned, and it's looking - if not more boat-like, certainly prettier!

Now: The Board of Pain...

 

It is looking pretty. That looks like a fun boat to sail.

 

Thanks! It's slowly getting there, Bondo. It was a train wreck (boat wreck?) when I got it off Craigslist for $225 (including trailer and 2-horse Yamaha, if that gives you any idea of its condition at the time). I've been learning a LOT about boat restoration...

Being a local guy, do you know of any places in SEA/TAC/BHM that deals in 2nd hand or consignment gear & sails for sailboats? With the demise of Pacific Marine Exchange in Bellingham getting sails is going to be a long process...

 

No idea where to start. Craigslist, I guess. I considered trying to make a sail myself but at the moment I don't need any more hobbies.