Works better than sandpaper.

  https://www.epoxyworks.com/index.php/scrapers-versatile-tools-for-working-with-epoxy/

You might find a single-edge razor blade works better. Hold between your fingers, blade almost perpendicular to the work surface. Then, using your thumbs, put a slight warp onto the blade so it curves just a little bit. This keeps corners from digging in, makes for better control. Then push blade lightly against the drips.

Cabinet scrapers work the same way, easier to hold too as they’re bigger. They need routine maintenance though (squaring edges w/file, setting a slight burr for cutting edge) but those are useful learned skills for tools that have a purpose over simply sanding out the defects.

I'm still trying to figure out card scrapers. Meanwhile, I've been using a triangular paint scraper to good effect on glue and epoxy:

Nick Schade recommends using a rectangular one.

I have been a fan of card scrapers for a long time – started using them for making musical instruments.  They are really great tools, but require a learning curve that can be daunting to new users.  They require relatively developed skills both for using the tool and for sharpening them.  Once you learn how to use them, you will find them very useful in all sorts of woodworking, but sharpening is always something of a frequent and time-consuming pain.  When they are sharp and you are using them correctly, they make small shavings (think of it as a micro-plane), but if they are dull or you don’t use them just right, they make dust instead.  

Then when I was starting to build a Chester Yawl, I ran across this new tool from the instrument-making world:

https://www.stewmac.com/Luthier_Tools/Types_of_Tools/Scrapers/StewMac_Ultimate_Scraper.html

THIS TOOL WAS A TOTAL GAME CHANGER!    

First, these are easier to use than a card scraper.  They are made of thick steel, so you don’t need to bend it to get it to cut.  It is also more forgiving if you don’t use it at the prescribed angle – it will still cut and make curls.  Unlike card scrapers, you can use it effectively at all sorts of angles, one-handed, pushing or pulling, in tight spaces… I even used them to true up some of my first attempts at epoxy fillets. It makes a much more aggressive cut than a card scraper.  BTW it loves epoxy, leaving the floor covered in lovely corrugated ribbons of epoxy.  In use they occupy a position between a standard card scraper and a block plane in their cutting ability.  For those new to scrapers, they not only smooth surfaces but true them as well, so you can get things really flat. When I watched the product video I was impressed enough with the size of curl that this scraper produced that I decided to spend the bucks to get one.  Now I own two of these in different shapes and they are one of the most used tools in my shop.  I still own card scrapers, but it has been awhile since I have touched them.

The other thing about these scrapers is how easy they are to sharpen once you get your sharpening system set up.  (A bench grinder is required)  Setting up was a bit time consuming, but once done re-sharpening takes literally seconds.  It takes me longer to walk to the grinder than it takes to sharpen the tool.  The product video shows a much more complicated procedure than I settled on. Basically, I just make a quick pass or two against a fine grinding wheel to make two cutting edges.  Sometimes I quickly lap the sides on a flat sharpening stone to get rid of the burr before grinding but not always.  That’s it.

I highly recommend these scrapers.  They are worth every penny. 

Looks like this thread turned into a scraper thread...  But as far as the original question is concerned, here's what I did on my boat, as well as I can remember - since I was involved in the threadjacking.

First I used the aforementioned scraper to flatten everything down. Theoretically you want to take the top points off the uneven surface until the low spots are gone, and stop. Since you don't want go through the epoxy into the wood, I stopped before the low spots were totally gone, just to be on the safe side.  Then I went over everything with 150 grit paper on a sanding block (using a block helps keep everthing flat), and then with 220 on a block.  By that time most of the low spots were gone, but there were still pinhead sized spots. Then I used a sheet of red scotchbrite over a sanding block.  The spongey pad reached in and either removed or deglossed all the little shiny spots.  That left me with with a flat paintable/varnishable surface.

I personally don't use a sander very much.  I want my surfaces as precise as I can get them with a reasonable amount of work, and there are so many things that can go wrong with a sander that it's usually not worth the risk.    

Hope that helps.     

i have not built a mystic river canoe....but i have built a wherry which i think is similar with respect to a lapped hull so each panel is pretty much flat in one dimension.

fwiw, when i have a flat surfact that is convex (the inside is concave) i will often use a hard sanding block with 80 to 100 grit sandpaper to quickly knock down a large epoxy drip.  it's easy to control and does not have the tendency of a scraper to ride over the bump and hollow out the epoxy on either side of the bump (it just takes the bump off).

its pretty easy with a sanding block to see when you have actually taken off the bump becuase you see it cutting into the bump...and you just keep going until it is back flush with the surface.

i am not against scrapers and use them as well....but i find they are not really effective in faring a surface which is what you are often trying to do with a big drip or uneven spots.  i find scrapers, particularly useful for prepping the surface of an already fare piece of work and working on concave surfaces (inside the boat) where sanding blocks don't work particularly well.

h

There are any number of ways to skin a cat, and I think everyone should use the tools and techniques that they can control the best and that they are comfortable using.  Sanding is a technique that virtually everyone who has built anything feels comfortable with, and it works very well.   

Using a scraper, on the other hand, is a skill that takes more practice to master. Likewise there are different types of scrapers, each one having different applications and a different set of required operating skills. 

The reason I like my scrapers for boat building (the ones I recommended in my previous post - because they are stiff and not bendy) is that they excel at fairing.  That is their talent and the primary reason I use them.  That is also why instument makers use them.  With the stiff scraper I am able to see exactly what I'm doing, and it's quite easy to surgically remove drips and runs without dropping into the low spots. You do need to pay close attention to what the tool is doing and not just run it around willy-nilly.  Because it is stiff, the tool cuts the high spots and does not fall into the low spots - the same reason that you use a sanding block.  Either sanding without a block or using a floppy scraper will only follow the existing contours without fairing anything out.

Use the tool(s) that you get you the best results, whether that's a scraper or abrasives.  I use 'em both.  Maybe this is a chance to learn a new skill (just practice on something besides your beautiful boat!).

Happy building!

Brian