1972 SN Promo Project

Depends on whether you can come pick it up before I have to move

Got the stringers bedded yesterday. It took 2 attempts, and let me tell you, the first one was not pretty.

As you guys know, I am figuring all this stuff out as I go. Two days ago I mixed a small batch of epoxy and milled fiber to see how it would act. I used 90 grams of resin and 30 grams hardener to make peanut butter. It worked great and was easy to adapt to my test piece. I calculated the amount i used on my 20" test and extrapolated it out to how much I would need for 2 - 16ft stringers. That is where the train came off the tracks.

For anyone trying this for the first time......DO NOT mix large amounts of 3:1 US Composite Epoxy. I started with 1200 grams and started adding milled fiber. The mixture stayed very liquid for 10-15min and then started to thicken. Right as it started to get creamy, it immediately set up and turned rock hard. I did not know how much heat this stuff gives off when it mixes. The more epoxy......the more heat......the quicker it "kicks" or turns solid.

The second attempt I cut the recipe in half and this ended up being worse. I got the peanut butter into baggies and into the boat to start applying. About 3 minutes into the application, the bag started heating up in my hands to the point I could not hold it. I had 2/3 of a stringer covered in epoxy that was quickly curing and turning unusable. Luckily, Steve and I were able to scrape all the epoxy off into a bucket before it hardened all the way. I threw my gloves, yelled a few choice words, and crawled into a bottle for the night.

Next morning after chatting with Tim, Steve and I gave it another crack. THIS time I only used 200 total grams of epoxy, added filler, and poured it into a ziplock sandwich baggie. I was in the boat applying the butter while Steve continuously made a series of 5 small batches of peanut butter. He kept handing them to me and I kept applying and scraping excess squeezeout. Here is my mixture for anyone looking for a starting point:

150g - resin
50g - hardener
25 - tbsp milled fiber (approx)
3 - tbsp cabosil (aprox)

It was a humid Wisconsin summer day around 84 degrees.








I am pretty happy so far with the results. The peanut butter was still tacky and movable when I left the boat an hour after the bedding. I will check on it tomorrow sometime to make sure everything stayed where it was supposed to be.

Question........What is the best method for sanding excess filler? There were a few spots that did not transition smoothly to form that nice 90 degree curve. I will have to go back and shape some of those areas and probably add a little more material in a few spots that "oil canned" when I was walking in the boat.

Yea......I figured it would not be easy to work with once set.

The hull really moved a lot when I was in it. As soon as I got an area smoothed in I would walk away and the shape of the filler would change. I have 7 support points and a set of boat dollies under the hull and it still moved a bit. I guess I will sand and smooth the areas I couldn't control.