Core Sound 17 #221

[SUKIE]

Randy,

this is a mistake I've made too, and boy did I learn my lesson. In my case I hadn't stirred the epoxy enough. Now I STIR, STIR STIR!! Then, after the epoxy is well mixed you can add your thickener of choice. STIR again. This should all take almost 5 minutes, depending on the amt your cookin' up.

[Greg Luckett]

I use no more than 3 pumps of epoxy at a time for thickner jobs, and it takes me about 30 to 60 seconds to properly mix the epoxy, then about another minute to mix in the thickners.  Oh, I also use the fast hardner, and it is West Systems at this time.  When I have used up my stock I intend to start buying from Graham and Carla, but expect to operate in a very similar manner

When the temperatures here get up into the 80s I start shifting to the slower hardner, but only if the temperature will stay that high well into the evening....a rare event here.

[Randy C.]

Greg,

I meant the thickener. I'm sure it was mixed. When mixing I clean the edges, mix, clean edges, etc. for at least a minute. Then I add the thickener and mix some more. I think I just didn't have the mixture thick enough. I will pry a little like Graham said and see if anymore comes loose, then reglue and hope for the best.

[Greg Luckett]

Randy C.,

I was making mine too thin too, then had a pro teach me the correct way.  It really needs to be as thick or thicker than smooth peanut butter.  When I then apply it to a freshly wetted surface, it tends to dilute a bit and turn out just about right.  I never apply it without the surface being wetted with just epoxy first or it would need to be thinner than what I now use.  I also try to squeegee the wetted surface to both save on the amount of epoxy used as well as eliminating as many drips as I can.  That's another thing I learned the hard way.  My first boat had lots of drips, which I thought at the time, "What the heck, I'll just sand it later".  Man was that a mistake.  That led to many learnings and then how to make up fairing compounds..... ;D  I hate sanding most of the time, never having reached the zen state I think Charlie may get to. ;D

[Randy C.]

Hull Parts...

The sides are in the first picture. The second picture is the butterfly. The third picture is the bow with the fiberglass joint, and a block of wood for support while opening the butterfly.

[Randy C.]

The Grand Opening!! These were all taken shortly after opening the butterfly. I now have the stitches about half done.

[Randy C.]

Seat stringers...the morning after. The joint let go in one place.

I checked the glue tonight and it is very hard, so the mix should have been O.K. I still feel I didn't put enough filler in the mix. I tried prying the stringers off to see if it was all bad or just one spot. It's only one piece, the rest of the stringers seem to be tight, it pulls the wood apart when pryed on.

Greg,

I'm used Hemlock fir for the stringers. No, I didn't wet before brushing on the epoxy. I didn't because I felt it was thin enough. As it turns out it must have been too thin.

[Gordy Hill]

Randy, I see your problem. You have way too much room for building a boat!

[Randy C.]

Gordy,

It's funny how a 2 car garage becomes a no car garage when you start building a boat.

[Garry]

Foul! No fair spending all that time cleaning and straightening up before you take the pictures!!!

[Randy C.]

Garry,

I really didn't do that on purpose. It was just to point that I needed to pick stuff up, sweep ,and start again. It certainly isn't always that clean!!

Greg,

After thinking long and hard, I don't think I wet the area under the seat stringers before doing the thickened epoxy. I did wet the edges of the plywood before the thickened epoxy for the scarf joints, and they are fine.

[Randy C.]

I have solved the mystery. When I did the scarf joints on the plywood I used the graduated cups. When I mixed the epoxy for the seat stringers I just used the pumps because I knew I wouldn't use as much as the first calibration on the cups. This morning I just happened to look at the pumps on the epoxy bottles. The pump on the "B" jug has a clip on it so that a 1/2 pump mixture can be made. So, now I know that the seat stringer mixture only had 1/2 enough hardener in it. I feel better knowing what went wrong. I wasn't having much confidence in my work. Now I'm ready to get back to it.

[Charlie Jones]

WHOA there. That clip is so it makes the CORRECT mixture. The two pumps are the same- you should pump ONCE on each. With the clip in place you get twice the resin than hardener, thus 2 - 1.

You should NOT pump one once, then the other twice. ONE stroke on each WITH the clip.

[Randy C.]

O.K. Now I'm confussed. The "A" pump doesn't have a clip. 1 "B" pump has a clip, the other "B" pump doesn't have a clip. So, what's right???

[Charlie Jones]

The one with the clip most likely. Look in the bag the other pump came in, sometimes the clip is not attached.

If you took the clip off, then you'd need TWO strokes of the "A" pump to one of the "B" pump, which could get really confusing.

By the way, I use the pumps all the time- always have. And I never have any problems with incorrect mixes unless I forget how to count. And I do the same as Ray on this one- one pump resin, one pump hardener, one pump resin, one pump hardener- then I don't have to count

[Randy C.]

It all makes sense now that I realized there's a clip!! I will get it right from here on out. THANKS!!

[Designer]

The hardener ratio is 1 : 2 resin. The pumps are identical and pump B has the clip which gives you exactly 1/2 stroke so that with one pump of resin and one pump of hardener gives you the right mix.

If you add more epoxy to your failed joint you will be bonding to weak glue. I would try to scrape out as much old glue out of the joint as space will allow and I would add some mechanical fasteners to assist the marginal bond. I would put 3/4" bronze or stainless ring nails through the ply into the seat stringer on about 6" centers.

[Greg Luckett]

I probably was not supposed to, but that is how I clamped the stringers to the sides on my Spindrift.  I used siliconized bronze boat screws from McFeeleys.  For me, it is a lot quicker than trying to get the long clamps in place and then also having the stringer slip out of place, and I can leave the screws in if I choose to.  I predrill and countersink the exterior of the hull, then temporarily clamp the stringer, then drill a pilot hole, then insert the screws, then remove the clamps and wait for the epoxy to set.  This also allows me to move around the boat on its cradle without worrying that the stringer will shift before the epoxy sets.

[tom151]

I tried prying the stringers off to see if it was all bad or just one spot. It's only one piece, the rest of the stringers seem to be tight, it pulls the wood apart when pryed on.

Randy,

I've had some luck cleaning out gaps like that by using pieces of a broken bandsaw blade to fit into the narrow gap between similar parts. In your case I might try cutting a couple of pieces of flashing to protect the plywood skin and help the blade to work better against the surface of the stringer. Hacksaw blades might work as well.

[Randy C.]

Graham,

I can get the two pieces that came loose off so that I can clean them up. The other pieces that are still attached I will nail as you suggested. Greg said he used siliconized bronze screws. Would screws be O.K. if I can't find the ringshank nails locally? If screws are O.K. what size should I use?

Are siliconized bronze screws different than bronze screws?