butterfly for Spindrift 10N

[okie geo]

I just bought plans for Spindrift 10N and am in the thinking stage of construction. Any suggestions about the stitch and glue process and early phase of construction would be appreciated. Does one glass just one side of the butterfly joint or both sides before stitching the two halves together? I liked the suggestion of using kevelar tape for that joint. Has anyone used nylon ties instead of wire for the stitching?

[Hirilonde]

Yes, tape both sides of the butterfly "weld". 2 layers on the outside and 1 on the inside. Kevlar is definitely more puncture proof than glass, and is used on some sailboats as a layer for that reason, Hinckley does it. I don't know that it is better for the weld.

[okie geo]

Thanks, Dave. I see you are from Charlestown. We lived in Kingston for 4 yrs in late 60's, a beautiful place.

Some of the directions in the plans are confusing, so I may pester you again.

[hokeyhydro]

fiberglass is fine for the butterfly - both sides. You can nylon zip ties rather than wire, but the holes will have to be larger. I prefer copper wire, - easier to control the squeeze with wire twist, and they can be loosened a tad and tightened again for adjustments - once, twice and they may break, but are easy to replace. .

[Hirilonde]

You can nylon zip ties rather than wire, but the holes will have to be larger. I prefer copper wire, - easier to control the squeeze with wire twist, and they can be loosened a tad and tightened again for adjustments - once, twice and they may break, but are easy to replace. .

I agree, I like wire. I don't know that copper is better than steel, not sure that it matters, but the small holes are better, especially in areas you may finish bright. I also like that you can remove the wire after filets and tape are done on the inside. I much prefer making the filets and taping in one cure period and skipping any interim sanding. I hate sanding and these boats have more than enough even if you use sanding saving techniques.

[Howard]

To Okie, since you are formulating the build process in your mind, a few things I'd suggest:

First, when laying out the patters, measure carefully......then before cutting anything, measure again. If in doubt, measure a third time.

When you are certain your cut lines are drawn correctly, it is best to cut both matching sides / bottoms at the same time. As it is difficult to cut accurately to a line, cut slightly outside the line, then plane both sides to the line at the same time. You will end up with two panels that are both accurate and exact mirror images of each other. You won't get that if you try to measure and cut them out individually.

Same goes when it's time to glue the butterfly joint on. Either glue them at the same time, or if you don't feel like that is possible, glue one, then stack the second exactly on top of the first when you glue it. Goal is to end up with two matching halves that are exact mirror images of each other. Hundreds of boats have been built using glass tape. It's plenty strong enough, provided you let it fully cure before you stress it out. You won't believe the tension that is created as you bend those forward panels into place. A fully cured, glass taped joint will hold it. A partially cured joint won't, regardless of what kind of tape you have used.

Same goes for the wire. If I had both options at hand, wire or zip ties, I'd use the wire. You will need to apply a lot of force to some areas to get the joints to come together and twisting wire will do it. You can tighten or loosen wire as needed to get good joints. As some areas will be highly stressed, I'd suggest the same thing for the epoxy "tack welds". Let them cure. Small dabs to hold them in place will do it, provided they are cured when you take the wire ties out. Take care not to involved the wires as you go and you will have no trouble getting the wire out of the way later on.

[okie geo]

thanks, Howard. these suggestions will be very helpful. geo

[Hirilonde]

Everyone has different ideas on the best way to do things.

Take care not to involved the wires as you go and you will have no trouble getting the wire out of the way later on.

I made my filets and glass taped over all of my wire ties, let it all cure and then removed them. I made no welds at all. I did not find it difficult at all. It does require a heating process. Some use a torch and others use a battery, but once you have done a few it gets quite easy.

[Charlie Jones]

I do the same, and have on every boat I've built tack and tape. Using a Jump-it, takes me about 1/2 hour to pull the wires on something like a Core Sound.

I prefer steel wire also.

[Howard]

I'd have to see the heated wire trick work. Not doubting it would work, just never tried it. Seems like the trade off between the two methods is the choice of a "tack weld" step and any extra work to clean up the joint prior to fillets and tape vs. the additional step of heating the wires to pull them. My first thought was the wires would get in the way of making the fillets, but not if the fillets are large enough to bury the wires. It seems to me it would also leave the wire holes in the inside fillets and maybe even the ply sides? Part of that might get filled when the outside joints are taped, but no assurances small voids won't be left. But since they are fully encapsulated inside and out, it probably doesn't matter.

According to some references, fillets for 1/4" ply should have a 3/4" radius (fillet tool being 1.5 inches diameter). That would be big enough to bury the wire. Mine were not that big. But had they been, they would have also buried any and all of my tack welds. I think the mistake of tack welds is making them too large. A little dab will do it (but it has to be cured).

I keep mentioning the cure issue. I had a bad experience once using a slow cure hardener at temps in the 60s. I did it to gain the extra work time with a too large pot of thickened epoxy when making fillets. It was mixed right and set up hard enough not to dent with a fingernail, but even after a couple days, it was not set up hard enough to hold a stressed joint together. It slowly pulled apart like taffy. The right hardener, time and temps are the three key considerations in getting a fully cured joint prior to inducing all the stress. If you use the medium or fast hardeners to get things moving, mixing small batches and getting them out of the mixing cup is the best way to keep thickened epoxy from going off before you are ready.

[Charlie Jones]

after making the wire ties, you go in with a screwdriver blade and push the inside tight into the corner. This adds a tiny bit more to the pressure, and gets the wire out of the way of the filet...

And yes, the external taping covers any little holes very well.

Long ago I did a post about using the Jump-it and a piece of copper wire to heat the tie wires. Search doesn't seem to find it, but in a nutshell, clip the wires close on one side. Walk along and "POP" the wire with the jump it, touching both ends of course, then go back with pliers and pull the wires. Takes about 30 minutes to do an entire boat, like a CS 17. I pop about a dozen, pull .'em, then do some more.

On the epoxy curing. 2-1 ratio epoxy doesn't seem to like cooler weather, say under 60. WEST's 5-1 ratio does better in those conditions, and that's about the only time I use WEST anymore. Of course, down here on the Texas coast, all I BUY is slow hardener- Carla doesn't even ask anymore- just ships it

[Steve W]

I used copper wire and tacked it all togeher between the wires with thickened epoxy. I took the wire out after the taks hardenned and it all stayed togethe nicely. I put masking take on the outside of the joint, and then fileted and glassed the inside in one step. The masking tape prevented the filet from running out and once the epoxy started to kick I peeled the tape off. After hardenning I radioused the evterior a bit and taped the outside. No issues and it came out nice.

Take Care,

Steve

[hokeyhydro]

To heat & pull copper wire I have used a small butane lighter or a soldering iron. The lighter was fast - 5 or 10 seconds of heat, grab wire with pliers and slide it out. Usually I can untwist the wire - then snip off one end and heat the other. I've also used tack weld method with a mix of resin and fumed silica (cab-o-sil) runny enough to squirt out of syringe. squirt, lightly push in joint with gloved fingertip - repeat . . .

[Charlie Jones]

I used copper wire and tacked it all togeher between the wires with thickened epoxy. I took the wire out after the taks hardenned and it all stayed togethe nicely. I put masking take on the outside of the joint, and then fileted and glassed the inside in one step. The masking tape prevented the filet from running out and once the epoxy started to kick I peeled the tape off. After hardenning I radioused the evterior a bit and taped the outside. No issues and it came out nice.

Take Care,

Steve

Yep- that works fine, but it's an extra step or two, which is why I never spot tack with epoxy. So much quicker to just fillet and tape, then yank wires from outside, for me anyway.

But hey- whatever you are comfortable with

[Hirilonde]

.................but it's an extra step or two, which is why I never spot tack with epoxy.

I hate extra steps

[Charlie Jones]

lol- me too, particularly when I'm building for a customer.

Even just for me, I do too. Seems like a waste of time.

I guess that's a difference between someone building on their own time, as time permits, and someone working at it every day though.

If someone is comfortable doing it like that, so be it. I'm not

[djmeaney]

I built a Mirror Dinghy about 35 years ago using the stitch and glue method. I think that the directions just called for trimming the the copper wire as close as possible to the panels once the glue had set. Don't recall that the copper wires were removed -- just glassed and epoxied over. Is that not acceptable any more?

Dan

[okie geo]

tehani, what is this jump-t thing you mentioned. something to heat the wire. I have used a small blow torch, like plumbers use. It worked OK.

[Hirilonde]

It is a rechargeable jump starter. It is a battery with connected cables and some have meters built in.

[Charlie Jones]

Exactly Dave.

I clamp a short chunk of heavy copper electrical wire in each main clamp, touch one wire on one end of the tie wire, and just "POP" the other. That's all it takes- the wire gets red hot very quickly, doesn't scorch the outside of the ply and is easy to pull. Fastest way I've found, bar none.

As I said before- I can pull all the wires from something like a CS 17 in about 20-30 minutes.