Thread: Gallery of stitch-and-glue building photos

Hi Ross,
Thanks for posting.

Warning novice question, why do you use zip ties and not wire. I would have thought the larger holes required discount any advantages.

Cheers Mike

Dear Mike,

Thanks for the reply. I understand your concern about the size of the holes, and it worried me on the first boat I built using cable ties instead of wire. However, it doesn't tend to be a problem when taping up the boat, as the holes get filled during the filleting process.

I used to prefer the idea of wire and the associated small holes, but the practicality of inserting and tightening ties is very much in favour of cable ties. I frequently need to use one hand to hold components in alignment, and it is still a relatively simple process to tighten a cable tie using the thumb and forefinger of the remaining hand. Also, the width of the cable tie distributes loads withing the drilled hole far better than is the case with an 18ga wire - there are far fewer cases of ties breaking through the wall of the drilled hole, which can be a problem with wire.

Having said all that, it really doesn't matter which system you use - just use the method with which you feel most comfortable. I strongly recommend Sam Devlin's book, "Devlin's Boat Building" - a concise but valuable treatment of the stitch-and-glue subject.

I hope this helps - let me know if you would like more information.

Ross Lillistone

A couple years ago I built a Murray Isles 15 ft stich and glue canoe and used cable ties for the same reason. I was doing it single handed and it was easier to tighten the ties while holding panels in alignment. No sign of the holes once finished. Must admit it was taped seams only and painted as well
Pete

Nice job Ross!

I think the cable ties work best when the interior is "stitched" as you have done, and then remove the ties before glassing.

Glassing over the ties ends up being a bit problematic if you don't do that, whereas wire can be pressed down and countersunk to an extent. The ties aren't too obvious even in clear finished boats.

Thanks for the link!

P

Howdy all,

To choose cable ties or wire may depend on the tensions in the plywood too.

I don't know what the difference was but the first Eureka 155 I tried to stitch up broke all the cable ties.

So we moved to wire in the ends where the tensions were greatest.

The little 13ft Eureka used to stitch up fine with cable ties but was specified in 5mm gaboon which is not available. You have to move up or down a size (6mm or 4mm).

So I don't know whether we got a bad batch of ties or whether it was the extra tension in the ply. I'd be playing it safe after that experience for my own boats - I'd just use the wire off the bat to prevent any problems.

BTW the plans for the 13ft boat are no longer available in case anyone is tempted to ask. It had stability problems with adults aboard reportedly.

MIK

Midge,

Thanks very much for the kind comments about the posting. I agree with you regarding the business of taping over existing ties. I always use the "tack weld" method of doing the initial (very small) fillets. After they have cured, I remove the cable ties and then run the full-sized fillet over the top of the tack fillets and the bare timber where the cable ties have been removed. If the "tack weld" fillets have been in place for more than about 12 hours, I abrade the epoxy surface thoroughly to ensure a good secondary bond when the full fillet goes over the top.

Mik,

I haven't had any problems with cable ties breaking, but that is probably due to the care I take to ensure that the panel shapes are developable, and that twist is kept even and as gentle as possible. In the attached photo of "First Mate" you can see that the cable ties are spaced a long way apart - the drilled holes you can see are at 100mm intervals, but most of the ties only have to go in at every third hole. One exception is in the case of the f'ard sections of my "Flint" design, where I deliberately introduced the maximum twist that I could get away with, in order to produce a fine and deep entry at the stem. In that area I put ties every 50mm, and make sure that I use very high-quality ply.


Ross Lillistone

Hi Ross,

The Eurekas are quite developable so that ain't the problem )

I'm talking canoes - dinghies are bit less stressed in the ends as you don't necessarily want the amount of hollow in the front foot or so that allows a canoe to track well in waves and wind. I think that is where the extra stress comes from.

But it was still interesting that the little canoe worked OK with cable ties and the bigger canoe didn't.

One of those questions that can't be resolved without doing lots of tests - so I just stipulate copper for those particular boats.

(actually I just checked - THE MAN who built a Eureka in 2 weeks used cable ties - so maybe we did have a bad batches before.
http://www.woodworkforums.ubeaut.com...ad.php?t=66417

Most builders end up using the same method as you are - doing the "microfillets" first between the ties then removing the ties and putting a bigger fillet over the lot.

I'm such a lazy boatbuilder I hate the idea of the additional labour even with the improved appearance - as though it is possible to make the copper sit low enough to fillet over in one hit, you cannot always count on it. Saves a day or maybe 2 if the epoxy is a bit slow. But not totally reliable for perfect appearance.

Best wishes
Michael Storer

Thanks for the comment, Michael.

I think you are right about the cable tie batch. I've found that it pays to buy the very best quality that you can, as the extra cost is tiny in comparison with the overall job (the same applies to epoxy, additives, fastenings, paint etc - quality pays off).

Your comment about the two-step process is important. I find that there is a fair bit of time involved in preparing the first "tack" fillets for the secondary bonding, although I'm sure that many people wouldn't bother with that step. However, even the best is not quite good enough when dealing with boats, so attention to secondary bonding is very important.

Sam Devlin is quite specific in stating that wire ties MUST BE REMOVED after filleting and glassing, and he goes to extreme lengths to get them out (either using DC electricity or propane torches to heat the wires prior to pulling them through the joint). Sam knows more about stitch-and-glue in a commercial environment than just about anybody, so I heed his warnings about leaving cut-off wire ties in place after epoxying. If the ties are pulled out, the remaining holes must be filled - I think I'd rather use the "tack weld" system in the first place.

Having said all that, all systems will do the job, as long as the builder pays attention to detail. One good point about cable ties is that they don't give you "needle stick" injuries!

Ross Lillistone www.baysidewoodenboats.com.au

Originally Posted by RossL

Sam Devlin is quite specific in stating that wire ties MUST BE REMOVED after filleting and glassing, and he goes to extreme lengths to get them out (either using DC electricity or propane torches to heat the wires prior to pulling them through the joint). Sam knows more about stitch-and-glue in a commercial environment than just about anybody, so I heed his warnings about leaving cut-off wire ties in place after epoxying.

Since Sam isn't here yet: Ross, why do you think that is?

In a canoe at least, the wire is so thin I can't even begin to imagine a problem. If one was using gal wire or some form of tiewire that wasn't copper, I could half see the reason, but it all ends up encapsulated in any case.

Perhaps this is a leftover thought from the polyester days, when "waterproof" wasn't quite what it is today?

Cheers,

P

Dear Peter,

I've pondered the question myself, and I believe it comes down to two things: -

• differential expansion of the wire. For copper, I don't see that as being much of a problem. In my work, I remove ALL of my temporary screw fastenings (even though they are stainless steel) for the differential expansion reason. Eventually, there will be a de-bonding between the screw and the epoxy, leaving an avenue for water movement. Even though the wire is under layers of glass, there are other paths which will allow water to migrate to the wire. I try to leave NO fastenings in place if at all possible, but where it is unavoidable I always use silicon bronze. Having said all of that, I don't think it is a huge problem in practice if the boat is dry-sailed;
• Sam Devlin claims that wires will eventually migrate to the surface at one end or the other. As you have suggested, I don't imagine it being much of a problem with a small boat and copper wire.

My experience has been that when someone with specialised experience makes a comment like Sam's, it is worth thinking about. I hate to think of how many times it has taken me several decades to finally understand a very simple concept....

Ross Lillistone www.baysidewoodenboats.com.au

Well thankyou,
I hesitated to ask the question but given the detail in this discussion I'm glad I did.

Certainly helps hearing from people who have been there done that.

Thanks again

Mike