Ply on Frame/Stitch and tape

Hi All,
2nd post on here so getting used to it now,

I have (possibly unwisely) bought a cd full of boat designs, which turn out to be largely photocoies of 1950s/60s magazines.

There are however a selection of design that are quite attractive. These are largely ply on frame design.

Now my point is, will the ply on frame technology of the 50s/60s transfer to modern Stitch and tape do you think? (I told you Im an amateur here ) or do you think stich and tape will prove too flimsy, I do appreciate some tweeking of the design will have to be done, but will the transfer stand in theory?
Hope this all makes sense to you all, Any observations/points/info will be hugely welcome
Thanks
Sam

 

Yes many ply on frame designs can be modified for S&G. S&G does not produce a flimsy boat, just the opposite. Get Sam Devlin's book and he will describe the difference and how it is done. That does not mean that all boats should or can be done in S&G though.

 

Thanks Tom,
I do actually have Sam Devlins book in my library (of about 10 books) so Ill have a reread of that, I dont intend to go over at most 20' or so, so I dont think Id be stretching the idea, my main concern is that i would be underestimating the strength required in a boat,
Thanks again, Its the permision I need to start experimenting with designs

 

Tom,

Good job with that permission. Wish I had of asked much earlier in my life.

BidBowen,

Stich and glue does not mean the ply joints cannot be strong, and it does not take a lots of glass/ epoxy to get good strength. Just make up a joint with a 2 ft section of plywood in both types of joints then pull on them till you break the joint or the board. Its the best way to convince yourself, and a lot cheaper than building a boat and not trusting it.

Marc

 

Here is a company that offers plans in S&G and has some good pics. Just more info for you. They are not weak boats. http://www.bluejacketboats.com/bluejacket_25_5.htm

 

In order to convert from one to the other, you must understand both methods fairly completely. It is a case of reverse engineering followed by rengineering- you can't just "do it differently". Many boats will not convert easily. The S&G hull may want to be thicker for easiest working, and then not be able to make the bends at the ends. Then you go back to thinner with more glass added later and pretty soon it costs 50% more than the PonF boat. If you undertake an adaption, it helps to be willing to adapt the hullform a bit to take advantage of the strengths of the method. If there is some particular aesthetic element you are determined to preserve exactly, stick to the original method.

I think the plank on frame method is generally more intuitive for a first time builder. You work on a solid frame and can see what you're going to get.

Stitch and glue involves having a little faith that you will eventually discover you have built what you set out to build. The first time you build this way, your faith will be tested once or twice.

 

Hi Phil,

Good point, I apreciate what your saying here, Im not trying to copy the boat exactly, Its what Im aiming for but I have a wide target,
I dont know if I understand both methods particularly comprehensively, thats probably a question aimed for the proffessionals view of me,
with that in mind I believe I understand enough to have a go, Im starting fairly small so I see it as a challenge, wether or not I would be successful remains to be seen. that said I accept your point that as a beginer for ply on frame,
When it comes to it I have not made a final decision on what I will do anyway
Thanks again for your opinion, I do apreciate it,
Sam

 

There was a post a week or so back that referenced a stitch and glue design at

http://www.ptwatercraft.com

I spent the money and bought the construction manual, not because I am building the boat, but to get some detail on how they do it.

It has a lot on common with Sams book, and video, but it shows just how involved S&G can be.


In both cases they use the phrase "adjust the wires to bring the panels in line" is a two second throw away line that covers a lot of sins.

I have a couple of S&G projects coming up, and I will be building a 'nest' to assemble the panels in, to remove the 'doubt' in the alignment process.

The thing that sells me on the idea of S&G is the virtually smooth and seamless interior which doesnt attract dirt and moisture the way that framed construction can. A few other posters also commented on how fasteners can just 'dissapear' from hulls from corrosion. I havent come across it myself, but anything metal can be problematic in boats.

 

Rwatson,

Don't get too concerned about "adjust...to bring..in line", this a matter of correcting a position of less than .030" not gross adjustment to the shape of the boat. If you are making your own panels from tables there might be some concern, but I don't know how you will make a nest or tool accurate enough to help yourself. The entire concept is to avoid that extra tooling and cost. Too bad you are in OZ not Texas or you could come see my Pygmy kayak. It was built in the living room in Japan with nothing but a couple of saw horses. Works great.

There is really no "doubt" about the alignment at all if you can make 2 identical parts.

 

Hi Upchur

Thanks for those words of encouragement, though I was thinking more of the bigger project for alignment accuracy. But besides accuracy, the reduction of time wasting processes is also important to me.

For example, in the kayak project I have built a test hull out of mdf to check out the process, and some of the techniques can do with considerable improvement.

For example, in the plans, it gives dimensions for three temporary frames that are fastened to the two keel panels, and that the other hull panels are offered up to.

For the same amount of work, I can cut out three female jigs - where I can simply drop the panels into, as they are wired together , doing away with all that floppy 16ft narrow planking trying to drop away to the ground.

Likewise, when the hull is wired together, you are supposed to pin it to a straight plank to pull the keel line flat and straight, and somehow ignore the wire ties that are already in the keel. How much easier is it to fasten it to a decent straight edge ( aluminium or steel ) from the first, and save all the hassle.

So basically, the building jigs are also intended for efficiency as well as increased accuracy.

For a one off, maybe I could put up with the aggro of 'living room carpentry', but I am planning on doing boatbuilding workshops, and for student builders, having much easier methods will make the experience a lot better.

 

rwatson,

I don't know what might be different about mdf instead of Okume marine grade plywood, but I certainly was working alone and had no issues with "floppy 16 ft panels dropping to the floor". Sounds like you built the identical boat that I did. I just have a few questions.
Where are you going to mount your female molds to keep everything in line? a strongback? Thats part of the tooling to be avoided. What will you attach the aluminum or steel frame to? The strongback? How then will you attach the aluminum or steel to the keel line? For the wire ties on the keel line - since the wire can be pressed up against the keel in a very consistant manner it should not interfere with making the keel straight. Just one suggestion (based on my problems) do use a 4x4 like they suggest. I used 3/4 ply sheets (full width to protect the floor) and they lifted leaving me with a hogged keel. Created a boat that would only go straight. Fixing it was a long term issue.
I wasn't going to let out my secret, since my stupidity had nothing to do with stitch and glue making a straight boat.

Living room was the only place for me to work, not my choice. My point is that if it can be done in a living room with minimal tools, not much can be easier. If I had of spent the $100 for the 4x4 there would have been no issues at all.

Have fun,

Marc

 

Well, what held the 16ft panels from flopping off to 1 side when you were trying to stitch them together ? You have to either temporaly tie them roughly in place while you stitch, or gravity will make them fall to the floor. That situation is not very condusive to easy working or accurate assembly.

As you said - you needed one, and the designs specify a 'strongback' - thats what the 8ft length of wood is - a strongback! There is NO avoiding it if you want a good result.

aha - you are very right - the steel or aluminium will be the 'strongback' and hold the frames in line and at the correct height - (at a comfortable working height on trestles) and will also have matching holes drilled in it - so the wires will pass through the ply and through the strongback - thus pulling the hull down tight and straight for the sections that need to be flat. There is nothing 'consistant' about wire wrapping - so you cannot assume they will all be the same thickness when pulled down to the level support. Even cable ties can vary depending on the angle they have been laid on the keel line.

Honesty is the best policy - after building the test hull, this was a really obvious problem in the building process - getting a straight keel ( vertically and horizontally) makes a great deal of difference to a small boats performance.

My preference for steel or aluminium is because it is %$^*& difficult to find straight bits of softwood timber without machining them. Also, steel and aluminium can have thin enough sections to wire directly to - the idea of wiring the hulls and then having a seprate step to pin them to the timber seems inneficient to me.

Thats what a lot of stitch and glue builders who have problems say - but they, and you shouldnt feel guilty, its a flaw in the process that makes lots of warped S&G boats. Even with a 4x4, you would have suffered - its a mediocre method. The 4x4 is a poor mans strongback - and is actually more difficult to use and 'build' than a proper support.

yes, - its a dedicated person who has to work in limited facilities, and more power to them. I am lucky not to have the limitations - and I go to a lot of trouble to avoid as many problems as I possibly can foresee. A boat build will have enough problems even after getting rid of the obvious ones.

You havn't shown it easy to build in limited facilities - but in fact your honesty has revealed how poor facilities tend to produce less than optimum results.

 

rwatson,

Good luck with the classes. Actually due to later experiences, my next boat will be strip planked. I didn't like the look of kinked plywood even though I think it probably makes just as good of a boat as completely smooth strip planking.
Using wood working glue for the stripping (not epoxy) is the key for me - no need to take excessively long to install the strips. I will glass and epoxy inside and out of course. If you taper each strip in a consistant, mechanized fashion it does not take very long to build the hull, but it reduces the opportunity to make those really gorgeous boats with the complex surface patterns like Nick Schade makes. I do wish I was that kind of a craftsman.

I don't have the living room limitations anymore so now I can try other options.

I still believe it was my limitations, rather than the process limitations that caused me the problem.

I would really like to see one of your student / class built boats. Have you choosen the boat you will build?

Marc

 

RWatson,

Without knowing the design or layout of the boat you are building, its difficult to know what problems you are having. You seem to be offering a lot of blame to the the S&G process. Is it possible that you may be doing something wrong? Like any project, S&G demands a certain understanding, proper execution and sequence of events for a good result. Thousands have done it and thousands of excellent boats with proper shapes have been the outcome. Where the floppy panels wandering about come in is a mystery since that is not normal. In large boats where the builder must climb inside during the early stages, adequate alignment and support is necessary to prevent distortions.

 

Tom,

rwatson and I were discussing a 16 ft kayak, possibly the exact same boat. The panels on mine were 4mm Okume and certainly would be "floppy" and in need of adequate support while wiring up the joints.
The only real difference seems to be a preference for more support during the intermediate steps before glueing the joints. In this size of a boat you don't really get an opportunity to get a "straight" hull until it is all together, and then you have to force the keel line straight for ~8ft.
I would make one again in the prescribed manner, a second chance would improve a lot of detail in the execution. Actually I have plans for a 20' CLC triple gathering dust - but my kids are grown up so I don't need something so big and heavy.

Also I have found I am not good enough to be happy with my "clear" finishing. So I would paint, which opens up the possibility to round over the seams between the panels. I would copy Jim Brown's Searunner construction and tape the seams on the inside, round over the outside joints to make the seams less noticable, then glass the outside to finish setting the shape. The rounding would expose the three ply layers which would not be nice looking unless you paint. But all that complication is just to satisfy my desire for rounded and smooth. Perhaps the current hybrid construction, panel hull and strip planked deck, would allow me to round over the hull (painted) and get complicated with the deck pattern to try and compete with the craftsman with a varnished deck, which gets noticed the most.

So many choices, so little time, and such limited tolerance on the household budget controller. Perhaps in the next life.

Marc