Double plating a hull, Stronger?

[ted655]

Would double stagger or cross plating a hull with thinner sheets of steel or aluminum, (plywood effect), add rigidity & strength to a hull?
I'm wondering if doing this would be easier on round hulls or hulls without a hard chine. The thin sheets could be worked by hand & rolling costs/equipment wouldn't be needed.

[lazeyjack]

no, you can NOT, and even if you could you would have corrosion between, and , of TED ME BOY that a really silly idea)
it is very easy to learn to shape metal. look at my pics
here is an extract from the draft of my book, it was started before CAD really came into things in big way
smaller in length a yacht is the trickier she will be to plate. This is because the sharp end happens faster, as does the stern end. Long boats say eighty feet and up, may have almost no compound in the plates mid ships, whereas the 36 footer seen in the photo pl1 has a great deal of compound right round the boat from stern to bow in most of the plate runs, and only on the top run forward is there little wrap along the boat.
You will see here how narrow in width the plates are. As the boat gets longer and bigger wider plates cam be used. At the bow of a 45 you may start with a 1200 wide plate narrowing down to perhaps 800 at the transom where there is more shape. Some bows may have some “Clipper” in them, which is as the name implies reverse curve in the stem and therefore the plates forwards this can look very nice, but requires skill if a coned bow is used, more on cones later.
Firstly you must go back to the body plan and draw in your plate lines, using the profile designers plan you can draw your first line in and transfer the vertical measurement by scale to the body plan, you will not be able to scale that accurately of the profile but near enough that when you fair in with a soft batten on the body plan, you will eliminate the kinks. Plate lines should run fair, that is without humps or hollows
Draw in all the plate lines Plate OVER the centerline bar as this saves a huge amount of fitting. Of coarse you cannot do this with vee bottom. Or sharp ventral line. Often the bottom plate too can be wide
It is a good idea to take at this stage the amount of “banana” in the plate, you can offer a batten to the boat the same length as the plate you will use, and measure this amount 4800 is a good plate length to handle but I have used up to 6000.The amount of banana will determine the width you can use, at the turn of the bilge 600 is a good workable width. When you have done this on the loft, transfer the marks to the set up boat. Run a long batten along the marks to check for fairness. At this stage you can cut your slot in the frame, so that the inside weld can run under the frame, or if you prefer a half round hole, made with a hole saw, you must never cut these with a meat axe or grinder as the sharp cuts will make a point for a crack to start. This is just sound engineering practice.
When you run the batten on the boat you may find that the frames are in or out. Don’t panic, you must make sure that each frame is the EXACT distance apart,. If you are not using plate where the frames are marked by plotter on the plate, then make up frame spacers out of scrap and tack them around the frame. Do not start trimming, this should never happen if you have built to the loft.To hold the batten on the frames make an L shaped cleat and vice grip to the frame.
You will see in the body plan below

in the photo below you will see the temporary spacers holding the frames at , in this case 400 centres. You can see that master boat builder RalphFerguson has started with a wide plate forward and then had to narrow down, on the top run of this 40 footer. Notice hear that there are no wheeling marks on the outside of the plate, handy when an unpainted hull is specified, the reason being is that we used a synthetic forme rto wheel the plate.The inside of the plate will have the hard marks left from the stretching process
The marks on these plates are water stains, the plates having been stored wet.
Notice that the plates are left high at the top, after the boat is all welded off, the sheer line will be drawn in with the aid of the dumpy level
So when the plates are streched to put banana in, to get them around lengthwose, then they must be formed to make fit around the boat up and down
This means a pattern at every frame, on every plate, ,
the plate is run back and forwards through the wheels, and the patterns are offered up to the marks that are sketched on the plate with felt pen, , the patterns look like thin slices of new moon, It is possible to make the plate fit very accurately

[lazeyjack]

plating body plan

[lazeyjack]

plating

[Arvy]

Hi Lazeyjack,

I was just looking at your picture and found the building order kinda strange, I would think one would start at the bottom plating and not at the shell plating.

As I want to start building my own yacht in a couple of months (after all the number crunching I am doing now..) I would like to know why you started the plating at the sheer and not at the centerline. Just being curious about this.

[lazeyjack]

the deck always goes on first, set the boat acrossways,
then the top run
If you use CAD and all the frames stations and waterlines and buttocks are marked on the plates then I guess you could start from bottom, I would,nt
The top run, sets boat up and down
Put deck on first, but if you put bottom on first you would have to chain block or pulllift the boat into shape
Complete accuracy needs be observed all the way along
I usually build a diamond shaped platform at a high waterline from steel, I then hang all the frames on it building the right way up , saves lots time, easier, an you can see where you are at
i dont know of any pro yards that build upside down
you can pm me if you want, was in Holland Ijmuiden show thisyear