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Planking the hull, running the planks (Part Three)
Planking the hull - by [RG] CC++
(Click on the thumbnails to view full size image)
Preparing the hull to receive the second layer
Now that the gunwale is installed it needs to be sanded to match the ship’s plan. Number all the frames drawn on the hull and determine the height of the gunwale at each frame. Mark the height on the inside of the gunwale and sand it down until the top of the gunwale meets the markers. It is wise to construct one gun and check if it is going to fit in the gun port you have to make later (if any).
When the gunwale is finished the virtual frames can be extended to the top of the gunwale. We need these frames to determine the location of butt ends and nails for the gunwale planking, which needs to be inline with the hull planking details.
Here a picture of how things look like now:
Determining the running of the planks
Now the run of the second layer of planking can be determined. As with the first layer of planking a table has to be created showing the circumference of each frame drawn on the hull. When this task is completed divide all the circumferences by two, and mark the position on the hull. Take one of the planks used for the first layer and put it on the hull following all the markers, as done when planking the first layer. At some markers the stress on the plank will increase, but lay the plank is such way the it follows the markers as close as possible.
When the plank is pinned down the run of the planks can be determined by letting the plank veer to a more natural position. Eye the plank and take the pin out of the plank were you want to let it veer into a more natural position. This exercise will have effect on the width of the planks and the number of planks needed to cover the hull.
Here a picture of the test plank, used to determine the running of the planks:
Let’s examine the consequences of letting the plank veer of its original markers. For example the largest measured circumference of a frame can be 90mm, note that the largest circumference can be found mid ships. To cover this section with 5mm wide planks we need:
90mm(mid ship frame circumference) / 5mm(max. plank width) = 18 planks.
More to the bow of the ship, the circumference of a frame can be 40mm, thus to cover this section with the 18 planks, each plank must be tapered to:
40mm(bow frame circumference) / 18(planks) = 2.22mm wide.
This calculation only holds when the test plank runs through all the markers on the hull, marking the circumference of each frame divided by two.
When we let the plank veer 5mm at mid ships it will not only effect the width of the planks needed here but also the number of planks required to cover this section of the hull. For example:
We let the plank veer 5mm towards the keel. 90mm(mid ship frame circumference) / 2 = 45mm. This creates the following situation:
45mm – 5mm = 40 mm / 5mm = 8 planks (needed for covering the space between the keel and the test plank)
45mm + 5mm = 50mm / 5 mm = 10 planks (needed for covering the space between the water way and the test plank)
We still need to install 18 planks 5mm wide to cover the frame mid ships. So not much effect here. Now let’s look what happens at the bow of the ship. 40mm(bow frame circumference) / 2 = 20mm.
20mm – 5mm = 15 mm / 9 = 1.66mm (maximum width of the lower planks at this frame)
20mm + 5mm = 25 mm / 9 = 2.77mm (maximum width of the upper planks at this frame)
Here we can see the effect of letting the plank veer 5 mm towards the keel. The planks that run from the keel to the test plank get compressed, as we still need 18 / 2 = 9 planks fitted in this section (1.66mm instead of 2.22mm). The planks that run from the waterway to the test plank need more width to cover this section (2.77mm instead of 2.22mm).
We cannot compensate the width of the planks by adding more planks because the planks added will effect the width of the planks at mid ships. So what is said here that you must choose between the desired run of the test plank and the consistence of the plank width throughout the planks.
To correctly compensate for the different plank width stealers can be used. Examining the documentation available on hull planking it is stated that no planks can be tapered half it’s width. So if we look at this fictional example the planks at the bow covering the circumference between the keel and the test plank are too narrow(1.66mm). We can use a stealer here to make two planks run into one.
In the example we need for the too narrow planks 4 stealers of 2 x 1.66mm = 3.32mm. Now we have the created the following situation at the bow frame:
4 stealers x 3.32mm + one plank of 1.66 mm = 15mm (original circumference of the bow frame between the keel and the test plank)
Now our problem here is almost solved, the difference in width between the upper and lower planks at the bow frame is now 3.32mm – 2.77mm = 0.55mm instead of 1.66mm – 2.77mm = 1.11mm.
The only problem here is the single plank of 1.66mm at the bow frame we left over after using the stealers. This plank width must be consumed by the garboard plank, but it’s only 1.66mm wide. Thus we need to rerun the calculation and determining the width of the garboard plank.
Let’s look at the facts that hold for the bow frame. 9 planks of 1.66mm come towards the bow frame and are converted into 4 stealers of 3.32mm running from the bow frame and of course the garboard plank of 1.66mm, which is still to narrow.
What we can do now is decrease the width of the planks that are converted into stealers even further, making room for increase of the garboard plank width at the bow frame.
The minimum width required for the garboard plank is half the original plank width, thus 5mm / 2 = 2.5mm.
Now calculate the width that is leftover for the 8 planks:
15mm(circumference between the test plank and the keel) – 2.5mm = 17.5mm / 8 planks = 1.56mm
Now we can use 4 stealers of 2 x 1.56mm = 3.1mm and a garboard width of 2.5mm at the bow frame.
Of course 1.56mm is way too narrow for the planks that come towards the bow frame we are speaking of, so we need to find the frame position were the planks are just over half the plank width and start the stealers from here. Thus:
9 planks x 2.5mm = 22.5mm, (convert 8 planks into 4 stealers of 5mm and the garboard of 2.5mm)
We need to find the frame which circumference is at least 22.5mm between the keel and the test plank, and start the stealers from there. As a consequence the following facts will hold for the bow frame in our example:
4 stealers coming in and the garboard plank. Thus the tapering needed for the stealers and the garboard can be calculated:
15mm(bow frame circumference) / 5(4 stealers + garboard plank) = 3mm width for the stealers and the garboard plank at the bow frame.
Thus the difference in the upper and lower plank width installed at the bow frame is now:
3mm(stealer width, lower planks) – 2.77mm(upper planks) = 0.23mm
Of course more planks are installed now between the water way and the test plank than between the keel and the test plank, but in fact the stealer counts for two planks equaling the difference.
In this detailed calculation you can see the possible consequences when changing the run of the test plank. It is up to you to choose between the run of the planks and the number of stealers you want to use. The more the test plank deviates from the markers marking the middle of the frame’s circumference, the more work you have to do to compensate in the planks width at a certain frame.
Of course you can determine the maximum amount of deviation between the test plank and the frame’s circumference middle markers without using any stealer but I will show this when using this example calculation in a practical manner on the hull I am building.
Applying the second layer of planks
When all the circumferences of the frames have been measured and noted down in a table, the markers can be applied on the hull. The markers indicate the width of a single plank at each frame. The width of the plank can be determined using the calculation explained in the previous paragraph.
Number all the markings so no mistake can be made in which marker is for what plank.
Here is a picture of the markers and the green line showing the run of the planks:
The bow of the ship however need some special attention. When the markers are just drawn on the bow of ship, then the planks will overshoot them. This is because the planks do not run square over the frames. As is clearly shown on the pictures the angle of the planks with respect to the bow frames is almost 45 degrees. This means that the width of the plank must be larger than calculated. This problem occurs at the bow and at the stern of the hull.
So for instance: if calculated that 18 planks are needed to cover the hull and the bow frame circumference is 60mm, then the plank width at the bow should be
60mm / 18 planks = 3.33mm
However, the planks come towards the bow frame in a angle of 45 degrees so the plank width at the bow will be:
( a x a ) + ( b x b ) = (c x c )
Square root of (3.33 x 3.33) + (3.33 x 3.33 ) = 4.7mm
( a x a ) + ( b x b ) = (c x c )
Here is a link to the Pythagoras
This means if the width of the planks is calculated to be 3mm at the bow, then the planks must be cut to :
a = b
a = square root of ( ( c * c ) / 2 )
Square root of ( (3mm * 3mm) / 2 ) = 2.12mm plank width.
Here the bow of the ship is shown, notice that the bow planks need more space than their width:
This effect is valid for all the planks that do not run square over the frame, this is certainly the fact at the bow of the ship. This calculation must be done to predict were the planks end up on the hull.
The markers of the bow can be calculated and drawn on the hull, then the planking can start. Use the same plank length as the deck, start with the bow of the ship because this is the most difficult part as these planks need lost of tapering.
Make sure all the planks are fitted without gaps between them, and clean the planks regular to avoid excess glue making stains on the planks installed.
Here is a close-up of the planking:
I have a book containing some nice illustrations, here are some of them:
Here a drawing of a Dutch ship under construction:
Here a drawing of some guy bending the hull planks:
Here another drawing of a Dutch ship under construction:
Notes on the planking
As is obvious the planks length is determined by the pattern used and the spacing between the frames. In this example there are three planks between each butt end on a single frame, thus one hull planks must cover four frames.
Do not use short planks on the model, when a planks only covers two frames then use planks covering these two frames besides the other frames it covers. Very short planks that only cover two frames were rarely used on ships, it was easier and structural stronger to use a planks that was a little longer.
Marking the planks
Optional is to mark the edges of each planks using a black pencil to simulate the tar. Doing so makes each hull planks stand out and one can see its outline easily.
Needless to say that the hull planking must be near perfect, as each error in the shape of the hull plank is amplified by the black lines surrounding the plank.
When using small planks make sure to alternate between the planking strips, so no adjacent planks as the same run of grain. This even more amplifies the individual planks on the hull.
Here is a picture of the finished lower planking, you can see each individual plank clearly:
The method of tapering used to make the planks fit is of your choosing. But keep in mind that each planks must be tapered to fit a curved hull. Tapering planks by means of cutting with a knife will produce straight lines which is not always desired. When a planks needs a curve to fit then sand the planks so match the curve and do not stress the planks into place.
Here is a picture of the stern of the model, notice that there are no gaps and no stealers present:
Of course using small planks instead of strips is optional, but as I found out working with smaller planks is more easier. You can plank the bow first and works your way to the stern of the model. The bow planks and the stern planks are difficult to make, so using small planks you can concentrate on this part without concerning about the tapering needed mid ships or at the stern.
Some after thoughts on the detailing
Remember that trunneling the hull is optional, you can leave it out. I am no expert, this is my second build, adding detail is no guarantee for a successful model. It is up to the builder what detail to add or leave out.
For instance: I know my deck planking is probably to wide, because I use the wood supplied with the kit which is 5mm wide. The kit suppliers use the same wood over a range of kits regardless the scale. Also my nails might be to big for this model, I didn't check it.
But I am happy with the way it turns out, you build the model for yourself not for others, so don't bother with the details if you don't want to. Leaving out details does not mean the model will be inferior, maybe it will even be more beautiful than a model with a lot of detail. In the end it is the builders skill that counts, not the number of cannons.
What I want to say is, don't believe blindly all the advise of the so called "experts" including myself. Build the model the way you think is comfortable, building a wooden ship is for fun not to impress others because there will always be someone better than you and I.
If you have any questions, please ask!
Back to Part One | Link to Part Four
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