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[Greggy1964]

Planking issues on deep heeled coastal and fishing craft.

The following is hopefully a clear description of how I tackle planking a model boat hull. At the end are a few photos of my models that will hopefully show my system works very well. Both hulls are lapstrake as opposed to carvel or edge to edge planking described here but the principles are basically the same for both planking methods.

Here goes.

When planking a boat hull it must be realized that the girth of each frame is wider at the centre or mid-ship section than near the ends of the ship. On ships with a deep heel such as coastal drifters and sailing trawlers the girth of the frames towards the stern are actually wider than the mid-ship section and so the lower 6 to 10 planks are much wider than mid-ship width.

The trick is to decide first how many planks per side you need forgetting width of planks at this point in time, this is best done by laying a strip of paper along the edge of each frame from keel to deck to work out its half girth from keel to deck line.

Let’s say for instance your ship has 20 planks per side port and starboard and you have all your strips of paper for each frame (hopefully at each frame your strips match for length port and starboard!).

Measure the mid-ship frame paper strip and using a calculator divide this by 21 divisions giving you 20 planks and this will give you the width of each plank at that point. It will be noted when this is done for the subsequent frames forward of mid-ship frame to the stem, that each plank will get narrower (rather like the staves on a wooden beer barrel). Each set of plank widths is now transferred from the paper strip to its matching frames either side of the keel.

On this particular model the girth of the frames as mentioned earlier will get wider towards the stern, this is because of the deep heel where the keep slopes slightly downward from stem to stern when the ship is floating level, and here we take a different tack.

We want the first 6 to 10 planks up from the keel to be wider as we come back from the mid ship section so the top one of these particular planks reaches the point where the stern post disappears up into the hull and the rudder post pokes down through the rudder port. We'll go with ten planks from keel to tuck at this point for the sake of argument.

The 11th plank will then cut across the side of the stern post and the planks extreme end will stop on the stern posts aft edge at the rudder port If you grab a piece of planking stock and cut across the end at about 20 degrees and toss away the wedge just cut off, this new face would marry up against the side of the stern post.

Plank 12th and subsequent planks run past plank 11 and meet their opposites on the centre line of the boat from the rudder port to up and under the lower edge of the transom. If you google Brixham or Lowestoft Sailing Trawler and look at some of the photos during restoration of these lovely ships you can see the run of the planks in this difficult to visualize area.

http://www.vigilanceofbrixham.co.uk/gallery09.shtml      heres are some great shots of Vigilance's underside at her stern post showing perfectly the run of her planking.

Next comes the impossible area at the sharp turn on the transom near the deck, here the planks near this tight turn become very narrow, on the real ship they might go right down to 3" wide or less to get around the turn, where as at the mid-ship area the same plank might be 8" to 10" wide.

The trick I use at this point when planking is to get some fine piano wire and a tin of hard stainless steel dress makers pins. The pins hold the wires on the marks you have just made on each frame edge representing the plank seams. The idea is to help you visualise how the planks run around the hull.

The wire represents the seam between two adjacent planks and because it is springy it will show you a fair run around the hull. Take care as you run each wire around the hull that you are following the correct mark at each frame for that plank seam from stem to stern, i.e. the wire on the seam between plank 6 and plank 7 does not jump to the marks for the seam mark between plank 7 and plank 8.  Also avoid kinking the wire as this will not give a fair curve.

If you play about with a number of these wires you get a view as if the planks were invisible and only the seams can be seen.

The idea is to plan out the run of planking before planking begins avoiding frustration and wasted precious planking material. Each wire can be moved up and down frames a fraction until a set of fair and sweet lines can be seen.

At this point the marks on each frame edge may be made permanent with a fine bladed saw. Move each wire out of the way a fraction and cut a shallow groove where the wire crosses each frame to fix these points.

A thought here about the guard-board plank.

This is the one next to the keel. I was usual on this type of hull to keep the mid-ship plank width all the way to the stem post allowing it to reach up the stem as far as it would go.

This gives a pleasing up sweep to the rest of the planks at the bow and avoids the planks taking an ugly down-sweep when viewed directly from in the front of the ship. Then the rest of the frame girths are divided up with the remaining 19 planks.

The second plank can be treated the same way to lift up those plank ends at the bow. Look at the wires around the hull at the bow and follow your instincts. You will see if they dont please you.

If this is your first time at planking a hull, I would suggest getting some cheap pine and have it ripped up on a fine circular saw into thin planks so that they turn out wider than the maximum plank width you have on your ship (don't forget the wide boards at the heel of the sten post).

Start planking at the keel and work towards the turn of the bilge and from the deck down alternatively.

Google the process of lining and spiling off planking. There is a good article here.

Spiling is the laying of a thin wide board across the hull as close to the position of the new plank as possible. The position of each frame is marked on the board for reference. A set of dividers with a fixed gate are then used to prick off the edge of the new plank from the last one fixed in place at each station or frame onto the board. The board is then taken off and laid out flat. A flexible betten coonects up all the points and the bottom edge of the new plank is found. The top edge is found by transferring the widths of the plank in hand from the frames as described above. These are also joined with the flexible batten and the true shape of the planks is given.

On these types of vessles planking was fairly straigh and they were sprung into place with clamps and wedges, but on something like a small rowing boat planks will turn out a lazy s's or bows

http://www.duck-trap.com/building.html

if you mess up a plank it is no big deal because the material you are practicing on is cheap. Tack each plank in place with your dress makers pins as you go. No glue at this point because you may need these planks to become templates for your expensive mahogany material later.

Just a side track here.

When cutting your planks you will probably want to use a small modeler’s plane to shave the edge of each plank to the scrived lines you have marked on your planking stock. So we are going to make a plank clamp that will hold your planking stock firmly and will allow you to plane its edge down to the scrive line on your lap as I do, or the whole thing may be clamped in a bench vice.

Grab yourself two pine boards about ½” thick by 3” wide and at least as long as your longest plank Mark the centre line down the length of both boards on their widest face and clamp them together so that you have effectively one board with ends 1” x 3”. Drill a series of holes to allow a carriage bolt and wing nut to pass through both boards side to sides along the marked centre-line at about 6 to 8 inches apart down their length. 

The carriage bolts will be passed through their matching holes and tightened up using wing nuts thus closing up the two boards together rather like the jaws of a very wide vice. Along the edge of one of these boards, glue and pin a strip of your planking stock. This will now become the bottom edge of your plank clamp and become a pivot closing the jaws inwards towards each other when the wing nuts are tightened.

The plan is that when you sandwich a length of planking stock between these two boards of your new plank clamp, your scrived pencil line on the planking stock will be seen above the plank clamp upper edges.

When tightening up all the wing nuts on each carriage bolt, the plank stock will be gripped very firmly allowing you to plane down the exposed edge of the plank stock. It will be found that if you taper the upper outer edges of your new plank clamp, it will give better access with the plane to shave down the edges of the plank stock rather than leaving them square. See last photo for a sketch of this device.

Back to planking the hull.

Soon you will end up at the closing plank, this is the last plank and it runs from half way up the stem, around the bilge and will tuck up at the stern somewhere between the stern post and the transom

If you work patiently tapering each plank so that it matches the widths at each frame position along its length you are going to end up with a very pleasing result with a hull that will be picked out by the beautiful run of its planking. Before each plank is fixed it is used as a template for its matching partner on the opposite side of the ship. This way the planking will be a perfect mirror image either side of the keel.

Your ship will be strong and tight as a bottle; the planks will be regular and describe a smooth sweep from stem to stern.

Be sure not to fill up the seams between each plank too much because these ships were built in a workman like manner where the seams could be seen. Only on yachts did the sides of a ship present a glass like appearance.

You will be so pleased with your efforts that you will want to varnish the hull to show off your efforts!

[Greggy1964]

With reference to developed plank shapes.

The reason builders have trouble with planks laying neatly against a hull with plank edges standing off from frames on one edge or both requiring conciderable clamping force to make them lay down is due to the fact that they are trying to bend a straight strip of wood around a 3 dimensional form.

The paper trick, try bending a sheet of A4 in two planes at the same time, it wont go.

To find the true shape of a plank the frames must be lined off first and then the planks must be spiled from the frames as mentioned above.

To give an idea of the sort of plank shapes developed from lining off and spiling see the image below.

These are the actual plank shapes that went into forming the sailing canoe hull in the above article.

[Greggy1964]

Drilling for nails or pins while planking can often cause headaches and the pulling out of hair .

Pay a visit to e-bay and buy yourself a set of Watchmakers Pin Vice's, they cost around £5 to £15 depending on quality. Each one can hold a drill bit within a range, i.e Sizes 0 - 0.8mm, 0.8 - 1.3mm, 1.3 - 3.1mm, 3.1 - 4.8mm. These can hold very fine drills or pins, and the pin vice shank varies between 3mm and 6mm diameter depending on size and can be gripped in a battery drill chuck.

I like to use dress makers pins for nailing planks in place while the glue sets, and a simple drill can be made from one of these pins. The head is cut off and two opposing flats are ground on the sides of the pin at the point using an oil stone or similar. This helps to avoid the wood burning smell in the kitchen while drilling and upsetting she who must be obeyed!

Micro drills can be bought from ebay in a range of 0.3mm up to 3mm, but can be expensive and a pin drill is capable of drilling through plank thicknesses of up to 6mm without much problem.

Where a pin is to be driven through a plank into a frame, the plank is drilled clean through but only a small way into the frame. This gives your plank nail or pin a start into the frame and avoids it wandering and comming through the side of the frame. The head of the pin is carefully driven until it reaches the plank surface avoiding bruising and will be ground off flush with the plank surface when the hull is cleaned and faired during sanding.

Keep all your scraps of 1mm birch ply as these make excellent pads for under the nail heads avoiding hammer blow damage to the plank and also offering a greater holding surface area to the nail head in areas where more force is required to get a plank to lie flush with the frames.

The hood ends of planks where they meet the stem and stern posts are treated in a similar way but small pads are first place on the nail before being passed through its hole in the plank hood end. This avoids the hood ends splitting as the nail is driven. The nail is driven in until the pad bears on the plank end sufficient to hold it in the correct position in the rabbet.

When the glue holding the plank in place has set, the pads can be split away and the nail driven home flush with the plank face.

Chinese bamboo chopsticks can be slit length wise with a sharp blade and make excellent tree-nails used in areas like the ends of planks where they meet the stern post and the deadwoods are narrow. This is so that when drilling for planks on the opposite side, if a treenail is hit while drilling through it is no big deal and it wont destroy your drill bit as it would if you hit a brass or steel pin.

When the desired size is reached after splitting down the bamboo strips can be rounded off by gently scraping down along their length with a sharp blade held at 90 degrees to the bamboo. Finally, after a point is formed on the end of the bamboo strip, the treenails can be cut off to the desired length and a new point is formed at the end of the strip for each successive treenail.

A 4oz pin hammer is suitable for driving pins or nails but I find if the face of the hammer is ground flat it avoid miss hits bending your nail as it is driven home.