BCVSP Picture Gallery - Hull Planking Pictures

Hi there! Welcome to the Viking Ship hull planking picture gallery!

Here's where you can check out the BC Viking Ship Project in action planking and riveting the hull.

All thumbnail pictures are clickable and will bring up a full size picture.

This page has these sections:

• About planking a Viking Ship hull (text only)
• Laying up planks (pictures)

About planking a Viking Ship hull

It may help to understand the progression of hull construction to put the pictures in context. So let me give you a very brief overview of how a clinker built hull is put together once the keel is ready.

The starting point

Planking starts from the keel and moves up the sides of the hull. When the planking reaches a certain point at, or just above, the turn of the bilges, the internal frames are fitted. The internal frames are permanent and will be holding the hull in shape once the station molds are removed.

Holding the hull in shape while planking

We don't know all the techniques of the ancient masters, but we do know that they mostly built their ships out in the open. They couldn't use a boat shed structure to hold temporary frames in place. In stead, they used rocks placed inside the hull to hold planks in place. If you look closely, you can see that see that, besides molds, we are using devices like Spanish windlasses anchored to the keel to provide a similar kind of control over the planks.

On rivets, old and new

The planks are fastened together with rivets. In the olden times, these rivets were made from bog iron in charcoal forges. This produced an iron alloy with rather amazing durability even in a salt water environment. From old finds we know that boats more than fifty years old still had their original rivets. And we are not talking about toy boats either.

This is astonishing because the Danes working out of the Roskilde Museum and various replica projects have found that modern, galvanized rivets become unserviceable from electrolysis, rust or both, in as little as 8 to 13 years.

So why can't modern rivets compete? It has to do with the way we convert iron ore to ingots. We use coke, not charcoal and put in a number of different additives in the smelters that the ancients never used.

A note on bog iron

Bog iron, by the way, is so called because it was found in peat bogs. The presence of iron ore was spotted by the rusty looking water floating in the bog. Long sticks were used to probe for the precise location of the iron. Then the dirty and strenuous work began to physically dig out the ore. We can imagine that this must have been dangerous, too, if the iron was buried deep as the unstable bog couldn't have supported much of a shaft.

How to date an old wooden boat

As an aside, we can know the age of old wooden boats with a very high degree of precision due to a technique called dendrochronology. This works with the growth rings in trees which have been mapped in an unbroken sequence at least as far back as the Viking Ship era in many European countries. Thus we can tell not only how old the ship is, but also where it was built.

The rivets we use

Needless to say, we don't have easy access to bog iron rivets today, so we decided on copper. A complete rivet consists of two parts: a rivet and a rove. The rivets we use have about a 3/16" inch diameter shank with a tapered point and a flat head. The length is a little under three inches. The roves are round and dished with a diameter around 3/4". They have a central hole which is less than the shank diameter to ensure a tight fit.

After strakes comes internal framing

Once all the strakes (i.e., full length planking rows) have been laid up, the remainder of the interior frames, knees and stringers can be fitted.

A note on strakes and scarfing

A strake usually consist of several planks scarfed together. A scarf is simply a joint of two planks where the abutting ends have been mitered (i.e., cut at an angle) to make an overlapping joint. Scarfing is as old as boat building itself and is used in clinker, lapstrake, carvel and strip planked hulls.

A scarfed joint is very strong and can be further reinforced by fitting a backing piece on the inside. The miter must allow enough wood on both sides of the rivets to provide the necessary holding power. On our planks which are just under one inch think, a three to four inch scarf seems to be all we need (i.e., a 1-3 or 1-4 scarfing ratio). (This relationship holds for solid wood. For plywood, you may have to go as high as a 1-9 scarfing ratio. But there's no plywood in a Viking Ship, in case you wondered.)

Trenails; the internal frame fasteners

The internal frames in the bilges were fastened with trenails (pronounced "trennels") or even with leather lashings to cleats (as found on the Gokstad ship). We will use trenails made from 1 inch round fir stock at least 6" long with tapered shoulders to a 3/4" shank. A trenail is locked in place by driving in a wedge on the inside of the hull and then trimming off flush both inside and out.

Removing station molds

The station molds are removed once there is sufficient internal, permanent framing in place to support the shape of the hull.

That's the quick, high level description of the hull building process.

Let's get back to the planking itself, then.

How we are doing it

We started the hull planking when the keelson had been bolted to the keel and the stations molds (i.e., temporary frames) had been put in position. A rabbet was cut in the stem, stern and along the keel to take the garboard and the end joints of each strake.

The garboard

The first strake to lay up, is the garboard which is fitted at the keel. This plank is extremely important and requires perhaps the most exacting workman ship of all. This is because the keel will not flex along with the garboard the way two lapped strakes will. Consequently, the fit with the rabbet in the keel and along the keelson must be flawless.

Furthermore, the joint with the garboard typically cannot be riveted like the remaining seams. We are using galvanized boat nails to fasten the garboard to the keel and keelson. These boat nails are also used to fasten the end joints of the strakes to the stem and stern.

From the garboard up, all seams are riveted the full length of each strake.

Shaping and fitting planks

Before the riveting can start, we must shape and fit the planks. This involves laying out some battens along the frames, taking some measurements, holding up a rough plank and working in stages to get lines curves, bevels and joint positions right.

The shaping of a plank is done with skill saws for trimming and mitering and power planers for most of the beveling. The final detail fitting is often done with various hand planers. No two planks are the same, so there is plenty of room for creative wood working here.

On the outside of each plank, a narrow, shallow rivet groove is put in with a router. This gives the riveters a reference point to line up the rivets and it gives the plank a distinctive look. Similar lines can been seen in original Viking Ships.

Laying up a plank

Once the plank is shaped and fitted, it is ready to be laid up. The first step is to tar the scarfs and lap joints and lay down cotton caulking. Then the plank is put up to the beginning frame. Clamps are used to hold the plank in position. Working from the start position, the plank is then slowly bent in place and clamped. The turns are gentle enough that we can lay up our planks without the use of steaming.

Riveting

Properly lined up and securely clamped in place, the riveting can begin. The new plank is pre drilled along the rivet line for rivets spaced 5-6 inches apart, the lower plank is not drilled. A rivet is inserted into a hole and simply driven trough the inside plank. It helps to have someone hold a counterweight of some sort against the inside plank to ensure a tight fit.

All rivets are driven through and then the roves are fitted. This is done by seating the rove on the rivet and using a special tool with a hollow centre to drive the rove onto the rivet and firmly against the plank. Since the rove is dished, this allows it to flex so that the compression from riveting exerts force on the planking. This keeps the seam more firmly together.

All roves are fitted before the rivets are cut off to leave somewhat less than 3/8" of an inch protruding. Then the peening can begin with one person hammering and one person holding a counter weight against the rivet on the outside. Depending upon your experience and how fussy you are, expect to take about 125-150 strikes for a decent looking rivet. It is faster than you think, though, because you don't strike all that hard. The trick is to use the right weight of hammer and let it do most of the work.

Some rivets cannot be completed the first time around because they are too close to station molds or other obstructions. This is unimportant because there are more than enough rivets to hold everything together as it is. The remained can be finished off later finished them off later.

Pictures make things clearer

Well, there you have it. The pictures will hopefully help fill in the blanks and give you a better idea about what is involved. I can tell you it is really fascinating to watch.

Laying up a plank

This was our starting point. All the battens are in place marking off where each plank will go. Each batten is used as a guide to make the templates for the individual planks. © Copyright 2001 Preben Ormen

Laying up a plank starts with tarring the joints and putting down strips of cotton caulking. As you can see, we put down a double strip of cotton in the scarfs where the rivets will go in between. © Copyright 2001 Preben Ormen

Properly tarred and fitted with caulking, the plank is moved into place. It helps if there are several people to assist, especially if you are working with a long plank. © Copyright 2001 Preben Ormen

Here you can see how a plank is clamped in place. You don't need a lot of pressure, the idea is to keep the planks together while you fuss about aligning it properly. Then you tighten the clamps so everything is snug. Then you double check that nothing moved. Then you triple check... Well, you get the idea. © Copyright 2001 Preben Ormen

The clamps we use are home made. You can easily make these yourself. The pattern is very simple. The most critical measurements are: The distance from the bolt to the tip of the clamp (determines the plank width you can work with) The length of the overlap at the tip (you must have enough to support the joint) The thickness of the clamp stock itself to give you sufficient strength (watch which way the grain runs when you cut out your blanks) The bolt is just a standard galvanized carriage bolt. The wing nut is made by welding on two pieces of round stock to a nut. The hinge is made from leather. The same leather is also used for padding to protect the planks. © Copyright 2001 Preben Ormen

This gives you somewhat of an idea about the size of a rivet and rove compared to a hull plank. The tool on the left is a rove setting tool. It has a hollow centre to slip over the rivet shank as the rove is being driven flush against a plank. The claw hammer shown here is actually too light for peening the rivets we use. (Truth be known, I realized too late that I grabbed the wrong hammer for my picture.) Use a true ball peen hammer with a weight matched to the size of rivet you use. Remember, let the hammer do most of the work, not your muscles. That's why the weight is so important. © Copyright 2001 Preben Ormen

Here's a rat's eye view of a rivet being driven into a plank in the third strake. Notice the thin, routered rivet line in the plank being riveted. You also have a good view of a clamp in place. The white fluffy stuff just to the right of the hammer is some caulking cotton protruding from the garboard seem at the keel. © Copyright 2001 Preben Ormen

Another rivet being driven home. Notice the use of an axe head as a counter weight for the rivet going in. © Copyright 2001 Preben Ormen

All the rivets are in. Now the roves are being seated with the special tool. Here you also get an idea of the size of ball peen hammer we use. © Copyright 2001 Preben Ormen

That axe head is just the ticket, isn't it? Here it is in action seating roves. Looking at this, my guess is that you'd need a counter weight at least 3-4 times the weight of your hammer. © Copyright 2001 Preben Ormen

With rivets and roves in place, the rivet shanks can be trimmed down. An ordinary little bolt cutter is perfect for the job. © Copyright 2001 Preben Ormen

Now the real action begins: the peening of the rivet shank. It is easier with two people, but I have been told that the real pro's can handle both hammer and counter weight by themselves. © Copyright 2001 Preben Ormen

Here you can see a scarfed joint. The plank has been riveted along the seam. Now it's time to check out this joint. Perhaps the plank moved a little as the rivets were going in or maybe the mitre was a little off to begin with. This joint isn't closing up properly, it's gaping just a tad. A fix is needed. © Copyright 2001 Preben Ormen

So fixed it was. Here's how that was done. A wedge was fitted, tarred and driven into the joint. A cut line was scribed and no-one will be the wiser. With the rivets in, the joint will be closed up just fine. Arne smiled when I took the picture and said: "These are the little details you don't like to talk about too much." I took the picture anyway, because I learnt something watching him fix it. He didn't seem too worried. The point is, no need to panic just because of a little glitch. Fix it and move on. Can you imagine the amount of extra work involved to grind off the rivets and fit another plank? I can. I like Arne's way better. It takes experience, though, to make that judgement call on what is fixable and what should be redone completely. Oops. Not so simple after all, then. © Copyright 2001 Preben Ormen

This picture attempts to show rivets and scarfed joints. There are three scarfs in this picture. In the bottom right corner, you can see how the two rivets have been run in between the two cotton caulking strips in the joint. All told, that joint will be supported by four rivets: one in the lower seam (in place already), the two in the scarf itself and one in the upper seam when the fourth strake is laid up. © Copyright 2001 Preben Ormen

In this picture you can see how the planks have been fitted into a rabbet in the stem. The forward (right) edge of the planking is flush with the stem. If you look at the top edge of the top strake, you can see a tapered rabbet running towards the stem. This rabbet is there to allow the next strake to taper from an overlapped to a flush seam. Look at the strakes below and you notice that where the seams join the stem, the seams are flush. The fitting of the planks in this area is a little bit tricky and requires experience to get it right. Besides fitting the garboard strake, this area is probably the most difficult of the whole planking job. © Copyright 2001 Preben Ormen

Back to BCVSP

Home | Coaching Voyage | BCVSP | Musings | Recreation | Runes | Sailing | Stories | Viking Ships | About this site | Contact me | Links