Nibs and Joggles: Laying a Deck The Good Old-Fashioned Way!

Does your deck look like the example on the left or the example on the right?

Unsure what we’re looking at? Here are two more examples.

We’ve resisted the temptation to make a post denouncing Type B as ‘totally wrong’. This is of no use to anyone. Instead, we hope to explain some of the reasons why the method shown in the Type A pictures represents a very sensible way of laying a deck. We will look into why it was originally done this way, since it is not information generally obtainable on the internet at this time and doesn’t appear to be as common knowledge as it ought.

The key difference between these decks, if you haven’t cottoned on already, has to do with the deck plank ends. Notice the outer ends of the planks in the A pictures (hereon referred to as the ‘joggled’ method) are staggered; they have the points cut off (in some places) to form a blunt end. This blunt end is notched into the covering board.

In contrast, the ends of the planks in the B images have been cut with a router to create a smooth, curved edge to the deck. This curve follows the outer curve of the covering board and the planks do not intrude into it. This latter method is now extremely common in the world of traditional wooden boats (both in new builds and, sadly, restorations). It is a more modern technique, brought about by the advent of the Age of Powertools and, we dare say, perhaps a touch of laziness. It differs from a ‘swept’ deck, where the planks themselves follow the curve of the hull and are nibbed into a central king plank.

To make the difference abundantly clear and also to highlight some terminology which we shall introduce momentarily, we have put together the following diagrams:

As far as we at Britannia Sailing Trust are concerned, wherever the end (rather than the side) of a deck plank meets the margin (or covering board in some boats) one must consider whether it ought be joggled. You will notice in the diagrams below, in the foremost part of the bow the planks are sawn off straight at a diagonal.

There is a simple, and rather catchy, rule for determining when an otherwise pointy plank end should be blunted and set into the margin or the covering board and when it can simply be sawn off diagonally.

Credit to https://www.modelerscentral.com/model-ship-building/how-to-do-deck-planking-on-wooden-model-ships/#joggling-deck-planks

There is a simple, and rather catchy, rule for determining when an otherwise pointy plank end should be blunted and set into the margin or the covering board and when it can simply be sawn off diagonally.

“When the snape of the plank is more than twice the length of the width of the plank, then the hood end must be joggled into the margin.”

Nautical jargon at its very finest! This lovely quote comes from the manual of shipbuilding used to construct the Victory. It was passed down from boatbuilder to boatbuilder when our lead shipwright was mastering his trade in Bristol. As with so many precious fragments of knowledge, however, it seems to be in the process of being forgotten.

“But what does this mean?”, you might ask…

The point of all this, is that we avoid long, pointy and often curved snapes – which are weak, difficult to fasten down properly and prone to movement. Take another look at this image of an unjoggled deck below and see exactly how fine and pointy the snaped ends are! This method may be a lot less fiddly, but the end result is the introduction of an easily avoidable weaknesses in a fundamentally important structure of the vessel.

In his 40 year long career restoring wooden vessels, our lead boat-builder has noticed that un-joggled decks have a far greater tendency to leak around the edges, mainly due to the fact that long un-nibbed ends have a lot more flex and movement in them than is ideal; they also lack the bracing effect of being properly set into the margin. Over time, this movement will worsen and contribute to the development of leaks around the edges, which will in turn lead to deeper problems. Having seen this same issue occur in un-joggled decks time and time again, why take the chance that yours will be the exception?

The aforequoted rule does allow for instances where the snape ends need not be joggled: in the event that the snape of the plank is not more than twice the width of the plank. However, in this instance the plank ends should be sawn straight, never curved with a router.

Notice how in the following image, as the planks continue towards the bow, the inboard side of the covering board offers a straight edge to the hood ends of the decking, despite the curve on its outboard edge: in this instance the decking planks are cut diagonally, straight across, because the snape is not more than twice the width of the plank.

Proper joggling and, in instances where the snape need not be joggled, sawing it off dead straight, facilitates the practicalities of traditional caulking. As this surprisingly sensible article from Classic Boat puts it:

“If, on a traditionally-laid deck, the planks had been tapered to a point where they met the covering board, the ends would have been too fragile to caulk. The taper was therefore cut off with a square end the same width as a narrow caulking iron. The covering board on a boat with straight planks or the king plank of a swept deck, was then cut to accept these ‘snaped’ or squared off ends.

“These ‘snaped’ ends on new decks are often cut with a router. This, however, creates a curve at the end of the planks. Plank ends like this could not have been caulked conventionally.” – https://www.classicboat.co.uk/practical-advice/how-to-fit-deck-planks/

Here on Britannia, when the ship came back into the Samuels’ possession after 30 years in strangers’ hands, the deck had unfortunately been relaid – un-nibbed and un-joggled.

The fancy new un-joggled deck – while sawn from great, high-quality timber – had predictably led to leaks around the edges of the deck, resulting in rot setting into the tops of some of Britannia’s frames.

It’s very difficult to reverse engineer a deck that has not been laid correctly, thus the covering boards and margins (or ‘spirketting’ as they’re referred to around here) have had to be entirely remade in order to accommodate the now newly nibbed and properly joggled hood ends.

It’s a seemingly small thing, but it can make a big difference to the eventual longevity of the vessel, hence why our boat-builders have gone to such trouble to rectify the issue aboard Britannia.

At the end of the day, in the world of traditional boats, there is almost always a sound explanation for why things are done as they are. Rules like this only evolve after thousands of attempts’ worth of trial and error. The shipwrights of yore really did know their stuff, having honed their craft into an artform over hundreds, if not thousands of years. But in today’s fast-paces world it’s easy for this deeper understanding to become lost or obscured – particularly when modern tools and products are added to the mix! The least we can do is try not to forget it all, or throw all our ancestors’ teachings out the window in favour of innovations with only a few decades provenance at best.

We’re doing out best not to let this small trick of the trade become another forgotten fragment of wisdom dropped by the wayside. It is worthwhile and was hard-earned – distilled from generations of shipwrights’ blood, sweat and tears over centuries of successful shipbuilding. Just one more reason why it’s so important that the chain of knowledge not be broken, and that the next generation of boat-builders learns the craft face-to-face, passed down from hand-to-hand, not just from Youtube!