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Sunday, 26 April 2009

Chatham Dockyard contains an interesting structure now known as the BIG Store. In fact it was originally a covered hall in which the great "Wooden Walls" such as HMS Victory were built. At some time in the early 20th Century the slipway it covered was levelled and filled in and a mezzanine floor inserted as a storage space for ships' boats.

The main structure is all oak beams and the engineering is quite remarkable. This roof had to span over a hundred feet - a ship like Victory is 90 feet in the beam - and in length cover the full overall length of the largest ship being built within it's confines. And it had to do it without any internal props or supporting columns. The picture was taken on the mezzanine floor and shows the length of the hall, but not the depth - the mezzanine is around fifty feet above the main floor.

Ships built in the age when this was created (Mid-18th Century!) would have been "framed out" and then the bare skeleton allowed to stand unplanked over a winter season to "season" the frame and allow the joints to settle and "marry" properly. These frames were held together and in place using wooden pegs called "trenails" and after seasoning a Master Shipwright would have supervised his team of men to go round the ship and drive all the trenails fully home before planking started on the hull. The building ways were covered to prevent the rain, snow and damp from allowing fungus or rot to get into the timbers and, even once launched, the ship might have a "roof" built over her upper decks to keep them dry while the internal fitting out was done.

The methods may have been crude and the materials simple - but these fellows knew their trade.

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