Are ship's frames perpendicular to the keel or to the waterline?

Example of horizontal keel, sloping waterlines. From Chapman's Architectura Navalis Mercatoria, Pl LIX #3: English smack for flatfish (Fishing Vessels).

If you check a number of 17th, 18th and 19th century shipbuilding manuscripts, such as Deane's Doctrine of Naval Architecture, edited by Brian Lavery, Steel's Naval Architecture, Stalkartt's Naval Architecture, Rees' Naval Architecture and Chapman's Architectura Navalis Mercatoria, you will see that lines plans and framing diagrams included in these works show the frames (particularly the "full" frames in the mid-body of the ship) to be perpendicular to the keel, not the load waterline. Lines plans from these as well as other contemporary 18th and 19th century sources, which were drawn during the design phase, before construction was begun, always show the keel, the baseline and the design waterlines to be parallel to each other and horizontal, regardless of how much 'drag' there was to the keel. The more drag a ship had to her keel, the more of an angle there was between her frames and her load waterline.

Drag was designed into a ship as a consequence of the hull design having greater deadrise and higher, easier bilges, a form typical of vessels such as Baltimore clippers. Ships were given drag in order to make them sit deeper aft than forward, so that the rudder would be deep enough to have the proper effect, and in order for the vessel to sail correctly and in the proper 'balance' in consideration of her hull form. Design drawings frequently made the sterns look very high and the bows very low, especially if there was a large amount of drag to the keel. On these draughts, the load waterline (which for design and construction purposes is really unimportant, once the designer has established where it needs to be) appears as an angled line to the baseline, keel and design waterlines. The 'low' end of the lwl is at the bow, while the 'high' end is at the stern.

Example of horizontal waterlines, sloping keel. From Howard I. Chapelle's American Small Sailing Craft, p147: Plan of a late Isle of Shoals boat.

Some draughts that modelers might obtain from sources such as the Smithsonian Institution (NOT 'Institute'), the National Maritime Museum in Greenwich, Mystic Seaport, and other archival sources will show the load waterline (and sometimes the design waterlines as well) to be horizontal, while the keel is at an angle. This is because these lines were taken off the ship after she was built. The lines were taken off with the ship either in the water and floating to her marks (not often done), or with the ship in drydock and chocked up with her lwl horizontal, just the way she settled onto the blocks. In order to use these plans ACCURATELY, they must be redrawn and refaired, rotating the whole construction so that the keel and baseline are horizontal, so that the frames will be correctly shaped and beveled and the hull form will be as accurate to the original design as possible.

Several modern sources illustrate and/or explain wooden ship construction very clearly. These include The Shipwright's Trade by Sir Westcott Abell, Building The Wooden Fighting Ship by Dodds and Moore, any number of "The Anatomy of the Ship" series, especially The Naval Cutter ALERT, 1777 by Peter Goodwin, Plank On Frame Models, Volume I by Harold Underhill and The Built-Up Ship Model by Charles G. Davis.

While it is true that on smaller vessels, the entire frame was first assembled and then bolted together on a flat platform and then raised as a unit onto the keel, the process was somewhat different for larger vessels, especially warships. As has been stated, the slipway and the ground ways (the 'permanent' part of the ways) was constructed at an angle to the water. However, most ships, especially larger ones, were built so that the keel was level. This was accomplished by using keel blocks with wedges to level the keel when it was laid.

With the building of larger ships, all the floor timbers were first laid across the keel. Next, the first futtocks were erected on either the forward or after sides of the floor timbers (either with, or without spacer chocks) and bolted to them. Then the second futtocks were chock-bolted to the heads of the floor timbers and through-bolted to the upper sections of the first futtocks and so-on until the full frame was erected. The keelson was then placed on top and bolted to the floor timbers. Every few feet, a bolt was put all the way through the keelson, floor timber and keel. The ends of these bolts with their roves and forelocks were hidden under the false keel or shoe which was spiked on from underneath after the keel blocks had been removed just prior to launching.

When the ship was ready for launching, launching ways were built to slide on the ground ways. The launching ways had a cradle at either end to carry the ship. The launching ways were built 'under' the ship, while it was still up on the blocks. To prepare for launching, the keel block wedges were carefully split out and slowly removed until the ship settled down into the launching way cradles, the tops of which were then temporarily spiked to the hull (if the ship were coppered on the ways, the cradles would only be spiked to the hull above the copper line). The remaining keel blocks were then removed and the ship was now sitting in the launching ways, AT AN ANGLE, ready to slide. The ground ways were greased and the wedges were knocked out from under the launching ways, allowing the launching ways to slide down the ground ways and put the ship in the water. When the ship hit the water, the lightly spiked-on cradles usually tore off, but sometimes parts of them had to be removed right after launching.
{Jim Roberts}

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