I reviewed my materials, and although I have no contracts from prior to 1750 I did review the Sloop of War Peacock contract found in the History of American Sailing ships. No mention of the Load Water Line. It gives the general specifics of the ship in the contract and advises it will be built according to the plan provided by the Navy Department. A William Doughty Plan. This contract is with Noah and Adam Brown of New York. The Dallas revenue cutter was built to the Doughty Mid sized revenue cutter plan and was also built by the Browns. See Post # above.
Maybe its time we think in a different direction. My observations.
The Math was there to be able to determine the Load water line. However, there may have been relatively few mathematicians up to the task, and fewer who were shipwrights. As time marches forward and more scientific principals are applied to ship design, more designers have the math skills and have a more formal education.
In the design plans I have seen, no load water lines appear.
It is likely that the ship designer and shipwright has a very good Idea where the ship would float but did not put it on the plan.
If you look at the plans we have, even us ship modelers can look at the plan and see where the ship should float, or was meant to float probably within a foot.
Although ships have sunk at launching due to stability problems, I know of none that sank because the were too heavy and settled below their maximum sustainable load.
They always floated High and Dry as light ships.
The test for the new ship comes after it was fully outfitted with Masts, equipment and Ballast for stability. I think in most cases the ship still floated High and was a light ship.
The test becomes whether it can carry the load that was intended. Such as the stores for a 400 man frigate crew for a cruize of 3 to 6 months or longer together with all its guns. I think the ship fails if it can not carry its intended load to be useful.
Achieving the Load Water line I think was easy because ballast and stores are a very flexible thing. If stone takes too much room, use Iron bar. If Iron bar takes too much space use Kentledge. In the end it comes down to how much beef, pork, peas, water and rum you can carry to support the crew or how much usable space you have for cargo storage.
Thinking about all that I have read, in warships , best sailing trim and the load water line was subject to constant management during a cruize. Every meal eaten by the crew changed the draft of the vessel.
Let us not forget that, depending on the Ocean, salt water densities vary. In some waters you can carry more, in others you can carry less. I pulled down my Nicholls's Seamanship and Nautical Knowledge, C.1942 together with a Blue Jacket Manual or two. I reviewed Plimsoll lines and load marks.
In the merchant service the crews were smaller. We know that many companies and their captains ignored loading conventions. After all if he can get it in the ship, the ship must be able to carry it. Right? On a trip the load line did not vary by much as the crew was too small to have an impact. We all have seen the pictures and read the stories.
Saying all of this perhaps the load water line was not a primary design concern. In fact, it might have been a minor thing. The ship will float where it will. You must add or subtract weight to make it sail correctly and efficiently.
Perhaps Load lines came much later as safety at sea regulations?
I reviewed all the posts above. Many make the same points I am making here. It looks like determining a load water line in an existing ship was learning exercise to determine if you could apply the knowledge to build the next ship.
Wayne, in any of your research do you have any references to load water lines as part of a design parameter, or is calculating it always an exercise on and existing ship?
Edited by roach101761, 10 March 2015 - 01:57 AM.