I am very excited to be building a steam powered wooden launch from a scaled-down Nat Herreshoff design. Throughout the process, I will be posting here so that those who are interested can keep up to date. To start with I’d like to give some history to the design we choose, and how we went about having the boat scaled down to produce the hull I will be building.
The primary design was boat No 94 from the Herreshoff Manufacturing Company (HMCo.) It was built only once for the United States Fish Commission to be used as a steam cutter for the USS Albatross. The Albatross was built in 1882 and out of the 8 boats that she carried No 94 was one of two steam powered boats built by HMCo. The other one had a very interesting center propeller attached to a universal joint that could be retracted when not in use or when it entered shallow water. Both boats had auxiliary schooner rigs and reportedly moved along nicely under sail alone.
The 26′ No. 94 was built to steam for 3 days and hold 12 passengers when going on marine research voyages from the larger (234’) Albatross. I haven’t yet found out what happened to the original boat but I assume it was lost or broken up, as later photos of the Albatross don’t show this boat. As with all Herreshoff designed boat, the lines are pulled from a half model and then scaled to the desired size.
After Nat Herreshoff carved a half model he would create a table of offsets and then it could be scaled to the appropriate size. The table of offsets for No 94 were also used for many different boats ranging of 20′ to 50′. To accomplish the various scales, Herreshoff used a variety of methods. One was to proportionately scale in all dimensions. Another way was to stretch the center section of the boat. The final method was to keep the width and height of each frame the same and adjust the spacing between them.
We had a challenge with the scaling on this project. The owner’s vision is to be able to steam around Marblehead Harbor as opposed to 3 straight days in the Arctic and with 4 passengers rather than 12. Most importantly her berth requires a length of no more than 23’. Thus while the owner loved the look of No. 94 he needed to have it made smaller than the original. As we approached the process of scaling down the original design the goal was to keep as much free-board and beam as possible while bringing her down to about 22’ 6”. This would allow for easier handling by the owner while still being seaworthy enough to handle occasional rough water. With these guidelines and the original offsets from HMCo, Doug Zurn of Zurn Yacht Design was able to generate a computer model and scaled down the boat using modern CAD programs. This technology allowed us to achieve the desired size while staying as faithful as possible to the original Herreshoff hull shape.
While I move forward with building the hull. I will be working with the owner to find an appropriate engine and boiler combination. With this digital model will be able to see the effects that different combinations would have on stability and displacement.