To create a concise and relevant summary of the text, the following sentences should be included:
- John Fitch combined old methods of constructing boats with new technology to create the first steamboats.
- It wasn’t until after his death that Robert Fulton created a commercially successful steamboat and became known as “the father of steam navigation.”
The first sentence provides important information about John Fitch's contributions, while the second highlights Robert Fulton's eventual success in the steamboat industry. The other two sentences are either subjective or not essential to understanding the main points of the text.