Steamship bow design

[Susan Morrison]

Hi all - I've been looking for the answer to this elsewhere on the site, so I do apologise if I've missed it and you've already discussed this.

I've been looking at the bow design of early steamships, and I find myself wondering why the bow of early steam vessels was so blunt? Wooden ships of the time, especially ships designed to move at speed like clippers/racers had seriously raked bows, but the designers of the first steam driven ships seem to have gone for a much blunter design. Was it a strength thing? Or am I wrong? Wouldn't be the first time....

 

[Stanley C Jenkins]

I suspect that custom and tradition played a very large part in ship design during the 19th and early 20th centuries. Thus, if a ship builder had always built vessels with straight stems, he would have continued to do so after the introduction of machinery.

There was, moreover, no clear distinction between raked bows for sailing ships and straight stems for steamers. Nelson’s warships, for example, had bulbous bows, while Thames barges had straight stems. Clippers may have adopted raked bows as structural features in connection with their bow sprits.

The appearance of a vessel also seems to have been a major factor during the late Victorian period and, in this context, the profile of a typical Harland & Wolff vessel incorporated two sets of divergent angles — the rake of the masts and funnels being echoed by the upper part of the stern, while the lower section of the bow was similarly echoed by the (very slight) forward rake of the stem. I did in fact work all this out with the aid of a protractor, but I am afraid I have lost my tentative findings!

 

[Samuel Halpern]

The weight of a vessel increases approximately as the cube of its length. If there was no need for a bow sprit a seriously racked bow just added unnecessary weight. Modern cruise ship bows are a combination of a radical rake forward with flare on the sides and a bulbous bow below. The rake and flare push bow spray away from the ship, allows the ship to be moored from above the bulb, and provides extra reserve buoyancy far forward.

 

[Susan Morrison]

Many thanks - how interesting to see fashion playing a part in the design. Stanley, I do hope you find your trusty protractor! Samuel - we had the Golden Princess in the Forth a few months ago - I was fascinated by the overhang of the bow. We were literally underneath it, looking up. Then the crew got a bit over-excited and told us to go away in a variety of languages.

Do either of you know if the hulls were tested in something like the Denny ship testing tank? Would testing like that have been standard practice?

 

[Michael H. Standart]

I don't know if Harland & Wolff ever did any tank testing with models, but I wouldn't be surprised. I'd have to dig up the reference but I recall that the Royal Navy had already been doing this for quite some time.

According to http://www.scottishmaritimemuseum.org/dumbart.htm the Denny tank had been in use since 1882. According to http://www.btinternet.com/~philipr/froude.htm there was a testing tank at Chelston Cross operating in 1871.