Ship Performance after Reboilering

In summary: It is interesting to note that McNaught's work was not without its detractors and his proposals were not adopted in his own time. The main objection to his work was that it was not possible to make a single engine that could be used at both high and low pressures .In summary, the experts think that the change in weight of power plants, as a fraction of total displacement, is a minor factor in performance gains. They think that tonnage of fuel carried must also be a factor, but performance gains could come in terms of speed or range or munitions carried.
  • #1
Delta Force
I'm trying to do some rough estimates of how much additional performance a steam powered warship (World War I to 1950 or so) could get from receiving new engines. I'm aware that different hull designs have different impacts on drag in the water, but for the rough estimate I'm focusing on the propulsion systems. The largest changes for performance seem to be fuel type (coal or petroleum) and boiler pressure.

Presumably the ships of this era were using bituminous coal, as its been said that the switch to petroleum doubled a ship's energy density. Anthracite coal has been used to power some ships (it was used as a stealthy fuel in the American Civil War due to its cleaner burning) but it has about as much energy density as petroleum. Does that mean that switching from coal to petroleum would allow most ships to double their horsepower?

Also, it seems that boiler pressures were constantly increasing throughout the era. What kind of relationship does that have with power density and performance of the engines?
Engineering news on
  • #2
I think you can get your estimates from the historical record. The most relevant parameter is horsepower per ton of displacement for the same hull form and waterline length. You should be able to find the data, horsepower, displacement, and top speed for historical warships.

As a rough guess, I would say that the change in weight of power plants, as a fraction of total displacement is a minor factor. Tonnage of fuel carried must also be a factor, but performance gains could come in terms of speed or range or munitions carried.

I once visited the USS Texas (circa 1910). I think the plaque said it was the last steam-piston engine warship.

Higher pressures certainly add a lot of power/weight. But other big factors were the improvement in design of steam turbines, and speed reduction gears.

What about the weight of armor?
  • #3
Delta Force said:
Does that mean that switching from coal to petroleum would allow most ships to double their horsepower?

I doubt you could get such a big improvement unless the steam engines were uprated. Just changing the burner probably not enough? Main effect would be on range.

Google found some discussion here..
  • #4
Starting right back in Newcomen beam engine days there have always been schemes proposed to uprate the power output and increase the efficiency of steam power plant .

One of the earliest was devised by a Scottish engineer called William McNaught . He upgraded low pressure beam engine plants to use higher pressures by supplying replacement high pressure boilers and by fitting an additional high pressure cylinder to the original beam engine . This allowed the engine to work at the higher pressure and effectively to work as a compound .

This procedure did allow the engine to develop more power but only within the limits of the engine mechanical construction . The real advantage was the improvement in efficiency . There are credible reports that coal consumption for a McNaughted engine supplied with steam from the new boiler could be less than half of what it was previously .
Last edited:

Related to Ship Performance after Reboilering

1. How does reboilering affect a ship's performance?

Reboilering can significantly improve a ship's performance by increasing its speed, efficiency, and power. This is because reboilering involves replacing old, worn-out boilers with newer, more efficient ones that can produce more steam, resulting in faster and smoother sailing.

2. What is the purpose of reboilering a ship?

The main purpose of reboilering a ship is to improve its overall performance and ensure its reliability and safety. As boilers age, they become less efficient and prone to breakdowns, which can be costly and dangerous for a ship. Reboilering helps to prevent these issues and keep the ship running smoothly.

3. How often should a ship undergo reboilering?

The frequency of reboilering depends on various factors such as the type of ship, its usage, and the quality of its current boilers. Generally, a ship should undergo reboilering every 10-15 years to maintain optimal performance.

4. What are the potential drawbacks of reboilering a ship?

The main drawback of reboilering is the cost and time involved. Replacing boilers can be a costly and time-consuming process, and the ship may need to be taken out of service for the reboilering to take place. However, the long-term benefits of improved performance and reliability outweigh these drawbacks.

5. Are there any safety concerns associated with reboilering a ship?

Reboilering should only be done by trained professionals following strict safety protocols. There is a risk of accidents and injuries during the process, especially when dealing with high-pressure steam. However, with proper precautions and expertise, reboilering can be done safely without any major concerns.

Similar threads

  • Sci-Fi Writing and World Building
  • Mechanical Engineering
  • Earth Sciences
  • Mechanical Engineering
  • Aerospace Engineering
  • General Discussion