Calculating Speed of a Boat for Dumbo - Help Needed

  • Thread starter Thread starter Tai
  • Start date Start date
AI Thread Summary
To estimate the speed of the catamaran hull, the drag force must be considered, which varies with speed. The power output of the bilge pumps can be related to speed using the equation P = 1/2 ρ v^3 LW Cd, where ρ is the water density, v is speed, LW is the wetted surface area, and Cd is the drag coefficient. The drag coefficient should account for various types of drag, including viscous and wave drag. Given the hull dimensions and weight, the combined output of the pumps (84 liters per minute) will influence the achievable speed. Calculating these factors will provide a rough estimate of the boat's speed in either kph or mph.
Tai
Messages
1
Reaction score
0
Hi everyone,

I'm hoping for some help in calculating the speed of a boat I am planning to build, I'm not looking for a precise speed just an indication of what it is likely to be to ensure the pumps I would like to use are powerfull enough.

The boat is a catamaran hull with the hull dimensions 150mmx100mmx620mm (per hull), the remainder of the boat will be above the water line. Overall the weight will be 8.5 Kilos, the propulsion system I would like to use is made up of two bilge pumps, each bigle pump is capable of moving 42 litres a minute so combined 84 litres per minute. The pump output pipe is 19mm in diameter, which i guess fits into the equation somewhere...

Is someone able to tell me an approximate speed in either kph or mph? I don't even have a clue where to begin :blushing:

Thanks in advance,

Tai
 
Last edited:
Engineering news on Phys.org
You need to determine how the drag varies with speed. Then for a first approximation, you relate that to the power output of your engines:

P = \frac{1}{2} \rho v^3 LW Cd

Bear in mind that your drag coefficient would have to include viscous, wave and profile drag terms.
 

Thread 'Race car suspension Class'

Posted June 2024 - 15 years after starting this class. I have learned a whole lot. To get to the short course on making your stock car, late model, hobby stock E-mod handle, look at the index below. Read all posts on Roll Center, Jacking effect and Why does car drive straight to the wall when I gas it? Also read You really have two race cars. This will cover 90% of problems you have. Simply put, the car pushes going in and is loose coming out. You do not have enuff downforce on the right...
View full post »
Thread 'Physics of Stretch: What pressure does a band apply on a cylinder?'

Thread 'Physics of Stretch: What pressure does a band apply on a cylinder?'

Scenario 1 (figure 1) A continuous loop of elastic material is stretched around two metal bars. The top bar is attached to a load cell that reads force. The lower bar can be moved downwards to stretch the elastic material. The lower bar is moved downwards until the two bars are 1190mm apart, stretching the elastic material. The bars are 5mm thick, so the total internal loop length is 1200mm (1190mm + 5mm + 5mm). At this level of stretch, the load cell reads 45N tensile force. Key numbers...
View full post »

Thread 'Cantilever help'

I'm trying to decide what size and type of galvanized steel I need for 2 cantilever extensions. The cantilever is 5 ft. The space between the two cantilever arms is a 17 ft Gap the center 7 ft of the 17 ft Gap we'll need to Bear approximately 17,000 lb spread evenly from the front of the cantilever to the back of the cantilever over 5 ft. I will put support beams across these cantilever arms to support the load evenly
View full post »

Similar threads

Can someone help me to design a boat inclined lift ?
Replies
1
Views
2K
How Can We Design a Compressed Air Car for 300 km Travel?
2
Replies
82
Views
27K
Atmospheric humidity for water production.
Replies
3
Views
3K
Calculating Train Speeds and Time with MST3K: A Fun Experiment
Replies
3
Views
2K

Hot Threads

Recent Insights

Back
Top