Market size for the ship

Question

I have confusion to estimate market size of the engine of the tug ship (global) from the BCG Munich casebook.

The solution posted in the book is confusing as I am not sure why we need to know #ports (Show below)

MS engine of tug = #countries x # ports in countries and average # tugs in countries x #engine/tug .

I am wondering whether there is other way to estimate number of ship produced globally.

For more information, I posted the case and solution as per below.

Case:

Client is a manufacturer of marine engines - focus on small-engine ships (small tugs that help to maneuver and pull out large boats - Special propeller is necessary so that the ships can maneuver better).

The client is a supplier who only produces these rudder propellers and delivers them to the shipyard - these deliver to the end customer). Knowing nothing about the end customer (usage, problems, etc.) but would like to find out more about end customers. So is considering digitizing engines to find out more about end customers.

I want to know from you if this is a good idea.

Solution:

Estimate the market: countries * number of ports * avg. Number of tugs per country * Number of engines from boat * Market share Total market are 130,000 ships

10% of which are tug ships (13k), 10% market share (1.3k), 2 engines per ship (2.6k)
2.6 motors is our market share, 15 years life expectancy> 2600/15 = 173 motors per year> rounding up to 200

Answer 1

There might be another way, but the shown solution seems the most logical one.

The trick is that you need to understand the total number of tug boats globally. You might try to estimate the number of tug boats based on the number of container ships and tankers, or the number of tug boats per global trade volume, or so. But assuming you're not a walking factbook, those numbers are probably not intuitive to you.

So listing the top 10 ports globally, estimating that they make up x% of global trade and then estimating the number of tugs you need on a day or the number of tug boats per port seems like the mist intuitive solution.

Either way, keep in mind that there is no one right solution. These type of cases typically have several possible solutions, so if you can come up with another easy to use way, you're good to take that path.