Thank you for your question.
Yes, your figures are correct. The report states that a 50% confidence level equates to four ships. Raising that level to 80% would raise not only the likelihood of it being done, of course, but also the cost. The real answer to all of this is that there is a domino effect. The longer the delay, the greater the chance it will affect the building of other ships, the Canadian surface combatants.
In the event there are no delays or a delay occurs during the timeframe, the ships targeted for 2021, the next set of ships, will be in jeopardy or possibly delayed. Skills and expertise could be lost in the meantime.
The figures you cited are accurate. So achieving four ships with a 50% confidence level is more likely if everything stays on schedule. An 80% confidence level would basically require increasing the budget and, obviously, avoiding any delays.