Speed/displacement curve does not terminate properly

[DeMatt]

As you approach the limits of the speed/displacement curve, the required horsepower suddenly drops off right at the end.  For example:

• Open the Designer and set speed to 37 knots.  The default displacement of 3000 tons will be badly overstretched by the demand in horsepower.
  
• Increase tonnage progressively to 10000 tons.  Depending on your research, the machinery might fit within the hull before you reach that point, but continue nonetheless.
  
• Continue increasing tonnage by 100-ton increments.  Horsepower demand drops off drastically as you approach 11000 tons.
• Reach 11000 tons.  Horsepower goes negative.  If this had been an autodesigned vessel, then the designer would have displayed a popup for "Illegal speed/displacement combination!", but the popup does not appear for this bare-hull test.

The interpolation gets particularly egregious if you type in a displacement, such as 10995 tons demanding a mere 36 horsepower.  Since such displacements are not acceptable (hitting the Check Design button will cause it to insist on a tonnage of a multiple of 100 tons), this is merely academic.

This has been previously noticed in a thread here.  The suspicion is that, due to the way the curve is stored as discrete points, the final point on the curve is being treated as "requires zero horsepower" instead of something more sensible.

Attachments:

[seawolf]

I was doing testing today and recorded the cutoffs
54000 34 knots
22000 35 knots
18000 36 knots
11000 37 knots
7000 38 knots
6000 39 knots
I’ve confirmed it happens at each point and I think you’re correct on the cause

In the files it looked as if the curve was stored as thousands of tons and thousands of HP which is creating these issues along with the other issues of the games HP curve

[williammiller]

Thanks, we are looking at this.