Run two canoes to solve Italian's magazine puzzle "Quesito con la Susi n. 959"

Canoa.java

class Canoa
{
    private double pos; // m
    private double vel; // m/s
    
    
    public Canoa(double init_pos, double v) {
        this.vel = v;
        this.pos = init_pos;
    }

    public double getPosition() { return this.pos; }

    public void next(double elapsed) {
        this.pos += this.vel * elapsed;
    }
}

Simulation.java

// Quesito con la Susi n. 595
class Simulation
{
    private final static double delta = 0.1; // time increment
    private final static double speed = 1.0; // arbitrary speed
    private final static double prec = 0.1;  // for target distance comparison

    // any value greater than the solution. Tune accordingly
    private final static double max_dist_tests = 5000.0;

    // min dist between piers.
    private final static double min_dist = 600.0 + 400.0; // was 500 for test

    // this is chosen supposing the distance will match min_dist + N*dist_incr
    //
    // for the chosen value and the results, it could be 100; but we need
    // to reduce it in case the solution is something like 2012.
    // If we choose wrong values, we could miss the target distance and have
    // no results - unless we increase prec to, say, 100.0... then we would have
    // a broad interval for the solution, which will be given by the output result + alpha*prec)
    //
    // config values should be chosen thoughtfully, and tuning by trial might be needed
    private final static double dist_incr = 10.0;


    private static boolean approx_pos(Canoa c, double d) {
        return (c.getPosition() >= d - prec/2.0) &&
            (c.getPosition() <= d + prec/2.0);
    }
    
    private static void Simulation() {
        double cur_dist;

        for (cur_dist = min_dist;
             cur_dist < max_dist_tests;
             cur_dist += dist_incr)
        {
            Canoa susi = new Canoa(600.0, speed);  // 600 is from where Susi starts
            Canoa gianni = new Canoa(cur_dist, -2.0*speed); // Gianni's speed's 2 times Susi's speed
            while (!approx_pos(gianni, 0.0)) {
                gianni.next(delta);
                susi.next(delta);
            }
            if (approx_pos(susi, cur_dist - 400.0)) {
                System.out.println(cur_dist);
                break;
            }
        }
    }
    
    public static void main(String[] args) {
        Simulation();
    }
}