Oups, it is simply that this are not examples of the restrictive ne …que.

In first sentence, seulement is used to replace a ne … que, because effectively you cannot use two following rows. At most you could use:

Je ne me rappelle que du fait que je ne sortais pas beaucoup.

but it requires the du fait que expression that make the sentence heavier.

But in second one it would mean different things:

J’ai bien peur qu’il ne reste plus un seul bateau en état de prendre la mer.

No boat can sail here, because we use the ne … plus negation

J’ai bien peur qu’il ne reste plus qu’ un seul bateau en état de prendre la mer.

One boat can sail, because we use the restrictive ne … que and plus is only here to insist in the sense of only.