It depends on what 'believable' means.
Many find Christine Blasey Ford 'credible' or 'believable.' But there is a tendency among the commentariat to conflate her believability with the believability of the content of her allegation against Judge Kavanaugh. Those of us who want to think clearly about this SCOTUS confirmation business need to keep some distinctions in mind.
There are two main senses of 'credible/believable' in the vicinity and they need to be distinguished. There is the credibility of persons and the credibility of propositions.
Credibility of Persons
Within the credibility of persons we should further distinguish sincerity from trustworthiness. Does Dr. Ford sincerely believe what she alleges against Judge Kavanaugh? I think so. So I find her credible in that sense. I don't think she is trying to deceive us. She seems to be saying what she sincerely believes is the truth. One can say what is false without lying. So even if what she is saying is false, she can sincerely assert it. Bret Stephens says he "found her wholly believable. If she’s lying, she will face social and professional ruin." She is believable in the sense that she seems not to be lying. So that is one sense of personal believability.
But is she a trustworthy witness? That is a more difficult question. Even if she is a trustworthy witness in general, was she one that night when she was drinking? I don't know. A person can be believable in the sense of apparently sincere and apparently truth-telling without being trustworthy because, perhaps, she has a tendency to confabulate. So we should distinguish believability as sincerity from believability as trustworthiness.
Credibility of Propositions
But Ford's personal credibility is not really the issue. The issue is whether the content of her allegation is credible. The alleging is one thing, the content another. Part of that content is the proposition that Brett Kavanaugh sexually molested her. That proposition could have been alleged by people other than Ford. Is the proposition itself credible?
But what does credible mean? It means believable. But the '___able' suffix is ambiguous. Is the proposition such that some people have the ability to believe it? Yes, of course, but that is not the relevant sense of 'believable.' People believe the damndest things and thus many false and absurd propositions are believable. They are believable because they are believed.
The relevant sense of 'believable' is normative: Is the proposition alleged worthy of belief? Is it a proposition that ought to be believed by a rational person, or may be believed by a rational person? Is it epistemically permissible to believe that Brett Kavanaugh sexually molested Ford?
It is only if there is sufficient evidence. How much evidence is needed? Well, it has to be more than her say-so even if it is a sincere say-so. Suppose Ford sincerely states what she sincerely believes is the truth. That is not sufficient evidence that Kavanaugh in fact molested her. But no other evidence has turned up: there are no corroborating witnesses, for example.
I conclude that Ford is not believable in the only sense that matters: the content of her allegation is not supported by enough evidence to make it worthy of belief. Her testimony should be dismissed and Kavanaugh should be confirmed.