He that will not sail till all dangers...

[keannu]

I understand what this saying means. I means "If you are not ready to take the risk of overcoming hardship, you shouldn't be give an chance do try something". But doesn't "never put to sea." originally mean "never be put to sea" as a passive voice? I think it was probably shortened.

1)He that will not sail till all dangers are over must never put to sea.

 

[SlickVic9000]

(Not a Teacher)

No. Adding a "be" to that phrase means someone should not force such a man to sail. As the sentence stands, it means that a man not willing to accepts the risks of sailing should not, of his own volition, put to sea.

 

[Raymott]

"He that will not sail till all dangers are over must never put to sea."
I read it slightly differently. "Must not" here, rather than meaning "should not", means "cannot". He logically cannot put to sea, since the dangers will never be over. "It must be the case that he can never put to sea; he is constrained never to put to sea."
Literally, as advice to a potential sailor (male or female, by the way), it works well with "should".
But I think it means that, if you don't accept some risk before you do something, you will (or can) never start to do it. As a saying, it only works on this level if 'must not' is read somewhat archaically.
An example of this meaning: "He who will not take some risks in love must never marry." This is not advice to such a person never to marry; it's advice to take risks. And I think the original could be too.