Okay, so I'll go first, since I be the token queer pirate here in the Pub. Arr.
First of all, I think that it be difficult fer us to transport our 21st century morals, attitudes and thoughts on the subject of buggery to 16th, 17th, and 18th century society. Sexual secrecy was certainly much more the case then than now. Today gay men and women, as well as bisexuals, or people who simply enjoy sex with their own gender are much more visible, especially in all forms of media.
I do believe that buggery existed on pirate and naval ships. However, I do not believe that 'every man broke down at some point' and engaged in male to male sex. In fact, I would guess the number who did to remain low, but yet higher than the norm because of the long times at sea. I think one area of today that we can compare is the prison population, which has a much higher degree of same sex activity than the general population. Common sense should prevail here that if guys are locked up or kept together for very long periods of time, the temptation (for those who could be tempted) to engage in such activity would be greater. If one believes that people are simply not 100% straight or 100% gay, but are somewhere at different points on a scale of attraction, then it becomes much easier to believe that, yes, some people could engage in sexual activity with the same sex under certain circumstances, while others would not.
I do NOT believe that the fear of punishment or the Law would have deterred many men. How much did sodomy laws, even in this country, deter such sexual activity? In the height of desire or passion, people will follow nature more often than not.
One other thought about piracy and sodomy that comes to mind as I type is that, of course, pirates were not the sweet little Johnny Depp characters from the movies, but were more often scoundrels, criminals, misfits. I think if ye take an element of men who were from such a mix, combine that with periods of drinking and carousing, and throw in not having sex for long periods of time, living in tight quarters and possessing a 'devil be damned' attitude, ye might get a man who is a little more willing to engage in mischievous behaviour.
One resource that folks might like to read is the book, "Sodomy and the Pirate Tradition" by B. R. Burg. NYU Press. It's a bit of a scholarly read, but quite interesting.
Cheers, mates.