It wasn’t just because men were really sexist during the Age of Sail, but there were actually some reasonable and some totally outlandish reasons why sailors thought women were ‘bad luck’. There are two main reasons why women were seen as bad luck, the reasonable and the supernatural.
The reasonable explanation:
Back then, ships were backed with drunk/rowdy testosterone filled men who hadn’t been to port in months. They were most likely never married, or never saw their wives much. Since humans seem to be driven by the temptation towards sex, these men were extremely horny on the ships. Sodomy and buggery, to ‘fill the loneliness’ or lustful desire, were more than common aboard ships, despite the punishment for doing so being death. Of course everybody was aware that sailors would do this, but it was pretty much ignored unless the Captain heard about it and then punishment would have to be enforced.
So, now lets put these horny men onto a ship and give them a woman. The most likely situation that would arise would not be all that pleasant. Men would fight over the woman or rape the woman, and you can see where this is going. Just the mere suggestion of a woman aboard would cause manly ‘drama’. So having a woman aboard the ship would overall cause a big commotion that is beyond frustrating for a captain to deal with.
The supernatural explanation:
As I explain this reason, you’ll begin to see how the reasonable explanation evolved into the supernatural explanation.
Ships are and have been referred to as ‘she’. The reason why probably stems from horny sailors, or allowing the sailors to connect to their ship and think of her as a living creature (as ships very much are). Women also make better navigators (something to do with thinking patterns), which is why many ships have a lady at the front of the boat. Her spirit guided the ship. For similar reasons the sea and weather were also seen as a women.
Now earlier I talked about women attracting the attention of men aboard. This is where reality meets fiction. If a woman were to be aboard the ship, the sailors would pay more attention to the woman than the ship, sea, or weather. This would supposedly cause the female nautical spirits to grow jealous and angry and lash out at the sailors.
Eventually the superstitious explanation for a woman’s bad luck evolved. Sailors began to believe that because women always chat to each other, the women were able to speak to the sea spirits and in their womanly wickedness they would summon up storms. Women were also seen as being able to ‘whistle up storms’. During the age of sail, sailors thought that whistling was challenging the wind and would cause storms, and because women were evil they would whistle up the wind purposefully to punish the sailors.
~Thus women were feared and it was seen as bad luck to have a woman aboard~
The women being bad luck thing was less of an ardent belief by the 18th century (though some still held it, like Collingwood, funny fellow, who didn’t allow women on his ships). You actually did get quite a few women aboard ships- they were often the wives of warrant officers, though you did get a few on the lower decks, and some captains brought their wives and children away to sea- but it depended on the captain. Some captains saw women as a ‘nuisance’ but not because they caused fights between men - Jervis complained because they used up the fleet’s water too quickly (which is interesting in itself because it suggests more women being in the fleet than you might at first suspect) and another captain got annoyed with them coming and going from the ship to shore without his permission (he issued an order specifying which days they could go ashore to market and saying that if they disobeyed this he would throw them off the ship) and Nelson once wrote: ‘On Sunday we shall get rid of all the women, dogs, and pigeons, and on Wednesday, with the lark, I hope to be under sail for Torbay.’ so for him it was that women got underfoot all the time, same as a dog might. But not so much mention of fighting or rape or bad luck. Both those things happened, but they were equally likely to happen with or without women aboard. A lot of the court martial records for sodomy involve rape (often warrant officers taking advantage of the boys). The idea that sodomy was ignored is not really true - the 18th century attitude towards sodomy completely demonized it (more so even than the 17th century attitude), and those attitudes carried into the navy too, among the common sailors as well as officers. Men committing sodomy had to be very careful that no one found out, because it would not be ignored and in some cases even the most insubstantial evidence could get them hanged.
There’s no denying that sailor’s believed women were bad luck during the age of sail (apparently it even survives to this day in some places, which is hilarious) and had some weird beliefs about it (I’d never heard the whistling one before! That’s so cool!) but I don’t think I agree with the idea that it came from women causing fights and drama between men, since plenty of women did go to sea and live at sea without causing that kind of problem (though I admit, I’m talking largely about the 18th century since that’s what I know most about, but I have read mentions of women at sea in the 17th century). However the idea that women had powers over the sea (in a more positive way, rather than negative, being able to quell storms and calm the sea) is a very very old one, dating back to ancient Greece, and I can easily see such a belief morphing over time to make women unlucky or to have negative powers over the sea. So it may just be that the earlier supernatural beliefs created the later ones. It happens. Sometimes there is no reasonable explanation for something, and I can see that being the case here.
On the subject of female figureheads - interestingly the female figurehead is more of a 19th century thing. From the 1780s onwards you see more female figureheads, but before that they were often men, animals (such as lions and unicorns) or monsters.
BUT ANYWAY, this is just my perspective on the whole deal. Sorry for the ramble. Women at sea is an area of particular interest to me so I tend to explode with feelings and opinions whenever it comes up. I like discussing this stuff. A lot. >__>