Billyboys

[Wheldale]

Hi,
I'm a volunteer at Hull Maritime Museum and Yorkshire Waterways Museum. I normally crew on the Tom Pudding Tug Wheldale but I'm also very interested in the history of the region's Billyboys. I have plenty of pictures and info from the 19th century but very little on the origins and earlier centuries. There are 2 theories about the name origin but neither has been verified to the best of my knowledge.
1) They are based on the Dutch bijlander, a sort of cross between a keel and a bijlander, hence 'Billy'. This certainly makes sense to me.

2) Hull people famously were fanatical about support for King Billy, hence the golden statue. The theory goes that the name 'Billyboy' was applied first to Hull people in general, then to its seamen and then to the ship. Possible but it sounds a bit far-fetched to me.

Can anyone with a bit more knowledge point me in the right direction please? When I've a bit more time I'll get into the History Centre and check the Shipping registers but these only go back to about 1810 anyway.