We use a "deck snorkel"; a 12 volt hooka rig with ample hose to do the whole boat. It was a bit pricey @ around $1500.00, but at $150.00 to have a diver do the job, when he could get there, or oops, he got a flat or he's just too busy this week, the unit has paid for itself double. It's quiet, efficient and can even be used for sport diving w/ a battery in the dink. One of the best investments I've made for boat maintenance and underwater repairs or a line fouled prop, though fortunately, I haven't done that one in quite a few years.
But again as posted above, this should NOT be used if you have not gone through some type of training; anytime you breathe air underwater it can be extremely dangerous. Get scuba certified now and be safe.
Forget the idea of a longer snorkel, by the way. Your lungs cannot bring air down much farther that the standard snorkel length; that's why there aren't longer snorkels available, at any price.