I was scuba instructor for 34 years and serviced dive equipment
All of the things mentioned here are really good answers. The hose to surface idea is correct that it will only work to about 3 ft. You can try it yourself cheaply by adding a bit of hose to a snorkel and lower yourself slowly taking a breath every 6 inches. Even 3 ft. is tough.
Then there is whats called tidal air. Breathing through any hose you inhale the same air that you just exhaled. Each breath has less oxygen in it and increased co2.
A scuba certification
is lifetime and international. You do not need to buy equipment
to dive. It can be rented in a lot of places solving storage
and high cost of personal equipment and you wont need to refill your own tank. Just rent when you need to clean your hull
. If you have your own tank it will be required to have a visual inspection
every year and hydrostatic test every 4 years. All for a fee and wait times.
As far as hooka goes, you can use about any oil
free is the operative word. Scuba air is just normal air you are breathing now. Just compressed and filtered and moisture removed. The oil free is important because oil vapor inhaled will coat the inside of your lungs causing linphoid pneumonia. (forgive my spelling) and all it takes is 1 breath.
There are companies that make electric
powered hooka systems both ac and dc powered. They are compact but again present a storage
problem for a sailing cruiser. The pump itself is small but the hose and mouthpiece rig takes up a of of space. Dont use a garden hose. You need a hose that is certified for breathing air. Other hoses can give off harmfull vapors. Tiny but still there. Also, any compressor
will absolutly need to be placed upwind from and combustion exchast or it will suck in and compress the gasses. Again, not good at all.
Many years ago when we still used double hose regulators, (read Sea Hunt), we had troubles with an algea or mold
build ups inside the hoses. they would need to be removed and cleaned now and then.
I am a full time cruiser and am certified with more than 5,000 dives. Yes, actually more than that. I rent gear when I need to clean my hull, replace zinks, etc, etc. You will need to be certified to rent gear but you will not need to store or maintain anything.
and what is included varies tremendously for getting certified. You can get a complete course in Utila, Honduras
for 99 bucks equipment included. As you cruise
, look around for prices. Some places will require you to buy certain items from them only, as a way to help offset the cost of operations and equipment. Some will include everything for 1 price
For my money
, get certified and rent.