I am not able to retire at this point but am thinking of taking a few months from work.
This would not qualify you as a "local" by really any local business definition. As others have said, it will vary from shop to shop, but most of us agree that a "local" is someone that lives here full time as their primary residence or someone that lives here X amount of months per year. I don't even necessarily consider everyone with "permanent residency" cards as locals because they've become so easy to get simply by proving a certain income or balance in the bank and this has become abused in my opinion (and many others). Snowbirds, extended vacationers, or multi-time a year vacationers are NOT locals - unless you live here full time, you're a guest/visitor/tourist no matter how you slice it.
I also don't offer someone a discount purely on the merit that they are a "local" - but more so based on loyalty and it's always space available. But it is discretionary and totally up to me (and each individual shop owner).
What some fail to understand, that at the end of the day, this is a business - not a hobby and not a charity. We have fixed costs for every diver on the boat, then there are variable costs based on how many are on the boat, and then there is the overhead and general operating expenses that have to be factored in. Our margins continue to get smaller and smaller with the significantly increasing fuel prices, which also affects our costs on other things and we aren't here to subsidize anyone's extended vacation or hobby.
My general structure is a "space filler" rate for true locals. I have a list and send out a message each week with available spots and it's first come, first serve. They still have the possibility of getting bumped if we get a reservation and need the space. Then if locals aren't available to fill space, I will open it up to the public as a last minute promotion. I have loyalty discounts for those who live here and dive regularly and want guaranteed spots which is a sliding scale, the more they dive, the higher their discount. But even so, regardless of how many days someone dives, my costs are the same for that diver - so a full paying visitor with a limited number of available dive days will always take priority over those who live here, diving at a discounted rate and can dive any day of the week. Shop hoppers looking for the cheapest deal with no loyalty typically don't get much of a discount from me. I'll never give a spot away for less than my actual cost per diver however - there comes a point where it's actually less of a loss to send the boat out with a few people that to fill spaces for less than it costs me.
So in the end - it's all discretionary and totally up to the individual shop owner with what they are comfortable, willing and able to offer.