Congrats on looking for the new boat...I don't know all of the specifics on the 247 advance but I have the 257 advance, which was the 247 but updated for a few things in the early 2000's, such as the hull runs the length of the bottom of the boat. The hull on the bottom of the 247 stops a few feet before the transom (a step). The boat is a great boat and most on the market have been powered with a single 225, single 250 or twin 150's. I test drove a bunch of them prior to buying and the twin 150 application was the best performance in my opinion. There will be a million opinions on single vs twins in terms of performance, reliability / redundancy if far off-shore, maintenance costs, etc. Ultimately, just depends on what you're looking to do with the boat - if boating around the bay, a single is fine. If I understand you correctly, you mentioned that the motor is a 1999 with only 100 hours? A few thoughts...a 15 year old motor with little to no use could be in worse shape than if it had 1000 hours, which would indicate regular use, likely maintained etc. First, give a call to a boat insurer (e.g., Sea Worthy Boat insurance through Sea Tow) and they can give you estimated hull value for the make, model and year as well as estimated motor value (have the make, model and year of the motor handy). Once you have that, given that the boat doesn't have electronics, you'll be able to bifurcate the current sale price of $22,000 between hull and motor and see if its overpriced. If serious, I would have the motor surveyed by a tech - see if there are "red flags" of items that could be a deal buster, since a repower is an expensive project. I would also have the hull surveyed (my full survey on the 257 advance was $500) - looking for soft spots, water in the hull, transom being water logged / rotted, etc. But, reason for that is, say you could get the boat for $14k - $18k (depending on what the hull / motor values are), you could even re-power, which is costly, but given a solid hull that you'll have for years and years, its an option.
Second thought, which is a bit contrary to the above, is, look for a 257 advance, a few years newer and likely with four stroke power. Depends on your budget, but just another thought if you're set on the 247 / 257 advance model.
Good luck
