I own a 1988 281FF (Family Fisherman). In the 4 years I have owned her, the boat's primary use has been offshore fishing, ranging to islands (about 45 miles out) or open water, up to 55-60 miles offshore. It's well suited for purpose, carrying 2 to 4 people, full fuel load plus 65 gallon live bait tank (commonplace for SoCal style offshore fishing) plus tackle and supplies.
My 281FF has a hardtop with removable curtains all around. The back curtains are usually removed when boating, re-installed for storage. I don't know if the top was a factory option, but none of the 281 photos in the 1988 Aquasport brochure show a top. In my opinion, an enclosure of some type is essential for offshore use; the ride can be wet if swells come up when heading "uphill".
My boat is a single-inboard, powered by the original gas-burning carbureted Volvo Penta BB260: 350 cubic inches, rated 260 HP. At 4400 (maximum) RPM, the boat has a flat water top speed around 29 MPH. Fully loaded (4 people, full fuel, etc.) she cruises at 22 MPH at 3400 RPM, 24 MPH at 3600 RPM. From the specifications offered below, standard power was probably the 454 c.i. Volvo Penta. With today's fuel costs, I am glad she has the "small block" engine instead of the standard "big block".
Looking at Aquasport's brochure for that model year, there are differences in specifications between 1987 281 Osprey, and the two 281 models offered in 1988: the 281C (Coho) and the 281FF (Family Fisherman). The 281C has a "no frills" cabin, while the 281FF adds a deck hatch, a port hole on each side of the cabin, a head and holding tank. Neither model has a sink, so fresh water storage doesn't apply in 1988. Apparently the 1987 271 Osprey had a sink.
Standard power for the 281C/281FF was single inboard, There was also an option for outboard engine transom bracket. Big difference in fuel capacity, as you might guess.
Here are the 1988 specifications, direct from the Aquasport brochure:
Length including pulpit: 28' 10"
Beam: 9' 7-1/2"
Deadrise: 20 degrees
Hull Type: Deep V
Max HP: 550
Standard HP: 330 HP I/B
Approx. Dry Weight: 5400 lbs
Headroom: 6' 3"
Fuel Capacity: 150 gal Inboard, 250 gal Outboard
Draft (incl prop): 29"
I hope this helps,