I don't have reason to believe there is anything particularly unique to or special about a 1997 21 OUTRAGE boat. The bare hull is 2,500-lbs, so I'd anticipate with engine, fuel, and gear the boat will weigh almost 5,000-lbs. I'd get a trailer with tandem axles and brakes on all four wheels. Recommendations for trailers for Boston Whaler boats are given in
http://continuouswave.com/whaler/reference/trailering/There are six lengthy articles on trailer selection and use which should inform you before you buy a new trailer.
If the trailer will be used frequently in saltwater, invest in upgrades to the trailer to reduce corrosion problems, such as stainless steel fasteners, flushing hoses for wheels and brakes, and upgraded brake components.
I have been using an E-Z-LOADER trailer (an older model that is similar to a TEZ-19-22/24 5200-lbs model) for many years for my classic REVENGE 22 W-T WD boat. The trailer is on its third set of tires and has more than 40,000-miles of hauling in the past ten years or so. Find more E-Z-LOADER specifications at
http://www.ezloader.com/images/pdf/adj- ... ations.pdfBoat trailer sales are often quite localized. Check your local area to see what is available. Nationally-distributed brands are generally good choices, but often local manufacturers make good trailers, too.