My kitchen sink had a hairline crack in it but thankfully it was covered under warranty. If it wasn't I would have bought 3M™ Marine Adhesive Sealant 5200. I have used this for my boat and was very happy with its sealing properties. Apply to the underside and seal it up well. In an hour it will become tacky and fully cure in 2 days. Could be worth a try before you spend money and replace it.
2014 Jayco Whithawk 28DSBH
2012 F150 SCREW 5.0 XLT XTR Off Road package, 3.73 EL, tow package, Peragon retractable cover.