I'm bonding steel to a boat deck that's been coated with flowcoat. MMA adhesives seem to need less surface preparation than other adhesives. Do I need to remove the flowcoat and sand back to the resin or can I clean the flowcoat so that I can glue to it?
Thanks

Should be fine to bond direct to the flowcoat, but it sort of depends what you are bonding. If it is structural, it will be better to remove the flowcoat and bond directly to the laminate, otherwise you risk the flowcoat delaminating from the laminate under load. Polyesters don't have great bond strength, and gelcoats/flowcoats are quite brittle, so it wouldn't take a great deal to break the coating off the laminate. 

If it is something non-structural though, then the MMA will hold very well to the flowcoat. 

Even though some adhesives need "less" preparation, it is one area worth not skimping on.  As Hanaldo mentions, the best route is likely to be determined by how structural your application is.  In all cases, you will want a nice rough key to both bonding surfaces and a thorough clean and degrease to ensure whichever glue you choose in the end will adhere as best it can. 

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant