Timely discussion; thank you!
We too are having a problem with the drain on our 38 Ocean. After rebuilding the sump pump and replacing the filter, it now appears that I need to snake the drain, end to end.
Based on the comments above, it appears that I need to manually drain the tab and then I can disconnect the drain fitting in the GRP tub floor and the whole thing should lift out, at which point I can disconnect the drain elbow from the hose and run a snake through it to clear any debris??