All the portapotties sold in marine stores
have hold-down clamps, Dennis. You may even be able to order hold down clamps for the ones sold at camping supply stores, Walmart etc. What is the brand of the one you need to replace? (If there is no brand name on it, call Hunter and ask them which one they used then.) If you get the same one, you should be able to use the hardware that's already on the boat.
