Uh-oh, Rick...
Screwing the macerator directly into the holding tank is a bad idea. In fact, connecting ANYthing "rigid" directly to anything else that's rigid is a bad idea. For one thing, ANY movement--even a fraction of an inch--by the macerator puts stress on the tank fitting that can crack it. A hard shock--just banging the dock--is enough to do it. If the threaded nipple on the macerator is metal, it and the tank have different thermal co-efficients (expands and contracts at a different rate and to different amounts), which can also crack the tank fitting. And if you really cranked it down when you threaded it in, the tank fitting is almost guaranteed to crack because threaded sanitation fittings--on the macerator and the tank--are NPT standard, which is slightly tapered. Tightening a fitting more than one turn past hand tight puts too much stress on the female fitting, causing it to crack...not always immediately--I've seen it take up to a year, but it will happen. Finally, if there's ANY stress--iow a bend in the hose that pulls the macerator to the right or left, up or down, it'll crack the tank fitting. It's your boat, but if it were mine I'd "soft-couple" the macerator to the tank with enough hose to act as a shock absorber and take the stress off it.
