Notice:
The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.
I looked at them for our boat about two years ago but they seemed so tall that because of the raised platform in the head where it would go, one would need a step stool in order to be comfortable while using it.
I wouldn't call 12.2" onerously high, even on that platform, but 2.6 gallons is a little "low". The 550P appears to be the same head with a 5.5 gallon tank that makes the height 16.5". (Most chairs are about 18".) I have the Sealand 711 (or some older, almost identical version)--about 20" high, which is just a little higher than the popular new "comfort height" home thrones. It's also on a bit of a platform, due to the hull shape. My old knees like it. And the higher the bowl, the less splashing from us guys.
If you need the built-in water supply of the portable, I'd lean toward the 5.5 gallon version, which is very similar to what we had on our C-25. My Sealand operates from my pressurized fresh water system--maybe a half-pint per use. I really like it.
Because I go to lakes that do not have pump out facilities I installed the carry out tank model. So far, so good. I had to add a larger wood platform to the sole to sit it on. I placed blocks on the new wood to hold it in place and used a bungee cord to keep it from falling off when heeled over. I intend to make a more permanent method in future. It is a little high, but usable.
Notice: The advice given on this site is based upon individual or quoted experience, yours may differ. The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.