changing a porta potti to a marine toilet

I have a Robalo 1992, 2660, cuddy cabin. I want to change the porta potti and install a holding tank and marine toilet. I want to make sure my mechanic know how and where to place the holding tank and run the plumbing.
Any suggestions. I tried to contact Robalo, but could not. I want to make sure where things should be placed and run, especially if he has to cut or open areas of the boat. Please help. Any suggestions. Ronron
I do have a pumpout already for the portapotti. Thanks, Ronron

Re: changing a porta potti to a marine toilet

The first consideration is going to be space to mount everything. I converted my old cruiser from overboard dump to a holding tank soon after I bought it. First you need to get a good idea of the amount of room you have on board. I recommend you use the largest capacity holding tank you can fit in to the space you have.
You are also going to need a water supply to flush the head. You can draw raw water through a fitting below the water line or install a separate holding tank for flush water. It is not a good idea to tie your flush water supply to your fresh water supply. The possibility of contamination is too high.
If you want to use an electric macerator type head you must also consider the electrical supply. A hand pump type head is easier because it does not need power.
Use only high grade marine sewer hose for you connections. The extra cost is worth it. Marine sewer hose is designed to prevent permeation of odors through the hose itself. Most people don?t know that the smell comes from the hoses far more often than anything else. You will also need to run vent lines to the holding tank. The ideal situation is to vent the tank from two locations. Some applications even call for a vent pump to circulate air through the tank. I know it sounds crazy, but the fact is that the more air you can get running through the tank the less odor you will have. The bacteria that causes the odor cannot live in an oxygen rich environment.
I luckily had plenty of room for everything I needed. That's the real challenge.

Try a Google search for "how to install a marine head" you will get a huge amount of info on the subject, including technical information.

Its been a few years, but I would be glad to help you through the process when you get started. Do a little research in this project. You definitely need to "read the instructions" for this one.