I was just browsing and cam e across this composting head its made for 12 volt for a weekender
But to me it could be fitted to a boat
What I like about it is urine could be either directed over the side or collected http://www.abetterwaytogo.com.au/products/separett-weekender.aspx?lv.crumb=17384
I dont think its overly large like some designs
ASsume you've also seen these:
natureshead.net/index.php
www.airheadtoilet.com/
Was interested once but decided to leave my direct out and bought a portable camp loo for weekenders in lieu of a better option.
No.... You will need to take your vessel 3 Nautical miles from any land,island or reef to take a wee. Don't forget to take your Epirb!
Select to expand quotesouthace said..
No.... You will need to take your vessel 3 Nautical miles from any land,island or reef to take a wee. Don't forget to take your Epirb!
Select to expand quoteHG02 said..southace said..
No.... You will need to take your vessel 3 Nautical miles from any land,island or reef to take a wee. Don't forget to take your Epirb!
Dam Greeny 
I just ordered a nutri bullet perhaps you could run one of these through a inverter!
I doubt that these designs could handle being bounced about as happens on board a boat, without splashing the contents. Note that a Porta-Potti is sealed when not actually in use.
BTW one of the features I like about the Walker H28 is the head on the centre line of the boat. This makes it much easier to brace yourself, no matter what tack the boat is on.
Select to expand quoteYara said..
I doubt that these designs could handle being bounced about as happens on board a boat, without splashing the contents. Note that a Porta-Potti is sealed when not actually in use.
BTW one of the features I like about the Walker H28 is the head on the centre line of the boat. This makes it much easier to brace yourself, no matter what tack the boat is on.
they contents would be reasonably non splashable as you add moss and saw dust Yarra I guess it would depend on what sort of night you had previously 
But after much thought my head will return to the forward cabin and Ill lavish the proposed area with a nice galley instead a much easier option to make
Im taking the easy way out
Still thinking about options Ive a couple of weeks before I start on this project.
return the head to its original place and fit fridge and sinks to the port side next to the gimbaled stove. and then remove the old fridge from the starboard side and make full width draws starting with a chart draw and continue down
Photo above The bench top would continue just under that small shelf above in line with the stove top with sinks and fridge
Photo below
Full width draws starting with a chart draw for the top one. No fridge lid and new bench top matching the port side all draws being as deep as possible and the head return to its original place in the forward cabin
2 weeks to think about my two options the other option is the head fitted in a compartment next to the stove gimbal
Similar to this only on the port side
Then the sink and Day fridge would be in the old fridge cabinet( photo above) and a larger fridge freezer where the head was in the forward cabin
To utilise the bow as a wet area personally I think is the best choice (as I said from the start!) my yacht had the head in the port side when I originally brought the wreck, first job I did was to move the head to the bow and remove the false bulkhead which opened up the cabin sole. You can even add a good sized sink to do your hand washing and a retractable hand shower to wash your winkle!
