shower drain

[Ron Hill]

Antoni : You may be "opening a bag of snakes" with your plan!   I'd recommend that you leave things as is!!
There isn't that much space between the head floor and the hull!!!

A thought

[LogoFreak]

I hear ya Ron, but I want a useable shower in there and I refuse to fight gravity. As much as this will be a PITA to get right I'm willing to go thru with it.

[Ron Hill]

Antoni : In my C34 from 1989 thru 2015 my wife and I averaged 100 overnight per season and we showered each night (99% were ON the boat!!)
Gravity gets the water on the sloped floor to flow down to the shower drain. I calked a small piece of bronze screen over the top of the drain grate. Then I installed a filter in the intake line BEFORE the one way (no-back flow valve), I also sprayed silicone on the diaphragm pumps "rubber" diaphragm to keep it nimble. So if you keep the crap (frzzy wizzys and hair) from getting to the pump. It functions as designed!!  That system works and is still working today!! 

The only thing that the factory forgot is the filter in that line!!!  Any pump will fail with out water, because water is its lubricant!!

So if you want to screw around with trying to build a "box" in the SMALL limited space under the flooring - have at it!! 

A few thoughts

[LogoFreak]

Well Ron I screw around with things all the time and so far I'm very satisfied