Very Good to ALL - this is by far the most difficult mod I have ever attempted with the most moving parts.
When tlgeddes and RussMT said pump out for the galley sink I was surprised because the M boat uses a gravity drain for the sink and it works quite well. I suppose if you wanted you could plumb the galley sink into this box also, but I had not planned on it because the thru hull on the galley sink is so close to the waterline I worried about flooding the box. Herschel also shocked me when he said he already had a pump in the bilge and I was wondering how in the heck he ever got a sump box into the bilge and then i noticed he has an X boat. That's the main reason why this mod is a mod - because of the placement of the box and the impossibility of doing this on the M boat. This makes me wonder if Ponaldpe has already figured this out?
Jimmyt gets promoted from First Mate to Captain - he hit the nail on the head - it is indeed a shower sump - a very common item on almost every other boat except ours:
They are SO common that nearly every manufacturer of shower sumps uses the same two boxes - (I studied this extensively and talked to a LOT of manufactures). These two are the 2 smallest commercially manufactured sump boxes you can buy. BIG PROBLEM - neither one will fit in a MAC M boat.
Why?
To get to the LOWEST part of the ship and still have room for a box there is only one place on the M boat - the area between the ballast spline and the wall that holds up the rear dinette seat:
The area in the red circle above along the bottom of the boat on the starboard side is all we got - the area is only 7 inches wide so a sump box can’t be wider than 7 inches to get in there - there IS NO sump box available that skinny. Everything forward of the red circle is ballast tank - you can't get low enough for a sump up there.
So, I had to fabricate a custom sump box 7 inches wide with the same water capacity as a commercial box so that made my box very long - like nearly a foot.
The factory gravity drain on the galley is a work of inspiration here - that is actually a design of simplicity and genius because no moving parts no pumps and no check valves required and it can't flood. I know how we all think the plumbing on the MAC is such a cheapo crappo job but really, after spending months educating myself on bilge and marine plumbing systems I really came to appreciate the simplicity and safety of the factory design.
To do this kind of thing with a sump box with a waterline thru hull you would need a thing called a “vented loop” and a check valve and there is all kinds of marine hardware you must buy and things get really complicated real fast. I decided to UN-complicate things by putting my thru hull much higher than the waterline so I would not need to worry about flooding the box,
All accomplished by putting the thru hull HERE:
Now, you may think I lost my mind putting the shower thru-hull here - but I'm not as stupid as I look - here are the advantages:
1. it drains into a holding tank: by putting a cork in the motor well drain it becomes a perfect holding/settling tank that keeps me out of trouble with California and Canadian environmental laws. I can pull the plug when I am safely out of the no-discharge zone. If I am not in a zone I just let the shower drain into the well and that drains out the galley thru-hull.
2. The new thru hull can't flood the sump box because it's too high above the waterline (like the outboard steering push-rod) - so there is also no need for a vented loop!
3. The elevation from the sump box to the new thru hull is a gentle slope upward perfect for eliminating the possibility for airlock and because I made a custom box that holds a lot of water it can handle any capacity of back-flow from the hose.
4. in an emergency situation it's in a place that is easy to cork. - I carry a cork for the galley thru-hull also (and a rubber mallet) but that one is so hard to reach and made me consider a different location for the shower thru-hull.
5. this sump arrangement allows you to locate your shower anywhere in the boat that you want.
And this is just ONE system of many required to take a shower in the boat the same way the rest of the sailboat community does - here are the OTHER systems I need to create to make this work:
a.Hot Water setup
b.shower pan and curtain or some way to contain the shower in the boat
c.electric system to run the pump out
It's going to be a very difficult mod -