Adding Aft Deck Drain Port

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jefndeb

Guru
Joined
Jun 11, 2018
Messages
601
Location
US
Vessel Name
Indigo Star
Vessel Make
2006 Mainship 400
Well I think I have figured out why I get water down in the aft deck/generator area.

Our 40 has a slight list to port when loaded up and this causes water to collect on this port side of the floor access door edge (drain catch) and not drain out, as the drain is on the starboard side....geez...it spills over into that area.
I bought this drain port and I was thinking of installing it on that side and 'T" it into the existing cockpit drain lines just below it.

The starboard side has ample drainage as shown in the picture.

Sound good?

Are these 1 1/2 drain hoses that I will have to T into?

Jeff 20210418_095845.jpeg20210418_095858.jpeg
 
As Black Adder would say - "a cunning plan"
 
The other side has a 45 degree area for the drain fitting, is there enough room on the side of the gutter for the new drain fitting? If so then I would run a new through hull on that side of the boat for the water to go overboard. Putting a T into the other side may be difficult since it is already pretty much a mess of hoses. Also you are going to try to get the water to flow uphill to the other side of the boat. Putting a new through hull is pretty easy to do. I take a pair of rare earth magnets and stick one on the inside of the hull and tape it where you think you want the through hull. Then go outside and stick the second magnet on the side of the boat. It will find the first magent that is inside and stick to it. If it looks good then make a mark where the outside magnet is and remove the magnets. Then drill away.
 
My lazarette hatch drain did the same thing. Only one drain on the port quarter of the gutter to the port side of the hull.
I installed a through hull in the stbd quarter of the gutter and ran that to a new through hull on the stbd. side of the hull.
I also ran a common line between the two gutter drains so it does not matter which way the boat tilts, the gutter drains.
 
I did exactly what you are considering on our 400 and it works pretty well. I couldn't figure out a way to flush mount the through hull, so a little water still sits in the hatch gutter, but not enough to make it overflow, generally.


Pics attached.
 

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Remember to insert a water hose into the drain periodically, to flush any debris and to check that the drain is not blocked and still draining.
 
Remember to insert a water hose into the drain periodically, to flush any debris and to check that the drain is not blocked and still draining.

So true with any drain line.
 
Best way to make it flush (to drain completely) is to get a piece of G10 fiberglass tube the diameter of the hose you intend to use, and bond it in flush with epoxy.
 
Or cheat and use a lathe to modify the T.H. head so it is flush with a taper on the backside and the hole in the gutter also tapered.

If I had thought of the G10 I may have gone that route instead but it helped I was given two deck drains made of bronze.
 
Seems like all MS 400s list to port. I used cases of beer on the starboard side and leveled her out nicely. Then I drank them and the same problem came back....


I had also planned to put an additional drain, but never did it. Dougs looks great and I was going to do something similar and even put a hole in the transom, but above the waterline, unlike the original drains. Why Mainship put those drains below the waterline I don't understand.


I put a mat over the whole hatch that worked pretty well and simply slowed down the flow where it wasn't much of an issue. I used the same mat over the swim platform when raising and lowering the dinghy to protect it from the dinghy motor hitting it.
 
Yes, the PO had a large mat there when we bought it, now I know why....
 
Best way to make it flush (to drain completely) is to get a piece of G10 fiberglass tube the diameter of the hose you intend to use, and bond it in flush with epoxy.

Or get a threaded white PVC plumbing fitting and epoxy it in with a cabosil thickener. The fitting can be set flush and (with luck) will be long enough to make a standard connection on the underside easy.

Easy for me to say. I have tiny 1/4" weep holes on my lazarette drain gutter that can be plugged by deck dust or a feather and I haven't gotten around to that project.
 
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