Adding new thru-hull above water line

[Sykes]

I am adding a new thru-hull above water line and want to know if I can install it next to my exhaust or should I install it on the port side?

It will be at least 10 inches above the waterline either way.

 

[OldDan1943]

What is the purpose of this thru hull?

 

[Sykes]

Aft bilge and a large deck hatch drain with two 1 inch drains.

 

[OldDan1943]

Aft bilge and a large deck hatch drain with two 1 inch drains.

Aft bilge pump?
The deck hatch drain should be a separate through hull. You dont want the aft bilge pump filling up the area of a deck hatch.

 

[Sykes]

They run together always have without issue.
Prior setup ran them to a thru-hull under the boat. I have decided to use the underwater thru-hull for a new 16k A/C. As you know we need two 16k units to be comfortable down here..

 

[OldDan1943]

They run together always have without issue.
Prior setup ran them to a thru-hull under the boat. I have decided to use the underwater thru-hull for a new 16k A/C. As you know we need two 16k units to be comfortable down here..

You have one bilge pump for the aft bilge?
I am trying to visualize the current method of getting the water out.
From the bilge, sure.
I am not sure about the "large hatch cover".
Currently the bilge pump discharges underwater? Must be a strong bilge pump. A positive displacement pump?

How close to the exhaust outlet?

I added a couple of bilge pumps to my N46. I alternate the discharge port and starboard. My thoughts were, the Rule pumps dont put out an "exciting" discharge pressure so.... if the boat developed a list one of the pumps would have a 'clear' area to discharge, not fighting the water pressure.

I would think discharging to port would be safer and prevent a flood of water into the water-lift muffler and maybe finding a path into the various important parts of the engine, when tied to the dock.

 

[OldDan1943]

I have decided to use the underwater thru-hull for a new 16k A/C. As you know we need two 16k units to be comfortable down here..

I have a 16K and a 12K reverse cycle A/C.
The currently built boats put a smaller A/C unit on the floor of the tiny and only fwd stateroom hanging closet. Then use the current A/C unit space in the pilot house for 4 drawers and an official adjustable captain's chair. I have the traditional bench seat and am seriously considering the installation of a lap type seat belt. Perhaps it will be one of those project that will never happen.

In your case, adding another A/C unit I would think you would need additional outlets..... You might want to think about adding additional vents separate from the other A/C vents. You can push only so much air down the pipe. Think 'separate but equal' ducting.

 

[Bacchus]

I may not be the most experienced but I have only ever seen one discharge underwater and that from a macerator.
I would think all others hold some degree of unnecessary risk. Why do it??

 

[Comodave]

Agree, I would not want any of the above mentioned through hulls to be below water. No reason to do it and a big reason not to do it, sinking boat.

 

[OldDan1943]

Hmmm, lemme think. Thru-hull valves below the water line
Main engine
Generator
Water maker
A/C inlets
Macerator

What else?

 

[Bacchus]

Hmmm, lemme think. Thru-hull valves below the water line
Main engine
Generator
Water maker
A/C inlets
Macerator

What else?

All intakes that HAVE to be below the waterline.
How many discharges can you identify?
Would you want valves on supper drains etc and would you close them when leaving the boat for any length of time.
Why would it be beneficial to not be able to visually confirm AC pump is working?

 

[OldDan1943]

All intakes that HAVE to be below the waterline.
How many discharges can you identify?
Would you want valves on supper drains etc and would you close them when leaving the boat for any length of time.
Why would it be beneficial to not be able to visually confirm AC pump is working?

It is my preface not to have any valves on the overboard discharges with the exception of the macerator pump discharge. Most boat manufacturers do not put valves on the overboard discharges with the exception of the macerator below water discharge.

Per identifying the overboards...... I took the time to develop a schematic of all the overboards including tank vents.

Scupper drain valves? Perhaps I am misunderstanding the question. Scuppers are fairly large free flowing atmospheric drains in the cockpit and other necessary areas. They are basically large holes in the side of the boat above the water line. They do not have valves. They are 'passive drains'

Beneficial for visually confirming the A/C SW pump is working? No discharge, no A/C or turned off. If the system is turned on then the lack of flow could indicate hull inlet valve closed or the hull clam shell is plugged or the hose between the hull valve and strainer is plugged up or the strainer needs to be cleaned or the system needs to be acid cleaned.

Did that answer all your concerns?

 

[Bacchus]

It is my preface not to have any valves on the overboard discharges with the exception of the macerator pump discharge. Most boat manufacturers do not put valves on the overboard discharges with the exception of the macerator below water discharge.





Did that answer all your concerns?

That was my point... no valves on discharges because they are ABOVE the water line with the exception of the macerator. Below WL discharges NOT recommended for the OP.
Valved inlets yes as they have to be below WL to function.
It seems we are in agreement.

 

[OldDan1943]

That was my point... no valves on discharges because they are ABOVE the water line with the exception of the macerator. Below WL discharges NOT recommended for the OP.
Valved inlets yes as they have to be below WL to function.
It seems we are in agreement.

Bacchus, oh I love it when I ace the test.

Another way to look at it, if your discharge lines are below the water level, you are sinking.

 

[Sykes]

LOL ok thanks and thanks and thanks. Port or out the stern for a bilge discharge?

I want to put it on the stern out of convenience but never actually observed one or owned a boat with a stern discharge..

 

[OldDan1943]

LOL ok thanks and thanks and thanks. Port or out the stern for a bilge discharge?

I want to put it on the stern out of convenience but never actually observed one or owned a boat with a stern discharge..

At/on the transom? NOPE.
When you slow down water piles against the transom, not a good idea.

 

[Sykes]

At/on the transom? NOPE.
When you slow down water piles against the transom, not a good idea.

That's what I was thinking. Thanks

 

[Turtle Blues]

My vote is side outlets, single discharge.
See this on most newer boats. Have several manifold discharges with bottom outlets to 11/2 valves on through hulls. Never comfortable looking at them. Don't like the idea of a pressure bilge line and a gravity condensate sharing an outlet.

 

[OldDan1943]

Don't like the idea of a pressure bilge line and a gravity condensate sharing an outlet.

I totally agree with you.