Drains 101 ...

[TreblePlink]

Is there a good reference on drain, bilge pumps and seacock strategies?

My refit is now once again progressing, and I'm wanting to minimize below waterline seacocks and hull penetrations, and KISS ...

My plan is to reduce 4 seacocks to 1; two are currently for the marine toliet which will become a composting one; additionally, there is one 1.5" tapered-cone seacock just behind the companionway stairs which is the cockpit drain. Another plastic thru-hull which does little will be removed.

I need to 1. drain the cockpit, 2. Outlet primary bilge pump (3/4") 3. Outlet secondary bilge pump, and 4. Outlet sink drain.

Currently, the single bilge pump outlets into the cockpit.

If I "Y" into the cockpit drain seacock with my sink drain I may have greywater disposal inspection issues. I could route to a small "shower sump" holding tank, and pump out ...

So then I'd have three outlets to install, in the transom?

And another rub ...

My boat's lazarette contains a large bottom hull penetration, just a bit above the waterline, for the 9hp outboard. There is a waterproof bulkhead between it and the rest of the boat. So, I'm wondering if it might be better to outlet there?

All suggestions are welcome.

Chris

[TreblePlink]

Wow zero replies.
This must either be really simple and folks are laughing at me, or much more complex than I thought ...

[flee27]

I posted a while back asking why sea chests where not more popular and I also got no responses. Maybe I can piggy back on your thread and get some opinions. It all seems to be related.


I don't have a lot of experience but it I feel like if I was doing a major plumbing refit a sea chest would be a good way. This way all the systems that need sea water except engine cooling would be done with one through hole. I am sure there are disadvantages and would like to be educated. The only one I can think of would be more complexity in running hoses.


Good luck on getting your answers and your refit.


Foster

[Terra Nova]

Originally Posted by TreblePlink

...My plan is to reduce 4 seacocks to 1...
I need to 1. drain the cockpit, 2. Outlet primary bilge pump (3/4") 3. Outlet secondary bilge pump, and 4. Outlet sink drain...

Horrible plan.

[TreblePlink]

I know the existing plan is a kludge. Can you educate me just a bit on exactly what is horrible?

Chris

[Terra Nova]

Somewhere you got the idea that you knew better than the boat's (and all other professional boat builders) builder, and that you could simply combine all the thru-hulls into one, regardless of consequences. Where did that misconception originate?

[Cheechako]

I just dont have the "fear" of seacocks that some have. I went the "reduce seacock number" route on one boat.
-things didnt drain well
-All those fittings and hoses in the boat were very likely a bigger risk to sinking than a few seacocks would have ever been.
-horizontal runs are problematic.
-Bilge pump outlets can be above waterline with no seacock at all.

[TreblePlink]

Originally Posted by Terra Nova

Somewhere you got the idea that you knew better than the boat's (and all other professional boat builders) builder, and that you could simply combine all the thru-hulls into one, regardless of consequences. Where did that misconception originate?

Well, when I remove the now illegal marine toilet, and use a composting head, I go from 4 to 2.

The main cockpit drain is a 1.5" real seacock, and is a vertical hose - it drains well. There is a SMALL plastic thru-hull cockpit drain with the outlet so high that is only works when heeled over to one side, I'd like to eliminate that if possible.

The current bilge pump squirts straight out at ankle level into the cockpit.

The current sink drains into the bilge.

And I'd like to add a second, larger, bilge pump.

[Terra Nova]

NEVER combine bilge pump discharges.

[TreblePlink]

Originally Posted by Terra Nova

NEVER combine bilge pump discharges.

Yeah, that sounded problematic, with real possibilities of backflow.

But my real question, what about having both bilge pumps discharge into the bottom of the lazzarette, which has a large opening (for the outboard) just inches above the waterline?

[Terra Nova]

Unsubscribed.

[TreblePlink]

Being an engineering type, I've always been easily convinced that my great idea is poo when confronted with it's defects and WHY it's a bad idea ...

[HopCar]

Don’t worry too much about the number of thru-hulls you have. If done right, you are very unlikely to have a problem.

By done right I mean a bronze flanged seacock mounted to a fiberglass backing plate that is epoxied to the hull.

I would recommend the Groco BV series of seacocks and their ready made backing blocks. The BV series seacock is massively strong. The only maintenance it should need is a squirt of grease if you feel it starting to stick. They should last the life of your boat.

[Tayana42]

Trebleplink, I have a sea chest from one through hull and sea cock supplying my engine raw water, small water maker and salt water foot pump at galley sink. All discharges have separate through hulls and sea cocks. Routing your discharge plumbing to your outboard motor well may bring gray water sludge, fats, food particles as well as bilge detritus to the cooling water intake on you outboard.

[Suijin]

Originally Posted by Terra Nova

Unsubscribed.

Interesting that you subscribed in the first place. You posted three times, telling him what not to do with no information about why, or a better plan to pursue, or a pointer to where he could find more information.

To the OP: the boat has survived 49 years just fine with the current arrangement. Just maintain and inspect your thru-hulls and seacocks regularly and you should be fine. I have six thruhulls below the waterline and it does not concern me. In fact I had five until recently when I added one for a bow washdown intake.

Here's a good resource for evaluating your current thru hulls:

https://marinehowto.com/seacock-thru-hull-primer/

It's worth your time to confirm that your current thru hulls conform to best practices and remedy them if necessary.