Need advice on thru hulls, holding tank

[DanAndJenn]

Good morning, my wife and I are brand new to our C36 (1985) after owning a C25, and have a couple questions I can't find answers to in owners manual and a web search; the thru hull valves in the head, one for the sink and the other is for what? Should they remain open at all times at the dock and closed underway?

Also, holding tank; does the galley sink drain into the holding tank, because ours fills up quickly with just the two of us on board and I suspect because my wife does a ton of washing up after us, that the valve under the sink in the galley can be closed and the water will go out, is that correct?

We appreciate ANY help you can give, and any tips regarding short cuts you've learned along the way will be valued!

Dan & Jenn
WaveLength

 

[Stu Jackson]

Catalina 36

Dave,

Your questions are very boat specific. You may find more answers here:

https://www.catalina36.org/forum/c36375ia-forums

The holding tank is only for the head, not the galley sink. The galley sink drains through a thru hull directly out.

We, too, had a C25 before we bought our C34.

Good luck.

 

[Peggie Hall HeadMistress]

...the thru hull valves in the head, one for the sink and the other is for what?

That depends on its size...a 3/4" (hose sizes are always stated as their INNER diameter) would be the flush water intake for the toilet. First thing you need to do is trace the routes of every hose on your boat to find out what each is connected to at both ends...'cuz when you find yourself stepping into water over your shoes is NOT the time to START trying figure out which one is the source of the leak!

Should they remain open at all times at the dock and closed underway?

Again, that depends on what they're connected to.

does the galley sink drain into the holding tank...

Unless for some reason the PO rerouted the sink drain line to drain into the holding tank (there are a couple of lakes in CA that have started requiring gray water holding), all sinks should be plumbed to drain directly overboard.

that the valve under the sink in the galley can be closed and the water will go out, is that correct?

That valve under the sink is most likely the seacock on your sink drain thru-hull...close it and the sink won't drain at all! If it's not a seacock, post a photo of it so we can see just what kind of valve it is.

...because holding tank fills up quickly with just the two of us on board.

Let's do a little math to see whether it's filling up faster than it should: The average adult uses the toilet 5x/24 hrs...avg flush: .6 gals (2 liters)...so that would put an avg of 3 gal/person/day into the tank...6 gal/day for the two of you. Divide the size of your holding tank by 6 to find out many days it should last you. Do some research in the sanitation and plumbing forum for tips on how to "stretch" holding tank capacity.

I suggest you spend a day going over every inch of your "new" boat to find out exactly what you have--and exactly where things are...what's connected to what else, what you really need to get the owners manual for (most are available from mfrs' websites) to learn how it works and--more importantly, how to maintain it. You're bound to have dockmates who are familiar with most of the systems on any boat...get to know your dockmates! Most people would much rather answer questions and help a newbie sort things out than start a pool to see who gets closest to the day and hour your boat sinks or hold their breath wondering whether you're about to blow up the dock .

And you'll always get answers to your questions here...a few of which might even be the right answers!

 

[DanAndJenn]

Thank you both for the quick responses! And Stu, I appreciate the link, am new here also and am just getting to know the site and how to navigate it. I'll check out the link!

 

[tahomathundr]

Do you have a macerator for pumping the holding tank overboard? If you do make sure the seacock is closed while sailing because I found that seawater can back flow into the tank on some points of sail. I have a C309 and that's what mine did. Your arrangement may not be the same but is something to check.

 

[Jackdaw]

I suggest you spend a day going over every inch of your "new" boat to find out exactly what you have--and exactly where things are...what's connected to what else, what you really need to get the owners manual for (most are available from mfrs' websites) to learn how it works and--more importantly, how to maintain it. You're bound to have dockmates who are familiar with most of the systems on any boat...get to know your dockmates! Most people would much rather answer questions and help a newbie sort things out than start a pool to see who gets closest to the day and hour your boat sinks or hold their breath wondering whether you're about to blow up the dock .

And you'll always get answers to your questions here...a few of which might even be the right answers!

BEST post/advice I've seen here in a LONG time!

 

[Tim C350 April IV]

Second thru hull under the head sink is probably shower sump discharge.

 

[Kings Gambit]

The thru hulls beneath the sink in the aft head on the Bavaria are sink drain & sump pump discharge (high), head intake, head discharge, and holding tank discharge (low). The last two are bigger, probably 1 1/2-inch hoses. In the fwd head under the sink we also have sink drain & sump pump discharge (high), head intake and head discharge (low), the last the biggest as above. Tank discharge of second holding tank is amidships under the port-side salon bunk. Incidentally, you should know the location and functions of all thru hulls on the boat. Perhaps should label them; at least one tapered wooden plug for each size thru hull should be taped or strapped to a hose under the sink where it can be seen and easily reached. A Velcro strap is probably best for quick use.

 

[sailme88]

Dan,

I suspect the other thru hull is the shower drain/pump out. In that area you should have a sink drain, head intake and shower drain.

Rick