Galley Sink Through Hull

[hetek]

The A25 has, imo, way too many under water through hulls, so I removed them all and 'glassed them over. The original galley sink drained through one.

I'm thinking of an above waterline drain. Short and sweet, but how high above the waterline? I had a boat once that had a 90 degree fitting on the basin and drained straight to the hull side. I'm not thinking that drastic, but a nice sweeping path overboard should do fine.

Thoughts?

Why ask? Why not just do? Because unlike an underwater fitting, a hull side "mistake" is harder to correct. If I can, I'd like to find out what works fine or what not to do before I pick up my drill. Thanks!

[hetek]

Just to add...

One benefit of an underwater drain is the sound of silence. How many marine AC systems pump water overboard above the waterline sound like someone with a bladder problem? A BAD bladder problem.

Too low to the waterline and I suspect the drain could regurgitate sea water up into the basin in a snap roll or a wave slap.

Yes, I know I don't need a galley grain before I go boating. But since I'm in there and my tools are out...

[dkirsop]

The bending radius of your drain tube will likely dictate where you place the drain outlet. Some materials kink easier than others and some can be really stiff and difficult. Don't forget you have the lower cabinet shelf to negotiate. Do a trial fit before drilling any holes!

[hetek]

Dkirsop - I was just looking at the hose and thinking the same regarding bending radius. A kinked drain is no good.

Didn't think about the shelf yet. Good call.

Now I know why that guy used a 90!

[jerridsc]

Speaking of below water through hulls, what is the small one located in the hanging closet on starboard side for? There are two in the head area, one big, one small.

[nebulatech]

The small thru hull in the hanging locker is the raw water inlet for the head.

[jerridsc]

Got it , thanks. I’m going with a composting (dessicating) toilet so I’ll cover them all.

[WillieC]

In the head, the biggun is the sea drain for the blackwater and the small one is the sink drain.

Please let us know how the dessicating project goes. I have been seriously considering the same route.

[hetek]

Well I stuck my head into the galley and took some measurements.

If I route the drain hose below the shelf, I'll be at or below the waterline.

If I turn the basin around and put the strainer at the rear, I may be able to sneak above the shelf.

But now the through hull will be well above the waterline, which makes me realize... the foot pump will now make the sound of the drain overboard sound like someone with a prostate problem. A BAD prostate problem!

[tribologist]

Personally i would just put it back where it was with a fresh seacock. Properly installed the risk is minimal. You will be looking at it every time you go for a snack. Its much harder to install it where the hull curves and its not very accessible. The scary ones are the hidden ones under the head.

[nebulatech]

Hetek, I replaced my thru hull at the sink. I made a backing block with 10 layers of woven roving. Regrettably, I did not use a flanged seacock. I was recently advised that instead of tapping bolts into the backing block, one can just use bronze screws. If I had known, I would have done that. Either way, it's pretty secure, just double up the hose clamps, and dont forget to grease the sea cock when you install it.

I dont know if it helps, but I will take a picture tomorrow.

(FWIW, I also just replaced the head sink and head discharge thru hulls yesterday)

One last thought; I guess our boats don't heel much like a sailboat does, but the general recommendation is to locate drains as close to the centerline as possible to avoid backflow into the sink when heeled. I understand your trepidation, but the sink is probably safer draining as designed. Besides, I know your work. Once YOU replace that thru hull, you'll know it's done right.

[tribologist]

I have all my original through hulls still in. Im not overly worried since i trailer the boat so its never left unattended. When you guys removed the old ones, did you find any in poor condition?

[nebulatech]

I posted a picture of the galley thru hull I removed. Not happy with the corrosion. It was very pitted inside the metal where the threads are. I posted a picture on a different thread (linked below). The head discharge thru hull was in pretty decent shape, apart from what was inside it of course. The smaller thru hulls (raw water sink, raw water toilet, sink drain) were worn to about 50% of the exterior mushroom surface, but did not seem to suffer from pitting. It's informative how much difference in wear there was between them.

I only have two more three more thru hulls, all to do with the engine. I'm going for broke and replacing them all.

Here's a link to the pic of my old galley thru hull. (When I quote posts with pics, they never show for some reason...)
http://www.albinowners.net/aog/download ... &mode=view
EDIT: The thru hull is the part with the curves on the outside radius. The part with curves inside the radius was the retaining nut

I haven't made it to the boat yet today to get a pic of the new installation.

[dkirsop]

I removed the through hulls for my foot pump intakes and the sink in the head as I had no use for them. I replaced the through hulls for the galley drain, waste discharge and head intake. They were mostly good but I seem to recall one broke and was thin walled, can't remember which one. The bronze engine intake had been replaced by the previous owner and is good.

I replaced the intakes with Marlon units and the sizes 1.5" and larger were fine. In smaller sizes the Marlon was prone to failure so I used bronze instead. Personally, I would not use Marlon again as it is easy to over torque the pipe thread and snap the fitting on the smaller sizes.

[nebulatech]

Here is the thru hull. Again, I wish I used the flanged base and screwed it in. Silicon bronze screws are available on ebay...

20200811_150812.jpg