Adding a raw water Y-valve

[Tryoung]

I am looking to add a raw water Y-valve to my cooling line and am looking for input as to how to approach it.

I have a '78 Catalina 27, raw water cooled, and sailed in the Great Lakes. The existing water line is 5/8" ID hose, running straight from the existing through-hull valve to the A4. I assume that the existing system was sized at 5/8" for a reason (could be a bad assumption).

Options for a T-valve seems to be 1/2" or 3/4". Would using a 1/2" valve cause restriction problems (using 1/2" NPT x 5/8" Barb fittings, and the 5/8" hose)?

If I go with a 3/4" valve and fittings (at West Marine) I would need to add reduction fittings to the T-Valve, then add the barbed fittings to the 5/8" hose. This seems like a lot of potential for leaks.

I did find brass 3/4" NPT x 5/8" barb fittings at Home Depot (no reducers needed) -- can these be safely used on a boat? Is there any issue with using brass fittings on a bronze valve?

I could also just use 3/4" throughout, assuming that I can find bigger fittings for the through-hull and the A4 - though I suspect that I will need reducers to get from 3/4" hose to the size of the threaded opening at the A4 and the through-hull.

I am thinking of mounting the valve in the engine compartment, on the starter motor side of the compartment, just inside the engine room door. This would roughly double the run of the cooling line, from about 3 foot to about 6 foot. Is this getting too long for the pump to cool the engine?

Am I over-thinking this?

Thanks,
Tim

[Dave Neptune]

Hunki-dori

Tryoung, my RWC A-4 does just fine with a 1/2" thru-hull and valve, so a 5/8 should be more than adequate. The water I run in varies from a hi this year of 75 and a low of 53 or so.

Dave Neptune

[JOHN COOKSON]

I don't see any problem if the new plumbing is at or below the water line.

TRUE GRIT

[Sony2000]

Last year my shipright installed a 3/4" thruhull with a valve incorporated in the inside 3 bolt flange. Afterwards he said, I could even walk on it without any danger of damaging it!

[ndutton]

What are you trying to accomplish with this Y valve??

[Tryoung]

I am trying to add the T fitting Don mentions in the "Winterizing your Atomic 4" post below.

First and foremost, I expect to use this for Winterizing the engine. Secondarily, I will use it as a way to temporarly shut off the water intake when I am having trouble restarting the engine. Third, I expect that I can use it, along with the bilge pump, to help pump water out of the boat if the boat is taking on water (obviously I hope to never need this).

__________________________________________________ __________
Winterizing your Atomic 4

COOLING SYSTEM

Step 1: If you operate in salt water, draw in at least one 5 gallon bucket of fresh water through the "T" fitting (which you should have previously installed between the raw water intake and the intake to your engine driven water pump). When the hose cavitates as the bucket empties, race the engine slightly for a second or two to partially evacuate the block and, more importantly, the exhaust system. This few seconds of running, after the bucket empties, will leave less water behind within the engine to dilute the antifreeze when you draw it in later. If you've installed fresh water cooling, proceed to step three.

Step 2: Remove the two drain plugs in the side of the block behind the starter and alternator, and the single plug in the rear of the exhaust/intake manifold. If crud has settled out behind any of these plugs, it's best to take a wire and open up the area behind the plug holes so as to reestablish drainage. Reinstall drain plugs.

NOTE: In engines with raw water cooling, I always felt it necessary to remove the thermostat prior to step 3 and to temporarily squeeze off the bypass hose to the thermostat housing. This precaution insures that antifreeze has to flow through the block.

Step 3: Draw at least one gallon of recreational type antifreeze in through the "T" fitting previously used to draw in fresh water, or until you see antifreeze come out the exhaust.

[ndutton]

Roger that.

My arrangement is the conventional flushing Tee. With it I can draw whatever from a bucket (or bilge) into the raw water side. To use it a short garden hose is attached to the spigot, the thru-hull valve is closed and the flushing Tee valve is opened. This worked well for me for acid and fresh water flushes prior to converting to FWC.

[Tryoung]

That would certainly work for me. Though I would also like to make the valve easily accessible. My through-hull valve is in the rear, starboard quarter-berth, under the cushion, under a hatch cover (and often under a bunch of stuff on the cushion). Not exactly the most accessible spot on the boat.

I will commit to shutting the through-hull valve off when I leave the boat for several days, but I am less likely to be careful about shutting it out on the lake if/when I am having trouble re-starting the engine. That's why I am trying to put it near the engine door. This would also be better if I ever need it for the third reason on my list. Of course, in doing this I don't want to make the pump work harder or reduce the effectiveness of the cooling system.

[ndutton]

Understood. We Catalina 30 guys are spoiled when it comes to engine access.

[sastanley]

The joys of NPT diameters!

Tim,

One thing I think you'll learn thru this process is that NPT fittings are NOT true to their advertised sizing. A 1/2" NPT fitting will have a larger ID than 5/8" ID hose. The Oberdorfer pump on the engine is 3/8" NPT, but that is about the same size ID as 5/8" hose.

Also, 90 degree machined fittings have a lot more restriction than cast (smoother) fittings due to the way they are constructed.

When I went thru my system (eventually converting to FWC), I used 3/8" NPT pipe nipples instead of hose barbs in most places, because there was less restriction, and the OD of 3/8" nipples matched up with the ID of 5/8" hose..a hose barb tapers, and the opening at the end of the barb creates another flow restriction. The only problem with using a threaded nipple instead of a barb is the tendency for them to leak..the threads on the nipple are not designed to be a liquid blocker for hose like a barb, but if you retighten the clamp a few times after some hot/cold cycles, it will keep water from dripping thru the threads.

At any rate, your realistic limit on the amount of flow you can get thru is the water pump..again...3/8" NPT. It is not too hard to find 3/8" NPT to 5/8" hose fittings, or if you get a ~2" long 3/8" NPT nipple (get one with a little smooth area between the threaded ends for a good clamping surface), you should be able to slide 5/8" hose on it and tighten it enough to avoid leaks.

[JOHN COOKSON]

The only problem with using a threaded nipple instead of a barb is the tendency for them to leak..the threads on the nipple are not designed to be a liquid blocker for hose like a barb, but if you retighten the clamp a few times after some hot/cold cycles, it will keep water from dripping thru the threads.

I use TFP paste to help seal and make it easier to remove the hoses if and when it becomes necessary.
Also an idea is to make the hoses a bit longer than necessary. If you ever have to pull an end off of a fitting you can usually get away with cutting a bit off the end and not replacing the entire length of hose.

TRUE GRIT

[edwardc]

Use two clamps. One on the threaded part, to grip it well enough not to slide off, and one on the smooth part beyond the threads to get a good seal.

This, of course, won't work on a "close" nipple, as there is no smooth threadless part.

[sastanley]

Ed, that is exactly why I made sure none of mine were 'close', for that very reason..getting the hose up onto the smooth part seems key to avoiding the leaks.

[JOHN COOKSON]

Tryoung
The replumbing project would be a good opportunity to add an internal strainer if you don't have one already.

TRUE GRIT

[gfatula]

My solution is a T fairly close to the rw thru hull. I have a 90 degree L off my thru hull so it lays down. One branch of the T leads to the large internal strainer sitting above the wl then on to the rw pump.... The other branch includes a 90 that takes the hose up the engine bulkhead to a place above the wl where a valve controls its connection to the bilge hose. I left the bilge hose long enough to uncoil so its terminal strainer can be lifted into a bucket. Routing it was not easy. I used a brass quick connect fitting on the bilge hose side of the valve so I can change the hose easily if necessary. (It deserves regular attention and lubrication) I can open and close both valves from the cockpit.