Fresh Water Flushing -- Water Supply Question

[PhilPB]

Perko Flushpro came on our boat. Flush fitting for garden hose is in cockpit cabinet.

 

[Caballero II]

Hi
Thats why I have a flying tag that says Seacock Closed and place it at the ignition switch when I have it closed and move it to the seacock when open. memory fades as years unfurl!!
Cheers J.T.
PS Nice Lindell

This is what we do. We wouldn't close the sea cock if we're on the boat overnight, since we're there. But once we're back at the home dock, we would fresh water flush the engine, and put up the warning plaque over the ignition switch that tells me not to start the engine because raw-water sea cock is closed. Therefore open seacock first, then start engine. Fool proof because you have to remove the tag before starting. Highly recommended, helps preserve the engine, and saves me a remarkable engine anode changes. Maybe on a year, as opposed to nearly every time I checked before I added freshwater check (like each 2 months).

 

[Greg QS]

My flushing system last 2 boats. I have been doing this method for 20 years. Flushing once a weekend when done. I installed directly from the water system of the boat and injected the water AFTER the sea water pump. Installed a simple ball valve. No running of the engine required. I simply Turn the water on for 5 min or so and then do the other. Makes an easy way to winterize the engine too.

This only works if you have shower head that points down. Not applicable for a lift muffler application The water must be flowing on the downward side of the exhaust to make sure no water can back up into the engine!!

WATER OUTLET ON THE DOWN SLOPE OF THE EXHAUST ONLY, NO LIFT MUFLERS

 

[Comodave]

One thing to think about if you basically leave the engines full of freshwater the majority of the time is the type of anodes you use in the engines. Zinc anodes are for saltwater not freshwater. If you flush with freshwater then you should look at using aluminum anodes since they work in both fresh and saltwater. Zinc anodes get a coating on them in freshwater that prevents them from working, so they last a really long time (and you don’t want that).

 

[firehoser75]

One thing to think about if you basically leave the engines full of freshwater the majority of the time is the type of anodes you use in the engines. Zinc anodes are for saltwater not freshwater. If you flush with freshwater then you should look at using aluminum anodes since they work in both fresh and saltwater. Zinc anodes get a coating on them in freshwater that prevents them from working, so they last a really long time (and you don’t want that).

+1 on what Comodave said about aluminum engine anodes!!!!! Very important.
I am also with the group that closes their through hulls when docked (even at anchor for me) and using a label/tag on the ignition (key) to avoid starting the engine without opening the through hull. To me, this ensures that water stays outside the boat should the unlikely and unthinkable happen (eg. clamp failure, hose failure, etc.). I carry insurance (for many things), but hope to never need it!!! Same with this, a type of insurance. Also this will regularly exercise the through hull ensuring ongoing operability (problems like stiffness, etc. will be noticed early). This procedure also "forces one" to go into the ER, and therefore, since you are already there, do your "pre-use" checks before each use!!!
JMHO, yours may differ

 

[DrissZougari]

Would 5 gallons run thru engine be enough? My thought is to have a 5 gallon container to which the garden hose is also attached and let the engine suck from there with a bypass valve the amount of flow it wants. Observation will tell you if the garden hose can keep up.

I totally agree with Steve K as long as the hose between the bucket and sea strainer is of a none collapsing type and a specific sequence to flush the engine:
1) fill the bucket first.
2) start the engine.
3) close the seacock.
4) keep filling the bucket.
5) shut the engine off when satisfied.

 

[egbauman]

I have a hose connection on the top of my sea strainers and nearly always flush the engines with fresh water after every trip. Here’s what I do.

- connect hose to strainer. Strainer seacock is open.
- turn on water flow to max. This pushes all the salt water out of the strainer.
- start the engine
- close the seacock
- run the engine 3-5 minutes
- open the seacock
- shut down the engine
- shut off the fresh water flow
- disconnect the hose

I sometimes see bubbles in my port strainer when I close the seacock but in no way is the water being vaporized. The vapor pressure of water at 80F is well below 1 psi. Perhaps some air is getting through the strainer lid.

 

[crazyguamboy]

Good luck with your quest. I was tired of the smell of the fresh -- but at times murky with algae -- water going into the toilet. So I built a fresh water supply going directly to the toilet and located on the other side of the wall in the front berthing area. Since the water container was higher than the toilet, it was gravity fed, so no need for a pump. I built a "thru-cabin" connection for easy refilling of the fresh water. I don't know how acceptable this was amongst the trawler community, but it worked wonders for my purposes. Again, good luck.

 

[rwaldrop13]

I am considering trying regular (every time I return to port) fresh water flushing, but I have a concern that I hope you might be able to help me address.

I have a fresh water garden hose connection to the top of the Groco Sea strainer assembly (from Seaboard Marine) for fresh water flushing that should work quite well.

https://www.sbmar.com/product/groco-arg-series-bronze-cap-with-freshwater-flush/

However, when I connect my fresh water supply hose to the bronze fresh water flush cap, at idle (Cat 3126 engine), and begin to close the through hull raw water supply I can see bubbles forming throughout the water canister of the Groco sea strainer.

This raises the following questions:



1). I worry that I might be supplying insufficient water supply to properly lubricate the Sherwood (engine driven) raw water pump? Is this concern reasonable when the Sherwood pump is being supplied at idle by an average garden hose water supply?

2). Since the fresh water garden hose supply volume is clearly less than the water supplied by an open through hull, am I at much risk of contributing to engine and wet exhaust component overheat IF I run the engine at idle for approximately 5 minutes?

3). When you fresh water flush, do you leave the through hull open and put up with a mix of sea water/fresh water, or do you close the through hull to achieve 100% fresh water supply?

Cheers...

Marcus

I'm in Ft Myers, FL. While we lost our liveaboard 54' Hatteras in Hurricane Ian, I did freshwater flush frequently thru my AC system plumbing, as part of routine maintenance as well as the engines. I used a Trac Ecological fitting for my Groco strainers for the AC system, and since I was connected to dock water, I had washdown pressure thru the entire system from the strainer out to the overboard discharge. Here's a link to the Groco cap I used -https://www.amazon.com/dp/B01C04HAN8/?coliid=I2ZFGVDSQGPOLH&colid=3RLYOXZI89OLB&psc=1&ref_=list_c_wl_lv_ov_lig_dp_it

We had only had the boat 25 months when Ian destroyed it along with our entire marina, but I had also been talking to vendors about this flushing attachment for my engine raw water strainers - https://www.amazon.com/dp/B071KZG27...XZI89OLB&psc=1&ref_=list_c_wl_lv_ov_lig_dp_it

The response I got from my vendor friends was that anytime you can flush with fresh water, do so especially if it's "city water". One of our marina neighbors actually followed a process he called 'pickling' his engines, where he closed off the intakes, flushed the engines with fresh water overnight, then closed the overboard and filled the system with fresh water. He'd leave his boat for 2-3 months at a time and swore by this.

I hope this all helps.

 

[bvaldyke]

Seaboard Video

SeaBoard Marine made a video to explain installation and use of their kit.
https://youtu.be/gYLIGFYR8IA?feature=shared

 

[Csellars]

Seaboard Marine does have a video on how to properly flush the engine.
They recommend leaving the thru hull open as the preferred method.

 

[smith6]

I am considering trying regular (every time I return to port) fresh water flushing, but I have a concern that I hope you might be able to help me address.

I have a fresh water garden hose connection to the top of the Groco Sea strainer assembly (from Seaboard Marine) for fresh water flushing that should work quite well.

https://www.sbmar.com/product/groco-arg-series-bronze-cap-with-freshwater-flush/

However, when I connect my fresh water supply hose to the bronze fresh water flush cap, at idle (Cat 3126 engine), and begin to close the through hull raw water supply I can see bubbles forming throughout the water canister of the Groco sea strainer.

This raises the following questions:



1). I worry that I might be supplying insufficient water supply to properly lubricate the Sherwood (engine driven) raw water pump? Is this concern reasonable when the Sherwood pump is being supplied at idle by an average garden hose water supply?

2). Since the fresh water garden hose supply volume is clearly less than the water supplied by an open through hull, am I at much risk of contributing to engine and wet exhaust component overheat IF I run the engine at idle for approximately 5 minutes?

3). When you fresh water flush, do you leave the through hull open and put up with a mix of sea water/fresh water, or do you close the through hull to achieve 100% fresh water supply?

Cheers...

Marcus

Don’t do it. I did this exact same thing and the hose pressure was too much and broke seals at water pump. You would not think that would be the case but the positive pressure from the hose is more than the natural sucking/ pull the FWP does from the sea. Just take caps of strainer and put hose in. A little water in bilge doesn’t hurt. I actually made a 90 degree copper hose connector with a valve so it stays in the strainer and I can do other things while it flushes.

 

[armando]

I have just installed a water garden hose connection in my 2 Volvo 250HP using it successfully about 20 minutes by engine.
Some bubles arrive but the engine temp do not increase at idle 650 or little more, 1000 rpm. You can control if the impeler's cap(lid) it is cold. Then no worry at all.

 

[armando]

Sorry. I have forgotten to say...the sea cock it is open at the beginning then the fresh water and then I close the sea cock.

 

[dhays]

I do something similar.

I connect the hose with the seacock open. I then turn on the hose. Then start the engine and then close the seacock.

When the water in the hose is first turned on, I do get bubbles in the strainer. These are are bubbles in the hose. One reason for turning on the water before starting the engine or closing the seacock is to flush those bubbles out through the seacock. You can see them rise from outside the boat as they break the surface.

At idle the dock hose should provide plenty of water for engine cooling.

I then shut off the engine at the same time as I close a valve I have in the hose line. This keeps sea water from mixing in and prevents having and pressure on the cooling system without the engine running.

 

[Surboum]

When I run antifreeze through my engines (Yanmar 6LYA-STPs) I follow this process:
- Fill 2 5-gallon buckets with the anti-freeze
- Close engine raw water seacock, open sea strainer, and remove basket
- Start engine on idle
- Pour antifreeze into sea strainer at a rate to keep the strainer full
- Shut down the engine when we see antifreeze flowing out of the exhaust
- Replace basket and close sea strainer
- Since I’m winterizing the boat the seacock remains closed
This is done one engine at a time. Theprocess requires two people: One in the engine room at the sea strainer with the bucket; and a second person at the helm to turn the engine on and off, watch the exhaust flow, and refill the buckets if needed.

Wouldn’t a similar process work for a fresh water rinse? The main difference would be you can’t see when fresh water is flowing out of the exhaust so you would have to time the process; and at the end you may open the seacock.

When rinsing the engines, does anyone add a product like Salt Away or Barnacle Buster to the rinse? The websites for both those products have instructions/videos for how to rinse engines with their products.

 

[J.T kearney]

Surboum
check out post #10 on this thread. It's a one man job and you don't have to be a good shot with the 5 gallon bucket. My 6LYA-UTE takes about 4 gallons until it comes out the exhaust.

Cheers
J.T.

 

[magna 6882]

I was looking into the fresh water flush. Got me wondering how many folks flush there engines and how frequently ? I have never seen anyone flush at the marina. Is flushing very popular or normal? I do see the benefit but my sea strainer and valve is not very accessible without moving floor panels.

 

[Caballero II]

I was looking into the fresh water flush. Got me wondering how many folks flush there engines and how frequently ? I have never seen anyone flush at the marina. Is flushing very popular or normal? I do see the benefit but my sea strainer and valve is not very accessible without moving floor panels.

You don't need to flush from you raw water strainer. I've been doing it religiously from plumbing placed from my inlet (after the strainer) through to the impellor for a few minutes after shutting down. It reduced my zinc needs to nothing.

You wouldn't know if they're fresh water flushing. Just hook up, run the flush for about 5 mins., and call it good. Keep the thru hull closed and put up a placard to warn you not to start until the raw water inlet (thru-hull) to the engine has been opened

 

[Caballero II]

Seaboard Marine does have a video on how to properly flush the engine.
They recommend leaving the thru hull open as the preferred method.

Yeah. And I disagree with that. Close the thru-hull, if even a little late to flush salt water out of the intake, then close and keep fresh water running thru the engine for a few minutes to leave the whole thing with fresh water. I don't understand why they would recommend leaving the thru-hull open after you just flushed it.

 

[DennisB1]

I am considering trying regular (every time I return to port) fresh water flushing, but I have a concern that I hope you might be able to help me address.

I have a fresh water garden hose connection to the top of the Groco Sea strainer assembly (from Seaboard Marine) for fresh water flushing that should work quite well.

SMX Bronze Freshwater Flush Cap for Groco ARG Series Strainers

However, when I connect my fresh water supply hose to the bronze fresh water flush cap, at idle (Cat 3126 engine), and begin to close the through hull raw water supply I can see bubbles forming throughout the water canister of the Groco sea strainer.

This raises the following questions:



1). I worry that I might be supplying insufficient water supply to properly lubricate the Sherwood (engine driven) raw water pump? Is this concern reasonable when the Sherwood pump is being supplied at idle by an average garden hose water supply?

2). Since the fresh water garden hose supply volume is clearly less than the water supplied by an open through hull, am I at much risk of contributing to engine and wet exhaust component overheat IF I run the engine at idle for approximately 5 minutes?

3). When you fresh water flush, do you leave the through hull open and put up with a mix of sea water/fresh water, or do you close the through hull to achieve 100% fresh water supply?

Cheers...

Marcus

The bubbles are a result of the hose not capable of supplying sufficient volume to keep the pressure above ambient. or in other words there is a slight vacuum in the line with the external valve closed hence the bubbles. I start the engine with the outside valve open and when engine is running closed the outside valve.

I have two cat 3208 ta's and have a similar GROCO strainer and see the same resulting bubbles at idle speed which is all I do when flushing the engines with fresh water. The impellers have suffient water flow with the garden hose supply to lubricate the rubber impeller and at idle the engines will not overheat. So I would recommend closing the valve and flush for about 5 minutes then shut off the hose and then shut off the engine. This keeps hose from pressurizing the cooling system.

The raw water pump has a higher flow capability than what the garden hose can supply at idle rpm.

 

[kapnd]

Don’t do it. I did this exact same thing and the hose pressure was too much and broke seals at water pump. You would not think that would be the case but the positive pressure from the hose is more than the natural sucking/ pull the FWP does from the sea. Just take caps of strainer and put hose in. A little water in bilge doesn’t hurt. I actually made a 90 degree copper hose connector with a valve so it stays in the strainer and I can do other things while it flushes.

This could well be the reason that Mr Athens recommends leaving the seacock open when flushing.
Even if the dock water supply volume is lower than the pumps ingestion rate, the salt content will be greatly reduced, enough that you should see significant improvement in the life of the zincs.
Also there’s that little guy named Murphy that rides along on all boat trips, encouraging the operators to forget to reopen the seacock!

 

[lwarden]

The concern of over pressurizing the water pump when the engine is off (when turning on the line pressure before or leaving it on after the engine is running) is easily prevented. Just add a check valve leading to something like the generator raw water, or AC cooling. That way the through hulls for the mains can be closed for flushing and you get 100% fresh water in the system. I found there was still a high concentration of salt after flushing with the through hulls open so went with the check valve option and it's working well.

 

[rwaldrop13]

Just an additional observation in this, with regards to the Groco strainer and the TRACS flushing cap. I had this onboard my boat, but not for the engines - I was working towards that before Ian destroyed the boat in 2022. My wife and I were liveaboards in Ft Myers, FL with marine AC units in the boat. I had 2 pumps running 3 units, and 2 Groco strainers on separate thru-hulls. Part of my routine maintenance included closing the thru-hulls, and putting dock water thru the AC water piping to flush the systems. This was a big help, especially after a large boat came in/out of the marina, or nearby boats had divers underneath cleaning hulls, resulting in silt or hull scrapings winding up in my systems. Yes, the strainer baskets caught a lot of it, but enough would still get by to catch later in the system. So 30 minutes with a flushing cap made a huge difference.

 

[motion30]

My first thought was to agree with Comodave, but the bubbles bother me. I don’t think they are air bubbles but vacuum bubbles because the engine is pulling water out faster than the hose can supply it. The adapter does constrict what the hose can supply at least a little. My guess is that running for just a few minutes won’t be a problem but you might want to ask Seaboard Marine.

That could be true but you will certainly see the level in the sea strainer dropping if the motor is drawing more water than the hose can supply