Clogged AC Seawater line

Bolo

Member III
Having a boat on the Chesapeake Bay that has an AC/Heater unit on board comes with a risk of sucking up a sea nettle (Chrysaora quinquecirrha) or two. For those not familiar with the Chesapeake Bay these creatures are found mostly drifting and undulating around the docks at a marina and can, on occasion, be sucked up into the sea water intake. It’s a fairly common occurrence that happens to me and my neighbors one or twice a year. If you’re lucky you can get them out of the basket strainer (wear gloves because they can sting) where they look like the biggest snot ball you’ve ever seen. But they can also clog the seacock which is what happened to me the other day requiring that I disassemble everything from the circulation pump back to the sea cock. In the process I had to cut the hoses and install new ones because of the tight quarters around the pump, strainer and seacock. In short, it was a real pain in the transom and only happens when you need AC on a hot Chesapeake summer afternoon.

After I made my repairs I remembered that there is no strainer on the outside of the hull, where the seacock is located, just at there is on the sea water intake for the engine. The boat came that way and I never thought to add on till now. But why has there never been one? Is it because the sea water intake for the AC requires much more water then the engine intake and putting a bronze strainer over the through hull would restrict too much water? When the AC is running the amount of water coming out of the boat, after it passes through the AC, is substantial. Water coming out on the engine exhaust is much less.

So my question today? Is it OK to screw on a bronze strainer over the through hull for the AC and not restrict its flow? The pump is rated at 6 GPM. Does anyone have an outside strainer on their AC setup? I think it would great reduce the chance of another sea nettle intrusion. Oh, and how did I clear the clog in the sea cock? After taking everything apart I rigged a garden hose, the one I use to fill the water tanks, and flushed out the sea cock. It took three attempts and about fifteen minutes of full pressure on the hose to clear it of sea nettle snot. This was the worst yet.
 

1911tex

Member III
Bolo can't answer your question 'cause I am a couple thousand miles south; however, had the same scenario with lake zebra mussels growing in the basket strainer clogging it up...just installed a new Dometic ac/heater unit to replace the old original broken Taylor unit and will post pics mañana of the install. Our boat does not have a strainer over the outside thru-hull like the engine water intake...I was told it would do no bueno simply because zebra mussels start out pin head size...and grow in the basket strainer!
 

goldenstate

Member III
Blogs Author
Knowledgeable contributors recently suggested to me to remove my hull-mounted screen for my engine raw water intake, I think due to the risk that the grate could gum up and if not observed in time, cause damaging engine overheating.

It seems like a pick-your-poison choice - is it better to have flotsam and jetsam up in your hose system, or accumulating below the waterline?
Sorta depends, with some dice rolling involved.
 

Bolo

Member III
Bolo can't answer your question 'cause I am a couple thousand miles south; however, had the same scenario with lake zebra mussels growing in the basket strainer clogging it up...just installed a new Dometic ac/heater unit to replace the old original broken Taylor unit and will post pics mañana of the install. Our boat does not have a strainer over the outside thru-hull like the engine water intake...I was told it would do no bueno simply because zebra mussels start out pin head size...and grow in the basket strainer!
I wish sea nettles were pin head size.
 

Bolo

Member III
Just received some additional information about adding an outside strainer to the hull. It just so happens that when I was repairing the sea nettle clog I noticed that the plastic mounting bracket for the Dometic sea water pump for the AC was broken. So I contacted them to order a replacement via my marina who is a dealer for them. During my email exchange with Dometic customer support "Applications Engineer", Rob Long, I asked if there would be any problems with adding a strainer to the outside of the hull while using their PML 500L pump. It just so happens that Rob also a boat on the lower Chesapeake Bay in Virginia and is very familiar with the sea nettle problem. He said that the addition of an outside strain won't affect the pump and would go a long way in reducing sea nettle intrusion BUT...."Occasionally a nettle will still get wrapped up in that stainer requiring back flushing". So, during next haul out I'm adding a strainer and also a more convenient way of back flossing the sea cock without having to take everything apart. Just posting the additional information that may help some other poor soul that has the same problem in the future.
 

Christian Williams

E381 - Los Angeles
Moderator
Blogs Author
Bob, how about a Groco, as for engine raw water? No external strainer required and they're easy to clean out.

 
Last edited:

Saverio

Member II
Hi, I replaced the sea water filter with this one, it has a large stainless steel cleaning basket, it works perfectly
 

Bolo

Member III
Bob, how about a Groco, as for engine raw water? No external strainer required and they're easy to clean out.

Christian, I do have one of those (or something similar) but the nettles not only clogged the strainer (which was the easiest to clean out) but also the hose preceding it AND especially the sea cock. This has appended to me before and that time I was able to disconnect the hose to the sea cock, after cleaning the strainer, and connect another hose long enough for me to blow through while the sea cock was open. After a few tries the valve cleared and I went up on deck to see the top part of the sea nettle “capsized” without it tentacles. The blowing method didn’t work this time so I resorted to back flushing. I think in both cases the tentacles get sucked into the though hull and then the “head” of the poor creature covers it like a bottle cap. I just can poke something through the though hull because it has a 90 degree elbow on it which would be very difficult to remove while the boat is in the water.
 

Christian Williams

E381 - Los Angeles
Moderator
Blogs Author
Gad I hated those nettles. But I miss the fecundity of the Chesapeake, a breeze off Thomas Point Light, at anchor on the Miles or shady Galesville, the conviviality of raftups. Well, the nettles will be gone soon again.
 

Bolo

Member III
Gad I hated those nettles. But I miss the fecundity of the Chesapeake, a breeze off Thomas Light, at anchor on the Miles or shady Galesville, the conviviality of raftups. Well, the nettles will be gone soon again.
Christian, I'm fairly "new" to sailing on the bay. I've only been at it for about 20 years which is amazing since I'm originally a Jersey boy (Camden and Cherry Hill) with sailing just a short distance away. I discovered the beauty of the bay because of a number of photo assignments I had in Maryland during my career but now I'm so glad that I sail on it. Actually my wife, Beverly, got me into sailing since she started years before me. I've never been "stung" by a sea nettle but I've had guests on board who insisted on going in for a dip while we were anchored in Hockley Branch off the Severn River and they got stung several times. It wasn't pretty but fortunately I had some lotion aboard that was advertised to sooth sea nettle stings which seemed to work along with the few beers they drank. Galesville is one of our favorite spots to anchor also. Recently we ventured north to Fairlee Creek (North of Rock Hall) which is scary for the first time boat visitor since you aim straight for the beach, turn hard to port, and then run parallel to the beach about a boat length's away before finally turning hard to starboard to enter Fairlee. To our delight after we anchored we realized that there were no sea nettles to be seen. Probably because of the more northerly location and the fact that we had lots of rain a few days before changing the salinity of the water. So, we took advantage and went in for a nice cooling dip. Nettles were not even seen in Annapolis a few days after that rain but they did come back looking for my sea cock. Do you ever get back east? If you do then look me up and we can go for a sail.
 

Steve Jerromes

New Member
Having a boat on the Chesapeake Bay that has an AC/Heater unit on board comes with a risk of sucking up a sea nettle (Chrysaora quinquecirrha) or two. For those not familiar with the Chesapeake Bay these creatures are found mostly drifting and undulating around the docks at a marina and can, on occasion, be sucked up into the sea water intake. It’s a fairly common occurrence that happens to me and my neighbors one or twice a year. If you’re lucky you can get them out of the basket strainer (wear gloves because they can sting) where they look like the biggest snot ball you’ve ever seen. But they can also clog the seacock which is what happened to me the other day requiring that I disassemble everything from the circulation pump back to the sea cock. In the process I had to cut the hoses and install new ones because of the tight quarters around the pump, strainer and seacock. In short, it was a real pain in the transom and only happens when you need AC on a hot Chesapeake summer afternoon.

After I made my repairs I remembered that there is no strainer on the outside of the hull, where the seacock is located, just at there is on the sea water intake for the engine. The boat came that way and I never thought to add on till now. But why has there never been one? Is it because the sea water intake for the AC requires much more water then the engine intake and putting a bronze strainer over the through hull would restrict too much water? When the AC is running the amount of water coming out of the boat, after it passes through the AC, is substantial. Water coming out on the engine exhaust is much less.

So my question today? Is it OK to screw on a bronze strainer over the through hull for the AC and not restrict its flow? The pump is rated at 6 GPM. Does anyone have an outside strainer on their AC setup? I think it would great reduce the chance of another sea nettle intrusion. Oh, and how did I clear the clog in the sea cock? After taking everything apart I rigged a garden hose, the one I use to fill the water tanks, and flushed out the sea cock. It took three attempts and about fifteen minutes of full pressure on the hose to clear it of sea nettle snot. This was the worst yet.
Here's an idea I learned from someone keeping a boat on Lake Mead with a Zebra problem.... Have a small floating pool chlorinator tied near a through hull. The chlorine keep the unwanted buggers away, and the excess evaporates.
 

Steve Jerromes

New Member
Here's an idea I learned from someone keeping a boat on Lake Mead with a Zebra problem.... Have a small floating pool chlorinator tied near a through hull. The chlorine keep the unwanted buggers away, and the excess evaporated.
 

Bolo

Member III
Here's an idea I learned from someone keeping a boat on Lake Mead with a Zebra problem.... Have a small floating pool chlorinator tied near a through hull. The chlorine keep the unwanted buggers away, and the excess evaporates.
Not a bad idea. My even help to clean up the bay a little. ;)
 
Top