Engine water intake

[gareth harris]

I have never liked the through hull for water intake in the 35-2, as it is impossible to mount a sea cock on, and would like to seal it off.

Would making a T below the water line of the cockpit drain, and running it through a vented loop, be asking for trouble from air bubbles in the system?

The alternative seems to be drilling a new one under the galley sink.

Gareth
Freyja E35 #241 1972

 

[jmoses]

Cockpit drain = engine intake?

Gareth,

Splicing together sea cocks for items other than drains is not recomended.

A couple notes:

When a drain and an intake are spliced in, the suction line (vacuum) will eventually over come the minimal head pressure in the line and suck itself dry. Take for instance when the vessel rolls to port and the deck drain is now almost at the water line - the engine will suck air and this is not a good thing.

If the sehead pressure is quite high, then the suction line may take the path of least resistance, which may be the drain line itslef, and suck air through the drain line (or soap or whatever).

Also, think of the crud that will be sucked through the cockpit drain/suction line: soap from wash downs, bird crap, deck dirt, wine, beer, you name it.

When two suction lines are spliced in, one line will more often than not have a higher suction (vacuum). As a result, the lesser vacuum item will starve itself to destruction (cavitate, over heat, melt down, etc.), or never prime itself. Also, the higher vacuum line may reverse draw through the other item and both destroy themselves - not good either, but I've seen it on occasion ("Why doesn't the pump/engine prime" It's Tee-d into AC drain or something).

In summary, it's never a good idea to mix differing sea penetrations together, especially suction ones.

John M.

 

[Emerald]

Hi Gareth,

I had the same feelings about the water intake for my E-27 and my E-31. My solution was to ditch the old 1/2" thru-hulls and drill out the original holes to put in a 3/4" thru-hull which then takes a full flanged seacock. I also ditched the exterior strainer and put an interior Groco strainer that I can service easily while under way. BTW, if your thru-hulls are like the E-27, they are flushed mounted. I special ordered and have extra thru-hulls that have 3/4 inch stems but the flang fits the recess of the standard flush mounts with the 1/2" stems. Let me know if you need what I have, and we can do some cargo shifting.


-David
Independence 31
Emerald

 

[Jeanne]

I have an Ericson 38 and my mechanic wants me to put in a strainer for the engine intake. Is it possible that I have an exterior strainer? I have never heard of this. Sorry to go off track......

Jeanne

 

[Loren Beach]

installing a raw water strainer

The explanation that made sense to me was that if weeds (or whatever) plugs the holes in the outside "strainer" cover over the thru-hull opening, you are very likely going to have to dive to clear it.

The raw water strainer you install inside will allow you to see the buildup of weed/leaves/crud and then pull out the screen and clean it before you get enough restriction to overhear the engine.
Admittedly, it is always possible to get something large enough to plug a 3/4 inch thru-hull but the odds are against this, IMHO.
Do a search on this site to look at photos of mine and another Ericson installation. Use words like "raw water strainer" for your search.

Best,
Loren in PDX

 

[e38 owner]

My Ericson 38 had an outside strainer. When I replaced the seacock I could not find a similar one so I added a forespar Strainer with a 1" hose from the 3/4 Seacock to the Strainer.

Water flow is much better without the buildup of paint etc on the exterior strainer

 

[jmoses]

Outside grid Vs. Inside Strainer

usually what I find with outside 'strainers' is that barnacles and growth fill up the internal void and thru-hull because they are hardly ever removed for cleaning (except with a screw driver between the slots). Plus painting in there is dodgey at best. Clearly an internal sea strainer is preferred, but it isn't always easy to find an accesible location AND be below the water line.

I ran into a baffleling case where a boat was running very hot at high rpms until I thought it through and found the top 2/3rds of the strainers were mounted above the water line combined with a minute crack in each of the caps sealing o-rings - hence the induction of air at high suction and resultant high temperatures. Bad install from the boat manufacturer. Plus the strainers had to be primed manually when checked as they would air lock when they were opened and cleaned.

Not great practice to mount them above the water line, but what are ya gonna do if you can't find a good location? But in the above instance it was plain stupidity on the manufacturer's part as there was plenty of room below the water line.

Plus, I'd rather pop open a strainer than dive in to get a baggie off the thru-hull grid.

John M.

 

[Bayleif]

One of my winter projects is to replace the engine water intake on my 71 E35 (buy the way is a 71 an E35-2?). I am happy with the flush mounted thruhull and the external strainer. However, the strainer has deteriorated over the years and left a hole large enough for a barnacle to get in and clog the input.
Can anyone tell me were I can find a replacement? All I've been able to find is the basket variety.
My present setup has a simple ball valve screwed on the thruhull (all 1/2''). The PO had a two way valve set up so that he could use the engine as an emergency bilge pump. Seemed like a good idea until one day the shaft to the ball valve broke with the ball positioned in between the sea water and the bilge water position. Lucky I noticed before the boat sank.