Engine coolant inlets

What do yours look like?



What are your thoughts on the subject?

Pita to get in there to scoop out the barnacles and other creatures that like to lurk in there. You can get screens like that one that are hinged so you can get in to commit murder.

Xsbank said:

Pita to get in there to scoop out the barnacles and other creatures that like to lurk in there. You can get screens like that one that are hinged so you can get in to commit murder.

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Out of the water (done once a year), we can access the inlet from the boat's interior. This hasn't been necessary in the boat's four-year life. (We're not in the tropics.) And we haven't sucked up any plastic bags either.

These are great! Remove the 2 screws and the perforated plate (screen) slides out for easy cleaning and antifouling painting. I believe they will work with up to a 3" through hull. Have had 2 on my dive boat for 10+ years and have never had anything cover them to stop the flow of water. This one is for the trawler. Will swap the screws for 1/4" bolts though.




Ted

I decided to try without external screens/strainers 4 years ago just to see how it went....3 trips to Florida and back and no issues (nearly 8,000 miles all ICW).


Only once had to clear internal strainers one underway....3 small fish had managed to swim in and got wedged in the entrance to the internal sea strainer.

Probably won't use external srceens till I have issues.


One reason I may not have issues is due to low flow as my intakes are 1-1/2 inches and my demands on those inlets are 1 inch at a time.

I have the same style scoop as yours. When I initially purchased Sherpa, my marine surveyor (Davis and Company) had an issue with it, but I never had it replaced. Their comment is below:

The raw water intake on the port hull had a forward facing clam shell or scoop type intake. Anytime the boat is moving forward this generates pressure in the raw water system. Facing the scoop aft, may create a vacuum which can restrict the water flow. Consider removing the scoop type screen.

We have screens on all our inlets. Swore on our last boat that I would not have another boat without them. After cleaning out jellyfish (stinging kind) from the generator strainer in the middle of the night and hoses it was a must. New ride has the Groco units with a trap door and pull pin.

Vashon_Trawler said:

I have the same style scoop as yours. When I initially purchased Sherpa, my marine surveyor (Davis and Company) had an issue with it, but I never had it replaced. Their comment is below:

The raw water intake on the port hull had a forward facing clam shell or scoop type intake. Anytime the boat is moving forward this generates pressure in the raw water system. Facing the scoop aft, may create a vacuum which can restrict the water flow. Consider removing the scoop type screen.

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Guess they thought you were putting Sherpa up on plane. Fail to see how a little water pressure going forward at displacement speed is a problem.


Ted

Vashon_Trawler said:

I have the same style scoop as yours. When I initially purchased Sherpa, my marine surveyor (Davis and Company) had an issue with it, but I never had it replaced. Their comment is below:

The raw water intake on the port hull had a forward facing clam shell or scoop type intake. Anytime the boat is moving forward this generates pressure in the raw water system. Facing the scoop aft, may create a vacuum which can restrict the water flow. Consider removing the scoop type screen.

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I believe you shouldn't have a forward facing scoop for the generator particularly on a SP or planning hull but I don't see the issue for the main engine. Did he quote any specific reference or is it just his opinion?

Agree no scoop on genny.
Some of those scoops are held by screws and just cover the separate mushroom inlet. The south bay strainer with small holes is good for keeping out grass but lots of water is what I want for my diesels so scoops have worked well for decades.
A good diver with long skinny tool is needed to clean them

Larry M said:

I believe you shouldn't have a forward facing scoop for the generator particularly on a SP or planning hull but I don't see the issue for the main engine. Did he quote any specific reference or is it just his opinion?

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I am imagining Sherpa on a plane! Defying the laws of physics! :lol:

No ABYC reference in my report. It was original to the boat (1979), so I figured it will be fine for another 30+ years. Never had a problem during my ownership. Lots of sea grass floating in my area, so this style inlet is very helpful.

The only risk I see is if the boat were towed then pressure might cause flooding, like my jetski does... If you have a forward facing scoop on gennie and motor along with the gennie off, you might have issues on some gennies, but from what I see, it would be unlikely that much water would push past the impeller blades.

Any other ideas?

My theory is I would rather clean strainers in the engine room than try and figure out how to unplug a screen from the outside.

My guess is when I change my cruising habits...a change maybe needed...but now it works for me.

One of the nice features of the through hull cover in post #4 is that shutting down the engine (water suction) may allow anything covering the screen to just fall away.

Ted

I don't have a good shot of the sea chest on our Defever, but it looks a lot like below. All raw water for the engines, genset, and AC feed off of it. I'm told that if something gets by the heavy grate on the hull and into the sea chest, blocking a through hull, you can look through the plexiglass, usually see what it is and decide whether to try poking it out to clear it.

O C Diver said:

One of the nice features of the through hull cover in post #4 is that shutting down the engine (water suction) may allow anything covering the screen to just fall away.

Ted

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definitely the type I would use also...and easy to add with a few screws. Could even be added while in the water.

I have the intake in post#4. My issue was trying to paint it with antifouling without clogging the holes in the grate. How do you apply antifouling?

Mine gets Propspeed. Before adding a new coat, the screen is removed and sandblasted. Would do the same if using bottom paint. While sandblasting will remove a little metal each time, mine have been done 10+ times and are still in great shape. If the screen gets too thin, they sell just the screen as a replacement item.

Ted

Could soak them in paint remover....if you have the time on the hard.

Scoops or Screens

Having had both I'd say a lot depends on the waters and speeds you run. Here in SW Florida the scoop at slow speeds (under 10) seems to be a perfect turtle grass collector. The blades go straight in and never even get to the strainer. You get a nice solid clump of grass that has to be pulled out of your intake hose. No fun. Screens completely eliminate the problem. Same with weedlines offshore. Screens are more drag, no question, and aren't the best for faster boats. I'm putting one on "Adventure Time" this week. Big screen, big strainer, little problems. I hate hearing the buzzer go off!