AC Thru-Hull Strainer/Scoop

[feudalkaos]

I have a Hunter 410 with a strainer/scoop style thru-hull fitting. This is where the strainer/scoop is on the outside of the boat. It also has an internal raw water strainer.

I am replacing thru-hulls and was wondering if this really needs to be the strainer/scoop style or if a standard thru-hull would work just as well.

Any thoughts on this would be appreciated!

[wingless]

Welcome to the forum.

My boat was built w/ three of the Apollo Conbraco 65-BF8-XX One-Piece Intake Scoop Strainer / Through Hull devices, for the A/C and for the engines.

These parts were horrible. It was impossible to pick out the marine growth from between the slats, even with those organisms dead while the boat was on the hard, it was a long, difficult process to get that cavity clear of junk.

The parts I use now are the Groco APHS Hull Strainers along with a regular through hull. I electrically bond the APHS using a through bolt to an internal bonding wire. The screen may be unscrewed for cleaning below. The trap door latch may be unclipped so the through hull may be cleaned.

To your original question, yes, the A/C should have a scoop and not just a mushroom. An A/C centrifugal pump is great for moving lots of water, but not good when the head (lift) requirement is high, resulting in cavitation (making air bubbles instead of pumping water).

The scoop helps the A/C centrifugal pump work and NOT cavitate, especially when the boat is underway.

[wingless]

Here are the Groco APHS strainers on my engines. The A/C strainer is similar, but smaller.

[feudalkaos]

Thanks for the feedback. I understand that the AC pump is not able to self prime and so the scoop would be useful when underway however I do not intend on using the AC while underway since it requires so much AC power.

Does this scoop give any other advantages over just a normal mushroom type thru-hull besides using it while underway?

Thank you

Originally Posted by wingless

Welcome to the forum.

My boat was built w/ three of the Apollo Conbraco 65-BF8-XX One-Piece Intake Scoop Strainer / Through Hull devices, for the A/C and for the engines.

These parts were horrible. It was impossible to pick out the marine growth from between the slats, even with those organisms dead while the boat was on the hard, it was a long, difficult process to get that cavity clear of junk.

The parts I use now are the Groco APHS Hull Strainers along with a regular through hull. I electrically bond the APHS using a through bolt to an internal bonding wire. The screen may be unscrewed for cleaning below. The trap door latch may be unclipped so the through hull may be cleaned.

To your original question, yes, the A/C should have a scoop and not just a mushroom. An A/C centrifugal pump is great for moving lots of water, but not good when the head (lift) requirement is high, resulting in cavitation (making air bubbles instead of pumping water).

The scoop helps the A/C centrifugal pump work and NOT cavitate, especially when the boat is underway.

[a64pilot]

Originally Posted by feudalkaos

Does this scoop give any other advantages over just a normal mushroom type thru-hull besides using it while underway?



Thank you

No, and I would not use the scoop style on an engine in a sailboat either.
Groco makes one you can open to clean out that isn’t a scoop, I have those, but in truth have begun to wonder if a regular thru hole with no scoop isn’t better.
https://www.groco.net/products/raw-w...ner/rsc-series
I only cruise in warm water so diving on one or clean it’s just a hassle, but if we cruised in cold water or water with dangerous critters, maybe the regular thru hull that can be cleaned from inside of the boat might be better.

Read this as an opinion, I feel pretty sure it’s what has me thinking the way I do.
https://marinehowto.com/external-strainers-omg/

[feudalkaos]

Thanks for the link. I have a lot of faith in MarineHowTo.com and it explains basically just what I was thinking. The fixed strainer thru-hulls just seem wrong and difficult to work with but beyond that I am not seeing a big benefit to the scoop unless underway.

We have 10 thru-hulls in total and the only one with a scoop/strainer is the AC however the AC only runs when we are not underway. Even if we were underway, we do not go more than 8 knots and so that thru-hull would stay under water completely. The only time it might get even close to being out of the water would be when healing over but for that to happen I would be sailing and so the AC ins't the best choice and a scoop wouldn't help anyway.

Anyone else want to weigh in?

Originally Posted by a64pilot

No, and I would not use the scoop style on an engine in a sailboat either.
Groco makes one you can open to clean out that isn’t a scoop, I have those, but in truth have begun to wonder if a regular thru hole with no scoop isn’t better.
https://www.groco.net/products/raw-w...ner/rsc-series
I only cruise in warm water so diving on one or clean it’s just a hassle, but if we cruised in cold water or water with dangerous critters, maybe the regular thru hull that can be cleaned from inside of the boat might be better.

Read this as an opinion, I feel pretty sure it’s what has me thinking the way I do.
https://marinehowto.com/external-strainers-omg/