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Jelly fish are dying to keep me hot

Jul 6, 2017
140
Hunter H 41DS Hampton, VA
So I am at a new-to-me marina this summer and WOW the jelly fish are a massive headache. They are everywhere. I had to clean my air conditioning raw water intake strainer five times in 12 hours this weekend including getting up multiple times at night and in one case having to back flush the system with a garden hose. The ac shuts down as the high pressure alarm goes off on the ac as a jelly fish gets sucked up into the system and gets stuck in the Shurflow strainer screen. I never had this problem with my previous boat in a different marina.

The marina office said; yes, many owners struggle with this issue here. They recommend a massive Buck Algonquin hull mounted scoop strainer to prevent this. I said wont this slow my boat down? She said yes.

I also found a Groco model. both types can have a cover removed or opened to allow cleaning from the underside if required. The effect is to substantially reduce the flow velocity at the strainer grid line so the jelly fish doesn't get sucked in at the higher velocity flow at the mushroom through hull fitting. Does anyone have experience with this? Does it work? I don't want to haul and install one on the boat and find out it doesn't.


://www.iboats.com/shop/rectangular-scoop-strainer-buck-algonquin-imf-1182566.html?opt=IB00366816&gclid=CjwKCAjw9vn4BRBaEiwAh0muDAhOTVTMt1sU2usLKU43yd3NPqrcpAUh1fXKll3I13x3YCn4G-QVqRoCM48QAvD_BwE#ib_size=2%22&configurable_option=Bronze%20Screen

Thanks.
 
May 17, 2004
2,675
Beneteau Oceanis 37 LE Havre de Grace
We have a strainer on our AC. No experience with jellyfish, but a few weeks ago it did still suck something up and needed backwashing with a dinghy air pump. To be fair that is the first time in over 6 years we had that problem. I don’t love that a problem with an external strainer might be harder to clear than one that makes it straight into the filter though.
 
Mar 26, 2011
2,629
Corsair F-24 MK I Deale, MD
Yes, the way you reduce sucking them in is an external strainer large enough to reduce the suction power.

If you don't want to haul, you can probably glue on a cheap plastic one with underwater epoxy (JB Waterweld is very god for this) untill fall. Very stiff and sets enough to hold in about 10 minutes.You kind of have to work it into the surface for a few minutes. But honest, it really does work underwater.
 
Jul 6, 2017
140
Hunter H 41DS Hampton, VA
Yes, the way you reduce sucking them in is an external strainer large enough to reduce the suction power.

If you don't want to haul, you can probably glue on a cheap plastic one with underwater epoxy (JB Waterweld is very god for this) untill fall. Very stiff and sets enough to hold in about 10 minutes.You kind of have to work it into the surface for a few minutes. But honest, it really does work underwater.
Thanks. I jut have to learn how to hold my breath for 10 minutes. ;)

I met with the yard this morning. They are doing a quick haul next week and install a large bronze scoop strainer with a removable screen.

We will see.
 

capta

.
Jun 4, 2009
3,899
Pearson 530 Admiralty Bay, Bequia SVG
Have you asked anyone if this is just a transitory situation? Perhaps they are migrating through and will be gone in a week or two. I've had a lot of those type screens blocked by things like plastic bags, jellyfish and leaves, so you might have to jump into jellyfish infested waters to clean the screen instead of being nice and dry and unstung at the sea strainer.
 
Jul 7, 2004
6,865
Hunter 30T Cheney, KS
Hopefully they will move on.
Back in the 70's during a detachment on the USS Midway we stopped in Hong Kong. The jellyfish were so big and so thick it looked like you could walk to shore. We plowed thru them in a WWII vintage landing craft.
 
Jul 6, 2017
140
Hunter H 41DS Hampton, VA
Have you asked anyone if this is just a transitory situation? Perhaps they are migrating through and will be gone in a week or two. I've had a lot of those type screens blocked by things like plastic bags, jellyfish and leaves, so you might have to jump into jellyfish infested waters to clean the screen instead of being nice and dry and unstung at the sea strainer.
I'm also going install a back flush tee so I can blow out the system as needed.
 
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