Removing Debris from Raw Water Intakes

Hey Everyone:

I've had a problem a few times where I go to a marina and when I run the A/C the through hull gets clogged with debris. It doesn't make it to the sea strainer and seems to be stuck on the intake outside the hull. I have no way of cleaning this without getting in the water and it usually comes free during the ride home.

Does anyone know of a way to clean debris away without getting into the water?

A brush on a cleverly designed handle?

We run a regular thru hull with no external strainer for the AC and Generator intakes and strainer basket units inside of the boat that can be serviced. Additionally, threaded onto the thru hull is a "T" fitting with one plugged end straight up (lined up with the seacock) and hose is attached to the "T", perpendicular to the seacock. We can clear any blockage by closing the seacock (ball valve type), removing the plug from the "T", open the thru hull and run a dowel rod all the way through to the outside of the hull. With all of that in place, we have yet to need it.

Thanks, I did try a boat brush but I wasn't sure if I was actually getting to the through hull or not since it didn't work. An angled handle would probably make it easier

you should be able to blow it off with the out on a vacuum cleaner . I have a funnel for the strainer that adapts to the vacuum hose.

I have used the foot pump from a tender to back flush with air.

timb said:

you should be able to blow it off with the out on a vacuum cleaner . I have a funnel for the strainer that adapts to the vacuum hose.

Click to expand...

Yep, that's what we do, too. Close the seacock, open the strainer and remove the basket, attached the adapter (basically a funnel), attach a vacuum cleaner hose to the output side of a wet/dry vac, and then push the end of a vacuum cleaner hose into the funnel. Turn on the vacuum cleaner and open the through hull. In a few seconds, you'll hear air bubbles outside your hull. Your through-hull is now clear. Reverse the process to button it all up. Takes less than five minutes for the whole thing.

flboy,
I have one of those funnels that are discussed above. They are made for "backflushing" (the thru hull) and "freshwater flushing" (the engine) using your seawater strainer (with the basket taken out). It is called "Seaflush". Considering it is just basically a plastic funnel with a hose with a fitting on it, it is relatively expensive, but it could get you out of a jam without having to go over the side. Mine works well for freshwater flushing (used it many times). The one time I tried to use it to backflush a blockage, it did not work (no fault of Seaflush). It turned out that a "perfect sized" fish entered my generator seawater intake and wedged itself tightly in place. Luckily my raw water flow alarm sounded instantly and I was able to shut down prior to damaging my impeller. I had to go into the water and use a wire coat hanger from the outside to "break up" the fish into pieces to get it out. It took me about 15 minutes to free it up. At the time I entered the water, I did not know what had blocked my intake. Not fun, and not how I normally fish!!!

The " Y" style strainers are very easy to clean .

We install one before and a second one after any rubber impeller pump.

Seconds to see if the rubber has come apart.

Beware , some jelly fish parts can burn as you remove them!

Just put a water hose to the outlets and flush stuff out. I often taped a cone shaped nozzle to a boat pole and stuck it into the outlet. It does not matter if the pump is running or not.

I have a bronze scoop strainer for my engine through hull, which does not open for service. I disconnect the hose and use a dowel through the seacock to ensure it is not blocked. The hull also requires a monthly dive to ensure all is clear.

I once had barnacles growing in the hose barb on my Perko strainer. It reduced flow enough to increase my engine coolant temperature significantly. It took five seconds to clear the block. I now flush my engine with fresh water after use, which will prevent this from happening.