Seaweed in engine water intake

Flossdog

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Last week I went to dry out on a sandy estuary for a scrub off and just as I was about to drop the anchor, my cooling water alarm went off. Dropped the anchor and dried out to find the skin fitting stuffed with weed. It was easy then to clean it out but I am now thinking of how to clear it if this happens at a more inconvienent time! Has anyone got any tried and tested ideas like disconecting the hose from the engine and pumping water back to try to clear it? I am not keen to go over the side to clear it from the outside!!!!
 

alldownwind

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[ QUOTE ]
Trouble with that is you will get quite a jet of water coming up the strainer hole!

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If the boat is fitted out properly the strainer will be above the waterline!
 

Flossdog

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Water intake is about 18" below WL so no, it is well below WL. Can't see how the strainer could be above WL without a very long (unobtainable?) strainer tube. Boat is from a very reputable builder (Northshore).
 

capnsensible

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Have had sucess with various inlets on various boats using dinghy pump to blow back through the fitting. Not 100% but when it does work, relief!!
 

tillergirl

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Some interesting 'generation' answers here. There are many 'modern' boats with the strainer about the water line and a long strainer tube. My neighbour's boat has one and blocked liked yours. (His 'strainer' tube looks very vulnerable to me). However, he also has a right angled elbow taking it to a skin fitting in the bottom of the transom (it's a motor boat) so you can't prod it out. Solution was the dinghy pump and pretty hard work.

On TG, the strainer is part of the seacock and you unscrew the top and poke any blockage back out. It is one of the joys of life that you get an armful of water and that is never going to change. I had it blocked by a Jelly Fish once. When I took the top off, the back pressure from the engine, flipped it out of the strainer, under the engine to live in the bilge. I suppose its still there.....

Take the water pipe off the engine and use the dinghy pump. Might work but I think it will be asking too much of the pump if the blockage is in anyway substantial. Don't blow the other end of the pipe off the strainer.
 

brianhumber

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Systems I have seen on yachts

1) have a grill protector on outside - purpose to prevent weed getting up pipework into seacock but if engine is run fast high suction pulls weed hard into strainer and then you have to either dive and scrub the weed off the grill or try to blow out with air hose . I don't like this arrangement myself.

2) Proper lift out strainer in strainer compartment which screws onto full bore sea cock rather like merchant ships. When blocked normally you shut cock and deweed strainer plate at your convience by undoing two spin off nuts holding the strainer lid on. With heavy weed blocking the sea cock itself you rod out as others have described and get your arm wet.

3) Sea cock onto hull and Vetus spin off lid type strainer fitted at above sea level as my own yacht is. Weed normally lifted up into strainer and is easily removed. Heavy clogging of the sea cock involves undoing hose clips and rodding out through the cock. You can see the sea when clear, yes water coming in and its amazing how much volume comes in through such a small hole ( memo to look at bilge pumping arrangements!) but not in such amounts as to be really alarming in the short time you push the plug of weed out and see clear water under your hull!! before smartly closing the sea cock. You must have a standby wooden bung to hand doing this.



It seems to me that more and more weed is around certainly I seem to be picking up more of the stuff these days including midchannel and get at least one blockage of the cock itself per season now.
 

reeac

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[ QUOTE ]
Last week I went to dry out on a sandy estuary for a scrub off and just as I was about to drop the anchor, my cooling water alarm went off. Dropped the anchor and dried out to find the skin fitting stuffed with weed. It was easy then to clean it out but I am now thinking of how to clear it if this happens at a more inconvienent time! Has anyone got any tried and tested ideas like disconecting the hose from the engine and pumping water back to try to clear it? I am not keen to go over the side to clear it from the outside!!!!

[/ QUOTE ]
I keep a specially whittled length of wood which is long enough and narrow enough to go down through the strainer body and seacock and a couple of inches out of the hull. That way you can get rid of any really persistent blockage. The top end is large enough so that it can't be lost fully down the inlet system. I had to invent this implement "on the run" after getting a hefty lump of bladderwrack in the system whilst on the Thames near Gravesend.
 
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When it happened to me I just dismantled the seacock. There was quite an impressive whoosh of water towards the ceiling that cleared any blockage. I had a wooden bung handy in case of any problem reassembling (like dropping part of it into the bilge...)

If the blockage is above the seacock (as seems much more common) then just close the seacock and dismantle whatever's necessary above that.

I also had a jellyfish last year. Some of it made it past the strainer and I had to pick bits out of the impeller /forums/images/graemlins/frown.gif
 

Flossdog

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Thanks everyone for your input. My problem is that I have a grill on the outside over the skin fitting. Methinks I must work on a different system for next year so that I can rod down the inside strainer to clear the weed from inside the boat.
 

Oldhand

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Disconnect seawater inlet pipe from strainer with sea cock off. Connect hand held cylinder/piston type bilge pump to end of pipe. Turn on seacock carefully make sure you have a good pipe to pump joint. Pump air furiously with hand pump down pipe. Has always worked for me.
 

lw395

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If you need to run he motor with a blocked strainer, can you take the inlet hose of the seacock and feed it from a bucket?
Or even the fresh water tank? (some people do this to flush out salt).
It's good to have a plan for these forseeable problems.
Personally, I would get rid of the grille. I know I can clear the strainer PDQ, motor running even, just be careful of those moving bits!
 

paulwitney

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On my boat I simply unscrew connection to internal water filter and take a big breath and blow through the tube to intake. Clears in seconds. It doesn't take much effort.
On jelly fish!!!! Intake is no more than 1cm diameter. Somehow a jelly fish disolved itself through this hole (was sucked in) and completely blocked the filter.... like being covered in glue!!! Also very smelly to clean off. But it pays to have fittings that can be unscrewed by hand when needed in an emergency.
 
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