Blocked Engine Cooling Sea Water Inlet

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rgsmg53

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I've owned a rather elderly Fisher 30 for nearly a year now which had been carefully looked after for 20 years by the previous owner.

Last month I suffered a blocked engine cooling water inlet which, try as I might, I cannot unblock from inside the hull. It is blocked so comprehensively that I can open the sea cock fully without the hose attached and get just a trickle of water coming in. The previous owner tells me the inlet is fitted with a scoop with fine vertical grills. This, of course, prevents me from 'rodding out' the blockage.

I can't tell what is casuing the blockage but I'm wondering if it is marine growth that has grown inside the scoop. If it is then the shells must be strong as I can't break them with a rigid stainless steel rod.

It looks as if I will have to have her out of the water and remove the scoop (or whole skin fitting if it is integral) and replace with new. So, I've got whole lot of questions for you experts:

1. Should I refit a skin fitting with a scoop, fit a flat one with grilles or fit one with just a plain through hole? The latter would allow me to rod through more easily. And if I went for a scoop, should it be fitted facing forward or aft on a slow motor-sailor?
2. Should I install a new second inlet skin fitting and sea cock whilst I'm doing the repair so I would have an 'emergency' cooling water inlet supply I could switch over to whilst on passage? (I guess this might re-open the 'number of holes in the hull' debate!)
3. Assuming I take the opportunity to replace the existing skill fittings and sea cocks, what material should I choose? I had been thinking of bronze but what about the composite skin fittings and sea cocks available these days? Any recommendations?
4. Are any of the skin fitting materials more resistant to marine growth than others?
5. What sealant is best and does the choice vary depending on skin fitting material?

Any other advice would be greatly appreciated. Thanks in advance.
 
Plain hole skin fitting. Bronze or DZR (dezincification resistant) are the most commonly used. Probably worth taking the opportunity to fit a water strainer immediately above, and above the waterline so that you can rod through without water coming in. Extra hole is overkill! Well sited arrangement as described is fine. Bronze/DZR can be antifouled but chances of marine life growing to fill the hole very low. You can get composite, but will have to replace the whole assembly as they are not directly interchangeable as components. Personally I use Polysulphide sealer, but a Polyurethane such as Sikaflex of CT1 will do fine - just a bit more difficult to dismantle if you need to, although current practice is to grind off the outer flange rather than dismantling, usually because access from inside is a PITA.
 
Since you appear to be at Portishead you benefit from a significant rise and fall of tide. Take advantage to dry out and examine the blockage from outside before going to the expense of replacement and maybe a lift-out/lift-in. It should be easy to rig a temporary water supply to the engine for the purpose.
Making use of nature's tides has been commonplace in the Severn Estuary/Bristol Channel for such work for generations.
 
The dinghy pump trick worked for me recently (attach the dinghy pump, blag one off someone if you haven't got one, to the internal pipework as close to the sea cock as possible and then pump like billy-o - some peeps advise attaching the pump via a length of hose above the waterline to prevent the pump getting sea water in it, I didn't bother!). That was clearing our intake which was solidly blocked with a plug of weed which nothing else had suceeded in shifting
 
Erbas said:
My dinghy pump is a stirrup type (I should perhaps have mentioned that - not sure whether a foot pump would do the job but it would be worth a try I suppose)
Click to expand...
Can confirm an Avon foot pump works wonderfully especially when you stand on the thing.
Quick and easy option is the compressed gas fog horn. Stick that on the end of the inlet pipe and press "go" - soon shifts things !
 
Poecheng said:
Can confirm an Avon foot pump works wonderfully especially when you stand on the thing.
Quick and easy option is the compressed gas fog horn. Stick that on the end of the inlet pipe and press "go" - soon shifts things !
Click to expand...

Hadn't thought of that! Much more fun :)
 
Earlier this year I replaced my engine's inlet water cooling skin fitting, the old one had a grating built into it and not removable, when antifouling each year I had to scrape the barnacles out through the slots the best I could.

I didn't like the idea of the grating so my the new fitting is just a plain skin fitting without a grating which works fine
.
The old fittings grating was mainly on it's aft face.
 
I second the idea of removing the external grille. My boat has no such feature and I carry a 2 ft. Length of hardwood which will fit right through the inlet strainer and seacock.. I've had such blockages twice and both times after spending a bit of time with the engine idling in a lock. First time I had to do some quick whittling to create the rod which I've kept available ever since.
 
Thanks to everyone for their advice, especially those trying to save me the cost of lift-out. I've tried 'blow back' methods - although not the fog-horn - to no avail. I'm in Portishead Marina with no cooling to the engine so beaching her is out of the question. The previous owner suggested the chemical route too but I'm very wary of chemical attack on threaded bronze.

So, it looks like a lift out and replacement with a plain skin fitting. Although I'm very tempted to fit a second inlet skin fitting whilst I'm at it! Thinking about it though, as long as I have a plain-ended straight through strainer, sea-cock and skin fitting and keep my piece of stainless rod to hand, I should be OK.

Reeac's experience is of particular interest as the blockage occurred on exit from Portishead Marina lock and, yes I did have the engine idling in the lock. I might be learning an expensive lesson!

Thanks all,

Richard
 
rgsmg53 said:
The previous owner suggested the chemical route too but I'm very wary of chemical attack on threaded bronze.
Click to expand...

That is nothing to worry about - none of the chemicals suggested for dissolving the crud will have the slightest effect on the bronze. However, I doubt it would actually work because you would not be able to get a strong solution to stay in there long enough to have any effect on the solidified critturs as it would escape through the smallest gap.
 
Could you move / extend the engine cooling inlet hose to another seacock to allow you to move the boat to a beach to dry out.

I has the same type of skin fitting which included a grating. I removed mine using a big screwdriver to break out the grid bars then clear any crud inside the fitting .
 
The type of seacock?is it Blake's pattern conical lever type?
Most probably, in which the following will not apply:
if a lever Ball valve type, the ball may not be connected anymore to the lever due to internal corrosion.
Just a thought.
Fishers no doubt have the tried and trusted Blakes pattern, just not sure!
 
You may well have picked up a polythene bag in your seacock- they get pulled through the grating, and if you try to blow the blockage through the poly folds over inside the grating and seals equally well
Remove pipe fittings if you can, shine a torch down through the open seacock and see what you can find.
 
rgsmg53 said:
....... I'm in Portishead Marina with no cooling to the engine so beaching her is out of the question. ............
Click to expand...

As Rogershaw suggests temporarily use an alternative inlet seacock for you engine cooling. My suggestion is use the heads inlet seacock. If you can free the blockage by beaching it will save you hundreds of pound. If really necessary change the skin fitting when you lift out for antifouling, probably during the winter.

PS. WRT engine idling in the lock. I thought virtually all marinas banned that practice because of the possible build up of poisonous fumes, especially when many boats are locking.
 
theoldsalt said:
As Rogershaw suggests temporarily use an alternative inlet seacock for you engine cooling. My suggestion is use the heads inlet seacock. If you can free the blockage by beaching it will save you hundreds of pound. If really necessary change the skin fitting when you lift out for antifouling, probably during the winter.

PS. WRT engine idling in the lock. I thought virtually all marinas banned that practice because of the possible build up of poisonous fumes, especially when many boats are locking.
Click to expand...
 
I takes the pipe off th pump with engine stopped and blow down the pile this has always worked for me dislodging whatever from the skin fitting
 
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