Weeds up me pipe

[Jmc1764]

Todat excited to go for a trip down the river, all prepared with with engine running and sails ready to hoist we slipped from the mooring, go into the middle of the river and the engine high temp alarm started bleeping, check the back and hardly any water coming out the exhaust. in a panic we managed to get back on the mooring before the engine shut off on high temp. The next two hours were spent checking the raw water pump and pipes etc. Last thing was the pipe past the sea cock to the through hull. This is where I found a load of weed had been sucked into the pipe, I mean loads of it, I can't imagine how it got so far up the pipe ! A lot of picking and huff and puffing down the pipe finally cleared it. Is there any better kind of through hull that has a mesh or something on the outside to stop weed going up my pipe ?

 

[Wansworth]

Doesn’t your seacock have a filter?

 

[vyv_cox]

Putting a grille on the outside is not the answer. How are you going to clear it? Arrange the seacock so that you can rod it through from above. I did this about 100 times going through Canal du Midi. The old inlet valve with a basket immediately above it is good for this, unscrew the lud, push a rod in, open the valve and rod through, remove the rod and close the valve. Very little water comes in.

 

[Jmc1764]

Doesn’t your seacock have a filter?

Nope, the pipe come through the hull to the sea cock, then from the sea cock runs up to the Vetus strainer, then from there down to the raw water pump and from there to the heat exchanger. I like the idea to arrange the sea cock to enable rodding, or maybe keep some compressed air on board to blow it out ?

 

[[70521]]

Always start at the intake and work forward through the system.

 

[Jmc1764]

Always start at the intake and work forward through the system.

Good point, I could have save myself a couple of hours...I think it was more of a panic and then more panic situation for me. As a new sailor I was worried about being stuck drifting in the middle of the river with no engine.

 

[Lucky Duck]

Nope, the pipe come through the hull to the sea cock, then from the sea cock runs up to the Vetus strainer, then from there down to the raw water pump and from there to the heat exchanger. I like the idea to arrange the sea cock to enable rodding, or maybe keep some compressed air on board to blow it out ?

In my experience the dinghy pump will suffice.

Edit - please note the exhaust 'waterlock/muffler' can be damaged by running a dry exhaust!

 

[Catalina36]

At the risk of repeating previous posts, I tee'd in a feed via a stopcock from the galley pump, between the inlet strainer and the raw water pump on the engine, which is primarily to fresh-water flush the heat exchanger and exhaust injection elbow after running. That's used with the engine running and the seacock closed but it can also be used with the engine off to blow back down the open seacock to clear a blockage. The caveat is to be ready to turn off instantly if the blockage is stronger than other parts of the system, eg the lid on the inlet strainer box. A 2 bar galley pump should easily clear the blockage but could do damage elsewhere.

 

[Jmc1764]

At the risk of repeating previous posts, I tee'd in a feed via a stopcock from the galley pump, between the inlet strainer and the raw water pump on the engine, which is primarily to fresh-water flush the heat exchanger and exhaust injection elbow after running. That's used with the engine running and the seacock closed but it can also be used with the engine off to blow back down the open seacock to clear a blockage. The caveat is to be ready to turn off instantly if the blockage is stronger than other parts of the system, eg the lid on the inlet strainer box. A 2 bar galley pump should easily clear the blockage but could do damage elsewhere.

That is a simple solution....why did I not think of that ? sometimes the easiest solution is the hardest to see. Brilliant,,,many thanks I will do this, and what a great idea to flush through after a run,

 

[Catalina36]

That is a simple solution....why did I not think of that ? sometimes the easiest solution is the hardest to see. Brilliant,,,many thanks I will do this, and what a great idea to flush through after a run,

Cheers. It's often surprised me that everyone sees the benefit of flushing a £500 outboard after every run but not many see the benefit of doing the same to a £6k inboard even though there's usually a tank of fresh water and a pump right alongside it.

 

[LittleSister]

Cheers. It's often surprised me that everyone sees the benefit of flushing a £500 outboard after every run but not many see the benefit of doing the same to a £6k inboard even though there's usually a tank of fresh water and a pump right alongside it.

I would have thought that's because the small water passages in an outboard can quickly block with salt crystals, whereas in an inboard that is not (usually) a problem.

 

[Catalina36]

I would have thought that's because the small water passages in an outboard can quickly block with salt crystals, whereas in an inboard that is not (usually) a problem.

True, but outboards don't have 10 quid anodes in the £500 heat exchanger or £300 exhaust elbows to worry about.

 

[cherod]

This happened to me the other day upon starting , but i always check water out when starting so shut down immediately , ( this may come as no surprise ) but i managed to blow down the inlet to clear , had to do It a few times tho , took a bit of clearing on the slip today w th jet wash

 

[LittleSister]

True, but outboards don't have 10 quid anodes in the £500 heat exchanger or £300 exhaust elbows to worry about.

Try, but I doubt flushing with fresh water makes much difference to those, especially the exhaust elbow.

 

[Catalina36]

Try, but I doubt flushing with fresh water makes much difference to those, especially the exhaust elbow.

I can only say that my Beta 35 consumed a stick anode in the heat exchanger approximately monthly until I started flushing. I haven't had to change the current one for two years, which tells me that the environment in there must be a lot more benign. As for the exhaust elbow, hot brine is recognised as a source of failure of the welds. Why else does that part of an exhaust fail but not the parts which merely carry exhaust gas?

 

[Spirit (of Glenans)]

I can only say that my Beta 35 consumed a stick anode in the heat exchanger approximately monthly until I started flushing. I haven't had to change the current one for two years, which tells me that the environment in there must be a lot more benign. As for the exhaust elbow, hot brine is recognised as a source of failure of the welds. Why else does that part of an exhaust fail but not the parts which merely carry exhaust gas?

A recent post on another thread informed us that when new, Beta engines rapidly consume their heat exchanger anodes, but after a while in use they settle down and get longer use from the anode.

 

[LittleSister]

As for the exhaust elbow, hot brine is recognised as a source of failure of the welds. Why else does that part of an exhaust fail but not the parts which merely carry exhaust gas?

I don't think that hot salt water is the sole source of failure of elbows. I believe it is the combination of that with corrosive gases at much high temperatures, and severe local temperature changes/gradients.

Even if it were, how hot do you think your exhaust elbow is when not in operation? How long do you think the small amount of seawater in the elbow takes to drain down the pipe and/or turn to steam when you turn the engine off.

I would not be surprised if the presence of salt (as opposed to fresh) water in the elbow at shut down contributes to elbow erosion, but I imagine that contribution will be a very small percentage of that from when the engine is running.

I would emphasise that I have no problem at all with people flushing with fresh water if they have sufficient water supply and the inclination. I am just sceptical that it will make a valuable difference to the life of the anodes, elbow or engine generally.

 

[vyv_cox]

I don't think that hot salt water is the sole source of failure of elbows. I believe it is the combination of that with corrosive gases at much high temperatures, and severe local temperature changes/gradients.

Even if it were, how hot do you think your exhaust elbow is when not in operation? How long do you think the small amount of seawater in the elbow takes to drain down the pipe and/or turn to steam when you turn the engine off.

I would not be surprised if the presence of salt (as opposed to fresh) water in the elbow at shut down contributes to elbow erosion, but I imagine that contribution will be a very small percentage of that from when the engine is running.

I would emphasise that I have no problem at all with people flushing with fresh water if they have sufficient water supply and the inclination. I am just sceptical that it will make a valuable difference to the life of the anodes, elbow or engine generally.

It depends on the design but the concentric stainless ones on Yanmar 3GM fail by thermal fatigue. Caused by the restraint of the relatively heavy flange when the thin exhaust pipe heats and cools. It is under Fatigue on the website