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Old 18-12-2007, 01:20   #46
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Darryl, the exhaust leaves the engine via a water cooled manifold. The mainfold is cooled by the Engien coolant. The exhaust has a riser and on the down side of the riser is where the Saltwater is injected into the exhaust system. The Vetus plastic Water lock is imedeatly below. With no water being introduced, hot exhaust gas goes straight into the Water lock. The water lock melted and the exhaust pressure blew a hole in the side of it, thus blowing exhaust straight into the engine room. The air intake is also in the engine room. Not a good place and needs venting and has been on my to do list for sometime. I am now going to make that job a priority. The exhaust thus gets sucked straight back into the engine only to be blown out the exhaust pipe and back around getting thicker each time. Plus the melting plastic added to the smoke also being sucked in a blown out to be sucked in again. Thus the engine room must have been totaly deprived of oxygen and the engine would not repond to throttle.
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Old 18-12-2007, 01:27   #47
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Here's a picture of the Water lock.
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Old 18-12-2007, 01:58   #48
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This is the best we can do I'm afraid.

I already tried zooming Google more - but the image distance for this 'more remote' area - is much higher than populous areas and big cities - where you can zoom up a lot closer and get better detail.

But we can still see all the channels and landmarks you describe.

I don't suppose your boats there is it?

Rodney

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Old 18-12-2007, 02:08   #49
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Darryl, the exhaust leaves the engine via a water cooled manifold. The mainfold is cooled by the Engien coolant. The exhaust has a riser and on the down side of the riser is where the Saltwater is injected into the exhaust system. The Vetus plastic Water lock is imedeatly below. With no water being introduced, hot exhaust gas goes straight into the Water lock. The water lock melted and the exhaust pressure blew a hole in the side of it, thus blowing exhaust straight into the engine room. The air intake is also in the engine room. Not a good place and needs venting and has been on my to do list for sometime. I am now going to make that job a priority. The exhaust thus gets sucked straight back into the engine only to be blown out the exhaust pipe and back around getting thicker each time. Plus the melting plastic added to the smoke also being sucked in a blown out to be sucked in again. Thus the engine room must have been totaly deprived of oxygen and the engine would not repond to throttle.
That might serve as a cheap low water flow alarm Alan. If your engine was able to breathe properly you might have run it long enough to seriously damage it.
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Old 18-12-2007, 02:17   #50
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Cool. OK, so you can see the Marina. Hmmm, interestingly, this image must be some what Old. The Marina has expanded dramaticaly now. But anyway, the channel is a straight line from the entrance to the point (Cullens point), which is the first headland you round. Just as you approach the point, the channel is a little wider and allowed me room to turn the boat around. I cannot make out the actual channel and suspect the differences in water colour is not depth, but is possibly fresh and Salt water. A splot of white appears just of the Marina on the right of the photo. This is a small man made island of tailings fromt he dredgeign of the channel. The Channel is supposedly dredged to 1.8m. Rounding the first point, you hug the shore line, (and I mean hug the shore line) all around the headland. It is called "pull in be damned". Then on the top most part of the point, you take a line to the tip of headland shown across to the right. You follow that route till you line up two markers in a mud bank which is actuall a darker patch shown on the photo down to the right. A marker sits in the channel in about the centre area of the two headlands down near that dark splodge. Once you get the two markers lined up, you swing to starboard and head to the Marker in the channel in the middle nar the splodge. You round the marker turning to port and head to that far headland. Once at the headland it's a starboard turn to another marker adn so on all the way out. This continues for a total distance of some 7Nm. The I have about 30Nm of deep (150ft) sound till I get to the open sea.
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Old 18-12-2007, 02:18   #51
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That might serve as a cheap low water flow alarm Alan. If your engine was able to breathe properly you might have run it long enough to seriously damage it.
Cheap? not at $350.00. Plus the stress :-)
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Old 18-12-2007, 02:18   #52
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Where in the world is Alan Wheeler?

It's New Zealand.
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Old 18-12-2007, 02:46   #53
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Here is a snip off the chart, marina in bottom left corner and depths in metres -

Can also see Cullen Point that Alan refers to.

Have thought about going up there myself in the past and thought better of it (we draw 2m) .

Sorry about the size of the image download but compressed it as much as I could without it getting too fuzzy.
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Old 18-12-2007, 09:09   #54
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Not for nothing, but I have a prestart check list that I always go thru prior to starting. One of the items is, Main Water Intake Valve - ON. I certainly dont mean to be a Monday Morning quarterback, but I was a private pilot for a while maybe it comes from that. And my son who is a B-52 Pilot has pounded into my head to use check llists.
Mike would you be willing to share the check list with us so that I don't have to reinvent the wheel?

I was reading a book, can't remeber the name, that contained tips that people had written in to Sail magazine. This problem reminds me of a setup that I thought was rather anal but now I am rethinking my assesment.

The guy plumbed in a line from his galley sink discharge line to his raw water intake. It was plumbed in such a manner that by shutting off the thru hull for the sink and the raw water intake then opening a valve from the sink discharge line to the raw water intake any water poured in the sink would run thru the engine's raw water system. This guy would then flush out his heat exchanger after every use by filling the sink with fresh soapy water.

By having such a sytem in place you could a) run a limited amount of fresh water to your engine to keep the operating temp stable and/or b) you could bucket brigade salt water into the sink.

The cost benefit ratio is really good. I bet it could be done for less than the cost of an impeller. Saving a single impeller would justify the cost and saving the engine . . .
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Old 18-12-2007, 10:06   #55
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Gosh, that opens up all sorts of possibilities. How about (as a last resort) you cross connect the raw water intake to the holding tank? You'd have a built in emergency supply of "water" and ... nevermind... that's just too icky!

Steve B.
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Old 18-12-2007, 11:48   #56
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It's not a silly idea to have the ability to connect the salt water pump intake to some other means of pump. I know of it being done and actually having to be used. The owner connected to his washdown pump. It got them home. You don't have to have a physical connection in "standby mode". Just the ability to connect if in the unlikely event of an emergency:-) alternative pumps could be washdown, a bilg pump you can chuck over the side or even the fresh water pump if you have enough capacity to get you a short distance.
As for check lists. We have a log book that the club send out each year. In that is a basic check list. It notes water, fuel, Batteries, VHF.
What I suggest is, post idea's of check what needs to be included in a check list here. Tonight when I get home from work, I will make up a "Study Hall" list from the suggestions, that can be copied and printed and then you can laminate it and keep it as a check list.
I propose we have a pre-start list and a post-shutdown list.
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Old 18-12-2007, 13:25   #57
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As per my previous post run a small hose from the top of your riser overboard where helmsman can see it, only has to be small. and then you have a visual check that water is flowing, no mechanical parts to break no electrics to fail, follows KISS principle
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Old 18-12-2007, 13:44   #58
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I had a Perkins 6/354 (that I marinized) on the previous yacht - and a somewhat similar setup to you, Alan.

The saltwater that was injected into the exhaust line though was regulated by a small overflow take off line that fed into a cockpit drain (that went straight down from the cockpit to an underwater thruhull).

So - when there was no water going through - exhaust back fed and came up through the cockpit drains like gas vents at the tar pits. You certainly knew you had a problem then.

It wasn't quite as bad as that - but it certainly was a visual and nasal warning - that there was no water in the line.

Is all of your engine seawater fed straight out the exhaust?
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Old 18-12-2007, 13:47   #59
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Cheap? not at $350.00. Plus the stress :-)
No that's not cheap at all. What size is your exhaust? would this fit?

Whitworths Marine: Nanni Water Lock 60/80mm

or even better, one of these?

Whitworths Marine: Water Lock 50mm (2'')

I have gotten into the habit of looking for water at the exhaust outlet as soon as I start the motor. That might be a good one to get into.
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Old 18-12-2007, 14:07   #60
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To be honest Alan - I think you're copping a fair bit of flack about this 'water' situation - that's not warranted.

After all - you did say straight out in your first post:

Quote:
I was at a rather critical navigational area when I suddenly heard a change in the exhaust note. The other Tutor said he couldn't hear anything different, but I knew something was up. I senses were hightend and I noticed the sound of water wooshing out the back was not there.
Well what more - did you have to do? You noticed it as soon as it happened apparently - that there was no water coming out - and the exhaust note had changed - and you realized AT ONCE what the problem was.

It all sounds pretty seaman-like to me.

Your only problem at that stage - was that because of the narrowness of the channel and the surrounding dangers - you had to try and get the boat to a 'safe' spot - you could NOT STOP right where you were without endangering the vessel and all aboard.

And it was this situation of being 'forced' to motor some distance to safety - that has done the damage.

No - I reckon that any one of us put in the same situation would find themselves having to do exactly the same.

So all this talk about early warning systems - and better setups (even from me) - while interesting - isn't really necessary - your system worked OK - YOU - knew immediately what had happened and what to do.

I'd go out with you anyday.

PS As for the 'sealing up' the impeller - and forgetting the skinfitting was shut - well those simple things could have happened to any 'senile old fool on a boat'
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