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Old 25-11-2017, 09:59   #31
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Re: Exhaust Plumbing Bypass Stern Squirt

Dale,

Instead of a hose think about using a SS brake line neatly run slightly down hill to the side of the boat.
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Old 25-11-2017, 10:20   #32
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Re: Exhaust Plumbing Bypass Stern Squirt

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Dale,

What you said about not being needed to reduce back pressure is only true if the boat builder follows the recommendations of the engine manufacturer. Sadly, many don't for various reasons; cost, interior design and space limitations to run the hose. Catalina sadly is not immune to these short cuts. On the 4JH series from the late 90's onward, Yanmar specified a 3" wet exhaust. Catalina has fitted a 2" wet exhaust and mixing elbow from an earlier series 3 cylinder engine. All done under the very watchful eye (wink wink) of Mastry. Those engines, especially the high revving ones fail the back pressure test. I know, I've done the tests.

Sometimes, fitting an overflow line of sufficient size in lieu of the anti siphon will reduce the volume of cooling water enough to reduce the back pressure readings to acceptable levels and still keep the exhaust temps low enough.

Hopefully your turbo charged Yanmar was fitted out with the bronze box mixing elbow and 3" wet exhaust throughout.
Hi, that's interesting. Yes mine has the 3 inch exhaust hose but has a stainless stainless steel riser type elbow. I do worry about the stainless riser, hot seawater and exhaust gases can't be great for it.
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Old 25-11-2017, 10:48   #33
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Re: Exhaust Plumbing Bypass Stern Squirt

If you're worried start looking for this part now Yanmar
129470-13541. That way you'll have it when you need it. You may need a longer 3" hose but maybe not, depends.

I say start looking now because that bronze box is $$$$$ from Yanmar dealers ~ $900. But you can find them elsewhere for less if you're patient. That mixer will outlast the engine!
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Old 25-11-2017, 10:53   #34
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Re: Exhaust Plumbing Bypass Stern Squirt

I didn't want to single out Catalina before. Island Packet has done the same thing on some of their models as well. The savings to the builder is about $800 per boat just on that one modification.
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Old 25-11-2017, 11:04   #35
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Re: Exhaust Plumbing Bypass Stern Squirt

I see they sell them with a adaptor, 3 inch to 2 inch? I'm assuming for smaller engine.
No problem with mentioning Catalina, the 470 is a great boat, but not perfect.
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Old 25-11-2017, 19:21   #36
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Re: Exhaust Plumbing Bypass Stern Squirt

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Dale,
Hopefully your turbo charged Yanmar was fitted out with the bronze box mixing elbow and 3" wet exhaust throughout.

Unless I’m mistaken the bronze “box shaped” elbow is only fitted on the normally aspirated 4JHE. I don’t think it will fit on the turbo motors?
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Old 25-11-2017, 19:22   #37
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Re: Exhaust Plumbing Bypass Stern Squirt

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I didn't want to single out Catalina before. Island Packet has done the same thing on some of their models as well. The savings to the builder is about $800 per boat just on that one modification.


Which model?
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Old 25-11-2017, 19:42   #38
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Re: Exhaust Plumbing Bypass Stern Squirt

Source for cast ss exhaust elbows

https://hdimarine.net
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Old 25-11-2017, 20:34   #39
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Re: Exhaust Plumbing Bypass Stern Squirt

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Threads like this are good, they bring things such as anti siphon valves to the forefront of my mind.

As mentioned in previous post, I've had a antisiphon valve salt up and hydrolock my engine on a previous boat, twice(I love decompression valves) this was due to it not being as high as I would like ( should of been) and not having the room to go higher, it was always a concern. I pulled the cap off (nanni) this particular valve and got into the habit of reaching under the sink and manually depressing the valve directly after engine shut down.

On my current boat the antsiphon valve is in a stupid spot that's not easy to access.

Now what's to stop me adding a hose to it like we are talking about, but with a antsiphon valve in the end and running it to a convenient spot that allows me to access it easily?

I can't run a hose with out a valve that drips overboard, and it's a hassle to reroute the current hoses and valve setup to a different location, but would be easy to run a hose of the end and direct that to a better spot.
Dale, just piss the anti siphon valve off completely and plumb a small diameter reinforced hose from the point where the valve was fitted to a convenient point as close as possible to the exhaust. Mine has been fitted into a cockpit drain just under the floor grate, easy to see if the system is working as it should and drains well. As others have said, keep it as short as possible with no place to hold water.
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Old 25-11-2017, 23:29   #40
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Re: Exhaust Plumbing Bypass Stern Squirt

HI. again, all this makes interesting reading, concerning my situation the Volvo Penta 2000 series 3 cylinder engine has a very expensive Cast iron mixing elbow. I had to buy a new one so I invested additional money in having a specialist drag racing shop ceramic coat it in side the water jacket and also the other surfaces exposed to the exhaust gas in the hope that will make it last longer in service. The barbed fitting has a 45 millimeter outside diameter so all my exhaust pipes and fittings are thus. The water lock and rubber Hose was obtained from the boat we salvaged the engine from, Which incidentally was being fitted out to explore the South Pacific Islands.

The silencer was picked up as 'new old stock' from a local marine store and the box had a rudimentary instruction leaflet in it. Some time later while poking around at the same store a 45 MM goose neck in its box was discovered in an obscure place at the top of the stairs. So I made a deal on it too. That box contained a real book with much clearer instructions and installation diagrams. Option #3 seems to be most applicable.

So my point is this. It appears that almost every one just fits and clamps it all together as per the instructions. starts the engine and heads to sea?

Obviously that also seems to be my only option? However perhaps I have a more inquiring mind? I do like to know the details, So I have been trying very hard to find a detailed explanation as to exactly what is going on inside that piping system/ Vetus calls for a minimum length of 12 inches of rubber pipe between the mixing elbow and the water lock. Clearly within that short length of pipe there must be a lot going on with exhaust gasses in the 900 to 1,250 Fahrenheit range being sprayed with sea water that has been made warm after passing through the transmission cooler and the heat exchanger?

Thus My imagined area of concern is what state is the water in? as it leaves the water lock everything has to rise up though at least 2 feet of vertical pipe to get to the top of the goose neck. Water vapour does not have to be boiling... Because obviously clouds in the sky are water Vapour and they are not boiling. Thus IF this assent is made in the vapour state it presumably does not produce any noticeable additional back pressure.

IF on the other hand the pipe is flooded with water in the liquid state the diesel engine is required to pump it. That would consume a lot of available power? Does a water lock have to be 'cleared' every time the engine is started?
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Old 26-11-2017, 05:46   #41
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Re: Exhaust Plumbing Bypass Stern Squirt

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Dale, just piss the anti siphon valve off completely and plumb a small diameter reinforced hose from the point where the valve was fitted to a convenient point as close as possible to the exhaust. Mine has been fitted into a cockpit drain just under the floor grate, easy to see if the system is working as it should and drains well. As others have said, keep it as short as possible with no place to hold water.
To run a hose without a valve to the stern, or close by, would be quite a long run, but shouldn't be an issue.

Can the hose dip, meaning fall below the height of the loop before rising again, I can't route it in a way that it stays at the same height for the full length of the run.

I can't see that it matters that the line varies in height during the run.... am I wrong?

Second question, I don't have a standard elbow, I have ss dry riser. This seems to rise above the water line (I think) therefore even if valve stuck shut and filled the exhaust, the water would only rise to water level height not filling the engine, it's a foot of center so on a starboard tack this changes the height and the above doesn't apply?
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Old 26-11-2017, 06:10   #42
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Re: Exhaust Plumbing Bypass Stern Squirt

The dips would cause a problem, holding water in the dips would be an issue?
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