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Old 10-05-2021, 18:27   #1
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Need help locating Vetus water muffler

I'm installing a new exhaust system using Vetus water muffler LP 50, an LT50 gooseneck and 51mm hose. My motor is below the water line and according to the instructions the muffler must be located a minimum of 2 inches below the water inlet on the exhaust and no more than 5 feet below the top of the gooseneck. I don't have ANY place where I can put the water muffler and meet both these requirements.

The main problem is the distance to the top of the gooseneck. With the muffler placed properly below the water injection, the top of the gooseneck is about 6 feet above the muffler.

How critical is the 5 foot requirement? I've done the calculations and with all the hose to the gooseneck there is more than twice the capacity in the muffler to handle any back flow when the motor is shut down.

Any help is greatly appreciated! Jim
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Old 11-05-2021, 11:22   #2
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Re: Need help locating Vetus water muffler

How much hose length do you have? If there isn't enough to fill the muffler, you should be able to get one ordered from fisheries supply.

As for how important is it, well that is up to you but the requirement is there for a reason.

Personally I wasn't able to achieve a proper design and with a turbo seized due to salt water at 480hrs, I went what I feel is the best way - a custom dry exhaust from turbo, past the engine (v drive so engine is reversed) into a 'hump' where I inject the water.
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Originally Posted by jimjimmyjimjim View Post
I'm installing a new exhaust system using Vetus water muffler LP 50, an LT50 gooseneck and 51mm hose. My motor is below the water line and according to the instructions the muffler must be located a minimum of 2 inches below the water inlet on the exhaust and no more than 5 feet below the top of the gooseneck. I don't have ANY place where I can put the water muffler and meet both these requirements.

The main problem is the distance to the top of the gooseneck. With the muffler placed properly below the water injection, the top of the gooseneck is about 6 feet above the muffler.

How critical is the 5 foot requirement? I've done the calculations and with all the hose to the gooseneck there is more than twice the capacity in the muffler to handle any back flow when the motor is shut down.

Any help is greatly appreciated! Jim
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Old 11-05-2021, 11:30   #3
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Re: Need help locating Vetus water muffler

How much more rise is needed?
I wouldn’t hesitate to exceed the riser height by a little, especially if it could increase the mere 2” drop from the injection elbow.
The specified 2” drop there is a minimum, and a very critical number, where I would like to see about triple that to insure no backwash.
A muffler drain could offer you some peace of mind when under sail, I like knowing that the muffler is not going to flood the motor when the boat is bucking and heeling under sail.
Contact Venus, they may have something better suited to your needs.
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Old 11-05-2021, 13:09   #4
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Re: Need help locating Vetus water muffler

I finally got through to a Vetus tech guy and this is what he says: The 5 foot max. stated in the Vetus instructions is really just to insure that the muffler has the volume to handle the back flow when the engine is turned off. You can exceed that height if the muffler is big enough. I have up to 10 foot of 2 inch hose going to the gooseneck so I need a muffler with, at least, .388 gal or 1.47 liter capacity (that includes a margin of error). The one I have has a 10 liter capacity, so I can exceed that 5 foot limit.
The really crucial measurement is the distance between the engine exhaust manifold and the waterlock muffler. The muffler has to be at least 2 inches below the manifold. If I put the muffler in the bilge I can exceed that by several inches. So, I'm good to go.
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Old 11-05-2021, 15:50   #5
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Re: Need help locating Vetus water muffler

Quote:
Originally Posted by jimjimmyjimjim View Post
I finally got through to a Vetus tech guy and this is what he says: The 5 foot max. stated in the Vetus instructions is really just to insure that the muffler has the volume to handle the back flow when the engine is turned off. You can exceed that height if the muffler is big enough. I have up to 10 foot of 2 inch hose going to the gooseneck so I need a muffler with, at least, .388 gal or 1.47 liter capacity (that includes a margin of error). The one I have has a 10 liter capacity, so I can exceed that 5 foot limit.
The really crucial measurement is the distance between the engine exhaust manifold and the waterlock muffler. The muffler has to be at least 2 inches below the manifold. If I put the muffler in the bilge I can exceed that by several inches. So, I'm good to go.

Just want to say thanks for posting the reason. Often it doesnt happen & its frustrating when you are following the thread.
Good result!
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Old 12-05-2021, 09:02   #6
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Re: Need help locating Vetus water muffler

I'm curious as to how you arrived at the 1.47 litre figure.


The capacity of the 10 foot hose is much more than that (5.9 l) - although admittedly it should never be completely full of water.
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Old 12-05-2021, 09:25   #7
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Re: Need help locating Vetus water muffler

I hope this doesnt sound silly. I'm also in the process of re-locating part of my exhaust. Has anyone ever connected a tiny bilge pump to the drain on the muffler so you could pump it dry before long passages or very rough weather? manually operated only of course.

I suppose you would need a decent debris filter similar to a shower pump filter but seems like it may be a way to get most or all of the water out of the muffler. Also would be useful for winterizing.
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Old 12-05-2021, 17:12   #8
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Re: Need help locating Vetus water muffler

Check back pressure at full power,that will tell you how good your exhaust design and fitting is ,minimum back pressure is a must for the life of the engine.⚓️⛵️
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Old 12-05-2021, 23:11   #9
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Re: Need help locating Vetus water muffler

I don't know if I have the same unit as you but my Vetus exhaust muffler is about 18"above the water line in the transom. My engine is completely below the water water line.

Since my engine is about fourteen feet from the transom I have custom built exhaust elbow (machine shop) and water collector that box I built myself since the Vetus one would not fit in the bilge blow the cabin sole. When the engine shuts down there is about 1.5 gallons exhaust water that back flows into the collector box which can hold over two gallons. The collector box has a valve to allow it to drain the back flow into the bilge.

Under sail with the engine off this valve can be left open direct any stern wave action from being pushed into the system and maybe make it up the exhaust elbow and manifold. This is highly unlikely. except in sever conditions. since the muffler at the transom is nearly four feet above the water line.

Down stream of the elbow the raw water is sent to a conventual U-shaped anti-siphon unit. I threw away the little bleed valve that is provide since they usually clog up and ran a small diameter hose from there to one of the cockpit drains. A peek into the cockpit drain when the engine is running will tell me if the anti-siphon unit is doing its job.
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Old 13-05-2021, 02:21   #10
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Re: Need help locating Vetus water muffler

[QUOTE=BAD ORCA;3405822]Has anyone ever connected a tiny bilge pump to the drain on the muffler so you could pump it dry before long passages or very rough weather? manually operated only of course.


>>That is exactly what I was planning to do. Being worried that the water in the hose between the engine and the water lock could surge back to the engine... Doesn't sound silly to me.
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Old 13-05-2021, 14:24   #11
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Re: Need help locating Vetus water muffler

[QUOTE=EqPierre;3406251]
Quote:
Originally Posted by BAD ORCA View Post
Has anyone ever connected a tiny bilge pump to the drain on the muffler so you could pump it dry before long passages or very rough weather? manually operated only of course.


>>That is exactly what I was planning to do. Being worried that the water in the hose between the engine and the water lock could surge back to the engine... Doesn't sound silly to me.
yeah i think i will also. i just happen to have an extra little Rule pump hanging around and the bus bar is right next to the muffler so would take 15 minutes to install. i think i will add a debris strainer though. when i took off my old muffler there was a lot of debris in it when i emptied it.
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Old 13-05-2021, 17:18   #12
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Re: Need help locating Vetus water muffler

A large number of vsl surveyed have minimum sized exhaust hose the over all length is a major factor in designing an exhaust system , the HP at RPM plus cubic capacity of engine are also major factors in a successful installation .⚓️⛵️
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