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Old 07-03-2016, 10:55 AM   #21
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One the biggest issues with wet exhaust motor vessels is exhaust system layouts and builders not paying attention to the details. Cost to repair exceeds the cost of a Sarca or 5 to put it in perspective.

So yes, good subject.
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Old 07-03-2016, 01:34 PM   #22
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Not to mention that boat only draws between 4-5' of water I would think. So I doubt the mufflers are 4' below the water line.
My DeFever 49 RPH with 200hp Range 4 Perkins draws 5'7" and the exhaust hose is 26" from the top of the 12" high muffler. The mufflers are just below water line but not anywhere near 4' more like 8" to the top of the muffler and 18" to bottom of muffler, according to my measurements just taken.
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Old 07-03-2016, 02:41 PM   #23
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My DeFever 49 RPH with 200hp Range 4 Perkins draws 5'7" and the exhaust hose is 26" from the top of the 12" high muffler. The mufflers are just below water line but not anywhere near 4' more like 8" to the top of the muffler and 18" to bottom of muffler, according to my measurements just taken.
An element of optics then, I guess.
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Old 07-03-2016, 03:50 PM   #24
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Among the most common defects in systems like this I encounter is the lack of a continuous downhill run after the spill over point, the wet riser above the water lift muffler. Just about every engine and gen manufacturer out there calls for a minimum of 1/2" per foot downward slope or about 2 degrees. Many also include a minimum distance/drop between the water injection point and a water lift muffler, and a maximum lift height upon leaving the water lift muffler. I use this diagram to illustrate basic requirements to boat owners and installers, however I also caution them to follow precisely the instructions of the specific engine or genset manufacturer... http://www.northern-lights.com/media...t_drown_me.pdf

The Cummins installation manual, which is over 150 pages long, dedicates nearly 20 pages to exhaust systems alone.

None of this should be left to guesswork, Perkins published a manual called "Marine Installation Know-How" that walks installers through the exhaust system requirements, including required drop between injection elbow and muffler and required slope. Only engines that use a water lift muffler and wet riser can suffer from flooding caused by excessive cranking, dry riser exhaust designs, those that include a the continuous downward slope from the water injection point and an dry apex above the WL, cannot suffer from flooding as a result of extended cranking, as the water injected into the exhaust naturally runs overboard, it never has to be pushed up hill. Most genset installations on the other hand use the water lift muffler arrangement and they can experience flooding. I'm seeing some new gensets that include a placard warning users about this possibility. It can be overcome by either closing the intake seacock or removing the drain plug on the muffler during extended cranking.

Having temporarily installed a clear section of hose on wet exhaust systems on a couple of occasions to diagnose water/gas mixing issues, it's surprising just how much of the hose volume is gas and not water.

There is an entire ABYC chapter, P-1, on the subject of exhaust systems including, "P-1.5.11
The exhaust system shall be designed and installed to prevent cooling water, rain water, or raw water from entering the engine through the exhaust system under all normal operating conditions. The exhaust system design shall consider the drop height of the manifold above the waterline and a provision for downward slope of the exhaust system."
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Old 07-03-2016, 03:54 PM   #25
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The primary fuel filters lack heat shields and metallic drains...
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Old 07-05-2016, 08:05 AM   #26
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The primary fuel filters lack heat shields and metallic drains...
Or some one took them off so they could easily see what is in the bowls as well as easily drain them.
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Old 07-06-2016, 07:32 AM   #27
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Actually none of those filters are MA rated, all are Racor FG's, shipped without heat shields and metallic drains. The give away is the black support band and lack of blue MA labels.
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Old 07-06-2016, 08:37 AM   #28
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Steve

Guidelines aside, I've struggled with how the metal heat shields are a fire preventer. If it were truly that relevant ABYC would not find plastic acceptable and recommend we all use metal canisters like Fleetguard.

There must be some logic I'm missing.

PS - there are two different styles of filters, Capt Bill is likely correct about removing the metal bowls on the one set.
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Old 07-06-2016, 09:08 AM   #29
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I guess they realized that those with FG Racors would not buy MA rated filters to comply so a band aid approach is required. The heat shield and metal valve is on my to do list along with closing the fuel tank sight glass valves after taking a reading.
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Old 07-06-2016, 09:24 AM   #30
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I think the metal bowl is a heat shield so if you get an ER fire, the shield will give the plastic bowl more time before it is breached by heat. Protects plastic bowls from other fires, and gives more time before diesel is added to an already raging fire. That added fuel will make a bad fire worse, and also increase spill once the wreck sinks.

I think it is of marginal benefit, but not trained in fire research. If a fire is bad enough to melt an unshielded racor, mounted low in the bilge, good chances the boat is a total loss already.

I kept the shields on mine.

Maybe Cajun Rose will comment, he is restoring a boat that had an ER fire.

Dang, got a little off topic....
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Old 07-06-2016, 09:30 AM   #31
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IF the boat is common GRP a hull fire is almost impossible to to put out.

Grab the Ditch Bag and GO!
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Old 07-06-2016, 12:47 PM   #32
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IF the boat is common GRP a hull fire is almost impossible to to put out.

Grab the Ditch Bag and GO!


Unless you think you can fight a fire in bare feet!
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Old 07-07-2016, 02:29 AM   #33
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There is legitimate science behind the shield/deflector design. I've been to the plant where every one of the Turbine series filters is made in Modesto CA, I've spoken with the engineers there and watched a video of the fire test. In the test, which is described in ABYC H-33, the flame is directly beneath the filter, which of course will not always be the case. The engineers at Parker told me the plastic bowl can actually endure the flame exposure in most tests, but it wasn't 100% reliable so the heat shield had to be used.

The shield is not a "fire preventer". The shield simply buys time, 2.5 min is all that's needed to meet the standard. The plastic drain melts and leaks fuel very quickly in the test btw. All Racor turbine series filters that are MA designated are shipped with heat shields, metal drain plugs and a blue label. Removing the shield really makes no sense to me, and it may cause an issue with your insurer, I've encountered insurers who required the shield, among other things, to be installed as a condition of insuring the vessel.

ABYC doesn't prohibit plastic for use with fuel systems per se, instead they simply call for any material that's used to be able to withstand exposure to 2.5 mins of flame. This is why type A fuel hose is required, if the vessel is to be compliant with this standard. Needless to say, plastic fittings, or tubing should not be used for fuel. The once common Racor diesel fuel liquid tank vent traps are plastic, and they are non-compliant.

EU standards don't allow any plastic bowls, in those cases the bowl must be entirely metal (a Racor option, used on military vessels as well), which is a shame because that negates a lot the advantages of this filter. FG series filters can be easily updated for non-inspected vessels, and personally I don't think the shield hinders visual inspections very much, if there's water in the bowl you can see it. The shield does not hinder draining. Inspected vessels must use a MA series filter, not an updated FG series. I once asked a CG MSO why this was the case, he said, "because when they sift through the ashes, they will find the filter housing and its serial number will tell the investigators if it was equipped with a heat shield".

Granted, fires are uncommon on recreational diesel vessels, and how much of a difference the shield will make is debatable, but for the cost it's cheap insurance, and your insurer may insist it be present.
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Old 07-07-2016, 06:28 AM   #34
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"The plastic drain melts and leaks fuel very quickly in the test btw"


A switch to a metal plug would seem to be a very low cost upgrade for folks .
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Old 07-07-2016, 08:54 AM   #35
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"The plastic drain melts and leaks fuel very quickly in the test btw"


A switch to a metal plug would seem to be a very low cost upgrade for folks .
At least switch to a metal valve. The metal plug makes it a PITA to drain the bowl.
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Old 07-07-2016, 09:29 AM   #36
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Or just - GASP - get rid of your Racors and join the tens of millions of diesel powered setups that use spin on filters. PH makes these with drain valves on the bottom of filter for those looking for water in their fuel.
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Old 07-07-2016, 01:19 PM   #37
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Or just - GASP - get rid of your Racors and join the tens of millions of diesel powered setups that use spin on filters. PH makes these with drain valves on the bottom of filter for those looking for water in their fuel.
Well there's that.

Remove perfectly good filters to replace them with perfectly good filters.
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Old 07-08-2016, 07:07 AM   #38
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For boats that operate with questionable fuel sources , the old style large glass jar with a fine cotton mesh for water seperiation is about as good as it gets.

THe water is simply emptied , no replacement is required , and away you go.

Your boat insurer may have problems tho.
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