New exhaust layout

[scottnewcombe]

I've just replaced the transom on the old wooden tub. Now to bolt all the bits back together.

So here's the thing. The old exhaust set up was exhaust manifold-water injection point(below water line)-1m length of exhaust hose (50mm)-2m length of yellow(gas?)plastic pipe- straight out the back under the water line.

Now I know enough to a bit worried to say the least about the old set up. Plastic gas pipe eh??


So.. I was thinking water lock and swan neck and exiting above the waterline.
However there is only about 350mm between the waterline and the deck level. This is not enough to get a normal type swan neck in at the transom.


So my questions are

1. exhaust outlet above or below w/l. (would like to see water pumping)

2. alternatives to swan necks.

3. any other bright ideas??


TIA

Scott


2.5BMC deisel 27' wooden MB

<hr width=100% size=1>

 

[jbate]

You have a few options, muffler / water lock, riser, direct through hull / transom. Check out "http://www.halyard.eu.com/products/silencing/exhaust1.html" for some info.
I think that an above-water through-hull must be preferrable and safer, if you have enough room...
JB


<hr width=100% size=1>

 

[scottnewcombe]

Thanks JB

Nice site. Looks V expensive though. I'll give them a call anyway.


Scott

<hr width=100% size=1>

 

[vyv_cox]

Also look at <A target="_blank" HREF=http://www.vetus.com/frame-sea.htm>Vetus</A> Can't see an alternative there for a swan neck, your only option would seem to be to run the exhaust hose right up to the top of the engine room, then down to the outlet fitting. With a trap this should be OK, my first boat was like that.

<hr width=100% size=1>

 

[scottnewcombe]

I just spoke to a very helpful chap at Halyard marine who pretty much said the same thing. Suggested an inline waterlock/silencer and then up to the top of the engine bay and down to a flapper at the transom. Has to be 100% better than existing.

I have a vetus book here somewhere. I'll check them out too.

Thanks again chaps

Scott

<hr width=100% size=1>

 

[StephenW]

Hi - from what I hear it's often better to have a "looped" continuous exhaust going as high as you can rather than a gooseneck, particularly if its not fitted correctly.

Last year I took out my gooseneck and fitted continuous exhaust on the advice of Fox's engineers. They had come across a number of boats that had encountered problems ending up with water in the engine.

The results have been fine - the loop was easily fixed with a strip of stainless high under the transon and the boat would literally need to roll for water to get in. I'd also guess that the smooth flow for the water is easier to "empty" than a gooseneck iftting.

<hr width=100% size=1>

 

[scottnewcombe]

I agree. This is just what I will do.


The existing set up is 2". Is this enough for a 2.5BMC? I'm not even sure what the horsepower of this unit is. Probably around 40-50??


Scott

<hr width=100% size=1>

 

[StephenW]

Not sure about pipe diameter - I have 40mm on a 20HP Vetus 3 Cylinder so 2 inch doesn't sound too much off the mark, but probably woth checking with an engineer

<hr width=100% size=1>

 

[pheran]

A previous boat of ours had twin 3.8 BMC Commodore diesels rated at 60HP These managed just fine on 2.5inch exhausts (and one engine had a 16 foot run). This was the size BMC specified.

<hr width=100% size=1><font color=blue>A hangover is just the Wrath of Grapes</font color=blue>

 

[scottnewcombe]

Well it looks about right. Job done. (Well apart from actually doing the job that is.)




<hr width=100% size=1>