Is a Gooseneck in the Exhaust essential?

[dickh]

My boat doesn't have an exhaust gooseneck as such, but the hose loops thro' 360º before exiting at the stern. Surely this is as good as a gooseneck? - and one less thinh to go wrong/leak etc. What is the forumites views? (I'm probably going to re-engine over the winter and I'll need a complete new exhaust system).

 

[Mirelle]

Do you mean that it loops up under the deck?

If so, that is what I've got, and it seems quite OK.

We do have a seacock on the end, which we close when we think about it (when away from the boat, or in a following sea)

 

[jerryat]

No problem. Very similar to the installation on my boat, though mine actually forms a sort of 'swan-neck' rather than a complete loop. Seems a cheaper sensible solution to me if you've got the room.

 

[andy_wilson]

My Fulmar has a similar set up to yours. Exhaust pipe exits heat exchanger, drops to hull floor runs under tankage then rises in a loop before exiting underneath near transom.

Yacht has been sailed in every condition imaginable without any sign of water being forced into engine.

Bit noisy though!

Purists might argue:

1. Can't drain system without dismantling.

2. No spare water capacity in case of hard starting situation.

3. No syphon relief mechanism.

4. Noisy.

Mine has worked OK for many 10's of '000 miles sailed and several '000 engine hours.

 

[colvic987]

i have a vetus swanneck near to transom and never had a problem, a little noisy, but am looking on fitting a vetus muffler, and noise insulation...

 

[Guest]

MY boat since 1975 has had a straight run large bore exhaust without rise or neck .... it has been swamped at arse end etc. etc. and no water has got into engine from that route.
When we changed engine not so long ago - I asked the engineer doing it if he reckoned I needed any changes to it ... he agreed with my thoughts that all was fine and the bore of the exhaust - the amount of drop from engine was enough to be secure .... as he said - it would have to be an almighty lot of water and suction to to get up that girt big pipe !!! And most time the engines running anyway - chuffing out 40hp of exhaust !!

I might fit a muffler though !!!! :so I can hear m'self think ....
/forums/images/graemlins/grin.gif

 

[jerryat]

Hi Andy,

Hadn't realised that dickh had a Fulmar too! Re your 'bit noisy' exhaust, may I suggest inserting a Vetus muffler. My boat (also a Fulmar) was similarly noisy and I looked carefully into a suitable (read cheap!) solution.

I bought the Vetus muffler on recommendation from my friends and it's been a real success with the noise cut right down. I inserted mine at about the point where the exhaust hose reaches the end of the cockpit moulding in the cockpit locker. It tucks neatly down there just inboard of the hull reinforcing strake.

Highly recommend the mod!!

CHeers Jerry

 

[snowleopard]

I have the full Vetus 'best practice', i.e. waterlock, muffler and gooseneck. We can't hear any noise from the exhaust. What noise we get escapes through the sound insulation of the engine boxes. You really do know about it when a boat has a 'straight-through' exhaust. I passed a Contessa 26 this morning & it sounded like a single-cylinder motorbike!

The Gooseneck has around 3 x the volume of a simple loop of 2" pipe so will cope a bit better with water being pushed up the pipe by a breaking wave. The most important thing is to have a loop as high as possible so water can't just slosh in and fill up the waterlock.

 

[jerryat]

Hi Andy,

Snowleopard's post reminded me that I also have the Vetus waterlock fitted. This also contributes substantially to noise reduction as he suggests.

Cheers Jerry

 

[pappaecho]

Gooseneck is on the mast - Swan neck in the exhaust circuit.

Delievered a boat back from Spain to UK in early 80's, engine suddenly stopped in following sea. On inspection we had water in the engine - luckily not fatal.
During the inspection we found a metal swanneck in a locker, unfitted to the exhaust hose... the boat had obviously been from marina to marina and never been in deep sea.
Conclusion, a swanneck is mandatory unless you want to kill the engine, and at a most in opportune time

 

[VicMallows]

But we won't be able to hear the Westerlys coming!!

Seriously, yes the muffler makes a huge difference; you might even be confused for a Sadler /forums/images/graemlins/smile.gif

Vic

 

[charles_reed]

Not

if the engine is above waterlevel.

In most yachts it ain't.

If you fit a swan-neck with any likelihood of the water level in it being above the head, you also need a waterlock valve.

A direct exit exhaust, whilst noisy, if well above waterline is OK, a reasonable precaution is to fit a flap-valve over the end.
That's what all FVs have, and far fewer problems than yotties with their complicated exhaust arrangements - and you can hear them coming from afar.

 

[snowleopard]

Goose or swan?

For clarification of the terminology, look at this Vetus exhaust assembly.

I think the swan neck is a raised exit from the exhaust manifold, i.e. at the other end of the exhaust.

The way the gooseneck fitting works is that when a wave breaks against the exhaust exit, the water is forced into the pipe and compresses the air in there (engine not running). The pressure eventually stops the water going in and to be safe, it must not have reached the highest point in the exhaust or it will build up and eventually flood the engine. The greater the volume of water that can be accommodated below the high point the less likely it is to flood. The gooseneck fitting has a much bigger cross section than a plain pipe.