Which exhaust to suit

[Tremlett42]

After a lot of hull work we are now looking into exhausts. There seem to be 2 main types, gooseneck and watertrap?. The engines are 1.5 bmc diesel and the flex exhaust hose will be about 8 foot long. Should they be mounted above the water line, below or at the water line. I'm not sure my little deisel can push the water that distance?, thinking about that should the hose be run at an angle to help the water leave?.

I'm just looking for the quietest combination of hose length and exhaust type

Cheers all

 

[oldgit]

quick look here ?
http://www.abcpm.co.uk/vetus/exhausts/

 

[Tranona]

Water trap and gooseneck are entirely different things. You need a water trap, as in the Vetus catalogue (and probably an anti syphon valve). You also need a loop in the exhaust at the stern so that it is above the waterline before it exits the boat. That can be just a loop in the pipe or a moulded gooseneck can be useful if space is tight. You can also have a silencer in the exhaust line, but many installations are quiet enough with just the watertrap. I would be worried if your pump/engine was not powerful enough to push the water out. My little 9hp Yanmar managed very well over a greater distance than yours!

The Vetus catalogue www.vetus.co.uk gives you all the information you need to design and size an exhaust, but of course there are other suppliers of the kit such as Halyard Marine.

 

[Tremlett42]

Oldgit and Tranona, many thanks for the info, the pictures are nice and straight forward. On the engine their are what I assume is a cold outlet (blue) and a hot outlet (red). On my engines there only seems to be one outlet that's from the heat exchanger.

Just had a look and there are jabsco pumps, one one each engine, that are belt driven so must be working whenever the engine is on. But the inlet for these is in a tray under the engine which is there to catch spills?.

I'm sure to all the old salts on here these are daft questions, but if I don't ask I wont get

Off to have a rummage in the engine room.......

 

[oldgit]

This is from my Perkins manual,the exhausts are straight through on my boat and a luverly noise it is too,BUT it does get a bit drony after 5 or six hours,so intend at some point fitting a couple of silencers if a pair come along at the right price.
New they are silly money.

 

[Tranona]

Oldgit and Tranona, many thanks for the info, the pictures are nice and straight forward. On the engine their are what I assume is a cold outlet (blue) and a hot outlet (red). On my engines there only seems to be one outlet that's from the heat exchanger.

Just had a look and there are jabsco pumps, one one each engine, that are belt driven so must be working whenever the engine is on. But the inlet for these is in a tray under the engine which is there to catch spills?.

I'm sure to all the old salts on here these are daft questions, but if I don't ask I wont get

Off to have a rummage in the engine room.......

The belt driven pumps on the engines should draw seawater in from seacocks (probably through a filter) and pump it to the heat exchanger and from there an outlet hose (possibly with an anti syphon valve ) to inject into the exhaust outlet. This has heavy duty exhaust hose hopefully to a water trap and then another hose with a loop to the exhaust outlet through the hull. The engine itself is cooled by fresh water (with anti freeze) which is pumped round the engine and through the heat exchanger.

 

[moonraker 36]

This is from my Perkins manual,the exhausts are straight through on my boat and a luverly noise it is too,BUT it does get a bit drony after 5 or six hours,so intend at some point fitting a couple of silencers if a pair come along at the right price.
New they are silly money.

yep.. same set up on my moonraker.straight through.

 

[oldgit]

Have been searching for a couple of cheap silencers,but sods law states thatthey only ever appear as single items or if two,wrong bore size !

 

[Tranona]

yep.. same set up on my moonraker.straight through.

That works because all the waterworks of the engine and exhaust is well above the waterline.

 

[Tremlett42]

All seems to depend on the height on the engines above the water line (everything crossed so I can do the straight throughs).

Going to measure the water line with a thin bit of wood, then into the engine room and poke it through one of the sea cocks to get a rough idea.

please be high enough,please be high enough,please be high enough.............

 

[oldgit]

Wonder if you need to be fairly certain that,"lets say" you need to come to sudden halt and go astern ,that the stern wave created will not "get into" the engine ?

 

[Tremlett42]

Would looping the exhaust hose help?, thinking that would work as a non return valve of sorts?

 

[Tranona]

Would looping the exhaust hose help?, thinking that would work as a non return valve of sorts?

Just stick to the Vetus recommendations. Water trap first then straight exhaust with loop at the transom. Will stop any water getting back and quieten the exhaust. Fit an anti-syphon valve if the water injection point is close to or below the waterline.

 

[moonraker 36]

Wonder if you need to be fairly certain that,"lets say" you need to come to sudden halt and go astern ,that the stern wave created will not "get into" the engine ?

just fit some exhaust flaps to the end of the exhaust.

 

[PetiteFleur]

Just stick to the Vetus recommendations. Water trap first then straight exhaust with loop at the transom. Will stop any water getting back and quieten the exhaust. Fit an anti-syphon valve if the water injection point is close to or below the waterline.

I initially fitted a Vetus Antisyphon valve but it blocked up frequently so did away with the valve bit and just led a length of PVC hose from the valve to the stern so you always get a 'piddle' of water through this outlet. Seems to be more reliable than the 'valve'. Vetus make both versions so you have a choice.

 

[Latestarter1]

All seems to depend on the height on the engines above the water line (everything crossed so I can do the straight throughs).

Going to measure the water line with a thin bit of wood, then into the engine room and poke it through one of the sea cocks to get a rough idea.

please be high enough,please be high enough,please be high enough.............

Perkins stuff is OK, however 8 inches is a little 'tight' and drawing a little misleading as you can create as much hight as engine compartment headroom allows with a dry riser. Safer to shoot for minimum 12 inch 'spill over point' or greater and you can just create it. Gravity is free, just use it. Just remember W/L is LOADED W/L another point builders and installers simply forget about.

Ignore all the stuff regarding exhaust flaps and fancy valves. IF you you suspect there is likelyhood of a potential issue when going astern and very unlikely in your case, however real simple to incorporate a simple surge tube in the system if you feel the need.

Avoid Vetus toy town exhaust gear, expensive and problematical, Hallyard or Centek stuff 100% superior of you want to incorporate a muffler.

 

[Paul1962]

Hi,
Suggest you have a word with Bob Doyle at Darglow Engineering. He is a guru regarding exhaust silencing without performance loss.