How can I reduce exhaust soot?

[jfm]

We get a layer of soot on white transom and cockpit, it's just noticeable even after only 30miles or so boshing round Solent, and distinctly grimy after say 130miles round trip the cherbourg. This is despite newish well serviced engines that don't seem to smoke much generally. I read in Azimut 46 brochure that they vent the main engine exhaust underwater, and they claim this results in zero soot. Does anyone know if this is true? Someone on this BB has an Azi 39 I recall. Has anyone modified their exhausts to they vent underwater, can this be done? On the exhaust mods that people have mentioned for Turbo36, does this shove the exhaust underwater?

Could reengine to petrol, I spose

JFM

 

[paulineb]

It's good to use white diesel every now and again or a good grade red diesel (not the heating/gas oil crap). You can get really cheap white diesel in the CI - though you'll use it up coming back!! To stop the soot going on the transom you could put the extended stainless steel exhausts on, or even those shitty red sox thingies.

Pauline B

 

[kimhollamby]

Which make/model of boat and engines? Are the engines pulling correct revs or not making maximum?

Running exhaust underwater may or may not work (have to be really careful with exhaust back-pressure) but that is treating the symptom, not necessarily curing the problem.

 

[jfm]

Re: engine info

Boat is Fline Phantom 42, 1999 model. 'Gines are 370 Volvos tamd63p. 200hours. Yes it's pulling max revs, about 2750, and they run fine and top speed is right, 29knts

I dont think there's anything wrong with the engines. I mean, all engines exhaust and there is a small amount of soot in the exhaust inevitably. They do not smoke badly on start up nor when accelerating onto the plane or blipping throttle in marina. I just think it's an aerodynamic thing. When motoring along the air behind the boat swirls round and carries the exhaust onto the transom, and inevitably the soot sticks. I would guess (dunno for sure) that Azimut's idea is that the exhaust gas only gets out of the water and into the atmosphere when the boat is long past.

Wot happens wiv MBM Sealine 37? I mean if you do 100 miles are you saying the transom is perfectly clean without any layer of black at all, like if you run your finger over the transom does it go black or is it perfectly clean?

JFM

 

[jfm]

Yes good point. But it's not the redness/whiteness, that's just a dye to denote if duty paid. So I'm not sure if Jersey better than UK (?) The prob is that the diesel we buy for boats is crap compared with the clean low sulphur city diesel you can buy for car.

What are the red sox? fabric things you attach to the exhaust outlets? Never seen them, how long are they?

JFM

 

[peterg]

we currently have a Nimbus 31 with TAMD41P and it vents the exhaust through a small 'skeg' just aft of the rudder about 6 inches underwater and we get no marks at all on the white transom/bathing platform etc..

 

[kimhollamby]

Re: engine info

We certainly have to clean the transom after a run. If the boat is given half a chance and can run at a good speed (22-25 knots), the grime is there but barely noticeable until the soapy sponge looms. If we are doing something silly (as inevitably we seem to be doing with the MBM boat) and running at, say 14 knots with bucket loads of tab, the Sealine takes it well but the engines throw more black out into the wake which is then swirled straight back to keep us amused on arrival. As per yours, not particularly visible when underway, either close-to or in the distance.

The F37 exhausts actually exit into the water, or close to it when on the plane, but even when that happens on some boats the exhaust resurfaces close enough that the estate car effect happens anyway.

Reason for asking about spec and so on is that worst cases of grime always come from over-fuelling/overloading - also on older boats where the enginerooms run hot and cannot breathe properly. Ask the owners of any shaftdrive 41-engined Fairline Corniche about the latter, or just look when they pull in after a cross Channel.

In your case, there's not much of an excuse on any of those points, as I suspect that there's plenty of air being pushed through (and I'm sure air filters are okay).

Incidentally, are your 370s from the batch with a stop solenoid block on the side with three rubber fuel pipes leading out? If so, found a new glitch on those last month...check the pipe that is the low pressure feed from the solenoid to the injection pump. Caught one that had chafed clean through on the MBM Normandy cruise.

 

[jfm]

Re: engine info

Thanks for info Kim. Guess will have to live with it, it is estate car effect as you say. Just such a pain to clean off. At least on the boat it will clean off, but on the tender (a Valiant RIB, on chocks on the bathing platform, so close to exhaust) it has blackened the grey tubes badly and no amount of scrubbing wiv Jif will remove it!

Thanks for tip on chafing pipe. I will have a look at how it's all installed next time I'm down on the boat.

JFM

 

[Guest]

Re: barrier cream?

might sound daft, but it fills in the little gaps in skin, can't be corrosive so mebbe slop some on and swish off?

 

[BarryD]

Re: Dirty tender

Don't laugh - but on the tender try wet-wipes as in those for babys bum. Don't know what they put in them but they get red wine stains out of cream carpets and soot (as in fire place) off paint and carpet. Worse case you could try and evaporetti (spelling) steam cleaner.

Barry D.

 

[Guest]

Re: wind deflectors

Do you remeber those awful Allego estate cars? They had a little "ear" at the back ,and app it made all the difference. I bet some mucking abiout with sticky tape to get a small spoiler just behind transom or somehwere, perhaps experimental one made of aluminium. Or tubey things riveted or whatever above the exhaust, like an old motorbike headlamp, but different

 

[markc]

Now don't let pauline lead you up the garden path on this one - she knows full well that at 25 knots they shoot off!!!!

M

 

[markc]

Have a similar problem, Fline 45, Volvo 72's. Exhaust is through fibreglass elbows that exit under water, prob not when on the plane though. I am beginning to live with the slightly grey transom and f'bridge overhang. If you solve it - let me know!

As for your tender, I use Formula 1 (also known as Truck & Curtain Clean) - takes off everything, including skin so wear golves!!! Swear by it though, brings the tender up like new everytime!

M

 

[byron]

If I remember rightly this was an on-going problem with the Princess DS30 due to the boat's design pulling the exhaust back on to the transom. There was also a vessel built by American Marine they solved the problem by fitting aerofoils to the sides of the flybridge

©2001

 

[MikeBrazier]

Dont know if I am talking rubbish here, but Vetus do a Swisher which fits inside the exhaust pipe to swirl the water in with the fumes before it emerges from the transom. I seem to remember something about exhausts which lie fairly flat along most of the way do not mix the fumes with the water very well, I dont know if this is the case with your arrangment.
It is a ring with fins set onto it at an angle which is slid into the tube and clamped and simply encourages the gases to mix with the raw water outlet.
Just a thought! If you want me to route out more info let me know.

Regards
Mike.

 

[hlb]

I think we've all got the same problem and mainly down to Volvo coal powered engines But.
When I remember and dont do it all the time.
I use Millers Diesel Clean cos I got fed up with cleaning the transom and also it was a bit embarasing on start up and half the yachties pretending they'ed got TB.
It has good effect but might take a week or two before anything happens.

Haydn

 

[Guest]

Was'nt there some device advertised quite widely in MBY/MBM called I think exhaust king or similar. That was supposed to substantially reduce smoke and therefore one presumes, soot.

Alternatively, how about a black hull?

Nick

 

[Guest]

Re:red arrow

Its not all bad having black smoke coming out, you can team up with another old smoker and do boat aerobatics and entertain the beach bums!

 

[Guest]

Re: How do Volvo get away with it?

Most Volvos are pretty smoky when cold but the 41 series, especially the TAMD41A is about the worst. It was positively embarrassing sometimes starting up in the marina after a spell away from the boat. It is actually ridiculous that they are allowed to get away with it but they seem to have the European volume builders in their pocket - anyone know if Fairline, Princess and the like get a better margin on Volvos than other makes? If you look at prices to the great unwashed, there does not seem to be a huge price difference size for size across a range of makes of engine, especially once you build them into a boat costing several hundred thousand.

Broom now virtually refuse to fit them as do Haines ( slightly related to Broom I suppose), for the very reason of making too much smoke.

Nick

 

[jollyjacktar]

Service required

I would have thought that if your motor was producing soot then you had a problem with combustion and fuel mixture and need service to injectors etc. You are poluting the atmosphere enough as it is without depositing it into the sea as well. The best solution however is to get a sail and do away with motors altogether. Keep it clean.