Underwater exhaust conversion

baylabayla3288

baylabayla3288

Well-Known Member
Joined
7 Jun 2005
Messages
278
Location
South of Finland
Visit site
I'm concidering converting the exhaust system on my Fairline Phantom 38 with TAMD63ps to exit under water. I would be interested in your views on how to realize this without cutting too much in the boat. Adding external boots would not be a good solution as they would be sticking out too much and prone to get damaged easily. The exhaust outlet openings are situated at the rear corners on the Phantom just above the waterline at rest. I would be interested to see picures on how the underwater exhaust on a sealine 43 is built. It looks like there is a box type of solution running outside the hull. The reason I'm interested in this is because of some disturbing exhaust resonance on the fybridge at certain speeds and possible getting less soot on the transom. Thanks in advance for your views.
 
Had a look through my F43 phots but don't tend to take picture of the exhaust!

They do run down the sides in a sort of box. The box has an opening at the rear under the water, you still get soot on the transom/tender etc, I think it is just a fact of life with MBs....
 
Very nice boat the Phantom 38....we were on the very of buying one but decided flybridge wouldn't suit our cruising.

I may be way off the mark here but are there any design considerations with back pressure created by the exhaust entering water?
 
PRH said:
Had a look through my F43 phots but don't tend to take picture of the exhaust!

They do run down the sides in a sort of box. The box has an opening at the rear under the water, you still get soot on the transom/tender etc, I think it is just a fact of life with MBs....
Click to expand...


Hi and thanks for the pictures! Is there a by-pass opening above waterline some where on the Sealine 43? Most of the designs I have seen on for example larger Sunseekers have a smaller outlet to ease idling and starting.
 
Bandit said:
If you are talking about doing it on the transom Fairline Turbo 36 and Sedan 36 all had swan neck all though mine did not.

I fitted vetus dustbin type silencers and an amazing reduction in noise was the result.

I think from memory the 63p is a 6 inch exhaust, you need to check :

http://viewer.zmags.com/publication/06fa8bec#/06fa8bec/76
Click to expand...

Hi, my Phantom 38 has large dual chamber mufflers from Hylard already which make the engines very silent at idle and lower speeds. At cruising speeds there is some resonance that I would like to eliminate if possible. I guess the water is blown out of the mufflers and therefore the silencing effect is partly gone. I have noted that when pressing the bow down with the tabs at around 18 – 20 knots this noise goes away. This must be the effect of the changed water flow around the exhaust exits. The boat is reasonable quiet though but if there would be an easy solution to put the gases below water making is supersilent I would do it. Here is a picture of the boat where the openings can be seen. The hull extends all the way to the end of the bathing platform so external legs would be unprotected if backing against the dock. Hmm she is sleek for a 38 footer ... :-)
 
My Aquastar has 2 x 63p with underwater exhaust and also a small 1.5 inch ish by pass for idle but also to break a siphon if the boat was rolling or bobbing at anchor which is important to keep "oggin out of engin" so to speak or it acts like a pump.

If you fit swan neacks on the transom they normally have a quarter inch hole at the top for the same reason.
 
Later F43's have small brass fitting on the end of the exhaust, but they are not there on early ones. Not sure what they do.

The hull is moulded with a cut out to act as an exhaust chamber. It runs from the end of the engine room to the tip of the boat, exiting straight down under the water. The external cover is then stuck on the outside. I understand sealine no longer have the mould for the covers, so don't crack one when you lift it. Apparently it does happen.

Still get increased noise when the boat lifts on that side at planning speeds, but I get zero soot from my 63p.
 
You must log in or register to reply here.

Share this page

Top