Exhaust submerged

ghostlymoron

ghostlymoron

Well-Known Member
Joined
9 Apr 2005
Messages
9,889
Location
Shropshire
Visit site
The exhaust skin fitting on my boat is partially submerged. This makes it impossible to see if there's any water coming out. I may have to fit a pee pipe so I can check it.
Is there any other detriment such as exhaust back pressure that I should consider?
 
ghostlymoron said:
The exhaust skin fitting on my boat is partially submerged. This makes it impossible to see if there's any water coming out. I may have to fit a pee pipe so I can check it.
Is there any other detriment such as exhaust back pressure that I should consider?
Click to expand...

Not a problem. A lot of Moody yachts of 80s early 90s have the skin fitting on the waterline tucked under the counter. Some owners have fitted exhaust temperature monitors for peace of mind. I had a blocked inlet once meaning no raw cooling water and the exhaust became immediately extremely loud with no silencing so easily detected.
 
If the outlet is only partly submerged it is not creating any back pressure . IIRC there is no swan neck either.

How do you propose adding a pee pipe. Is there a vented antisyphon loop that you can utilise?
 
My moody has such as exhaust. Just before the cooling water goes into the exhaust elbow of my Bukh DV20, a small tube had been teed off, but strangely to me it rejoined the exhaust pipe just before the exhaust outlet, I can only assume it was so the previous owner could check and see the flow of water through the tube. I was getting a bit paranoid about wafts of steam from the exhaust so I disconnected the joint back to the exhaust and fitted a small skin fitting through the transom so now I can check the cooling water flow easily at any time.
 
VicS said:
If the outlet is only partly submerged it is not creating any back pressure . IIRC there is no swan neck either.

How do you propose adding a pee pipe. Is there a vented antisyphon loop that you can utilise?
Click to expand...
Mine has a Vetus swan neck and water trap.
Haven't thought about the pee pipe in detail but I'd have to add an anti siphon loop first.
Difficult to tell how submerged the outlet is because when you lean over the transom to look, it dips down because of my (modest) weight. I'll observe from the dinghy next time I'm down.
 
If you fitted a Nasa exhaust temp display and alarm - dead easy to do, I have one - you can see the running exh temp all the time from a nice big display (inc at night as its lit) and set the alarm at whatever you like to warn you if things were getting a bit hot.
 
That would seem a good idea but for such a low value boat like mine, I don't know if it's justified. I'll add it to the 'wanted' list for the time being.
 
I am another Moody owner with the half in exhaust that is not visible. My ears have learnt the sound of the correct water flow through the exhaust, if it is blocked the whole tone changes and I know without even thinking about it. Took about 8 years and several blockages to get to this stage though!
 
ghostlymoron said:
That would seem a good idea but for such a low value boat like mine, I don't know if it's justified. I'll add it to the 'wanted' list for the time being.
Click to expand...

Blimey, the NASA monitor is pretty cheap and easy to fit - your boat and more the point lives if the exhaust overheats at the wrong moment, must be worth it !
 
It's survived without one for over forty years. I've never had one on any other boat and finding somewhere sensible to mount the display is tricky on a small boat like mine.
PS Do you like my new avatar - that's not me in the photo just some nautical looking type that happened to be passing!
 
My exhaust outlet is underwater, it saves adding a silencer, the pipe has an incline from the engine and exits at the stern, back pressure is not a problem.
 
My Moody had an underwater outlet when I bought it but when I re-engined I filled the hole up and fitted a transom exhaust which I can see. I also fitted a pee hole, removed the valve on the Vetus antisyphon valve and fitted a pipe through to the transom. Does not pee on idle but does as soon as you speed up/
 
I quite fancy shifting my exhaust to below the waterline, as it currently lies beside the cockpit and is really loud. The cost of the sea-cock must be quite high, though...
 
You don't necessarily need a seacock unless you are putting it through the bottom of the boat, which would give you serious back pressure problems anyway. Much easier (if you can) to route the exhaust to the back of the boat and use a swan neck and exit just above the waterline.
 
Just a warning for all those with exhuast outlets under water. It is very easy and not so noticeable to have the boat stern down. ie stern heavy. It would be worth getting a photo of her sailing or get someone else to comment on fore and aft trim. But do it when you are sailing with typical crew in the cockpit.
Stern down will slow you down plus make the bow smack into small waves when going to wind ward. The fix is to move weight forward. good luck olewill
 
You must log in or register to reply here.

Other threads that may be of interest

jamie N
Chinese heater exhaust 'insulation smoking'
Replies
13
Views
693
Dellquay13
Dellquay13
ianc1200
Sureseal shaft seal.
2
Replies
20
Views
511
ianc1200
ianc1200
O
One for the plumbers
Replies
9
Views
376
Overandunder
O

Share this page

Top