Freeze Protection for wet exhaust

[CJ]

I will be keeping my boat in the water in Rhode Island (salt water) for this winter. I have a 6" dia exhaust tube from my diesel that is 3/4 submerged where it penetrates the hull, thus seawater extends about 10 feet up the exhaust when at rest.
Anyone have any suggestions for freeze protecting this exhaust system as I'd hate to experience a crack and take on water due to freezing within the pipe.
I've seen inflatable plugs used to block off piping in industrial service. Insert spherical plug and inflate to I.D. of pipe. Would something like that work? Am I worrying unneccessarily? Will this even be a problem?

Thanks,
CJ

[Chan]

Considering it's 60 degrees in Maine today and we are all on the global warming spiral,I wouldn't worry about salt water freezing in Rhode Island. When was the last time you saw the harbor in your area freeze to muchmore than slush on the surface.
Any fresh water in the system is another story.

[sdowney717]

Take a large rubber glove and stretch it over the end of the exhaust tube.

Then disconnect the tube at the engine and pour in some antifreeze.

If the glove wants to come loose, tie some twine around it to help hold it on.

[Gary E]

SD
Good idea except you dont have to disconect the tube, just open the salt water hose that puts the putput of the heat exchanger or the output of the small sea water pump if it's a keelcooler cooled engine and put it in there...


I have a 6" dia exhaust tube from my diesel that is 3/4 submerged
3/4 submerged? or 3/4 inch ???
That's a LOT... any way to trim the boat to lift that??

[mariner2k]

You may be able to get a rubber cap with a hose clamp from a plumbing supply place...worth a call..

[Doug B]

CJ
You really don't have to do anyting as long as your boat is in salt water. Salt water does not freeze like fresh water does. Sure , it freezes, but it dosen't freeze hard and expand with the force of fresh water. You have to be careful if your boat is in an estuary or saltmarsh, because fresh water floats on top of salt and after heavy rains, if there is no wind ,this layer can become faily thick. If a hard freeze followed this situation you'd have trouble.

[Ken Hutchins]

Considering it's 60 degrees in Maine today and we are all on the global warming spiral,I wouldn't worry about salt water freezing in Rhode Island. When was the last time you saw the harbor in your area freeze to muchmore than slush on the surface.
Any fresh water in the system is another story.


As I recall it was only 2 maybe 3 years ago that there was a hard freeze in RI, something like close to 2 feet of ice in all the harbors.

[Gary E]

Doug
You must not have been around in the mid 70's when everything north of Norfolk froze solid. I had my boat in the water near Atlantic City and the ice was foot and a half thick...The Delaware Riv froze over completly from Trenton to Wilmington Del and they ran a Icebreaker in from up north somewhere to keep the shipping lanes open. N.E. Connecticut area was colder... If his boat had been in that with that pipe 3/4 submerged, not just 3/4 inch submerged there's a good chance of rupture and sinking.

But you do what you want with your boat.

[CJ]

I wish I could simply clamp something over the exhaust discharge flange, but there isn't one. The exhaust is flush with the hull where it penetrates, so there's nothing to clamp onto. And, yes the exhaust is 3/4 under water (4" under water, 2" above) and sea water extends about 8 to 10 feet up into the exhaust where the waterline is.
I think I'll end up trying the inflatable plug shoved up into the exhaust, then drain what's trapped between the engine & the plug and dump in some anti-freeze. If I could trim the boat enough to get that out of the water I would, but that'd take about 1,000 lbs strategically located - nah.
I'm still open to suggestions though...
Thanks,
CJ

[Rob Wheatley]

I wish I could simply clamp something over the exhaust discharge flange, but there isn't one. The exhaust is flush with the hull where it penetrates, so there's nothing to clamp onto.
I'm still open to suggestions though...
Thanks,
CJ

Try going to a plumbers merchants, over here in the UK you can get plugs for testing drainage systems (have a set in my shed) 4" & 6" diameter, you could insert one of them up the exhaust to block it.
Regards
Rob

[Woxbox]

They do indeed make all kinds of plugs:
http://www.cob-industries.com/pipeplugs.htm
http://www.cob-industries.com/images/pipepl4.jpg
http://www.cob-industries.com/images/pipepl16.jpg
http://www.cob-industries.com/images/pipepl9.jpg
Something's got to fit.

[sdowney717]

ok, you want a cheap workable expandable plug?
what about a vinyl play ball like you buy at walmart.
get one that fits when normal sized.
simply deflate a little, push into hole then inflate till snug.
And that is that!

[donald branscom]

I will be keeping my boat in the water in Rhode Island (salt water) for this winter. I have a 6" dia exhaust tube from my diesel that is 3/4 submerged where it penetrates the hull, thus seawater extends about 10 feet up the exhaust when at rest.
Anyone have any suggestions for freeze protecting this exhaust system as I'd hate to experience a crack and take on water due to freezing within the pipe.
I've seen inflatable plugs used to block off piping in industrial service. Insert spherical plug and inflate to I.D. of pipe. Would something like that work? Am I worrying unneccessarily? Will this even be a problem?

Thanks,
CJ

simple awnswer - Anti freeze/ remove radiator cap/expansion tank
If it is right at the waterline cover the end with a rubber cap.