Insulation of dry stack

I am quite pleased with the wealth of info you guys have provided and I am leaning towards a dry stack system for our Union Jack. I was wondering if some of you would know of a good brand of insulation to use on the dry stack (i.e. heat insulation). Any info would again be much appreciated.

Iceman46

 

Run it outside and no insulation is required ,just a guard to keep folks hands off.

 

I don't know the specific type,but a friend's boat used rockwool.

If you're in the Arctic,uninsulated is fine-other than there- be prepared to cook.

 

dry stack; commercial boat

iceman, I'm not offering a brand name and source for either wire on batts sewn of fiberglass and rockwool or of plaster type wet-wrapped lagging for dry exhausts.

But I do have a couple of sketches that were done for another discussion that represent a heat reduction factor that is helpful in dry marine exhausts. I'm not suggesting this is the only way to build just that the chimney effect is very positive with this design.



here is a box/shroud/housing/chimney around the riser pipe. the top allows the top stack to be made of SS or aluminum to keep the inner mild steel pipe out of the weather.



Cut away of the top stack cover, but looks like I skipped cutting out the inner opening of the flat top cover where the outer cover fits to the plate.



I'm primarily showing that a chimney around the dry pipe will form a very active vent and the top two concentric pipes will form a venturi that helps air flow and cooling.

Probably stuff you already know ? but worth a reference to go with wrap insulation - ventilation can help move heat out of the boat's engine room and cabin.

Cheers,
Kevin Morin
Kenai, AK

 

Thanks WestVanHan for the info

 

Thank you Kevin Morin for the drawings

 

Thanks Fast Fred

 

There are a number of "wrap" products you can employ, from lava rock and rock wool, to Kevlar and the most common, fiberglass. Each has advantages and disadvantages to consider, but you have two main issues to contend with, heat, which you want to stay in the pipe and sound. If sound is the main concern, there's two areas to deal with airborne and mechanical (impact) and they're handled differently. For airborne sound, the simplest is an insulated double wall arrangement, possibly with a reflective material incorporated as well. For mechanical noise, an isolation or absorption barrier is the way to go.

For your needs, a simply double walled chimney will do, much like what's shown above, though insulation is helpful for heat and absorption.

 

If you go for a double-walled "chimney" stack à la Kevin M (which is a very good solution) the heat insulation should be attached to the inside of the outer box, NOT to the exhaust pipe itself.

This way, the chimney effect is increased, the insulation material is less affected by the high temperatures, the surface temperature of the cover is lower, and there is more insulation mass to reduce the noise transmission to the outside.

Use mineral wool, covered (kept in place) by hole plating for best result.

 

As has been mentioned, mineral wool or fiberglass are the traditional stand by's for this type thermal insulation. There is also ceramic insulation, a relatively new entrant.

Whatever you use, as mentioned support the piping with resilient mounts and supports to reduce structure borne noise through the accommodation decks.

 

The big money question is weather to use a std wet exhaust manifold plumbed into the setup.

OR

to purchase a custom made exhaust manifold insulated cover to lower the ER temperature.

My choice would be the water cooled manifold as its quieter.