Watertight Through Bulkhead Engine Exhaust Line - Possible?

[bristol27]

Problem: Passing an exhaust line through a bulkhead compromises bulkhead's water-tight integrity. Here's an image of the area:

Lazarette locker. A bulkhead will connect across the two middle pieces which will create a fully sealed stern chain locker. This is where the hoses should enter, then drain.

Background: I'm trying to build in water-tight bulkheads into my boat so if one area of the boat is holed, I can seal it off from the rest of the boat. So far, this has been successful inside the boat, but the lazarette presents a challenge arising from the number of hoses & systems involved in this area. I am also draining all of my hoses out of a sealed chain locker inside the lazarette. So, the hoses need to come up and over this bulkhead to drain out the transom including:

• Engine Exhaust Hose (1) - This is my main issue. Since the engine exhaust will be warm, I don't believe Schedule40 PVC would work (max. temp. range = 150F) to create a through bulkhead fitting as I plan to for the pump hoses. Further, getting the proper loop in the hose in the confined area of the lazarette is going to be very difficult. I would prefer to use some kind of piping to route the exhaust like stainless steel or high temp PVC, but I'm not so sure how acceptable this is.
• Pump Hoses (3) - Including the low & high capacity bilge pumps as well as a manual bilge pump hose. For the bilge pump hoses, I will thicken/fiberglass PVC pipe in the bulkhead. Then, on either side of the bulkhead, I will plug a hose on, allowing the bilge water to pass through a bulkhead without compromising the bulkhead's "water-tightness". (See attached image at the end of post to see how this looks).
• Engine Ventilation (2) - 4" engine ventilation holes that lead to the engine room. They are high above the water line and not such a big deal.

Questions: My questions are...

• How can I run the engine exhaust line through 2 bulkheads without losing the water-tightness of either bulkhead?
• If I used piping to route the engine exhaust, what type of material could I use? Metal? High temp. PVC? Other?
• If I use PVC piping, I find that PVC pipe to fit hose will need to be smaller. For example, if I ran a 3/4" hose, I would need to use 1/2" PVC so that the hose will fit over the PVC. This is a problem for water flow - right? Is it a big enough issue that I shouldn't use this method?
• How required is a loop for the engine exhaust line? If the line goes up to the deck, then down to a through-hull, is this enough?

Additional Information:
A somewhat poor image of what I've done before to create through bulkhead drainage that preserves the bulkheads water-tightness.

Water-tight through-bulkhead created by fiberglassing & thickening PVC pipe in place.

[Hirilondë]

Exhaust systems get hot, cool off, vibrate and eventually need portions replaced. Reinforced rubber hose is used because it deals with all of these well. I would concentrate on making a hole that could deal with the heat of a hose in close proximity and caulk it with something that could withstand the heat. I seriously question whether you can compartment your boat such that is will stay afloat after a serious hole without flotation material. And even if you did keep it up I question whether this is better than abandoning ship to a good life raft. Slowing down the sinking is still a great idea, giving you time to attempt an emergency repair or move into a life raft with the supplies needed to survive. But I think you are safer if you go with the attitude and practiced skills necessary to abandon ship if called for rather than the false security that your boat won't sink.

Good luck with your adventure, I am jealous.

[Carl-A259]

I suggest you fab a bulkhead fitting. For example if your exhaust hose is 2" use a piece of stainless pipe that will fit inside your exhaust hose make the pipe about 5" long where you can slip on about 2" per side of hose. take the pipe and weld on a 5-6" diameter flat ring /doughnut to the center of the pipe, cut a hole 1" smaller than the ring you used in the bulkhead and bolt to the bulkhead. Although if your exhaust isn't burning the hull where it exists the boat I doubt it would burn the bulkhead.... just thinking. My understanding is the exhaust loop should be above the water line.

[mitiempo]

The exhaust loop should be above the waterline and there should be an anti-siphon installed at the elbow to eliminate any chance of engine flooding.