Thru Hull Exhaust Fitting

C

C-Dude

New member
Good day all-

I am installing an Espar D2 on my new (to me) 2012 22 foot cruiser. The instructions state that the hole drilled around the thru hull exhaust fitting must leave 3/16" clearance between the boat hull and the thru hole fitting, i.e. I must over drill the hole.

What would be the best way to seal this hole? Epoxy? Just applied to edges of hole or try to over drill, fill entire hole with epoxy and then drill again? I think the hole would be to big to do this in a vertical position and have the epoxy stay in hole. Is epoxy heat resistant enough for this application? Is there no balsa in the hull side, so I don't need to fill it with anything, just go for it with no epoxy and the fiberglass raw edge will be fine with no additional sealing?

Also, the fitting comes with 2 heat resistant fiber gaskets to go between the outside of the boat and the fitting itself. Should I apply any caulking in addition to the fiber gaskets, between the gasket and the hull? If so, what type is recommended?

The thru hole fitting is not an espar, so does not come with a silicone gasket, just the 2 fiber gaskets.

Any suggestions would be appreciated.

Thanks-

Ben
 
When I added the Webasto to my CD25, the exhaust exited through the hull right below the rub rail. It was just solid fiberglass, no core.

The install kit for the Webasto included a high temp sealant (Permatex Ultra Copper I believe) that went between the hull and the fiber gaskets.
 
Our local Espar distributor said use 5200 on the outside and one of the fiber washers on the inside. Never saw a problem.
D.D.
 
beermanPDX":1op9lhsm said:
When I added the Webasto to my CD25, the exhaust exited through the hull right below the rub rail. It was just solid fiberglass, no core.

The install kit for the Webasto included a high temp sealant (Permatex Ultra Copper I believe) that went between the hull and the fiber gaskets.
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X-2 :wink:
 
Agree, no need for epoxy. The fitting needs "cooling space" between it and the polyester (glass cloth is fine with high temp). One of the few times for a specialized silicone can be in this type of installation--I have used that in the past. The Permatex Ultra copper would be fine.
 
I used Permatex for most connections. Turns out the the exhaust doesn't transfer as much heat to the outer ring of the exhaust through-hull fitting as I thought it might. I used butyl for the stove bolt holes and high-temp silicon for the rest. I used Permatex for some of the other exhaust connections to make sure I didn't have any tiny leaks (I think I developed a sensitivity to diesel fumes over the years). It might make disassembly more difficult, but hopefully that won't be my project.

Mark

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Ben: Sounds like we used the same thru-hull. Mine came from China and was 1/3 the cost of the same fitting with the Webasto name on it. Three screws pull the fitting together.

I installed my thru-hull three days ago and finished the Espar D2 install yesterday. My kit came with instructions for truck installation, so I had to wing it for boat install. I drilled a 1-5/8 hole (actually came out a little larger) and centered the fitting. That gave me close to your prescribed clearance. I also debated whether to use the green fiber washer on the outside because it looks a bit ugly, but logic said if the fitting gets hot this will isolate it from the gel and fiberglass. So I used the fiber washers on both sides. Essentially the thru-hull fitting floats not touching the boat skin anywhere. Most posts I found sealed the fitting using 5200 and I didn't see any complaints later, so I went that way. My fitting is about a foot above the water line next to the sink drain fitting. I used 5200 on both sides of the fiber washer placed against the outside of the hull, but none on the inside washer. I also lightly sanded the gel under the seal area so the 5200 would get a better grip.

I fired the Espar with the 22 on the trailer this morning. The exhaust pipe and connect point to the thru-hull fitting get too hot to touch. With the D2 on boost (highest setting) for 13 minutes I went out and felt the outside mount flange. I could touch the flange for about 3 seconds before I needed to remove my fingers. I turned down the heater to put it into cool-down mode, and had the thought to grab my non-contact thermometer. With the heater on cool-down for about a minute (prob didn't lower the flange temp much) I registered the outside flange at 127˚. How hot will the flange get? I don't know, but guesstimate 165˚ is within possibility. That being the case 3M 5200 or high temp silicone should both work fine. I'm glad I used the outside washer. It doesn't look all that bad with a little 5200 sedating the green color.

I get a little oil smell in the cabin. Not sure whether that is machine oil form construction or a slight leak around the exhaust fittings. If it persists I'll seal the connection points with high temp silicone.
 
AKMel":2obmfl2l said:
Ben: Sounds like we used the same thru-hull. Mine came from China and was 1/3 the cost of the same fitting with the Webasto name on it. Three screws pull the fitting together.

I installed my thru-hull three days ago and finished the Espar D2 install yesterday. My kit came with instructions for truck installation, so I had to wing it for boat install. I drilled a 1-5/8 hole (actually came out a little larger) and centered the fitting. That gave me close to your prescribed clearance. I also debated whether to use the green fiber washer on the outside because it looks a bit ugly, but logic said if the fitting gets hot this will isolate it from the gel and fiberglass. So I used the fiber washers on both sides. Essentially the thru-hull fitting floats not touching the boat skin anywhere. Most posts I found sealed the fitting using 5200 and I didn't see any complaints later, so I went that way. My fitting is about a foot above the water line next to the sink drain fitting. I used 5200 on both sides of the fiber washer placed against the outside of the hull, but none on the inside washer. I also lightly sanded the gel under the seal area so the 5200 would get a better grip.

I fired the Espar with the 22 on the trailer this morning. The exhaust pipe and connect point to the thru-hull fitting get too hot to touch. With the D2 on boost (highest setting) for 13 minutes I went out and felt the outside mount flange. I could touch the flange for about 3 seconds before I needed to remove my fingers. I turned down the heater to put it into cool-down mode, and had the thought to grab my non-contact thermometer. With the heater on cool-down for about a minute (prob didn't lower the flange temp much) I registered the outside flange at 127˚. How hot will the flange get? I don't know, but guesstimate 165˚ is within possibility. That being the case 3M 5200 or high temp silicone should both work fine. I'm glad I used the outside washer. It doesn't look all that bad with a little 5200 sedating the green color.

I get a little oil smell in the cabin. Not sure whether that is machine oil form construction or a slight leak around the exhaust fittings. If it persists I'll seal the connection points with high temp silicone.
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If you don't already have one on board, I'd recommend that you add a CO detector. It's cheap insurance and it will alert you if there is an exhaust leak into the cabin.
 
I do have a CO detector aboard. It didn't go off at any time during my heater tests, but I could tell I had some oil fumes in the air. I thought they might have been from manufacturing oil on the heat exchanger. But when Mark mentioned he has a similar situation I had to wonder about leaks. The exhaust tube has corrugation to help it flex, but I'll bet they don't seal well, and the instructions said not to over-tighten the clamps. I ordered High Temp Ultra Copper today, just to make sure. We'll see if that does the trick.
 
Thanks for all the suggestions. I installed a D4 on my north river and didn't put silicone on anything, and never had exhaust leaks. I did find that if the air is still, the exhaust will sometimes be detectable in the cabin.

You are correct, I have the cheaper thru hull fitting, not the Espar brand this time. I will put a fiber seal on each side of the fiberglass and also some permatex on the outside between the hull and the fiber washer.

Let us know if you figure out what caused the exhaust fumes
 
I picked up the High Temp Ultra Copper silicone and sealed the clamp ends of the exhaust tube. That took care of the fume problem.
 
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