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Temp closing off thru-deck chimney hole

6K views 30 replies 9 participants last post by  pdqaltair 
#1 ·
Your thoughts on this solution please . . .

I'm installing a Newport Dickinson bulkhead propane heater. The chimney requires a 3" hole in the deck. The vendor offers a SS weather guard to cover the chimney deck cap when it's not being used to help protect against moderately bad weather. Nevertheless, in case of really rough going at sea, I'd like to be able to temporarily remove the deck cap altogether and seal the 3" hole in the deck. I'd like to prevent water intrusion, even in the extreme circumstance that the boat were capsized.

Therefore, my solution is . . .
1. Instead of mounting the deck cap directly to the boat as suggested by the vendor, I'll permanently mount a teak ring on the deck around the hole. Four bolts will stick up through this, evenly space around the ring.
2. I'll mount the deck cap to a second teak ring of the same diameter, and both the deck cap and the teak ring it is mounted to will have holes that accept the bolts coming up from the teak ring mounted permanently to the boat. After placing the deck cap and its mounting ring onto the boat's teak ring, I'll secure the deck cap with cap nuts over these bolts.
3. I'll have a 3rd teak cover plate made of the same diameter as the previous teak rings, but in this case with no 3" hole in the middle. This teak cover plate will also have holes that accept the bolts coming up from the teak ring mounted to the boat.

Now, in really rough conditions, I'll have the option to remove the deck cap, and replace it with the teak cover plate. Of course inside the boat, I will also have to temporarily remove the flue pipe between the stove and the deck cap.

The other option I could think of was to fabricate a heftier water-tight cover to place over the deck cap and allow it to be secured to the deck in some way. The down-side of this approach is that it may be a little large / tall, so it'd be more vulnerable to green-water over the deck.

Any thoughts on these solutions or other better ideas? I realize I'm being a little paranoid here, but the boat is a Bluewater design (PSC 34) and I'd like to keep it as water-tight as possible.
 
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#3 ·
That's not a bad way to do it... but how hot is the exhaust gas from the chimney. If it is too hot, the teak would be at risk...
 
#4 ·
If I understand the suggestion correctly . . . Instead of installing the deck cap permanently to the deck using screws as the manufacturer proposes, I could install bolts into the deck around the 3" hole, then place the deck cap over those bolts and secure it with cap nuts. To seal the hole, I could swap the heater's deck cap with a cover plate / rubber plug, and omit the use of teak altogether.

This is a simpler and cheaper approach, thank you. The teak might look a little nicer, but it's a maintenance item (since I'd keep it varnished). Teak varnish may also be affected by the heat from the chimney. I'd have to be careful each time I swapped the deck cap for the plate and back, to get a good seal. This is also true with the teak ring approach, but mitigated a little by having the first teak ring permanently installed, using 3M 101 or similar between it and the deck. The chimney's cap is then up off the deck a little, which helps prevent water running down the hole if I don't get the seal exactly right when using the cap.
 
#5 ·
Or, you could get a larger metal deck ring and deck plate, with a spare plate, and install the deck cap into one of the deck plates, and use the other as a cap for the opening in heavy weather.
 
#6 ·
Yes, I've been thinking about this approach as well, but I couldn't see a way of doing it without requiring a hole larger than the 3" one already required.

Regarding the concern about the exhaust temp. and teak . . . yes, this could be a problem, I'll have to research this further. If so, I'm not thrilled about even subjecting the boat's gel coat to high temps. The deck cap is as in the attached pic, which draws air in from the lower part and exhausts it out from the upper part. The lower air inflow should provide some protective benefit from the exhaust temps exiting the upper part (which also gets deflected upward a little).
 

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#7 · (Edited)
Not sure exactly where you plan to mount the heater -- presumably on the forward port bulkhead in the main salon -- but depending on where the chimney exits to the deck, you may have to address the issue of deck camber.

We used a "Large Canted Teak Winch Pad" which helped to compensate for the deck camber. Otherwise, the chimney cap and shield hardware would be mounting to the deck at an angle very askew from the vertically plumb chimney.

There really is little concern about exposing the teak to the heat from the chimney. While nominally 3", I seem to recall the chimney is actually about 2 5/8" or so in diameter. This leaves a nice gap all around when you cut a 3" hole in the deck and the winch pad.

Also, the chimney is double walled, with air from exterior coming down the outer flue. This insulates and cools the inner exhaust flue (especially up near the top, where both the exhaust and intake air are cooler), so it does not get nearly as hot as a single-walled chimney.

As for capping it off in bad weather. I think, with the standard spray guard, that you will be in good shape for all but the nastiest conditions. That said, I too would devise a fallback for off-shore.

I think your approaches above will work pretty well. Seeing as I'm congenitally lazy, I would favor an approach that would not require any disassembly. Instead, I would want a solution that merely allowed me to cover up the cap and guard without taking them off.

I think what I'd do, is tap a small threaded bolt hole into the flat metal bands at the tip top of the cap guard. I would then permanently secure (epoxy?) a large nut on the underside of that hole. Then I'd hunt around and find a stainless steel kitchen bowl that was sized such that it could be placed over the entire cap assembly like a dome. I'd drill a similar size hole in the center of the bottom of that bowl. Then I'd get a bolt and secure the bowl to the cap guard, through the pre-drilled holes.

I would probably gasket it a bit too. A small rubber gasket at the bowl bolt. Then, probably a donut shaped gasket that would fit over/around the cap and guard assembly, lay on deck (or better yet the winch pad --that camber issue), against which the stainless bowl would snug.

Anyway, all this in theory -- I haven't attempted it. Hopefully that made some sense and you could follow what I was getting at.

I still don't have a good photo of it, but you can see our cap, with shield, mounted to the winch pad in this photo:



You can see that the canted winch pad did not alleviate all the camber, but it made it do-able.
 
#8 ·
I'd second the dog about using metal instead of teak for sealing up the hole. A teak bolted on teak ring, another piece of teak bolted down to seal it...... Ooops.... it cracked at the grain. Gives me the willies just thinking about it. Unless the surface is perfectly flat I think even a cheap piece of plywood would outlast teak. I love teak and its strong stuff ...... but grained wood to seal a rounded surface..... not for me. I installed the your heater on my last boat by the way, and I wouldn't worry too much about the heat....... but there is another strike against wood..... warm - cold - wet - dry - over and over again...... crack :eek:
 
#9 · (Edited)
Thanks John, I was hoping you'd weigh in with your thoughts as well. I appreciate the reassurance regarding the exhaust temps, and your descriptions are clear. I will have some camber to deal with, so that's another advantage of using a teak base, similar to your winch pad approach. BTW, if I recall, you mentioned previously that you built a bulkhead to mount your heater on for your PSC 31, and if I recall the related pic you posted . . . a very nice bit of craftsmanship, that.

Regarding the approach of using an inverted SS bowl . . . since I still haven't mounted the deck cap yet, I have it here in hand and observe that the SS pipe isn't the strongest. Since I'm being paranoid here to begin with, a concern would be that green water over the boat might easily just tear the whole thing off the boat, as your bowl would be dependant on the (not overly strong) cap itself as a mount point.

Perhaps a hybrid approach of a couple of the above suggestions? . . .

1. Install a deck plate with a larger hole into a winchpad (but keep the thru-deck hole at 3")
2. Permanently mount the winchpad to the boat
3. Cut a 3" hole in the metal deck plate cover and install the heater's deck cap into that
4. Have secondary deck plate cover on hand to use when the going gets rough
5. Use inverted SS bowl as head-guard in case of boom mishap? :)
 
#11 ·
Thanks John, I was hoping you'd weigh in with your thoughts as well. I appreciate the reassurance regarding the exhaust temps, and your descriptions are clear. I will have some camber to deal with, so that's another advantage of using a teak base, similar to your winch pad approach. BTW, if I recall, you mentioned previously that you built a bulkhead to mount your heater on for your PSC 31, and if I recall the related pic you posted . . . a very nice bit of craftsmanship, that.

Regarding the approach of using an inverted SS bowl . . . since I still haven't mounted the deck cap yet, I have it here in hand and observe that the SS pipe isn't the strongest. Since I'm being paranoid here to begin with, a concern would be that green water over the boat might easily just tear the whole thing off the boat, as your bowl would be dependant on the (not overly strong) cap itself as a mount point.

Perhaps a hybrid approach of a couple of the above suggestions? . . .

1. Install a deck plate with a larger hole into a winchpad (but keep the thru-deck hole at 3")
2. Permanently mount the winchpad to the boat
3. Cut a 3" hole in the metal deck plate cover and install the heater's deck cap into that
4. Have secondary deck plate cover on hand to use when the going gets rough
5. Use inverted SS bowl as head-guard in case of boom mishap? :)
The cap guard/spray shield is reasonably robust. By "cap guard/spray shield," I am not referring to the chimney cap in your photo. I'm talking about the piece of hardware that goes over that to protect it from spray and sheets. Did you get that with your kit? It was an optional add-on with ours.

I through bolted the canted teak winch pad to the deck (countersunk bolt heads in the teak, nuts at the underside of the deck.) The chimney cap and cap guard are each held in place with 4 large wood screws.

Pretty strong, but definitely not foolproof. If boarding water sheared it off, I'd be worried about those dorades too. I'd probably keep a toilet bowl wax ring handy just in case.

You could through-bolt the cap guard/spray shield in addition to the winch pad. Then your attachment point for the stainless steel bowl would be even stronger. I actually thought of doing that when I installed ours, but decided I wanted all the through-deck holes to be inside of the gasketed (and therefore not exposed) chimney cap.

P.S. Thanks for the compliments on the bulkhead. It looks good from 15 feet -- just don't inspect too closely.:rolleyes: Be thankful you have a perfect bulkhead location for mounting!
 
#10 ·
If it were me, You are going to be cutting a plug out to the teak winch pad. If you make the cut with a bevel from the top down to 3 inches at the bottom which can be done by setting the angle on a saber saw. you can make a teak plug that will fit perfectly. A SS bolt and washer though the top and a piece of flat stock and wing nut on the bottom side and you can tighten it down and it won't leak or go anywhere.
 
#17 · (Edited)
This won't work as IIRC the chimney will be in the way of the flat stock and wing nut inside the cabin. It has to be held down externally in some manner.
If it were me, You are going to be cutting a plug out to the teak winch pad. If you make the cut with a bevel from the top down to 3 inches at the bottom which can be done by setting the angle on a saber saw. you can make a teak plug that will fit perfectly. A SS bolt and washer though the top and a piece of flat stock and wing nut on the bottom side and you can tighten it down and it
Dog, If I understand triple wall chimney pipe you can have in contact with a combustible. All you have to do is make sure you have a pipe joint below the deck. Then the piece of the the cap on it is feed down to make the connection. When the time comes to seal things up, you break the join below deck and pull the pipe and chimney cap up from the cabin top. This would leave the room below deck to tighten down the plug. I failed to say that you would need to use a small piece of flashing around the pipe at the point where it enters the teak pad. use sheet metal screws to attached the flashing to the chimney. On the teak pad use storm window clips to hold the edge of the flashing fast. 1/4 x 20 bolts from the underside and wing nuts. These are recessed into the underside of the teak pad and do not go though the deck. I know a guy who did this way but he made his flange from a large ss funnel that was used on a dairy farm.
 
#13 · (Edited)
Great suggestion for the plug Bubb2. I've seen a similar suggestion for plugging deck chain pipe holes (which I could also use).

Unless I'm missing something though, I'd still need a means of easily un-mounting and remounting the heater's deck cap from the winch pad. This pushes me back toward using a deck plate doesn't it? If I'm using a deck plate, the top hole in the winch pad is larger (at least 4 inches). While I could just plug the deck's 3" deck hole with the teak plug, it'd leave the (deck plate sized) hole in the winch pad open. Or did I miss a beat? :confused:

Rant alert! . . . Why can't manufacturers just provide these solutions, it's an obvious enough requirement for sea-going vessels, no? :hammer
 
#15 ·
Rant alert! . . . Why can't manufactures just provide these solutions, it's an obvious enough requirement for sea-going vessels, no? :hammer
Yes!!

When I was corresponding with Bob Perry about the follow-on PSC 385 (years ago, before it got cancelled), I suggested that a dorade should be located in correct proximity to a main salon bulkhead and sized such that it could be unscrewed and a chimney with cap and guard could be dropped straight down through to the waiting bulkhead heater. Then secured via the same bolts as the dorade cowl. It would be a lot easier to contrive a "bluewater" cover with the dorade base and cowl hardware in place. And, it would be a quick swap for winter/summer usage.

Plus, we wouldn't have to take that hole saw to our decks!! :eek: :eek: :eek:
 
#14 · (Edited)
Bubb-

That won't work as IIRC the chimney will be in the way of the flat stock and wing nut inside the cabin. It has to be held down externally in some manner.
 
#19 ·
I want to thank everyone for their ideas and insight concerning this project, it's much appreciated. Based on this, I've decided to go with the following approach, but I have one additional question below:

1. Purchase two 6" diameter chromed bronze deck plates (8.5" OD)
2. Cut a 3" hole in the center of one of the deck plates
3. Mount the chimney deck cap (pic posted above) into the deck plate (the base of the chimney deck cap will be just a hair larger than the 6" deck plate, and I'll use the manufacturer's supplied neoprene gasket between them)
4. Install the base of the deck plate into a canted teak winch pad (mostly protected by the OD of the deck plate)
5. Install the winch pad permanently onto the boat deck

In the event of extreme conditions . . . unscrew the chimney deck cap, replace with the second (still intact) deck plate.

Since you've gotten me this far . . . can you suggest the best approach for having the 3" hole cut in the first chromed bronze deck plate? A drill press with a 3" metal hole saw blade?

Thanks again for all the input. I'll be sure to stamp the "Designed by SailNet" logo on the side (. . . oh, and suggest that Dickinson Marine add this to their product catalog for 2011 with royalties to all of us, of course).
 
#21 · (Edited)
That sounds like an outstanding solution. Well done!

Yes, getting those holes centered and cut properly will be tricky.

I had to really work at it to get the hole in the teak winch pad correct with only a hole saw (that canted bottom and eccentric base make it very tricky). So I think SD makes a good suggestion to find a machine or wood working shop with lathe that can do the work for you. (I really don't think you want to attempt the chromed deck plate with any kind of hole saw.)

If you can show up at the boat with the teak pad and deck plate already pre-cut, the installation will go much more smoothly. As it is, you'll still need to cut the hole in the deck yourself, which will take years off your life.;)

On that, measure at least five times:D before pre-drilling a pilot hole from BELOW. Then come at it from above with the hole saw and pilot bit. Start off by running the drill in REVERSE with light/no pressure, until you've made a nice cut through the gelcoat and into the laminate a bit (this will prevent the hole saw from tearing up the deck gelcoat as you get started.). Then you can put the drill into forward and cut more aggressively.

Even still, take it slowly and let the hole saw and drill do the work -- don't put much pressure on it. It also helps to have a helper that can brace a piece of thin, flexible plywood against the underside of the deck where the hole saw will come through.

Good luck!

Photos of the installation will be eagerly appreciated.:)
 
#20 ·
Do you have access to a lathe... that'd be the simplest way to do it. You could also use the lathe to cut the hole in the winch pad. :D
 
#22 ·
If you have good access to the underside, once you've started the hole saw cut from above and made it about halfway through, if you finish by coming up from the interior, you can run the saw in reverse and then finish the hole saw cut without splintering the interior fiberglass.
 
#23 ·
That's a good suggestion.

In my case, I didn't have the greatest access due to the fabric headliner. So I came through from above, but if I recall correctly I reversed the drill again to cut through the final 1/16" or so.

By the way, MC1, be prepared for a bit of a surprise as you drill that hole through the coachroof deck. It's over an inch thick!!
 
#25 ·
Thanks again for the advice . . . you have rightly anticipated my terror about drilling that 3" hole in the deck, and I will take heed of the suggestions to minimize gelcoat damage, etc.. I was advised previously to smear peanut-butter thick epoxy around the hole to seal the deck (I'll do some practice runs on scrap first), so unless you say otherwise, I'll plan on that as well. I have the same problem with the headliner as you did JRP, but at least PSC in their infinite wisdom has installed a zipper its full length (both port and stbd sides). The hole will fall exactly centered on the port side zipper, so dealing with that will be yet one more fun detail to manage.

Since I don't have access to a lathe, I'll take the advice to have a shop cut the holes in the deck plate / winch pad - no sense risking botching up the job's critical steps after having gone to all this trouble.

If it comes out as nice as I envision it, I'll be sure to post some pics, otherwise I'll post some creative excuses. :)
 
#26 ·
If the deck is cored, I would highly recommend routing out the core material for at least 1/4" and then filling the gap between the two laminate layers with thickened epoxy instead of just coating it. Also, don't forget to properly pot the holes for any fasteners going through the cored section of the deck.
 
#27 ·
If you are worried about cutting into the wedge-shaped winch pad, get two of them. Stack them so one is rotated 180 degrees, so the net effect is no slanting at all. Use clamps or creative use of (stretched) electrical tape to keep them together and then drill like you are drilling through a regular block of wood.

You could also use a piece of (approximately correct) wedge-shaped wood instead of buying a second winch pad.

Haven't tried it, but it seems like a viable option.

Regards,
Brad
 
#29 ·
I think this has gotten very complicated.



I've sailed with mine in 10-foot waves, taking some over the deck. I've sailing in winter gales on the Bay and been anchored in up to 50 knots. Never a problem. Please see the instalation post:
Sail Delmarva: Let There be Heat!

As for the stack temperature, it is a double stack with heat exchange. The outer never goes above 160F and the exaust gas never goes above 285F, as checked with IR thermometer. Warm, but not even enough to scource the bird poop on the cap.

I built my own spray/rope deflector - the angles on the Newport unit were too steap for effective rope deflection - but otherwise I just copied them. No problems.

Is a cap needed to seal the unit? Could be done, but for 99% of us it's overkill. If I chose to, I would simply epoxy inverted bolts into the deck where the spray guard screws down. Easy.
 
#30 ·
Yes, I admit this may be overkill with respect to conditions I'm realistically likely to see. I'm being "religious" about maintaining a water-tight boat as a matter of principle. I've invested in a "blue water" boat, so I'm trying to make choices when adding equipment that preserve this character. Had this not been a high priority for me, I could have purchased a lot more boat for the same money going a different route altogether. Therefore, I'm planning for the worst (a capsize), and trying to ensure I don't have a 3" hole allowing a high volume of water ingress before the boat can right itself.

The approach the Sailnet team has designed here mimics the setup PSC has used for the dorade vents on my PSC 34 . . . I can unscrew the cowl vents and substitute a deck plate cover when the going gets tough (and seal off the vents from below as well). The challenge is only that I have to invent this capability myself for the heater's deck cap (hence my previous rant about why I can't just purchase this setup - like we can purchase cowl vents that have deck plate lids that can be swapped in place).

Your point is well taken though, and I can understand why many would choose to take a simpler route, which would be fine in all but the most extreme circumstances.
 
#31 ·
True enough. I have a Cat and worry more about satying right side up...

Yes, I admit this may be overkill with respect to conditions I'm realistically likely to see. I'm being "religious" about maintaining a water-tight boat as a matter of principle. I've invested in a "blue water" boat, so I'm trying to make choices when adding equipment that preserve this character. Had this not been a high priority for me, I could have purchased a lot more boat for the same money going a different route altogether. Therefore, I'm planning for the worst (a capsize), and trying to ensure I don't have a 3" hole allowing a high volume of water ingress before the boat can right itself.

The approach the Sailnet team has designed here mimics the setup PSC has used for the dorade vents on my PSC 34 . . . I can unscrew the cowl vents and substitute a deck plate cover when the going gets tough (and seal off the vents from below as well). The challenge is only that I have to invent this capability myself for the heater's deck cap (hence my previous rant about why I can't just purchase this setup - like we can purchase cowl vents that have deck plate lids that can be swapped in place).

Your point is well taken though, and I can understand why many would choose to take a simpler route, which would be fine in all but the most extreme circumstances.
...and trapping air upside down. For example, above waterline sink drains are trouble on a cat because they let the air out. I've added some valves where they are not required.

I have something in common, with a relatively small but very solid boat. My last boat was flimsy.

Still my comments about the relatively low temperatures of the pipe and about epoxying bolts in upside down are still valid, I think. The second reason I went lower profile on my guard was to reduce leverage when it is struck from the side.

Good luck!
 
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