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Old 31-03-2013, 05:35   #1
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Converting to opening ports

I have been reading an interesting thread on CSF on replacing fixed ports. I have a related problem - I have fixed "plexiglass windows" bolted and sealed to a steel cabin side that is slightly curved fore to aft. I want to add opening ports to get more ventilation in the cabin, but the four 8 x 18" rectangular openings do not match the size of any available opening portlights. I am thinking of mounting opening portlights on new plexiglass or starboard frames, attaching the frames to the cabin side just the way folks are recommending for fixed ports in the related thread. Large stainless opening ports would then be mounted in these new frames. A second layer of plexiglass could be added on the inside to strengthen the assembly if the port design allows. To deal with the curvature of the cabin side (about a quarter of an inch over a 20 inch fore/aft run) I was thinking of using starboard and routing the inner surface to match the curvature of the cabin, leaving the outer surface on which the port would mount perfectly flat. The resulting frames would be bolted and sealed to the cabin side just like the original fixed ports. But starboard may be more difficult to seal to the cabin side, so would the same procedure work on acrylic/plexiglass, and would I get a better seal? Can I paint the plexiglass to match the cabin side?

Final note - I don't want to just weld new steel onto the cabin side to get the correct size cutout for opening ports as it would require ripping out the cabin interior to repaint after welding. But if the system above proves to be a bad idea, that is my alternative.

Comments and advice?
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Old 31-03-2013, 13:00   #2
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Re: Converting to opening ports

A bit hard to visualise what you intend - a Pic would help!

But if I am reading right then basically you are intending to put in a blank (of starboard or plexiglass) and then fitting the new windows into those.

Unfortunately I am also not sure if those materials would be any good - my gut shares your doubts! As I assume these will be bolted on why not instead use steel blanks? (bolted not welded) - and maybe with wood (epoxy coated) simply to deal with the curvature issue for the new opening ports.
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Old 01-04-2013, 09:34   #3
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Re: Converting to opening ports

No pics available - I'm in Costa Rica and the boat is on the hard in Florida right now. But I think you understand the issues correctly. Your recommendation of steel blanks bolted on doesn't deal with the curvature issue - but I could use wood/acryllic/starboard shaped to deal with the curvature, with a steel plate on top. Are you thinking that the steel is essential for strength in this sandwich configuration? I.e., steel plate with shaped wood/acryllic/starboard underneath between the steel plate and the steel cabin side, ports mounted through all of that. Is the extra strength of adding the steel top plate worth the hassle and expense? As noted in the original post, I have room on the inside of the cabin to add a reinforcing layer of wood/acryllic/starboard due 1 1/2 inch vertical frames to which the cabin sides are welded.
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Old 01-04-2013, 10:10   #4
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Re: Converting to opening ports

Quote:
Originally Posted by PaulSommers View Post
No pics available - I'm in Costa Rica and the boat is on the hard in Florida right now. But I think you understand the issues correctly.
Shame, as pics might encourage a few others to chip in. I am also not entirely sure what I am seeing in my mind is what you are seeing on your boat!

Quote:
Your recommendation of steel blanks bolted on doesn't deal with the curvature issue - but I could use wood/acryllic/starboard shaped to deal with the curvature, with a steel plate on top. Are you thinking that the steel is essential for strength in this sandwich configuration? I.e., steel plate with shaped wood/acryllic/starboard underneath between the steel plate and the steel cabin side, ports mounted through all of that. Is the extra strength of adding the steel top plate worth the hassle and expense? As noted in the original post, I have room on the inside of the cabin to add a reinforcing layer of wood/acryllic/starboard due 1 1/2 inch vertical frames to which the cabin sides are welded.
I was thinking Steel Blanks bolted on that would follow the curvature of the cabin sides (bend courtesy of a hammer?!). Basically a solid steel window pane ......and into that you cut the hole for the new ports.......and under the new ports (and ontop of the steel blank) you make a frame / moulding / packing (out of wood or starboard or maybe even epoxy - or steel?!) to deal with the curvature issue.

Whilst I don't think steel is essential for strength, my feeling is that plexiglass or acrlyic alone to bolt the new ports onto won't be good enough, for leaks over time if nothing else - and I only mentioned steel because it is a steel boat! I would personally be way more comfortable working in wood or even fibreglass to create a blank - but that due only to familiarity.

Obviously I am shooting in the dark here!, and I left my comfort zone on my post #1 .
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Old 01-04-2013, 16:16   #5
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Re: Converting to opening ports

Unfortunately I did not think of taking a closeup picture of the project sites before leaving for home (Costa Rica) and I won't go back to the boat until next January when I want to start this project. I think I have succeeded in attaching an old photo of the starboard side of the boat, showing a small opening port cut into the plexiglass aft window - the builder managed to install this tiny opening port over the galley stove. My hope is to put in four larger ports, as big as I can get into the four rectangular openings. You are recommending the opposite of the sandwich I was thinking of - your rec. is port/filler frame to accommodate the curvature/steel forced to follow curvature (by just bolting it down with a sealer between it and the steel cabin side. I was thinking port/flat steel sheet thru bolted through filler and cabin side (using existing bolt holes). It may not make much difference which way the sandwich is made up. Either way I have to shape the same pieces of wood or acryllic to follow the curvature. The only other possibility and I don't know who to ask is that the sealing gaskets that come with the portlights will take care of the curvature and I can just mount the ports on the slightly bent steel frames that would replace the existing plexiglass fixed ports. The curvature is only about 1/8 or 1/4 inch over a 22 inch fore/aft run (the length of the plexiglass windows now mounted onto the side of the cabin). They don't leak and neither does the small opening portlight mounted in a cutout in the starboard aft window. So I might get away without the shaped filler board we have been talking about. Is there a chandlery you could recommend who might have staff who actually know how much variation from a completely flat surface one can accommodate with just the gasket compensating for the curvature?

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Old 01-04-2013, 19:07   #6
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Re: Converting to opening ports

I would consider using G10 fiberglass sheets for the adapters. Adhesives don't stick well to plexi or poly, but the G10 is at least as strong, and bonds with epoxy. You could make up several layers and fill with conventional epoxy/glass to build up the curve, or use a grinder to make them conform better, and then bed them bed with something permanent like 3M 5200. A couple of layers of (presumably) white epoxy paint or topsides paint, and you should have a bristol job of it. And since the thermal expansion should be closer to your hull material than plexi would be, there should be less movement as well.
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Old 02-04-2013, 03:01   #7
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Re: Converting to opening ports

Nice looking boat.

I wouldn't say my previous comments were a "recomendation"! - more simply trying to kick out a few ideas......

Ok, I see what you are talking about - I would still not use starboard or Acrylic as the "blank" - either steel or fibreglass sheets, with the "filler" (under the straight "blank") for the curvature made out of epoxy and wood (and through which the bolts for the "blank" go into the existing holes) and the new opening port bolted simply to the flat "blank" (if the blank is beefy enough I don't think will need any reinforcement behind to hold the new opening port in place).

My feeling is that trying to accomadate any curvature with a gasket would make the result prone to leaks - I think better to stick with flat on flat for that seal.


Also, have you thought about replacing the round portholes with opening versions? Photo a little unclear, but also seems a bit short of deck vents. What about putting a hatch (or 2!) into the cabin top (heat likes to rise) - don't have to be full size hatches, indeed for security reasons useful not to be.....obviously not a 5 minute job!, but using wood frames and fibreglass might be able to get away without any welding.

Late thought! - appreciate that you probably can't get a new opening port that exactly fits the existing hole (at least not off the shelf), but instead of fitting as per the photo what about getting something that fits at least one dimension (or as close as) - either height or width and bolting through the cabin sides. The idea being that at some point you may fancy getting the welder out to fill in the existing hole so you can recut to an exact fit (obviously will still need a "filler" to cope with the curvature).
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Old 02-04-2013, 06:22   #8
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Re: Converting to opening ports

Thanks for the ideas, guys. The G10 sounds like the material of choice and I will see how close I can get to the existing cutouts. So far though I haven't found anything that will work with the existing dimensions in either direction. Most opening ports are substantially smaller than these cutouts. As for custom built, New Found Metals could do that but the price would probably be breathtaking. Does anyone else build portlights to custom sizes? As for hatches on the cabin top, yep, thought about that but we put the inflatable dinghy up there when underway so there would not be any air flow except when anchored and dinghy in water. In the Caribbean, leaving the dinghy in the water at night is asking for trouble, so I have been working on portlight ideas rather than hatches.
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Old 02-04-2013, 07:48   #9
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Re: Converting to opening ports

Paul, since the hull is steel (I missed that before) and you are considering a slightly smaller port, I suppose you *could* just as easily have someone weld in a flat plate, and then use a grinder to sculpt the edges of it, to transition from the curve of the hull to the flat of the plate, so the port was set in a flat piece. Depending on size and location, I'd ask the welder about whether they should weld in the new piece before or after cutting out the matching hole to install the new port, to make sure the new metal stayed flat and didn't warp from the work.

Or they might say they can grind down a flat spot on the hull, and then lap in some flat plate on the inside or out, if need be, to put the thickness back.

Somewhere...there's somebody who can do the job for you with the grace of a sculptor, not just welding up plate. In western WA there's just got to be.
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Old 03-04-2013, 07:05   #10
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Re: Converting to opening ports

Another interesting idea - I'll look for someone who can do metal work. The boat is in No. Florida and there is a large boatyard next door to the DIY place where I have the boat stored right now so maybe this is something the next door yard can tackle. I trying to find a solution that does not involve ripping out the interior to deal with the after effects of welding, but I have not talked to a metal work in FL so see what is possible and that is certainly a good thing to do before committing to a course of action.
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Old 03-04-2013, 08:54   #11
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Re: Converting to opening ports

Having worked with some different guys before...there are those who are geniuses at pipefitting or wrought iron fences, and those who can make stainless look like one-piece origami. Sometimes you just need to find the guy whose skill set matches the job. Might even be a guy from an auto body shop, who is used to using a grinder and making curves match up.

I hear that the oil platform companies won't hire a pipe welder unless he's got ten years of experience, because "simple" pipe welding is that hard to get right. Hmmm...
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Old 03-04-2013, 09:28   #12
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Re: Converting to opening ports

Why not just add some overhead hatches?
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