Deadlight Bedding deja vu redux

[tikvah59]

I've been frustrated for years with the deadlights (fixed ports) on my Triton. As anyone with similarly-constructed ports will tell you, they are not easy to install so that they don't leak. Especially (in my opinion) if you use silicone as recommended.

A recent Good Old Boat article discussed the use of double-sided foam adhesive tape made by 3M. They call the tape VHB for Very High Bond. The author of the article used the tape to install his ports and was pleased with the results. I used nearly the same tape (3M part number 5962) as described in the article, although the tape I was able to find in stock locally (http://www.btctape.com) was 1" wide, which worked out fine for me.

First I had to remove the ports and frames. They came off fairly easily. Even though I had tried twice to install the deadlights, I think I may not have used enough sealant both times. I also saw that the silicone did not adhere real well to the acrylic port lenses, but I guess silicone typically does not bond strongly to the acrylic.





I brought the lenses and frames home and used Digesil from RPM Technologies to chemically remove all traces of the silicone - or so I hoped!



I used both a brush and a putty knife to apply the Digesil gel. I used the gel on the sides of the cabin where the deadlights were installed. After letting it sit for a while, I washed the Digesil off and cleaned the frames up using a grinder with a wire wheel.



Next I'll have pix of the process of applying the tape and reinstalling the deadlights.

Mark

[Figment]

How long ago did you do the silicone?

[Rachel]

This is really interesting to me. I have thought about using VHB tape to install windows -- and from my reading of the technical literature it is resistant even to submersion -- but what I couldn't work out in my mind was how one would seal the "joints" between pieces of tape, presuming one could not run a single piece around the full perimeter of the port/window. (I was going to try it on my camper first and the windows are square so I would have to use four pieces of tape.)

I did find where people had used VHB tape on boat windows, but they used it in conjunction with sealant ("structural" silicone in the case I read about). Ironically, that person's conclusion was that the silicone itself would have been fine (and apparently many have used just that) and that his use of the VHB was probably overkill (however, he was putting on "overlapping" plastic port lenses, so not exactly the same as framed ports).

So... are you using VHB only? And are you able to use one piece all the way around so there are no joints? If not, how are you treating the joints?

Although I was thinking of trying the VHB on my camper windows/skylight, I was figuring I would stick with tube butyl for the boat. That said, my interest is piqued.

Rachel

PS: Here is a link to the article I referred to, in case anyone is interested in reading it:

http://www.thecoastalpassage.com/windows.html

[tikvah59]

How long ago did you do the silicone?

First time: about 6 years ago
Second time: maybe a year later?

They leaked both times - admittedly, due in part to my inexperience.

Mark

[tikvah59]

So... are you using VHB only? And are you able to use one piece all the way around so there are no joints? If not, how are you treating the joints?

Rachel,

Although 3M claims this is their most "conformable" tape, I could not get it to stretch/bend around corners. I did have to have seams. The 5962 tape is 62 mils thick, so I was hoping that I could get it to squeeze together to fill those small gaps. I can't see in to the "glue joint" but I did get the frames tight enough to get the tape to squeeze out some around the edges. So, I'm optimistic that those tiny gaps got filled as the tape smushed together! If not we'll need to consider plan B, whatever that is . . .

Mark

[tikvah59]

I should have mentioned: I've installed the newly-rebedded deadlights on the starboard side, and they apparently made it through Tropical Storm Irene without leaking.

Mark

[sscoll]

Timely discussion for my purposes, thanks. Are you going to treat the frames you've wire brushed clean? Looking forward to the next set of pics.
Steve

[tikvah59]

Timely discussion for my purposes, thanks. Are you going to treat the frames you've wire brushed clean? Looking forward to the next set of pics.
Steve

Here's the process I used with the second set of frames (from the port side): physically remove as much silicone as I could (mat knife, scraper, etc), treat them with Digesil, blast them with water, do a little light scrubbing and then use a household spray cleaner. For these frames I only used the wire wheel on the exterior (non-glue) side, and mostly for appearance purposes.

Hopefully I can find time to do an update this weekend . . .

Mark

[barrybrown]

Mark,

Just out of curiosity, have you considered butyl tape. When I did the deadlights on this boat I used some Velux butyl cord that was laying around the shop
it was difficult to work with but has been water tight. If I were to do it again I would use butyl tape, the kind sold by 'Mainesail' on this site. I bought some from him
and have become increasingly fond of it and it seems well suited for the deadlights.

Barry

[Rachel]

Along the same lines, another option is butyl caulk in a tube. This is not to discount the tape, as I have used both at different times.

(I think that Tikvah has probably settled on VHB tape, but since we are mentioning alternatives to the Devil known as silicone....)

The interesting thing about the VHB tape is that it can potentially eliminate the need for mechanical fasteners.

[tikvah59]

Just out of curiosity, have you considered butyl tape. When I did the deadlights on this boat I used some Velux butyl cord that was laying around the shop
it was difficult to work with but has been water tight. If I were to do it again I would use butyl tape, the kind sold by 'Mainesail' on this site.

Hi Barry,

I discover Mainesail's butyl tape very recently; I just rebedded some stanchions with it today. However, I had already bought and started using the more expensive 3M tape on the deadlights, so I decided to carry on with it through the project. Having used both, here's what I think:

- The 3M tape is much easier to layout and trim. The backing tape stays on until you want it to come off, unlike my experience with butyl.
- One thing about the 3M tape that made installation of the ports much smoother was it's tenacious grip. I could install the outside frame and it would stay there while I lined up the inside frame with the acrylic window already installed.
- The 3M tape goes on with a very uniform thickness, which I found difficult to achieve with the butyl.
- Even so, had I run across it sooner I would have been very tempted to use the butyl tape because I know I could take the deadlights apart again if needed.

Rachel - I've tried butyl caulk in the past, but I wasn't impressed. I think I need to find a source for butyl caulk formulated for marine use.

Mark

[Rachel]

I've tried butyl caulk in the past, but I wasn't impressed. I think I need to find a source for butyl caulk formulated for marine use.

I don't think there is such a beast. Meaning that I think butyl caulk is just... butyl caulk. Likewise, I believe the butyl tape that Maine Sail sells is "just" a good-quality butyl tape (vs. a marine-specific item). I'm not sure what made him start carrying it, but one guess is that it can be a bit hard to find certain brands/sizes in small quantities. I have managed, but it took a bit of hunting (too bad, as it used to be more common in lots of places - glass/roofing/etc.). I first used it on a camper - it's quite commonly used on them and sold at RV places (although you have to watch out for non-butyl putty tape).

None of this is to take away from butyl caulk or tape though -- I think it's fantastic stuff and doesn't need to be "marine." In fact, don't tell "them" as I like it costing $5 a roll ;)

I'm curious: what was it about the butyl caulk that did not impress you?

Another question: with the VHB tape, did you eliminate (any of) the fasteners?

Rachel

[tikvah59]

Deadlights part 2

Taping the frames

I meant to write at the beginning of this project log that I have never purchased any quantity of 3M 5200. I am very grateful to the previous owners of my boat that they did not use any such “permanent” adhesives, making it possible for me to take apart just about the entire boat! Of course, if I was joining a deck and a hull, 5200 would seem to be a great product for making sure the hull-deck joint was securely fastened.

So I was a little reluctant to use a product that was advertised as a replacement for mechanical fasteners and was deemed “Very High Bond.” I think this tape has a lot going for it, but I’m a little worried that if I ever need to get this stuff apart, it might not go well. Let’s hope that doesn’t happen!

Once I cleaned up the bronze frames I applied tape to both of the mating surfaces on in the inside and outside frames. Each frame has a surface that mates to the cutout in the cabin wall (I don’t have a headliner FYI) and another surface which mates to the acrylic deadlight lens (or pane, not sure of the exact term?). The tape I bought was 1″ wide, and I only needed it to be around 3/8″ wide. For the long straight sections I could lay out a piece of tape, cut off the excess width, and then apply the excess piece to the other, parallel mating surface. Even then there was a bit left over which I need to trim.

I used a retractable mat knife to cut the tape. As in most cases, a sharp blade works the best. This tape is very stretchy so if you don’t have a sharp blade at the right angle you have to saw through it a bit. But with a little practice you can make nice clean cuts – just like scissors through wrapping paper, if you know what I mean. I put wax paper under the frames while applying the tape so the tape would be less likely to stick when I dropped it.

I thought I might be able to get the tape to follow the curves of the frame, but it was easier to just cut the curves into the tape. I’d press the tape onto the section of frame, and then trim both sides to conform to the curve. With a little planning I cut apply the tape to the outer surface (mates to the cabin wall) and use the excess on the inner surface. I did my best to keep the joints tight between pieces of tape. I was hoping that when I installed the frames and tightened them down the tape would squeeze out of the edges and into the tiny joints as well. It also helps that the tape likes to stick to itself, so the joints are that much more likely to meld together.

Next: installing the frames (not too many pictures, though!)

Mark

[tikvah59]

Mark...

Great info, thanks for sharing! Out of curiosity how much do your port lite frames "bear" on the face of the fiberglass cabin trunk sides??

Glenn

Glenn,

I don't have the frames here - I just finished installing them this weekend. I'd estimate something around 3/8".

Mark

[tikvah59]

I'm curious: what was it about the butyl caulk that did not impress you?

Another question: with the VHB tape, did you eliminate (any of) the fasteners?

Rachel

When I used butyl around my opening ports it seemed to degrade fairly quickly in the sun and picked up a lot of dirt. So it went from white to greyish and was pretty dry and looks like it might crack. Maybe underneath it's fine, or maybe it just doesn't want to be exposed.

I didn't eliminate any fasteners, but I am happy that I'm now much less reliant on those little screws that grab maybe 3/16" of thread in the portlight frames. Once I pulled the frames in tight to the cabin wall I was confident that I could take out the screws if I wanted. As I mentioned elsewhere the bond of the tape also made installation easier.

Mark

[Rachel]

I bonded the interior liner to the cabin trunk with epoxy/1708 and then laid in 1708 to build the opening up so now the frames have full bearing with about a 1/16" overall clearance.

I apologize if this is too much of a side-track, but would you mind explaining your sequence in building up these areas? I'm familiar with filling gaps with thickened epoxy, and also with using some sort of waxed board or etc. to "widen" a fiberglass edge; but I still can't quite visualize how you filled the gap with both epoxy and biax, and then after that still added on the new cloth to make an extension. I might be missing something obvious!

Thanks,
Rachel

PS: Tikvah: Thanks for answering my questions.

[ILikeRust]

I re-bedded the leaking fixed port lights in my 1968 Pearson Wanderer - the aluminum frames seem to be pretty much identical to yours. I used butyl tape and thus far it's working like a charm. Time will tell...

I bought the butyl tape from an RV parts and supply place - as recommended by Maine Sail. As I recall, a 50-foot roll cost me something like eight bucks. I've used it on a deck hatch, the port lights and one or two other bits of deck hardware, and I plan on using it to re-bed a few other bits of leaking deck hardware. The stuff just seems to work.

[Rachel]

would you mind explaining your sequence in building up these areas?

I'll start a new thread in "Projects".

Glenn

Thanks!

New thread:

viewtopic.php?f=37&t=5680

[Tallystick]

The deadlights on my Triton are stripped to the bronze and polished nicely. I'm preparing to bed the new plexi windows into the frames and attach to the boat. Some of the threads are stripped however, and I don't know how successful I'll be in retapping them. Would it be appropriate in this case to use 5200 since the adhesion would be useful? I understand removal could be a huge pain, but I think I may have already experienced that (and could handle it again) when I removed them initially, as the white compound that was used required significant razer blade work and prying to remove them.

[ILikeRust]

I would not use 5200. Removal would not just be "a huge pain," it might well be impossible without destroying something.

Worse comes to worst, you might consider through-bolting with a countersunk flat or oval screw head on the outside, if it's that bad. Or just carefully drilling and tapping for the next size screw.

[Tallystick]

Agreed on the bottoming tap, and I had already purchased a 10-24 for that purpose. Even after chasing the threads with the bottoming tap, the screws only can be turned two full rotations before bottoming out.

I worry that doesn't provide sufficient holding strength, although a quick search turns up that the bolt tensile strength and thread stripping strengths are balanced when the nut thickness(t) is .47 times the bolt diameter(d), t=.47d. For 10-24 fasteners, the d is .19 inches with 24 threads per inch. So two rotations is two threads engaged with each thread equal to .0416 inches, which is .083 inches of engagement. Assuming the yield strength of the bronze frame threads and bronze screw threads are equal, using the formula above .19*.43 is .0893 inches of engagement for the thread strengths to balance, it appears that only two threads of engagement may be sufficient. However, I'd suspect the yield strength of the cast bronze is lower than my silicon bronze screws, so they would likely strip the frame threads before the screws yield.

At this point I'm thinking of either using 4200, or possibly through-bolting, although this will be a blue water cruising boat, and I don't like the idea of having exposed exterior fasteners that may encourage theft/break-ins at ports (possibly overblown concern?). Another possibility may be to braze in some studs, and use cap nuts on the interior. I'd seriously consider that route, except I can't locate 10-24 bronze cap nuts anywhere.

[ILikeRust]

If it's a blue-water cruiser, maybe it would be better to put in some more "serious" ports? Just replace those old aluminum-frame jobs altogether, with something a bit sturdier and better at keeping the sea on the outside? Just a thought...

I'm not as concerned about mine, since I have no plans ever to leave the Bay and local environs with this boat. I have zero plans to ever go into open water - except to the extent that crossing the Chesapeake, or maybe Pamlico Sound, can be considered "open water"...

[Triton106]

TallyStick,

James Baldwin also drilled through his port frames several years ago to improve Atom's large port window strength and to stop leaks.

I use to place heavy plywood shutters over Atom's cabin windows before each offshore passage because I worried about their strength.

Several years ago I removed the cabin windows and replaced them with 10 mm lexan. But first, when I had the frames out, I sealed the gap between cabin top and cabin liner with thickened epoxy. I did this to stop future leaks as well as to build up the width of the cabin side for the thicker windows to fit properly in their frames. The bolt holes on the inside of the frames were then drilled through the outside of the frames so that they could be thru-bolted. I countersunk the holes on the outside of the frames and inserted flathead 6 mm machine screws with cap nuts on the inside. These windows are very strong and I don't carry those awkward shutters anymore.

The frames that I recently purchased from Tim are also drilled through. I don't think the frames are as attractive when through bolted but if you intend to do some blue water cruising someday I would not have it any other way. I am also working on installing the new to me bronze frames. Please post pictures of you project when you have a chance.

Ray

[Tallystick]

Where can I obtain replacement swing bolts? I'm talking about the rod ends that latch the small opening ports.

[Tallystick]

I ended up bedding the PMMA windows into the outer frame with 5200, and bedding the outer frame to the cabin also with 5200. I used threaded rods with washers and nuts to hold the frames in place and together while the 5200 cured. To prevent the inner frame from sticking to the outer frame, I coated the inner frame with mold release (90% mineral spirits, 10% vaseline), although I was careful enough applying the 5200 there wasn't adhesive squeezed onto the inner frame. Once the 5200 cured for around 4 days, I removed the inner frames, and used additional 5200 to enhance the seal between the frame and cabin.

For bedding the inner frame I used butyl caulk from McMaster-Carr. They have lots of colors and I chose bronze thinking it would match, but I probably should have used grey.

Here are some photos. I still have to trim the excess caulk once it finishes curing.