[Rhodes22-list] Window replacement update

Wed Jun 3 01:12:37 EDT 2015

Great info for the list Graham.  This is a project I will need to do before
I leave the states.

On Tue, Jun 2, 2015 at 8:51 AM, The Rhodes 22 Email List <
rhodes22-list at rhodes22.org> wrote:

> Nice write up Graham but I must be missing a sentence or an email or
> something.
>
> If you are going to have Lexan windows, why paint them? I read the
> part about "to make sure that the grey tape and white sides of the
> cabin did not show through" but if you are painting the whole window
> why use Lexan at all? Or can you still see out through the paint? do
> the windows let light in?
>
> I'm confused.
>
> Mary Lou
> 1991 R22 Fretless
> (recycled 1998)
> still on the hard
> but just about ready
> to splash for the season
> in Rock Hall, MD
>
>
>
> At 11:16 AM 6/2/2015, you wrote:
> >For those who are interested in replacing cabin ports with acrylic
> >panels, I thought I would bring you up to date on my highly
> >scientific experiments using the method of attaching windows without
> >using any hardware.
> >
> >My experiments were intended to demonstrate for me the strength of a
> >joint using Dow Corning silicone # 795 and 3M brand tape VHB 4991
> >and the paint I intended to use to coat the inside of the acrylic panel.
> >
> >First, I joined some pieces of Lexan I had using the tape and the
> >sealant and let it sit for 48 hours for the sealant to cure. At  48
> >hours the sealant is about 90% cured but it continues to cure for 72
> >hours. I couldn't wait that long. I attached a small piece of lexan
> >(about 1.5" x 3") to a larger piece at a corner. I messed up the
> >sealant with the result that I got some on top of the tape - which
> >seems like a distinct possibility when I do the large panels so I
> >was curious to see what effect that had. By leaving the smaller
> >piece extending beyond the larger piece I had a tab that I could use
> >to peal the pieces apart. I have attached a picture of what I call
> >the "flex test".
> >
> >By holding the main piece down and lifting up on the tab I was able
> >to bend the panels far beyond any curvature on the cabin side of the
> >boat without any sign of the joint letting g. Also. the joint had
> >enough flex that the panels could move past each other slightly to
> >allow for a nice even bend. When I bent the joint to the maximum the
> >lexan broke (see photo) before any sign that the joint was
> >weakening. Lexan is very flexible and strong so that seemed to me to
> >be a good sign although I should note that the Lexan was only 3/16"
> >thick. I figure that if I can't break the join even on small pieces
> >without destroying the Lexan, that has to be a very strong and flexible
> joint.
> >
> >As an aside, the sealant has a useful life of one year. When I
> >ordered mine it was already 8 months old and expired in March 2015.
> >I called 3M last fall to see if there was any way to extend the life
> >of the material. The technical support person told me to seal it up
> >in plastic and put it in my freezer - which I did. He then told me
> >to test it before using it by laying out a bead and letting it sit
> >for 3 hours. If it skinned over, it was good but if it stayed wet it
> >will never cure - even though it looks fine coming out of the tube.
> >I Had thought that old material would harden in the tube so that was
> >potentially very useful to know. I have read online where others
> >complained that this sealant never cured and I expect they were
> >using material that was too old. In my case it appears the freezing
> >worked as the sealant cured up nicely.
> >
> >Although the acrylic panels I am using are dark tinted, I wanted to
> >make sure that the grey tape and white sides of the cabin did not
> >show through so I needed to find a suitable paint to coat the
> >inside. I wanted something that would adhere tenaciously to acrylic
> >so that in turn the tape and sealant would adhere to the paint. I
> >also wanted something that would apply by spray to give a perfectly
> >even coat and preferably was fast drying. Articles I read advised
> >using engine exhaust paint. The particular types suggested were not
> >available locally and a ridiculous price to order by mail across the
> >Canada/US border. Also I noticed that application instructions for
> >similar paints available locally specified that it dries easily but
> >does not cure until it is brought up to a high heat. That , of
> >course , is not going to happen with acrylic so I was left wondering
> >how it would work in an uncured state.
> >
> >I experimented with a number of paints - especially paints that are
> >intended for plastic. The first time I did this in 1995 I used some
> >sort of enamel that subsequently pealed of even though it was
> >between the Lexan and the cabin side. It was thick, soft and had
> >poor adhesion with Lexan. So I wanted something better than that.  I
> >noticed that the paints I was testing went on thick and took a long
> >time to dry. They also scratched off too easily for my liking. I
> >then tried some barbeque paint that I had. The paint is intended for
> >high heat applications but had a maximum temperature of 600 degrees
> >- which is much lower than the exhaust paint but still much higher
> >than anything the boat will ever face before I am jumping overboard
> >and it does not require heat to cure. It also sprays on beautifully
> >in thin coats, dries to touch in a few minutes - no dust problems -
> >and can be recoated several time within an hour. That meant that I
> >could apply multiple thin and even coats. It give!
> >  s a satin finish rather than high gloss which I thought might make
> > a better surface for the tape to adhere to. I first painted pieces
> > of Lexan and clear acrylic and let it sit for about 3 months to see
> > if there was any indication of incompatibility between the paint
> > and the plastic. There was no sign of incompatibility that I could see.
> >
> >I tested the adhesion of the paint by trying to scratch it off soon
> >after application and after several months and by applying a variety
> >of tapes - duct tape and packing tape, house wrap tape etc, - and
> >then peal it back both while the paint was fresh and after the tape
> >had been in place for several months. As the flex test shows I also
> >tried adhesion with the double-sided tape and, as noted, the lexan
> >broke before the seal showed any sign of letting go. I also applied
> >sealant, let it cure , and tried to remove it by pealing it back.
> >The "paint test" is shown in an attached picture. It shows packing
> >tape that had been left in place for several months. The tape was
> >firmly attached but came off cleanly leaving the paint firmly
> >attached to the Lexan. Scratching the paint with a sharp object left
> >a scratch, of course,  but did not remove any of the surrounding
> >paint. So I think this is a good paint for this application.
> >
> >To prepare the windows, I cut the acrylic panels from a 1/8" plywood
> >template, routed a slight bevel on the outside edges, laid out where
> >the opening in the cabin were, made a template for consistent
> >openings made out of Formica (which works well because it is thin
> >and hard) and then cut the protective paper around what will be the
> >openings using the template and exacto knife. I then removed all the
> >protective covering except where the openings will be and painted
> >the pieces with four thin coats of barbeque paint. I have attached a
> >photo of the painted pieces.
> >
> >After the acrylic is attached to the boat I will remove the masking
> >tape on the outside of the acrylic panes, the tape on the cabin
> >sides and remove the protective paper from the outside of the panels
> >and the inside of the open part.  I tested whether I would be able
> >to peel off the inside sections once it had been painted over
> >especially given that it will be difficult to raise an edge once the
> >panels are installed. I found that if I apply a strip of packing
> >tape to the covering paper leaving the end folded over so I can grab
> >it, when I peal it back the tape holds sufficiently to raise the
> >protective paper cleanly avoiding the need to scratch up an edge.
> >Hopefully that works in the real life situation. I would hate to
> >have acrylic panels permanently attached with paper coving the
> >opening that I can't remove.
> >
> >So I have chosen all the materials and tested them as best I can for
> >suitability. I have also worked out a temporary clamping system to
> >hold the panels in place while the tape and sealant cure. That might
> >be unnecessary but given the curve of the cabin I don't want to take
> >a chance on that part. I have masked the boat around the edge of the
> >acrylic and sanded the paint on the cabin side so that is flat ,
> >smooth but dulled (220 grit). Now all that is left is to attach the
> >actual panels and frankly that is what worries me most. While online
> >instructions suggest applying the tape and sealant to the panel and
> >then apply the panel to the boat, my thinking is that because the
> >cabin side is a compound curve I would be better to apply the tape
> >and sealant to the cabin and then press the panel into place.
> >
> >Time matters. I don't have forever to apply the sealant and remove
> >the tape cover before pressing the panel on and worse still, I only
> >get one chance to get the panel in the exact location. There is
> >really no room for error. I have "rehearsed" placing the panel with
> >my wife but that was without any of the tape or sealant. The cabin
> >side has a moulded in edge at both the bottom and the aft end that
> >are very helpful guides but one still need to make sure from the
> >moment of first touch that everything is aligned perfectly so that
> >the rest will wrap into place exactly where it is supposed to be. My
> >hope is that I can rest the bottom edge and aft corner against the
> >little raised edge first and then wrap the piece up into place at the top.
> >
> >If anyone has any clever ideas about how I could make the process
> >idiot proof I would be forever grateful.  The idea of having to use
> >a chisel and grinder to remove the misaligned panels has no appeal
> >to me at this juncture. I think I will need a very good shot of
> >Rummy's Mont Gay medicine to calm my nerves first.
> >
> >
> >Graham
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