Window coverings will play a more important role in the new FPB 78, given our goal of staying cool at anchor a majority of the time without a genset. This post is about the factors affecting the window covering decision, after which we’d love to have suggestions from SetSailors.
To begin with, we are loathe to compromise the view or the wonderful open feeling that comes from living with 360 degree views.
OK, this is still very cool looking, and certainly does not lack for visual space. But we want to feel like a part of the surroundings, not isolated.
Obviously the most efficient situation in terms of heat load is to totally cover this enormous expanse of window. However, the highest heat load comes from direct sunlight, so we will get the biggest benefit and the least cost in view with partial extension of the shades.
Which leads to using just the area of window coverings between us and the direct sun load.
There is also the privacy question to be considered. There are times in port and at anchor when a bit of privacy is warranted. This dock in the heart of Tromso, Norway, is a good example. Wind Horse was the object of much attention and discussion, and we met many wonderful Norwegians while waiting to head out to Svalbard. But we also needed a bit of privacy, and still wanted to preserve as much open space as possible. The answer was to use our window awnings in conjunction with the vertical weather cloths on the lifelines.
With the FPB 78, we have the window awning effectively built-in with the roof overhang. The higher freeboard means that in most cases someone standing on the dock, or looking from another yacht, will not be able to see beyond mid-window height. Which leads us to consideration of the top down, bottom up style of window coverings.
The following factors are part of the decision making matrix:
- There is space above the headliner panel edges–of as much as 6″/150mm–and a depth from glass face to headliner panel of up to 5″/125mm in which to store headrail and window covering when not in use.
- Given the large quantity of windows to cover, powered shades, if reliable, would seem a good idea.
- Maximum R value is worth having for when the boat is in storage, or when we leave for an afternoon and drop the shades–so we have less of a heat blast when we open the door on return at the end of the day.
- Room darkening is necessary for high latitude summers.
- Hardware reliability is essential.
- A top down, bottom up configuration would be nice, as long as this does not introduce other potential problems.
- Fixed rigging (strings) that run top to bottom and are always in view are not acceptable.
Our personal experience with window treatments is limited. We’d appreciate suggestions on types of window covering systems to consider, and your experience with same. We look forward to your comments.
Posted by Steve Dashew (October 18, 2013)
October 18th, 2013 at 3:26 pm
Based on residential use only, no experience with forces on a boat dropping into a trough, I see cellular shades as the best option. They provide insulating value and can be fully room darkening or block strong sunlight while still allowing some light through. Without having exposed cords or built in tracks you are not going to top down/bottom up or just bottom up units. You have to have some support for bottom up operation. Assuming you are looking at only rectangular windows, there is no practical way to install at the A-frame except with corded bottom up unit for full privacy closure. For top down units you can have power driven units or the hand operated, inertia reel types. For electrically powered operation you can go to individual unit or group unit controls, operated by user control, timer or even light level. As stated you have plenty of room for the shade to retract out of sight at fully up position. The slope of the glass will allow the shades to rest on the glass and prevent any swinging caused by normal boat motions. A fully automated, whole house system with light level control and manual over ride system allowing individual unit control on multiple large windows in a friend’s contemporary home has been operating for a number of years with no problems.
October 18th, 2013 at 3:31 pm
You might want to visit a local air traffic control tower and see how the shades mount in the cab (up in a nice pocket). They often use a double shade. They typically use a manual roller though electric do exist and seem to run fine. The manual have a single string under a lot of tension so it should keep things pretty quiet at anchor.
Low e-glass will really cut down the heat load. The air traffic control towers are starting to use low e-glass and it has made a huge difference in heat load. The next step would be insulated glass. The problem of fogging is now repairable by drilling a small hole in the glass and washing out the moisture with a special solution.
October 18th, 2013 at 4:20 pm
Thanks Kent-great suggestion. We will see if the local ATC guys will give us a tour.
October 18th, 2013 at 7:35 pm
Steve,
Also check out what they might use in commercial airline cockpits. Looks to be about the same deal as I’ve seen in towers. They do might a big difference.
Michael
October 18th, 2013 at 4:45 pm
As mentioned in the air traffic control example, a lot has happened in glass technology. It may be benificial to talk with one or more of the high tech glass manufacturers who supply window material for high rise buildings. Those windows need to be very tough and insulative against high and low temeratures.
(This is an edited version of my original comment, please delete the original and substitute this, also deleting this comment)
October 18th, 2013 at 7:51 pm
What about having external welded louvres on the top quarter or so of the side windows. Each louvre to be at a different angle. An angle which presents little more than the louvre’s edge to someone standing on the centreline of the boat. The angling would have to be a compromise between your and your wife’s eye height so it would not be perfect but I think it would be worth working out.
October 20th, 2013 at 3:47 am
We want to preserve the view, so fixed louvers are not an option.
October 19th, 2013 at 4:53 pm
You might check out the wikipedia entry for smart glass that can electrically completely control its transmissive properties of light, heat and u/v radiation. You will find it here: http://en.wikipedia.org/wiki/Smart_glass
With so much glass you are otherwise in danger of creating a very large greenhouse, for which conventional blinds/shutters would eventually be something of a pain to manage, especially when they get stuck as they always do. Such hi-tech glass would be expensive I expect but save you money on energy for air conditioning. I believe you will need such a hi-tech approach and it is already proven technology.
October 19th, 2013 at 7:31 pm
Have you considered window quilts? Although designed for residential use, they do have great light blocking capabilities, as well as good thermal insulation, I believe you can get them with manual or automatic raise / lower mechanisms. We’ve had them in our house(s) for about 30 years and never had any problems … They are raised and lowered every day, and all we do is give them an annual lube. All synthetic, nothing to rot/mildew.
Been following your site for many years, thank you for sharing your design and thought processes, it’s a real pleasure to read!
October 19th, 2013 at 9:08 pm
Couple of thoughts: as an airline pilot myself I can tell you that the windows in the cockpits of airliners have other design parameters in mind, namely the prevention of ice accumulating in icing condition, as well as impact resistance should a bird be encountered in flight. Both goals are accomplished by heating elements (usually utilizing gold, so the windows themselves are VERY expensive) sandwiched between two or more layers. The heat boat prevents ice from forming and decreases the brittleness of the windows by keeping them warm while ambient temperatures at altitude can be much colder than sea level. The temperature inside the cockpit, and indeed the entire aircraft, is handled by jet powered air conditioning. We do have sun shades available to us, but the specifics of those are going to be unique to each type of aircraft. In the airplane I’m currently on we have a clear, tinted plastic panel mounted on a track above the cockpit windows. We can loosen a tensioner that holds the panel to the track and reposition it anywhere we’d like.
No doubt ATC towers have really interesting shades (and I’ve been in none or two) and the windows themselves probably have some interesting treatments the primary function of the windows on a FPB are handling the loads imposed by any water or debris impact, so unless Steve & Co have found some window treatments that they like and think will last in the marine environment I think the windows of the FPB will most likely stay with the thick safety glass that has been used in the past.
Having spent three years in total on the road in the United States on a high end tour bus I can tell you that we had these day/night shades that were mounted on these tensioned strings. They’re a pretty common RV accoutrement that worked quite well for us, although retensioning them was a bit of a pain. With a little bit of engineering the basic concept would work well on an FPB allowing for both shades coming down from the top, as well as coming up from the bottom using one set of shades. They’re are electric versions as well but I don’t have any experience with those.
Lastly, if you wanted some shades for the irregular shaped windows in the front of the Great Room I’ve seen aircraft shades for irregularly shaped windows that work quite well. They’re essentially like old school spring loaded curtains, except the material is custom cut to fit the triangular or trapezoidal hole it’s filling, and you have a hook that you attach the material to while the spring loaded design keeps tension on the material to cover whatever hole you’re covering. So looking at the triangular window at the front of the FPB78, you’d have a spring loaded window shade at the bottom of the window, which you’d manually pull up and attach to a hook at the apex of the window.
Hope some of those ideas help.
October 20th, 2013 at 9:49 am
I think your main problem is that internal blinds are simply not very good at keeping out heat. Any air between the blind and the glass quickly heats up turning the window into a convection heater. With your sloping windows a smooth reflective layer resting directly on the glass might reduce the effect but wont stop the glass itself heating up. Power driven bottom up blinds without cords or guides would need something like a scissor lift or perhaps an inflatable blind. And could only work on sloping windows like yours. I doubt anyone makes them.
If external blinds are ruled out by your operating conditions and you want a clean bottom up option then I agree with Clive that smart-glass is potentially the best bet. You could have the glass divided into (say) three operating sections allowing you to dim the panels in a way which mimics bottom up/top down blinds.
Boeing use smart-glass on the Dreamliner instead of conventional blinds. So must have passed some stringent functional/reliability tests.
October 20th, 2013 at 5:13 pm
Many of our modern air-conditioned local railway carriages are equipped with roller blinds. For each window the blind’s horizontal shaft is out of sight behind the wall panel above the window. The roller blind’s sides are not guided by strings but by extruded sections/tracks at the window’s vertical edges. You pull down the roller blinds by hand, and they stay put where you release them. – That arrangement looks very smart. (On my next trip to Hamburg I could make a few photos – also of a carriage’s type plate with the manufacturer’s name – and send them to you.)
Being operated by passengers who are not always kind to public property, such an arrangement has to be very tough, indeed. As far as I can judge, the design and execution really stand the test of time. So far I have not seen yet a single roller not functioning or worse, having been ripped apart.
Ok, the above design only allows to shade a window from the top down. But I think if you talk to the designers they will come up with good ideas to work the system in both vertical directions. And I can imagine that instead of utilising roller blinds, you can have pleated shades (for which operation in both vertical directions is standard). This is the more interesting as there are chamber type blinds (manufacturers here call them honeycomb pleated shades) which have better insulation properties than standard blinds, and which can almost completely darken a room. This link gives you some idea how it looks like: http://www.plissee-experte.de/duo-4001 (sorry, German language only). Other manufacturers offer the same type of shade.
About manual or powered operation: Even in manual mode you will probably be much faster than rigging window awnings as you did in Norway.
October 21st, 2013 at 1:52 am
Hi Steve
look at http://en.wikipedia.org/wiki/Smart_glass – can this be a solution for you?
October 21st, 2013 at 3:31 am
I’d split the question into 2 parts: privacy & shades. For privacy I’d use one way mirrow glass. Or tinted glass like you have it with cars. This also helps a little for them control & shades. Additionally I’d use simple manual plissees with 2 parts, so that you can adjust them just as required. If at anchor, I’d use external shades, which could be clipped onto the deckhouse and fixed with lines to the rails.
October 21st, 2013 at 11:33 am
Switchable LCD smart glass from smarttint comes as a trimmable film, applied to the windows you can turn the opaqueness on and off at the flick of a switch, not sure of it’s R value though.
October 22nd, 2013 at 3:41 am
Some obvious observations.
The most effective way to reduce the heat load is outside of the windows, doing it inside always means more heat that has to be removed. There are nice mesh systems like Renson Fixscreen, the look of the vertical rails may be an issue but the big problem is mechanics vs. salt water.
Shading on the inside traps quite a bit heat between glass and shade which then continues to seep into the interior. It would be nice to directly remove the hottest air, between glass and shade shade, instead of heating the room fist but that wont happen unless there is already air ducting in place. – Say for defogging which you IIRC do by reducing humidity via the AC.
For a system without visible strings and the size of the windows, I’d guess roller blinds with guide rails are one of the options. Since this is on the inside the rails should be quite narrow and hidden by the trim for the most part. This also means that the sheet can extend into the rails which eliminates light leaks. In manual systems (Say in trains as mentioned above which may have have top-down or bottom-up systems) friction keeps the blind in position, spring force keeps the sheet tensioned. Automated systems usually use a weighted bar to tension the sheet, the motor keeps the position via gear friction. Another, more complex, way is to use cables to automatically position the blind and use spring force to tension tension it. The advantage is that the bar does not have to be weighted and can be smaller, it is also pretty much the only option to do automated bottom-up systems.
October 22nd, 2013 at 7:06 am
The outward cant of the FPB 78 windows will allow shades to lie direct on the glass. Using triple cell honeycomb, with a reflective layer on the outside, will give us significant heat reduction, if we choose to go this route.
April 27th, 2014 at 11:58 pm
would it not be possible to allow small vents at the top of the windows to remove hot air as it moves up behind the blinds of your choice?
April 29th, 2014 at 1:27 pm
Window vents are an interesting idea. But for our service probably no appropriate since they are a potential leak point in heavy weather.
October 22nd, 2013 at 3:48 pm
Steve,
I have used Mecho Shades on projects such as schools, hospitals, condos, and an art museum. The shades can be either a manual or electric operated unit (push button or remote control). They come in a variety of colors and the opacity can be specified. On the FPB you could have two sets per window. One set could be a blackout shade. The second shade could have an opacity (10% to 90%) which would let you see out through them, but provide privacy (depending on interior/exterior lighting).
I am in the Pacific NW, but I see on their website there is a dealer in Phoenix. http://www.mechoshade.com/manualshades/
November 7th, 2013 at 11:30 pm
steve,
I am planning to have some 3M Crystalline clear tint film installed on our pilot house windows. the specs are impressive regarding this film’s heat rejection (IR) and UV protection, while still transmitting a very high amount of visible light. might be worth a look…
November 10th, 2013 at 11:17 am
Thanks Brian: Looks like the next generation from 3M (we have been using a 3M non-metallic film for the past eigth years).
December 4th, 2013 at 7:55 pm
SAGE electronically tintable glass would make for a fantastic solution: http://sageglass.com/
It has an excellent dynamic range with fully automatic or manual controls and very low 12V power consumption. High strength tempered laminated glass can be incorporated. With power off, it has a high visible light transmittance (VLT) of 60% and a Solar heat gain coefficient (SHGC) of 0.41. Intermediate tint state 1 has VLT 18%, SHGC of 0.15.Intermediate tint state 2 has VLT 6% and SHGC 0.10. Fully tinted VLT is 1% and SHGC a remarkable 0.09. U value is a constant 0.28 Btu. Damage weighted transmittance (measure of fading)is a very low 15% in the clear state and 0.6% tinted. Total UV transmittance is a max 0.4%. It is not a privacy glass so at night at the dock for privacy, a light open weave blinds could be deployed. SAGE can do all the heavy lifting required in managing glare, Solar loads and maximizing occupant comforts.
December 5th, 2013 at 10:45 pm
Interesting looking product, Brian:
How long has it been commercially available in the marine industry?
December 10th, 2013 at 10:44 pm
Hi Steve,
Thanks for your response. SAGE is a great solution for the question you put in this post.
I have worked in the high rise Architectural glass industry for 35 years and this is a bit like the holy grail.
SAGE was a start up company based in Minnesota for quite a few years developing the technology, and last year it was purchased by one of the worlds largest glass/ building materials Companies, Saint Gobain.
We have used SAGE on 3 small projects here in Melbourne, Australia and are about to re-glaze our office in it. Other than the privacy at night when at dock issue, it really has all that you need: A high light transmittance which can be electronically tinted to give excellent glare and Solar heat gain control as and when needed, with uninterrupted views from inside. As to using it in a marine environment, It is only available as a hermetically sealed Insulating glass unit, so your framing rebate would have to be thicker and you must allow the rebate to be drained to the outside with pressure equalizing design principles. These are well known in the window glazing industry. The outdoor glass is always laminated with SGP (Sentry guard plus) Ionoplast inter-layer and the out door glass can be 12mm tempered which I think is what you use now for structural loads.
Cheers
Brian
December 11th, 2013 at 10:33 am
We’ll give this a look later, but double pane glass is tough to do in a seagoing environment.