We have finally installed sun-blocking window film on FPB 78-1 Cochise, and the results are excellent.
Cochise was launched without window film. We knew that it would eventually be required, but wanted to get a handle on what level of protection would be appropriate after some real world cruising experience. Obviously the FPB 78s have a substantial expanse of glass, more than any other FPB to date (in scale), so there was never any question we would need some form of film. Even in New Zealand winter, during sea trials, we would routinely find it necessary to reduce heat load by dropping the cellular window coverings.
After much deliberation we chose EIR window film by V-Kool. This material uses silver particles embedded in the film to reflect the heat (as compared to the 3M ceramic films we have used in the past which block the heat). The negative is that the silver does attenuate cell phone and GPS signals. In the photo above, you can see the difference between the unfilmed window in the middle and the ones on either side, with the film added.
We used VK 40 on the side windows, VK70 on the forward windows, and nothing aft. The film was supplied and installed by V-Kool of Florida.
There are all sorts of numbers about light transmission, heat rejection, and selectivity. It is hard to know what these mean in the real world, but after a few weeks of experience here is what we can tell you:
- The film works so well that we did not have to use the cellular window shades to keep the boat cool in Southern Florida in early March.
- There is no problem seeing small boat lights when on watch looking forward at night.
- The reduced reflectivity is very helpful with the FPB 78 outward slanted windows at night. There is less glare from overhead lighting and instrumentation.
- Cell phone signal attenuation is definitely a factor. Signal strength showing four bars becomes two bars when inside the great room. The Matrix deck is less of an issue as the opening windows, doors, and aft enclosure do not have film.
During the day the window film also provides a touch of privacy. More important, we like the look of the darkened bands of glass.
Posted by Steve Dashew (March 29, 2017)
March 29th, 2017 at 5:48 pm
Would you mind discussing why you chose to go with the silver based film, as opposed to, for example, the 3M ceramic based film mentioned in the post? Would the ceramic films not have a negative effect on cell reception?
April 3rd, 2017 at 2:27 pm
Hi Aaron:
The 3M ceramic films we have used in the past are a heat barrier, and so the glass becomes very warm. The EIR silver particle film reflects the heat so the glass stays cool.
March 30th, 2017 at 8:13 am
Might just be the picture, (or my aging eyes) but the difference on that internal shot looking out hardly seems noticeable…even side by side. The darker windows outside sure do look nice tho =)
So with the cellphone issue…would you go with ceramic if you had it to do over?
April 3rd, 2017 at 2:25 pm
Hi Gene:
No, we were aware of the signal attenuation beforehand, and think that the EIR film results make the cell call issue worth dealing with.
March 30th, 2017 at 8:16 am
I forgot to ask. Have you researched the electrically tintable (sp?) window coverings? You can go from almost clear to almost black out and back and I have seen some recently that apply just like a typical window film. The only possible downside–other than cost–is that the transition can take several minutes.
April 3rd, 2017 at 2:22 pm
Hi Gene:
Last time we checked was a year ago.
April 1st, 2017 at 12:06 am
Hey Steve, are you trying out a new set of “flopped stoppers”? These seem more like a bucket than the old ones. Anthony.
April 3rd, 2017 at 2:21 pm
Hi Anthony:
Good eye to catch that. Those are bags of saltwater we are using for transverse trim control at anchor.
April 2nd, 2017 at 8:42 am
Hi, further to the glazing used on the FPB’s, was the use of double glazing considered? With double glazing the conduction heat gain would reduce by 2/3 and with the use of low-e films etc the solar heat gain probably be less than the films can achieve.
April 3rd, 2017 at 2:20 pm
Hi Marco:
Window structure is a long discussion. For now, the side windows on the FPB 78s are two layers of special glass with three inter-layers of plastic sandwiched, the sum of which is enormously strong. Our concern is with impact rather than globally applied loads. We need the structure of these elements together rather than with a air void which is more efficient, but would be very heavy to have both structure and insulating value.