Would you like to have a cell phone booster kit that enables voice, data and SMS connections up to 20 miles offshore for coastal and waterway vessels? How about using it with up to 5 cell phones or USB cell modems for voice, data, and SMS with powerful amplification outdoors, and also seamless re-broadcasting of the cellular connection belowdecks? Sound good? 
With the GMN cell booster bundle you can be connected where others cannot.
In summer of 2015 we used this powerful technology on our trawler Bliss while completing a 2,500 mile East Coast trip from Annapolis to Acadia National Park and back. It made a tremendous difference in the quality of our communications and now we want to share some important information about the technology with you so you can experience the same ease of voice, data and SMS cell communications for your coastal cruising experience. 
This is what we have on our 40' pilot house trawler Bliss.
1. WeBoost 4G-X
2. Shakespeare 5239 Broadband antenna
3. 18' LMR 400 + 6' LMR 240 pigtail between the WeBoost and 5239.
Proper Installation is Key
The system worked very well indeed and depends on proper installation. Our record so far is having good 4G connectivity 21 nautical miles offshore during a passage between Gloucester and Province Town, MA. We also had very good ATT coverage while cruising Maine this summer with 20mbps LTE speeds in the islands south of Deer Isle.
Important Things to Know about the Antennas The booster has 2 antennas. One below decks and one above. The amplifier boosts signals arriving through the external antenna up to 60% and retransmits the signal through the below deck antenna. 
Here I am working on the internet underway thanks to the cell phone booster and the below deck antenna seen in the left hand corner next to the phone.
So here is the first important thing to note. The range of the below deck antenna varies based on the externally received signal strength! So.. the stronger the external ambient signal the longer the range of the below deck antenna. So... in weak signal situations your phone must be closer to the below deck antenna to get amplification. The stronger the signal the further away you can be from the antenna. For best results its best to keep your devices within 5' or even 1' from the below deck antenna. The External antenna should be located a minimum of 15' feet away from the below deck antenna and preferably directly above. This is very important. The problem with this type of setup is that when the external ambient signal is fairly strong the below deck antenna range transmits with more power which can cause interference (i.e. cross talk) with the external antenna. When this happens the weboost automatically decreases the amplification of the signal to reduce the cross talk. This condition exhibits itself as a blinking red light for the affected band. The reduce amplification results in reduced performance. If the two antennas are mounted close together or on the same horizontal plane then your system will not perform as expected since cross talk between the antennas will be difficult to prevent.
What happens if I'm close to a cell phone tower? The other thing to note is that if you are close to cell tower the weboost may shut down a channel altogether to prevent interference at the cell phone tower. 
Cell phone towers are rare on pristine remote islands, but Block Island has an obtrusive one.
The shut down condition is indicated by a solid red light. This condition is not really an error (although the manual is very unclear about the significance of blinking and solid red lights). It just means that the Weboost is too close to a cell tower and amplifying the signal would cause interference. Being too close to a tower may also result in blinking red lights. At first I thought this was being caused by cross talk between the internal and external antenna but it is not. Its just the Weboost reducing the gain to prevent saturation of the remote tower. So... if your ambient signal strength is strong then you should not use the booster since there is no need for it. Only turn it on when the signal strength on your phone is weak (i.e. 0/1 or 2 bars out of 5).
Where should you install the cell booster antenna?
Given the above the best place to install the external antenna is the top of the mast. Note that for most boats this means a long run of 50' or more. It is critical to use low loss coax for this installation. The larger the signal loss in the cable the poorer the performance of the amplifier. Use LMR 400 or bigger cable. Note that this cable is quite stiff and of large diameter. So a pigtail will be required to get an SMA connector attached to it and into the weboost. Note that you should not mount your masthead VHF antenna adjacent the Cell antenna. Although the transmission frequencies are quite different between the two the Cell antenna will impact the performance of the VHF antenna since it will occlude a large area creating a blind spot. Also... there could be interference caused by transmitted waves being bounced back. On Bliss I have my mast head VHF antenna on a stand off providing 18" separation between the two antennas.
Watch a video about antenna placement.
The following video by Dave Skolnick has a good discussion on antenna placement. The video is focused on WiFi but also applies here. Bottom line... if you have good vertical separation between the antennas and you have red lights then chances are you don't need the booster because the ambient signal strength is strong enough to use directly without the booster.
No set up required.
One of the really nice thing about this booster is that there is no setup required. Other boosters of this type in the market place (such as the Shakespeare Halo system not to be confused with the RedPort WiFi Halo) have two gain controls. One for the external antenna and one for the below deck antenna. The gain on these systems must be adjusted correctly for optimum performance. Few of them have auto gain capabilities which can cause problems with saturation of the shore station. This is particularly true of the in building type amplifiers which are designed for fixed locations. The automatic gain control of the Weboost removes these installation worries. There is nothing to tune or adjust. Just locate the antennas property and power on. 
Simple is good for cell booster usage in a gorgeous coastal cruising anchorage.
Other things to know...
When the ambient signal strength is 1 or 2 bars we typically see 4-5 bars on the phone when the amplifier is on and all lights are green. The amplification will be less or none if the booster has reduced power or shut down due to strong external ambient signal strength (see discussion above). The Weboost marine antenna is ** NOT ** a broadband 4G/LTE antenna. You will get very poor performance out of this antenna. I put mine in the dumpster in Camden Maine... Buy either the 5239 or the Digital Antenna. I have owned both and the performance in my experience when comparing the two very similar. Note that I did not do extensive testing... Just did a signal strength check comparing the two in SW harbor maine. I like the construction quality of the Shakespeare much better and decided to go with it instead of the Digital... The price between the two is quite comparable in the low $100's range. Early versions of the WeBoost were shipped with a 12V power supply in error. The booster runs on 6V! When running under 12V the booster gets very hot and eventually shuts down. One of the very nice things about this booster is that it works with all carriers in the US and Canda. It is a multi-band amplifier so it will probably work in other countries as well. Weboost states that its for US/Canda use. Not sure if this is a regulatory issue or if there are technical reasons why this booster won't work in other countries. It would be good if someone using this booster outside the US could comment. The booster works with multiple devices for voice, data, and SMS. This is nice since most boats have more than one Cell phone on board. We often put our cell phones in hotspot mode and tether our computers to them via WiFi to access the internet. To make things simpler for boaters the GMN cell booster bundle includes the Weboost 4-GX with the Shakespeare antenna and either 10 or 20m coax with appropriate pigtail.
