First, let me admit I don't have direct experience using 'Slingbox Technology' but your question intrigued me, so I decided to do a bit of research. What I found was v-e-r-y interesting and made digging further fun. Here's what I found, but I'm going to pad my answer with a preamble to ensure anyone else reading this will understand what we're talking about. It's a good topic:

When you purchase TV service from your provider, the incoming content arrives at your home and you normally direct that incoming content to your television. When a Slingbox is placed between your service providers HD Receiver and your Television... the Slingbox provides an opportunity for you to 'pipe' the incoming content (back out to the internet) so it can be viewed elsewhere, rather than only at your TV. This is referred to as 'place-shifting'.

The place-shift destination (limited to just 1 place, but changeable) can be a computer in the next room, your smart-device while you're out-of-province, or more likely... one of the above devices, while you're aboard your boat – anywhere in the world. Note: The software on your computer, or an APP you load to your smart-device, acts as a remote-control to your service providers HD Channel selector. Therefore, since it's the 'at your home' HD device you are controlling... both the local Television (in your home) and your Place-Shifted device... are confined to watching the same content. (The HD Receiver box at your home needs to be ON. The 'at home' TV can be OFF.)

Recap: All the pieces and parts are together, and the connected Slingbox is communicating with a decent internet service you also have – in your home. You have downloaded the APP to your smart-device or set up your Laptop for browsing, etc, etc. That's the 'at home' end. Phew!

To continue:   You still need to have internet service accessible to your boat, and that brings us back to your question. The quality of the connection. Beyond getting really permanent at a Marina and having High-speed internet delivered by wire to your boat... there are three ways. Satellite (It exists. Had to mention it.) Cellular Tethering, and WIFI.

WIFI is the first and least expensive choice. But there's a caveat. The WIFI signal itself might appear to be excellent, but if a 5 bar signal strength AP you've connected to is being serviced by a LITE internet service... then you're experiencing an excellent connection to Low-Speed Internet. Also, if a hundred boats have connected to that same AP, then the LITE signal is being split in a hundred different pieces. Now, you're experiencing r-e-a-l-l-y slow internet. I don't want to rain on a sunny day... but one needs to understand WIFI might not always be what it appears to be.

Generally though... and keeping in mind the above, it's safe to assume WIFI means a workable data rate. Here is the potential of a good, High-speed connection: Consider that a modern AP with a true High-Speed source will re-provision that source at about 70mbps. If you are only dividing that up between 20 boats – you should have plenty enough for Slingbox place-shifting to be happy.

Cellular Tethering: A good 3g or 4g connection (usually 2mbps-6mbps) will provide enough speed to look after anything you want to do. ATTENTION: Make sure you have a decent data plan or you won't like your next invoice! Note: If your phone shifts away from 3g/4g and drops to 'EDGE' you will see a huge drop in data speed. To something less than 384kbps (HUGE). You need to keep an eye on that.

Finally – Slingbox's recommendations: To faithfully regenerate HD viewing... Slingbox is expecting 2mbps or higher at the place-shifted location. The good WIFI connection or solid 3g or 4g cellular connection will do this hands down – no problem.

All the above has been referencing HD viewing. If you opt for SD viewing... you only need 600kbps. Ahhh... now we're talking! 600Kbps! At this point, 600 seems so low it has me feeling like anything will work. But wait! There's more! Slingbox says it has a Mobile version and that one is only 250mbps. So... if the signal is so rough you can't feed it to your boats TV or Laptop in High or Standard Definition, I guess you could always shift to your PAD or simply view it on your Smartphone in mobile mode.

So now I'm back to my opening sentence... "I don't have direct experience using 'Slingbox Technology' but...” it looks to me like almost any kind of connection can be made to work if you're willing to accommodate the existing rate by downsizing your viewing pleasure to match what's available. This product looks cool Cameron. I didn't know it was 'out there' and intend to look into this further.

Comments anyone? Remember... this is just research. Not experience.

From another person who has no hands-on experience with this technology...

Capability of Routers:  The upload speed of a home router exceeds anything an average internet connection provides.  With that said... the new 'super' internet connections ISP's are offering present upload opportunities which are more within the modem & routers upper range but most people are simply not 'there'. Therefore, I don't think you need to worry too much about your router.  The stated upload speed of your internet service provider would be the criteria to watch.

So then, considering the average persons choice of internet connection - it's looking like HD place-shifting might best be kept within ones own home. Mobile version is a clear winner and SD version might possibly work off-site for many people.  However... there's always a twist, and this time it's a few internet posts like the one that follows:      "....the good news is that it works great even with limited bandwidth. I currently live with DSL which has a meager upload bandwidth of .75 Mbits/s. Surprisingly I can actually watch video from it with limited buffering at a quality that is better than standard definition. I still don't get HD but with upload that lame it's practically a miracle."

I'm going to have to keep my investment low and make an eBay purchase to test this myself.  :-)

I will be looking for a good quality image without any hieroglyphics or stuttering - delivered to an android tablet via tethering from an Android Smartphone.  As far as I'm concerned, it will be a 'win' if that comes together and it will be a huge 'win' if I'm able to redirect a nice image to our boats LED TV via the tablets HDMI port.  We currently do this for NetFix with great success.

One more comment I suppose:   Specifically choosing a lower than HD download at the place-shifted location (assuming you can) is going to lower your download costs, and extend the amount of time (within your data plan) that you can view (re: cel phone tethering.)

FYI: Just ran a speedtest here:    DL = 24.3mbps  UL = 2.4mbps

Cameron

Just a quick note. You're posting this question aboutt sling boxes in the electronics FOR SALE forum.

It belongs in the ELECTRONICS Discussion forum a bit lower in the forum list. 

cheers

Jean B moderator