Jeff posted some excellent points that I can only agree with.

rob wrote:
> I'm hoping to provide 2x Load Balanced 8 Mbps adsl lines with a router that
> can carry out the load balancing. This would give a user more bandwidth than
> they would get on thier own ADSL line (providing that not many users are
> online at any one time)

Bandwidth is a misused term (like when I was sitting in on a meeting and a
manager said a buy didn't have enough bandwidth to do the job, i.e. his
plate was too full)...bonding or aggregating two 4 Mbps DSL lines won't
give a single user an 8 Mbps internet backbone connection, but it will give
two users a full 4 Mbps connection.

Jeff's estimates are in line. A 1.5 Mbps (DSL or T1) will comfortably
support 100 home users in the evening(peak residential load time) assuming
there is only one computer at each residence. Since most businesses close
at five PM, your capacity opens up some. A 1.5 Mbps connection might
support as many as twenty or more businesses as their profile of usage
does not appear as intense as a home user (from what wee have observed),
but then each business has multiple computers.

Some WISPs have a monthly download data limit of like 5 Gig and others
have a daily cap at 200 Meg (and then their connection drops to dialup
speeds for 24 hours). We have both limits in place - although are
considering dropping that to only 100 Meg/24 hours, but still allow
two or three occurrences per month two of a 200 Meg download to allow for
service pack updates.

A good Acceptable Use Policy would prohibit running servers and
peer-to-peer connections...but how are you going to enforce a policy?
That's why the daily and monthly bandwidth limits are in place. Give
them enough slack as to not cripple your network and shut them down
(well, cut back their access speed) when they do.

> They would also get the benifit that they would no longer have to purchase
> broadband and could in theory get rid of thier phone lines. This would make
> this alternative an attractive one. My target is users who live on
> houseboats in a marina. There would be distinct advantages from being free
> from a copper line. They would have access when they have to move thier
> boats. They could save money if they don;t pay for broadband and a phone
> line.

Encouraging VoIP is going to really knock your connection down. I don't
recall the study off the top of my head, but with optimum encoding a T1
can support twenty VoIP calls. Some users around here have dropped their
copper dialtone and use cellphones. But the real problem is when people
start using VoIP for international calls - they tend to stay on the line
for hours on end EVERY NIGHT. They will take advantage of a free service
at YOUR expense!

> I've only looked into this because friends of mine live in the marina and
> they would like wireless internet.
>
> I would like to think that I could deliver a reliable service and that the
> customers could actually save a bit of money in the process. Surely this is
> not a bad thing in the long run??

The selling point isn't so much of saving money, its the fact that they can
even get a high speed connection.

As Jeff mentioned about after hour service calls. What happens when someone
moves their boat and their directional antenna points in the wrong
direction? How easy will it be for you to find their new slip location? Are
you going to climb up their mast in the dark? That's why an omni antenna is
better, plus the signal won't fade (as much) when the boat rocks in the
waves.