Sorry Skid, believe you may have meant:
100km? !!! 
Make sure you take an EPIRB and a mobile phone in a waterproof bag that floats when you drop it overboard.
Good luck to you macro,
I have to agree with the weight issues, might be a bit on the heavy side. but at least someone out there is willing to try something, and not sitting at home doing nothing but ditching someone ideas.
Go for it Macro, but get an EPIRB:http://www.ebay.com.au/itm/EPIRB-MT400-by-GME-406-MHz-6-Year-plus-battery-life-/120580561805?pt=AU_Boat_Parts_Accessories&hash=item1c13295b8d&_uhb=1
it will save your life and anyone elses if there is an issue.
good luck with it. A hydra's hull's would be very easy to push so I don't think you will need as much power as you think. I used to have a 20 foot windrush cat and the little 2.5hp suzuki pushed it up to hull speed allmost as well as a 5hp but heaps quiter and lighter. I would stick with the rudders for turning and have the motor fixed. Dont know how comfortable it would sitting on a 16 foot cat for 200km though.
if $ are no problem, Torqeedo motors are really good as far as electrics go. have seen them pushing 30ft river boats.
post some pics of what you come up with
nev
what would work is a pressure differential device
where by a higher pressure is captured by the craft and creates an opposing lower pressure that draws upon the higher pressure in an effort to create equilibrium and hence moves the entire craft forward...
report of the progress in work
- I need to get the trailer registered, Just checking lights and there is something surprising : two lights on one side and only one on another. Is is legal ? Or I need to fix it first before trying to register ?? The previous owner claim that is was registered just like that 
-I found the easy way to attach outboard motor without any modification to the boat itself. Just smart and cheap attachment made old $20 trolley
Should be good enough for experiments
I hope to get on the water this week. Hulls seems to be in good condition, beside one soft spot at the rear, looks like somebody make some repairs to fibreglass.
I wonder if there is any way to access to the inside of the hull trough this blue top panels. Beside repair this soft spot there could be perfect space inside the hulls for battery bank. Not sure about petrol tank 
Re: the trailer lights, I think it varies from state to state. Some states require two tail/brake lights on trailers, others require only one. (that was from talking with a trailer maker some years ago in SA, may be different now)
I did first run with my modified catamaran last week.
At first with 6HP Suzuki outboard. Because is brand new I was allowed to run it only at 50-70% revolution.
I am quite impress with speed and efficiency. GPS reading shown around 17 km/h max and average fuel consumption was below 1 litre an hour for whole trip.
Whole trip take about one hour and half. Then I had still petrol in 1.5L internal tank.
First test is quite encouraging and the goal was met.
Propeller was at right depth most of the time.
I heard that to higher speed I may need to replace propeller with different pitch.
Is it right ?
Now I could prepare a bit stronger frame instead of my very rudimentary engine mount.
I started work today with purchase of new MIG welder to construct proper frame, but
possibly I made some mistake.
I bought UNI-MIG 180 but after unpacking realized that item that suppose to be new product was already returned to the shop and half of the items missing (gas valve including ! ).
Anybody could advice on good and cheap MIG welder for mild steel ?
up to $500 ?
IN the meantime I took to pieces my 48V lithium battery and will try to rebuild as 24V to match my 24 v electric outboard 1.1kW.
That will be very interesting to find out what speed we could achieve with that one
46 feet difference in the height i dont understand that. It would seem that you had your craft on the trailer towing it around and the gps recording,
, so to me, your figures are loopy, i,e, suspect.
i dont understand that. It would seem that you had your craft on the trailer towing it around and the gps recording,, so to me, your figures are loopy, i,e, suspect.
The old one was already 50 years old when I needed to replace it.
You could look around the model shops. Electric planes and helicopters have gotten bigger and bigger over the last ten years so there must be some big chargers and battery management systems to suit some big batteries for them.
Unfortunately, model shop stuff gets a bit pricey when the models get bigger.
Charge voltage per cell should stop at 4.2 volts exactly. Any more and the cell is damaged,. permanently.
Any less won't damage the cell but the charge capacity drops off rapidly below 4.2 volts.
Without a good balance system you are wasting your time and it's probably dangerous.
Don't blow yourself up.
I estimate with the electric you should get 4-7kmph Max - If you are using 1300mah batts I would not imagine more than 5mins max. In series (not sure about LiFe batts) would be needed.
I have boated many times in the Broadwater, there is a fair current through their - your elec setup has around 3.5kw less power (that is alot).
Would hate to see you on the news ha
Can the esc in the elect motor handle the c rating of the batts?
Water = very bad news for Lipo and LiFe. Big bang in little boat.
Personally I would have purchased an old Js440 or Js550 jetski, lightweight and I had to tow a Nacra near Horizon Shores Marina with my 550 I had at the time. At approx 25ktns the guy started screaming at me to slow down - took me a while to hear him, ah ha ha.. Check the net Macro some-one fitted a pod to a 16ft Hobbie.
