42" Aeromarine Sprint Cat re-build

[millzee]

After a long time building this hull up with twin 1717's, I failed to set it up correctly and burnt out one of the speedo's. I think it had a lot of potential but I simply don't have the time or experience to root around getting it right as a twin so I have decided it'll be rebuilt into a single. My plan of attack is to strip out the hull, fill in the transom holes and start again. I'll leave the servo mount and battery and see how things pan out.
The new set up will be:
Castle 2028 780kv motor
Swordfish 300HV speedo
Octura X457 Prop
Nano Tech 65-130c 8s lipos
Speedmaster inline skeg style rudder assembly
1/4 " flex drive with 3/16" step down

I'm aiming for a boat that'll be fast enough to be fun, maybe a little wow factor and reasonable run times. Any and all advise is more than welcome.

Here's what I'm starting with



Here's the goodies, they arrived today, thanks Steve!!

[millzee]

Here's a few progress pic's, I'm waiting on the k&s tube to come so I can get into the rest of it. Is 10s stretching things a little?? I have 4s and 6s 65-130c 5000mah pack to make up either 10s1p 5000mah or even 102p 10000mah, what do you think???

[srislash]

Should get her going bid, go 8s to start then move up but 10s2p is a reasonable goal.

[Fluid]

Don't waste time with 8S, that motor is a great 10S motor and pulls props from x457 through x462 easily. Running 8S will require completely different props and will draw more amps than 10S will, so you'll have less run time and will stress the equipment more. A setup which works for 8S will have to be changed considerably going to 10S - prop, strut depth, CG, etc. What speed goals do you have? How much run time would you like?




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[millzee]

I'd like to see 60mph as a good speed and around 5 minutes runtime, what height do you think I should set up the strut for a 10s starting point with the 457 prop?

[photohoward1]

Never getting 60 and 5 minutes run time. More realistic is 60 and 3 minutes. Prop down and slow down to 50 and you could see 5 minutes. Any other thoughts guys?

[millzee]

I'd see a good chance of coming close. Suggested strut depth with the 457 anyone?

[oscarel]

1/4" to 3/8" up would be a guess. 3mins if constant full throttle, maybe 4mins sport. You really won't know till you get it together and run it. Lots of things to factor in.

[RandyatBBY]

I had one that I ran a Lehner 3040 8T on 10S I can not remember the prop, but I raced gas guys in the district. I had a blast, nice size boat handles well. Not in gas boats prop turbulence though, but a good boat for all electric competition.

I usually start with a 3/16 shim under the strut and the boat flat on the table.

[millzee]

Well after a little time I've put it all together, programmed the speedo and she's sitting ready for me to test drive. I had a little self doubt on the cap bank but with a little help I managed to figure it out. There should be plenty of room for me to adjust the COG and I've set it up around 29-30% for it's first test run. I'll run 10s2p and see how the electronics go.

[millzee]

[high-tech]

Nice boat, I think you would like an offset rudder bracket, and pitch that prop 3 deg. to the right and you can run straight rudder which means less drag... Ask around and you will find most others chime in on this

[millzee]

3 degrees up or down?, I'm a little unsure what your saying.

[srislash]

I think he is saying to the side to compensate for propwalk Danny.

[high-tech]

3 degrees to the right and yes that is compensation for propwalk, to do this either bend the strut brackets that attach to the transom or fabricate a shim that fits between the strut bracket and the boat.