36" rigger

[Boaterguy]

this Is posted on rc groups but I wanted to post it here after I got all the questions out of the way, and have a bit of a cleaner thread.
there is a picture of the tub (the riggers aren't built yet) next to a 2S 4000 lipo, it will not be used in the boat.
I have not decided whether to put in twin motors, a gas motor, or a single brushless. HELP!
more pics will be posted as building progresses

[Meniscus]

Welcome to the forum. Is this a scratch build or is it based off of a kit?

What's your ultimate goal for this build? Fun? All out speed? Turning?

What electronics do you currently have or is it all to be purchased? If you're purchasing everything, then do you have a budget you're working with? What are the local water conditions or the size of the pond you will be running in?

Sorry for so many questions, but this will help other users provide input regarding what you want to achieve on your budget.

[Boaterguy]

It is completely self made, no plans, kit, anything.
I do not own anything, and my budget is approx 350-500$
I want speed, but budget speed, I am not a SAW racer and I don't do 146mph. Maybe something like 60-70mph.
I have a lake with a 50 mph boat i can run alongside for testing, and then a few large ponds with banked edges (to let the water run back into the pond after it is all taken out) :)
edit- I have some experience building parts and can probably make some pieces

[Meniscus]

Good info.

Have you ever owned or held a rigger in your hands? There's a certain level of distribution of weight and angles that may mean the difference of never getting on plane (diving in the water) and having one that does the speeds you're trying to achieve. Another consideration is that once you go over 62-63mph, aerodynamics come into play, meaning that your tub or center section you've already built may generate too much lift and cause the boat to blow over at speed.

My best recommendation is to start with a proven design. Since you obviously have the interest and initiative to build, then plans will put you in the right direction.

Right now, one of the more popular riggers is the JAE http://ne-stuff.blogspot.com/. On this website, going down along the right side, you will see various plans. The original plans were for Nitro boats, but there are some simple modification discussed throughout this forum to adapt to Fast Electric (FE). These are very simple riggers to assemble and learn about the elements involved.

So far as parts, you can go to go to the shop here and find everything you need. The owner of this website and shop will be happy to help you with a parts list. This way you have a proven design that outperforms your expectations and will be something to either sell or continue to modify for more speed in the future.

[Boaterguy]

I actually based the tub partially on the JAE, I am going to shape the sponsons to create downward force, and will adapt other parts of the hull (hatches etc.) so that I don't get any blow overs. I also plan to make it a long, slender hull in order to minimize air lift.
I have planned out some components for a single drive (hardware, esc) but I still haven't decided what I will do for a drive system, any input would be appreciated.

[Boaterguy]

I think I will go with the fegiao 540XL 2779kv. If I run this on 6S i will get approx 60k rpm unloaded, the bearings are 50k rated. Is it safe seeing as the motor will be loaded therefore probably only spin about 50k? or should I upgrade to the 70k bearings?
also.. Prop suggestions?
I think I will run this on the turnigy 180A, will it be enough?

[wparsons]

You want about 1500-1600kv for 6s, the highest you want the RPM is 35k rpm unloaded.

A 540XL on 2800kv on 6s will draw A LOT of amps unless you run a very small prop. 36" is also a pretty big boat for a 540XL so you'll want to be on the safe side for kv and amp draw.

[Meniscus]

Brydon, I just recently ran a very, very high RPM setup for world record time trials. That setup was a throw away motor and the entire setup was fully expendable. The motor was 2779kv running on a 4s setup. The first thing to go is one of the magnets. When you throw a magnet in the motor, it causes it to lock. Then you have extreme heat and amps, most often will cook the ESC. I'm not saying it can't be done, but that is not the motor for it. Even then, it will be a one time run, SAWs only.

[Meniscus]

OK, so if you want to run a higher RPM setup, then you join a few of us with that mentality. I recommend 37-38K on the top end. With your budget and going with a Feigao, I'd try something around 35-36K unloaded range.

With a higher RPM setup, you benefit from running a lessor diameter prop which consequently means less prop walk. I'd have to think some before suggesting setups and there are certainly some here on the forum that more experience with the higher cell counts. Keep these things in mind as you formulate your setup.

[Ub Hauled]

OK, so if you want to run a higher RPM setup, then you join a few of us with that mentality.

yup!!!

[Simon.O.]

OK, so if you want to run a higher RPM setup, then you join a few of us with that mentality. I recommend 37-38K on the top end.

Why is it that when ever high rpm is mentioned that I get to gather with these guys Jan and Ben
I'm here and I'll play !

2800kv 540-XL I would happily run 4S to some of my props and in a moment of madness run it on 5S,........ but 6S is just a RC smoke bomb on the water.

[Boaterguy]

first off, Meniscus, how do you know my name??!?
I understand what you are saying, and will lower the KV or cell count a little bit, once all the math is done.

[Boaterguy]

so, If I go with the 1600 on 6S, I get 37k unloaded, That seems fine.

[Meniscus]

I saw your name in your profile under about me. I was debating calling you boater, or guy and decided I'd just go through the trouble to lookup your name.

[Simon.O.]

Brydon....Your name is in your profile and Ben like me is polite and like to address folk by name, where provided.

You could lower the Kv with a different motor or lower the cell count. It all depends on what you have available and what you are keen to spend.

For me. I like high cell count and low Kv to keep the Amps (the killing bit) down. That said I still shoot for high rpm. It may not be right but it works for me.