Build Advice Wanted - Large Mono

[rickwess]

It's getting time to start working on the 54" Dumas Scarab I picked up last fall.

DSC_0965.jpg DSC_0967.jpg DSC_0972.jpg

Length: 54"
Transom Width: 14"
Transom Height: 5.75"
Weight: 4.5 kg

The orange just isn't doing it for me so I've called the shop that built my ski boat and they'll spray the boat with white gel-coat. I'll just have to smooth the seems with a vinyl ester filler to make sure the gel will stick. Not sure what I'm doing after that in terms of graphics. Perhaps get Jeff to make up some vintage Scarab graphics.

As you can see, I do have the fiberglass hatch, but it will need some work to fix what the previous owner did to try and strengthen it (just added layer after layer of epoxy), then strengthen it properly S-glass or core mat). I'll probably have more gel sprayed on it as well to cover up some of the spider cracks.

I'm not looking for anything crazy in terms of speeds, keep it more scale. My preference would be a large single motor on 8s, but I don't know it that's realistic or not.

I'm also looking for recommendations on the hardware hanging off the back.

Any and all advice would be appreciated as I have absolutely no experience with something this size.

[Doby]

http://forums.offshoreelectrics.com/...879#post605879

[srislash]

You can build your own hatch Rick. And where the heck you gonna run that big boy?

[rickwess]

http://forums.offshoreelectrics.com/...879#post605879

I saw that thread and since it was a tunnel, I figured it would be different. I was looking at the TP5670 which would be a comparable motor. Would 8s not be enough?

[rickwess]

You can build your own hatch Rick. And where the heck you gonna run that big boy?

I could build a hatch, but probably not with the same detail. I will have to do something at the windshield to account for the rise in the opening.

I'll run it at the cottage. Lots of room at the lake. Maybe even run it beside the J-Craft out in the middle of the lake. I'm sure this will handle some chop nicely.

[Doby]

I saw that thread and since it was a tunnel, I figured it would be different. I was looking at the TP5670 which would be a comparable motor. Would 8s not be enough?

Crap...thought it was a mono!!!

[flraptor07]

I built this big mono a while back http://forums.offshoreelectrics.com/...ilmer+viper+48 It had a Leopard 56110 950kv and a Swordfish 300 Pro Plus ESC on 10s Hobbyking has a killer deal on 10s packs right now too! http://www.hobbyking.com/hobbyking/s...Lipo_Pack.html

[olwarbirds]

Chris, tks for the link. That is a killer deal for a decent 10S...Rick I am following this build, I had one of those Dumas hulls many yrs ago running a big slimer (Nitro) marine engine. It is a great handling hull... DJ

[Doug Smock]

At 54" it's a big mono. Lots of wetted surface. I would error on the big side for the motor and certainly consider 10s.

A bit more than your looking for but may get the creative juices flowing.
http://forums.offshoreelectrics.com/...or-John-Snider

https://www.youtube.com/watch?v=4XeOsbN1Ik8

Neu 2230 1Y Castle Hydra 200HV 10s2p Hyperion 5000 45c Speedmaster hardware M cut 467

A castle 2028 or similar would work nicely in there.


Good luck with her.

[Make-a-Wake]

10s is really best as pointed out, however, It can be run on 8s with a lower kv motor and achieve speeds in the 40's........possibly 50.

My Dumas 45" runs on 6s and runs only a Leopard 4082, i like it as a more scale speed boat, top end is 37.

I would recommend a Leopard 5698 or 56110 in the 910kv for the 5698 or the 950kv in the 56110 for 8s2p. You will be able to spin a large diameter prop which you will need to push that beast without making a bunch of foam. Probably something in the x455-460 range.

This setup will not be real amp hungry and I would say a 220a should cover it, but a 300a is safer and a better choice.

[rickwess]

Thanks for the posts. Deep down I knew that a minimum of 10s is what I should go with. My wallet was hoping that I could use 4 of my 4s packs.

Does this make sense for the transom hardware?

rossi-dual-tapr_medium.JPG
http://www.offshoreelectrics.com/pro...=ros-spdr-011a


rossi-large-strut_medium.JPG
http://www.offshoreelectrics.com/pro...d=ros-spds-008


ose-80667_medium.JPG
http://www.offshoreelectrics.com/pro...prod=ose-80067


ose-83022_medium.jpg
http://www.offshoreelectrics.com/pro...prod=ose-83022

[flraptor07]

Looks good, Pretty much the same as I used except, I used a stinger instead of a strut Kintec has it. http://www.ebay.com/itm/Angle-and-Le...item3f3d1fc2e7 I also found this one that solves the stinger height adjustment problem roller bearings and all. http://www.ebay.com/itm/Promise-Hobb...item20eb631b81

[Roy Van De Sande]

Serious build, have you considered spinning low rpm and a big prop? Far more efficient than spinning a smaller
prop at high rpm for your size of hull. You will have the same speeds but longer runtimes if you chose the first option.

For 50-60mph I would use:

TP5850 or TP5860 , kv around 600-670kv
10S2P lipo
300A Esc (current peaks will be high if you need to accelerate from 0mph to 60mph, so you can use a good esc!)
Prop: X465 and X472 octura

600kv will give you long a runtime but less speed. Around 55mph with a x472. 670kv will
give you less runtime but speeds around 65mph with a x472.

For this application I would chose a TP58xx over leopard56xx because of their 6-pole design. You will need
the torque to spin a x472.

Good luck! I will follow your build!

[srislash]

This is what I was going to say, maybe style the setup after the gas guys. I would suggest reading on Jim's Dock but...

[rickwess]

Thanks again for the input.

By style the set-up after the gas guys, I'm assuming you're talking about lower RPMs as Roy suggested. I was looking at the TP5670 for the 6 poles design and will definitely consider a lower kv. If I can get a reliable 90kmph out of of this, I'll be more than happy.

What's Jim's Dock?