Build Advice Wanted - Large Mono

[rickwess]

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

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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/showthread.php?49996-Big-boat-conversion&p=605879#post605879

[srislash]

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

[rickwess]

http://forums.offshoreelectrics.com/showthread.php?49996-Big-boat-conversion&p=605879#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/showthread.php?46710-My-Next-Build-48-quot-Vern-Kilmer-Viper&highlight=vern+kilmer+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/store/__24297__Turnigy_nano_tech_A_SPEC_4000mah_10S_65_1 30C_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/showthread.php?44807-48-quot-SpeedCraft-Mono-for-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?

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http://www.offshoreelectrics.com/proddetail.php?prod=ros-spdr-011a


125700
http://www.offshoreelectrics.com/proddetail.php?prod=ros-spds-008


125701
http://www.offshoreelectrics.com/proddetail.php?prod=ose-80067


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http://www.offshoreelectrics.com/proddetail.php?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-Length-Adjustable-Aluminum-Stinger-for-1-4-Cable-Shaft-/271608431335?pt=Radio_Control_Parts_Accessories&hash=item3f3d1fc2e7 I also found this one that solves the stinger height adjustment problem roller bearings and all. http://www.ebay.com/itm/Promise-Hobby-95mm-adjustable-aluminum-stinger-drive-for-1-4-shaft-rc-boat-/141388094337?pt=Radio_Control_Parts_Accessories&hash=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?

[Make-a-Wake]

I would not go with a strut, i would use a stinger

[Fluid]

I support going with a gas boat power system clone, which is the Castle 2028 on 8S. Spins a big gas prop with better efficiency for a big hull. Some experienced racers run that 8S setup in T-Class Hydros with good success. Since the OP already owns the 4S packs he can try 8S and if he doesn't like the results he can put in 10S and prop down. The motor and ESC would not need to be changed.

i would NOT use the strut in the posted link. Get the extended version to keep the prop farther off the transom. A stinger does not give the adjustment needed if the OP wants the versatility of 8S and 10S.




.

[srislash]

What's Jim's Dock?

Jim's was where all the gas guys conversed Rick. Just like OSE. That last virus strike messed up the board and they packed it in. Or so I heard

[Roy Van De Sande]

90km/h is easily achievable with a low rpm setup. I would use a TP motor instead of a castle 2028. The 6 pole design of the TP's makes them the
better motors for the application. If you want to use a 8s setup I would suggest a TP5850 around 850kv on 8s3p. This would also be a good setup.

A MHZ scorpion 5035 760kv on 8s3p with a big gas prop would also work perfect if 90km/h topspeed is fine. If you want the most efficient setup, the scorpion is the way to go. Because of the 8-pole design they can handle some big props. If you use a 8s setup and a TP5850 I would suggest at least a 300A esc. Maybe you can try a alien 400A 16s esc. This is a flier esc but with slight changes to make them work better. I use a flier 400A 16s esc now for a while and I am very satisfied with this esc! One of the best I have ever had. If you chose for the 5035 scorpion you can use a SF 300A without any problems.

I prefer a stinger instead of a strut. A stinger allows more adjustment in prop angle and can make the difference between a good running boat or a normal running boat. Give the MTC 3 eco (115mm long) a try. You will not regret buying some good hardware for your boat!

[Doug Smock]

I would NOT use the strut in the posted link. Get the extended version to keep the prop farther off the transom. A stinger does not give the adjustment needed if the OP wants the versatility of 8S and 10S.


Jay is right.

IME
Seldom is stinger angle adjustment enough unless you know exactly what diameter prop you will be running.

Being able to raise, lower the strut has greater benefits and you can run any angle you could with a stinger. (Which should be minimal BTW +/- a degree or two)

Check out the extended strut in the pictures (link) I posted above. IIRC Speed Master pt# SPDS-010-250MR

Install some version of a "irrigated shaft alley", "flood chamber" etc. and you'll be set to run whatever prop the set up requires.

Having said that. If you just really like a stinger and have some prop skills, you'll be able to make her happy.

my .02 FWIW

Good luck with the build.

[photohoward1]

Jim's was where all the gas guys conversed Rick. Just like OSE. That last virus strike messed up the board and they packed it in. Or so I heard

Jims's has been back up for a long time.


Sent from my iPhone using Tapatalk

[Doug Smock]

http://jrcbd.com/forum/forum.php

[Make-a-Wake]

I actually had the same boat a few years ago, sold it since, here is the only vid i got of it in its maiden.

This was set up to be a "scale" boat as it had full interior and all so i set it up very conservatively with a 5692 1000kv on 6s.

You can expect about 30-40% more speed from yours with the larger motors you are considering as well as the 8-10s.

I incorrectly labeled it as a 60 incher cuz the guy that sold it to me said it was....................never checked til a month later that it was 54"!

Just thought I'd let you see one running:thumbup1:


Qx7hw_9hvX8

[rickwess]

Lots of good info here and as expected different thoughts. I won't say I'm confused, just so many ideas running through my head. Before I started this thread I wanted to have all the internal hardware made from aluminum. I thought it would make for a nice contrast against a CF inlay. Since I'm not a machinist and don't know of any, I might be overly optimistic with that.

I'm so so with props and don't expect to get much better since I've outsourced all my props to Chris. Regardless of which way I go, I'm confident that Chris will be able to work up the right prop for me.

Thanks for the video M-a-W. Do you have pics of the boat you can share? What kind of turn fins did you use? I was wondering how well that "skeg" that's built into the hull works to keep the boat planted in the turns.

[Make-a-Wake]

Pics as requested Rick:

[Make-a-Wake]

few more, i can only load 5 per post for some reason........

[srislash]

Jims's has been back up for a long time.


Sent from my iPhone using Tapatalk
My bad, haven't talked with any of the gas buddies in a bit.

[Roy Van De Sande]

Lots of good info here and as expected different thoughts. I won't say I'm confused, just so many ideas running through my head. Before I started this thread I wanted to have all the internal hardware made from aluminum. I thought it would make for a nice contrast against a CF inlay. Since I'm not a machinist and don't know of any, I might be overly optimistic with that.


For the inlay of your boat, you can buy some 5mm triplex wood. Cut out your rails/motormount/battery tray, than you put a nice layer of carbon fiber on it. I put 2 or 3 on the motormount and you have what you need for a low price. Some aluminium is nice but wood is easier to work with for me personally. Just like this: 125795

This is the result. The opening in the rails is to mount a servo.

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