Exceed Racing Flowmaster Catamaran 650mm build help.

[studioRS]

I plunked down and bought this, couldn't resist. Super nice scale looks.

I would like to request some help on deciding what motor, ESC, prop and other upgrades.

I'm willing to remove all ply and reinforce with CF kevlar cloth and epoxy if needed. I don't want to go too ballistic, but faster than stock would be nice.

Stock
2848 2636kv, 27A Feisuda, ~299w with 3S
Prop: 32mm three bladed

Slightly Modded?
Leopard 2845 2550kv 4D (6) ~800w
Prop: x437/3? (I'll need to shim up from 4mm)

Modded or too much?
Leopard 2860, 3400kv
or
3650 1900kv


I have a Turnigy Marine 120A

http://www.nitrorcx.com/99b-10117-650-ep-kit.html

[studioRS]

Would this setup work well or should I stick with a smaller Leopard 2845 800W motor and go slightly higher kv?

LBP2860/2Y, 2730KV
MAX: 60A, 21V, 1300W
Resistance: 0.0113
No Load: 1.9A
Weight: 176g

2 2S packs - 4S batteries, 50C on up, 2200mah range
37mm 3-blade prop

[studioRS]

This arrived today. Wow. What a piece of art, the paint and graphics are top notch, hull fiberglass and build is very nice too.

I dug into my parts bin and found a new Turnigy 2860-2700kv motor rated at 660w and 60A on 3S, should do the trick. Some have reported up to 975w on 4S.

[TheShaddix]

Surprised that no one has replied yet... This is looking really nice! The motor choice is good too. I would unbolt everything at the back and apply silicone to bolt threads to prevent leaks. I sold the same boat to a buddy, he's running it on 4S at around 40 mph and really likes the boat.

[studioRS]

Thanks for chiming in, beginning to wonder…

Glad to have your thoughts on this. I'll take more detailed photos but yes my idea was to run 4S. Looks like smaller 2S 2200mAh will fit on either side of each hull, I'll have to take measurements for what batteries will fit. I do have a Zippy 4000mAh 3S 20C, but just don't like the thought of it sitting in the middle so high. The hull looks pretty stout, still wondering if I should at least try to reinforce the bottom, tips and transom with CFK fabric or just mixed epoxy?

What are your thoughts on an upsized prop? I was thinking a sharpened, balanced X437/3.

[Pheyd]

I definitely like the hull, looks sharp. I always vote for CF inlay, it does so much to increase the hull's integrity. I have no idea what your budget is, but if you want to go crazy try one of these motors:

LMT 1530/6 LK (4763 KV), 155g, 70,492rpm on 4S ($251)
LMT 1535/5 LK (4899 KV), 175g, 72,505rpm on 4S ($260)


Both of the above motors are rated for 85,000RPM!
I'd start with a x432 prop with the above beasts and work your way up.
Also, if you consider the above, take a look at the flex shaft first, hopefully its beefy enough to take it.

[studioRS]

Thanks for these suggestions super helpful. It's always nice to hear from others experience. More Lehner Motoren love, someday I'll own one, they are dakine…

For now a little over my budget which is low—mostly dig in my parts bin! Found a Turnigy 2860 2700kv and I already have a spare Turnigy Marine 120A. I'm sure this hull will be a keeper and mod it up as I go.

Ok with x432, but couldn't I go larger (x437/3) to start with my lower 2700kv motor on 3S? Yes, I should drop down in size for 4S.

Yes, CF inlay will happen. Wonder if I can do it without having to remove the wood that is already glued in?
Received some CFKevlar cloth I ordered from HK. Guess I need some special cutting shears too, any recommendations for cutting kevlar?

I've been using System Three for building my 1/10 scale boats (Breathless U-22) and like how this epoxy works, but now out, so totally open for other alternatives. Has anyone tried US Composites brand 635, with 3:1 hardener?

Has anyone installed a twin rudder on this hull? Wonder if I should think about that also or is one offset ok?

[studioRS]

The motor mount has some tapped holes in the top (mine is silver). Quick look, I didn't see any spare brass water cooling nipples in the parts bag. In some of the stock photos, looks to have allen stubs installed? If these are cooling ports, this beckons for additional cooling.

[studioRS]

Will the stock 4mm flex shaft be adequate with the 2860 2700kv motor on 3S, and 4S?

[Pheyd]

Running on 3S and 2700kv, a x437/3 should be alright.

The more slits you cut in the CF, the less solid it becomes. However, having to re-glue all the mounts is a pain and easier said than done. Since I'm not doing it, I'll tell you to remove all the wood and cf inlay everything :P

with a 650mm hull, I wouldn't bother with dual rudder. Stick to a single, either in-line or offset, whichever you prefer.

Motor mount doesn't appear to be used for cooling. Get an aluminium water jacket for the motor and it should be enough.

[TheShaddix]

Definitely keep it as single rudder, inline just like the stock one is. If you need to make it longer, add a bracket to the base to extend it, but do not offset. The stock flex shaft is fine for that kind of power too.

This hull, as nice as it looks, is very fragile. A few crashes and you'll start seeing stress cracks in the paint. I cracked the top deck just by pressing on it gently... I reinforced mine with a cf inlay, upper decks, hatch, etc. I poured mixed/thickened epoxy into the transom to flood it as well as the tips. Then I used 2 part foam as well. I was trying to go for some high speeds, but the hull just can't handle it as a single motor, it wants to roll. So don't over-power it, keep it simple and you'll be happy.

And do not over-prop it! Start with a small prop like a 38mm, go up to 40 tops. Then you can try something with a bit more pitch which won't have as much torque but will give more top speed. From what I noticed, this hull benefits a lot from more weight so feel free to do all the reinforcement you want!

[studioRS]

Ok, thanks guys, keep the tips flowing in!

- Rudder will stay as is.
- Great tip on sealing bolts with silicone.
- @Shaddix - I noticed you added a transom water connector, rather than drilled and stuffed though the hull raw, I'll add one to the parts list.
- I have the following 2-blade props: TFL 432, TFL carbon 435, and s/b Octura x435 drilled out to 3/16" (but can shim back down to 4mm). The stock factory prop is a 3-blade D32, 1.4.

I'll go ahead and buy two props, 38mm 2-blade and Octura x435/3, which the latter I think will help keep this hulls rear arse up in the turns?

This is where I need help, I've never reinforced an existing FG hull before. You guys all make it look so easy in your photos (Shaddix I did review your Genesis CF mod photos too). I've come to the conclusion I need to add CF Kevlar and remove the factory glued in plywood and motor mount. Prying it off looks like it will lead to stress cracks all on the bottom as you mentioned. Take the Dremel to it and remove slowly?

Qs
- Looking down the inside at the transom it appears the nuts for the strut and rudder are blobbed over with factory glue… ugh. Tips on removal?
- I was planning to use 1/8" Birch ply to reinforce, then epoxy over, but now have second thoughts on any wood going back in. Trace outside of hull transom and cut CF plate to fit? Not any room back there!
- Toss the factory white foam stuffed inside and use 2-part foam. How much did you mix up?
- Any experience on US Composites 635, 3:1? OR should I stick with West Systems?
- Shaddix what did you thicken your epoxy with? (I'll buy black dye too)
- The factory mount certainly does have tapped holes for cooling, I will try to find some brass metric barbs that bolt in and use it.
- I was thinking that 3M Super77 will hold the CF Kevlar down well, then roll on the epoxy. Should I rough sand the FG surface first? I did see how you layer down the CF on clear saran wrap then how in the heck do you get it to lay in nice and smooth with it all loaded up with epoxy?

- How in the HECK did you get CF on the inside and the sides of the top of the hull? Confusered.

There will be more Qs, sorry to ask so much and TIA. I've been involved with RC boats since my first job at 16 working for Charlie Pottle at Marine Specialties back in 1976. I'm comfortable building wooden classic hydros, FG work, just need to get caught up with modern CF building and modifying methods.

Top 36" 1/10 Scale 1954 Breathless U-22, 25.5" Exceed Racing Flowmaster Cat, 18" Dumas Atlas Van Lines FE project





Bow


Transom

[TheShaddix]

The wooden plates will have to go if you plan on reinforcing, no doubt! They should come off without much of a fight. Tape up the underside (quite a few layers of tape), that might help avoid stress cracks. When you remove glue, try to "turn" it to break it loose instead of prying it off with pliers. For all the small remaining bits you can use flush cutters/nippers, then just block sand it flat. I had to do all of that on mine too. It's a project for sure!

To reinforce the upper decks you just gonna have to lay CF fabric as far in as you can reach. Sand it with 60 or 80 grit first. Then flip the hull upside down. Keep pressing the cloth into the hull throughout the cure. It doesn't have to go that far to make it stronger.

For the tips and transom, mix resin with some milled fiberglass/silica to add strength, then pour equal amounts into the tips, all you need is just a bit to fuse the two halves better. Roll the hull side to side once poured so the resin flows around a bit creating a thin layer that covers most of the bow tip area. Do the same with the rear. Make sure the hull is vertical when it's ready to cure.

For rear transom nuts: just unscrew the bolts first. Then use a larger drill bit and drill into the nuts, that'll break them loose for sure. But then you'll have to use new, larger (and longer) bolts for your rudder. Worth doing if you want it really strong.

I would not recommend using any adhesive first for your cloth as that will block the epoxy and be held on by said adhesive till it comes apart later. I always prefer to saturate cloth outside of the boat as you get it perfect this way with no puddling or dry spots, and you can remove excess resin with a foam roller too.
Once you lay the cloth in, just keep massaging it into all the corners continuously throughout the curing process. Work in warmer temps too as that'll speed it up. Don't worry about messing up the hull with resin, wipe it with alcohol afterwards.

Definitely get rid of the stock foam as that won't help keep the boat afloat with heavier motor/batts. I had a blackjack 29 sink like that only because the batteries were a bit heavier. It should have been accounted for in the first place when they designed it.

Be careful with the 2 part foam. If you mess up on the ratio, you get brittle or soft depending which part you mixed in more of. Also, pour both parts into two separate cups. Then mix them really fast in one. You can use some black dye for this too. Mix for 20 seconds, then pour into the boat. Try to aim for 2-3 pours total, don't do it all at once. Work in warmer temps too as that will expand the foam more. And always use a water bucket to dip your hull into as the foam gets really hot and will distort your boat no exception. When you mix the foam by weight, that's 1.2 of part A to 1 of part B if you buy it from us composites.

For resin, west system is great if you can afford it. There are always cheaper alternatives though. Just don't use kleer kote, i learned that it's not a good option for anything other than bar tops...

[NativePaul]

Received some CFKevlar cloth I ordered from HK. Guess I need some special cutting shears too, any recommendations for cutting kevlar?

I would really recommend getting Kevlar shears as it will be 50 times easier and you will get a neater cut too, but for a one off project it can be cut with fresh sharp razor (not scalpel) blades at a low angle on a cutting mat (not a wooden board), use very light pressure going over the same area again and again till it is through before moving on, and changing out for a fresh blade frequently.

[TheShaddix]

My suggestion is go cheap on the scissors because even really expensive ones will dull out quickly whereas even the cheap decent ones will cut nicely for some time. I just buy fiskars or something cheap for $10-15 from Lowes. I had a nice pair of shears at some point that I got for about $80 and was really disappointed when they got dull so quickly from cutting cf.