powering large boats with electric

[drwayne]

Wayne's right. The 100 mph club is small. It's almost and art.

There used to be some video on line of an HPR twin cat running a 120mph. Trying to remember. I think it was twin 3060 Lehner motors with Schulze 40.160's. Someone in Germany. Hopefully someone else will remember better than I.

That video is of ~54" twin on 10S2P .. lehners + schulze but Id wager his runtime is near exhausted after those 2 displayed runs

Ive a narrow tunnel Maritimo 36" twin cat on 6S .. castle 1512/1800 motors and SF120'sc at 88mph ..3+ mins
I had a wide tunnel Sprintcat 36"twin cat on 6S1P or 2P .. castle1518/1800 motors and SF240's at ~75 mph.. bigger motors + esc. but slower .... 3 mins
Wide hulls need more power to go fast, as the air packing beneath designed to help slower boats raise from water robs power..at increased speed that air induces hassles for stability ( vids on youtube link below may aid clarification )

jm3cw

[stumblinh]

May want to consider these bullets instead... xt150's from HK

[expresscraft]

Wayne I agree with what you are saying,and our MTI does have a thick airfoil, It works great in the gas world where we still do not have the power to run 125 mph in a cat, and at the 80 mph range the lift from packing air is a plus, but I agree once its up and flying the thinner airfoil will be faster,And we my not get the results of a smaller more streamlined boat.Keep in mind when I started this thread I only had some hearsay on the internet, and guys take for granted how much work goes into being the fastest. everyone else will work hard to be 15-20 mph off that mark. And then on top of that comes the parts used, and in my case its a bigger, slower hull with a large airfoil, our boat will make more out of less power, but then it will fall off after a certain point.And give up total performance to a more aggressive airfoil or wing per-say.I think with our boat and finding its place in the electric world,The top end esc will be overkill for the MTI's place in boats,I feel you may get what you pay for in motors, so im on the fence there, cheaper is better, but not if they will not last.I feel the same on the batteries,our doug wright hull will be a more aggressive wing for sure, but that boat is a ways off.I do think the MTI will be a great electric boat for most guys playing and having fun, as there is a huge amount of guys that would love a big boat and still do not want to spend 6000.00 on a model boat.At 60" scale looks and made out of carbon fiber its still a hard boat to beat at 350.00.

[T.S.Davis]

The video I remember was of the Paradise cat. It was from one of the German SAW events.

[drwayne]

Expresscraft
The thunderbolt is indeed a nice looking and setup hull... Im amused the tiny prop compared the transom !
However, like the MHZ Drambuie 54" .. it has more deck height than needed for FE motors.. making it a sail against the oncoming air.
The 54" MHZ Drambuie is well suited to twin gas application due it's immense inside dimensions.. Ive debated for a while of bandsaw-ing the top so that it return 1+1/2 lower to the bottom. offering less of the 'bulk' to air drag... reducing load for the FE setups.
Over 70mph, the scale dynamics/appearance of a hull can be more a hindrance than an appealing or beneficial attribute.

Ive researched some your other hulls... impressive.
With the information you're gathering here re fe cat profiles, if you do pull a FE cat of 45-55" .. let me know. !
regards
Wayne, Adelaide Australia

[RaceMechaniX]

The 3080 Lehner's and Schulze 40.3XX are excellent combo's, but also the highest priced combo you can put together. The 3080/5 is a dangerous amp hog monster. I ran a 3080/5 and 40.303wk in a 45" sniper for SAW on 8S and was hitting 450A. If you overprop just a little the current jumps up quite a bit higher. As Ken mentioned one nice aspect about the 30 series Lehenr's is you get two winds in one. I believe the 22 series are also available with the open connection now too. If you got a 3080/5 for SAW's in Delta Wind you can reconnect to an approximate 8.6 wind in Wye. This allows you to have a very hot motor and a comfortable motor in the same combo.

The table is available here: http://www.lehnermotoren.com/assets/...s/rpm/3080.pdf

In a big cat, large motors spinning reasonable RPM's are my best advice. Reasonable RPM's being under 30k. A castle 2028, Neu 22 series or Lehner 30 series are all quite capable of spinning gas props at slightly higher speeds than a gas motor would safely to achieve reasonable speeds. As previously mentioned though speed=cubic dollars and cubic risk. Proceed accordingly.

TG

[expresscraft]

well a deposit has been made, so we are off, i think everyone has agreed or at least mentioned the castle 2028 motor and ice 200 hv on 10s each motor will be a good choice,on x460 props, I will get mark f to take care of me on batteries,I did not want to waste to much of his time without a deposit.3/16 cables or 1/4" with a 3/16 turn? what kv 0n the 2028 or is there even a choice?connectors of choice? any tips mods or suggestions? or is it pretty straight forward?please do not let me order yesterdays stuff because I simply do not know what out there today,lol.Thanks again, I will be posting my build soon. once I let this post ride a few more days. I will start ordering parts.If you have any concerns with my choice please let me know.He is not going to go top end on this build,so I think from this thread this is the best direction, I was concerned about the 200 amp esc and the 2028 being to small, but it has been recommended several times on this thread.

[egneg]

Go with the 1/4 cable and 8mm bullet connectors - lots of torque and amps. The motor is 780 Kv - no options. If you are doing twins your selection of prop will need to be changed to one that has a matching RH one and also a RH cable will be needed to go with the standard (LF) one.

[expresscraft]

780 is right in there, and sounds great.In gas boats, counter rotating props is always best, but the benefits do not really always out weigh the prop selection in left hand props,not saying they are not better just bringing up the point,and would like feed back on that,would you use 457 left and right over 460 and the ability to change up or down,as needed to get the benefits of counter rotation?again just for conversation sake using a 7-8 hp gas motor with 75-76 mm props at 18,000 rpms the answer is no, not really.this is not speculation,this is info i know to be the case, in my mind the smaller prop at a higher rpm would have even less torque affect on the bigger hull.what do you think?

[RaceMechaniX]

Tom,

You are off to a good start. The Castle combo is plently strong and is certainly one of the best bang for the buck combo's. You definitely want 1/4" cable and I would recommend strong collets with shaft shafts. I have been using Aeromarine collets on the high power set-ups with little problems. Keep in mind on 10S you will be spinning around 24k RPM so start small around 60-65mm. You will be surprised how well these work. Check the current using the Castle link and then increase the prop load accordingly. If you have questions just post them up and we'll be happy to chime in.

Tyler

[expresscraft]

Thanks, How do you feel about no counter rotation?

[RaceMechaniX]

Tom,

With the more scale boats, CR is pretty key. I have tried same rotation and CR and the difference was night and day for low-mid speed manuverability. Assuming you could get the boat going straight and up on plane, the same rotation props were not bad, but still not as good as CR.

Tyler

[expresscraft]

ok, i dont mind going cr at all, just wanted to put it out there, what options are there in cr other then octura in this size? any suggestions?I do not have a problem with octura, i just want to know the options.

[RaceMechaniX]

ABC has some: 2116/3 L/R, 2316/3 L/R, 2616/3 L/R

[drwayne]

Propellers.

http://www.prop-shop.co.uk/index.php?id=25&section=store&sub_section=products&product_type=25

SS + BeCu.
Their range surpasses all seen in US market.