View Full Version : if you live by a body of water bigger than a bath tub....

2008.05.10, 08:52 AM
I would recommend these little boats a blast to run. With that said don't expect too much out of a stock boat if you want to go faster or longer run times. I've reasearched a little and have begun my thread on what I've done and will be doing to some of my boats feel free to add constructive comments or ask questions.

Day 1- Stock mini-z lamb Catamaran arrives. Took out charged stock battery. ran once in pool. pretty impressed but battery lasted 1minute ( needs a few cycles to build up to the 4-5 mins claimed by kyosho) Bought upgraded motor, aqua speed, difference in speed is like a stock mini-z motor compared to an xspeed. Fun but just not fast enough.

Day 2- Installed a lipo 2 cell about 500mAh. swapped out JST plugs for Micro deans, manufature of lipo put red/black wires on backwars, fried one of my fets un plugged, rewired, boat still operates on 1.5 fets lol. (will replace fets later)

Day 3- Test run at local duck pond, with lipo and aquaspeed motor this puppy flew! but not for long, at first I thought the battery died but it was the motor that blew a chunk of magnet and jamed the motor. Exchanged motor, installed new aquaspeed.

Day 4- Test run at pond, dejavu! motor blew up again. Decided the lipo is too much for the motor. Put back to stock batter and stock motor (will be using another aquaspeed when new one comes in.

Day5- Decided to keep this boat stock. And started plans to make a brushless second one.

2008.05.10, 09:17 AM
Day6- Took pics of stock boat today

Day7- looked up and researched brushless conversions for the mini-z boats, found the hull design for the lambo cat was overall better (lower cg and bigger area to work in) to use as the hull for the conversion

Day8- ordered parts, Catamaran hull rudder parts, drive shaft, trim tab set (a must) and prop set (good to dial in the top end speed). researched the internal electronics.

2008.05.10, 09:24 AM
Day9- I found that the micro-t brushless system 80k is the one I will go with, I will need to fabricate a custom motor mount and possibly a cooling jacket but I won't be able to tell that till the trial runs down the road. I looked around and ordered a few servo motors. the HS-55 and Hs-65 I decided were the two in the form factor that would fit in the boat, I will either use shoe goo to put the servo in place or custom brackets. Looking at the torque specs I decided I will got with the 65 not metal geared because of weight. The lipos is tricky since form factor is huge here, most from helis like the v4 lipos would work, I bought a few and will see how they lay in the boat, I need them to be idealy in the center of the hull so as to keep the boat balanced. I initally thought I would do this boat up 2.4 ghz style like all my mini-z are, but after looking at the options I had (Specktrum) none really fit in the boat, the sr3500 (I have three of them) would fit untill you needed to plug in your servo and ESC then they stuck out the top of the hull rendering it usless, I found several small 3ch with horizontal plugs that will work I may open the case of a 3500 and see if I can make it work I really want 2.4 in there lol. Well my next post I will include pics of parts when they come in and how the build goes. thx.

2008.05.15, 09:07 PM
Hey, Nic.

No I got have a boat yet, but I had been planning to get one hopefully in not-so-distant future. I too kinda wonder why this board is kinda dead, considering the Z population is huge on this forum...the only thing that is holding me back is the short runtime and the need for a calm water body. If the range of this puppy can go further and run longer, I think I will be more likely to get one.

Anyway, besides saying thank you for sharing your findings and info, I would also recommend to check out the DIY 2.4G car in the AWD forum, and many had been taken apart the spektrum 3500 to make it fit inside the car. Many had lied theirs sideway or even solder the wires directly onto Rx. There are also a few choices of ESC people had used for doing that DIY, which might be helpful.

I think going brushless is a great idea, since it probably will be more efficient than the average brushed motors. And you probably could go back to lipo with higher capacity so it will extend the runtime.

2008.05.16, 11:58 AM
Aurora- thanks for the comments, if you are worried about run time, add a lipo to a stock boat, that puts 20min easy run time, Range on these are really decent, if you look up on youtube many of the video's show decent distance and they aren't using 2.4 I am not going to run the pcb in the board for my custom boat, I am using the brushless esc from the losi micro-t but your idea of taking out the specktrum 2.4 out fo the case just may work.

Day 10- After comming home from a biz trip I got my brushless system, various lipos of different form factors and a few other odds and ends, now just waiting on the hull and small bits to start the build. I believe all sizes of lipos will work any where from 500mAh to 700mAh. Pretty excited.

2008.05.17, 09:40 PM
Day 11 parts came in today. and I decided to just buy a whole nother boat instead of buying the ASC hull and small bits. http://www.saltlakemini-z.com/forum/gallery/1/thumb_2_18_05_08_2_39_30_3.JPG

2008.05.24, 08:47 AM
Day 12- I picked up a servo with more torque, I am worried the cheap one I bought with only .5 kg isn't enough so I got a hitech hs-65 with karbonite gears, with 1.1kg torque also the karbonite gears will last longer with out the extra weight of metal gears. I got the trim tab set as well since most vids I see on youtube with brushless miniz cats tend to skip and bob, I wanted to trim that out and get this thing smooth as butta! Also bought a few more lipos with different form factors so I can test weight distribution and placement in the boat, I don't want too much weight in the back, but I don't want it too close to the motor and shaft. As a side note I have two of these boats and haven't been impressed with the decal work, both have runs in the seams from hull to body, not too pretty for those who are pretty boys like me lol.

2008.05.24, 08:48 AM
Day-13 I started gutting the boat and clearing it out for the parts. http://www.saltlakemini-z.com/forum/gallery/1/thumb_2_24_05_08_1_42_19_0.JPG

2008.05.25, 01:20 PM
DAy14- I finally figured out the layout of everything. I have selected the spektrum 2.4GHz reciever for two reasons. 1- Longer range and less chance for fatal glitch. 2- everything I have is 2.4 and I don't want to buy another TX. With that decided I had the problem of getting the servo plugs in and fit the top on as well (stuck out the top too much) I had the idea of just soldering the wires to the RX and not worry about it. After looking at it I still wanted to be able to un plug the servo or the ESC w/o solder, so I worked something out with the plugs that now lay flatter and will work even with the exsist OEM cap. However, given the new position of the RX its in the way of where I was going to put my lipo. I was going of what others put in their boats which was a 700 or 800 mAh lipo. I began to think about it, considering the cooling of the motor is non esistant because I don't have any air moving by it and not water cooling jacket that small. So given my current heat problem I didn't want to melt the hull or other bits. I began to look at the losi lipo batter for the micro-t (why not since I am already using the motor esc RX from one) and since its only a 150mAh I have enough run time (15 minutes) w/o melting any parts at the same time I can fit this small battery anywere inside and not worry about throwing the weight balance off. So I have everything test fitted, finished gettin the servo arm and ball stud in place for the rudder. I am going to shoe goo the servo and motor mount (custom made motor mount out of angled alm). I will velcro in the RX ESC and Lipo. since those will be more likely to need setting up or changing, I am waiting till monday to do this as my sister has yet again borrowed my camera.

2008.05.27, 03:08 PM
I fitted and set all the bits together, put the battery in and headed to the lake. First test run- much better than I expected, it leaned heavily to the left and had to almost set my subtrim all the way to the right to get it to go straight. Power wise the thing moved, however, I noticed if I punched it full throttle it would cut out. then a few seconds later it would cut back in. I now know why so many others put a 500mah lipo or better, I think I got a 2 minute run time with the 130mah lipo in there. Water is amazingly much more difficult to pull through, and taxes alot of torque on the motor.

2nd run- I relocated the battery so it was more centered, and adjusted the servo saver to more dead center. I also swapped out the prop with a four prop and then cut two of the props off. This all proved to be good I was still getting cut outs at high speeds, the new prop cuased for jump out of the water take offs but top speed wasn't as fast as the other, drove straight as an arrow this time, battery was still left to be desired. Also when the lipo dumps it just cuts off, no warning of slowing then again I am not going very slow.

3rd run- I was worried that my ESC wasn't set up properly so I swaped it out with the same brand one that I knew worked, this one, would not cut out at tops speeds however it would give a jolt at the beginning then die slower at the top end, so it was bolted out of the water then maintained a rather slow speed untill I let off the throttle and did it again. I think this is some kind of peak amerage thing built in the esc. I noticed a lot of skipping at high speeds so I put on some trim tabs that push the front of the boat down and no more bobing works very well, however I bleive the added torque is cuasing the motor to pull more amps which results in lower constant power. I swapped the prop out with a more top end prop, hopefully to raise the top speed again, I will take the tabs off to see if this efects the constant speed as well. At this point I love the boat, its stupid fast in burst and constant speed is still fast enought to suprize anyone. But if I have my cake and eat it too I would get a bigger lipo in there, and unlock the esc to push some major amps for prolonged time periods. Currently I am getting 3-5 mins on full power runtme on a 130mah lipo (not bad)

More to come after I tweak the prop and tabs today.

2008.06.01, 11:27 AM
Day 16- it would help if th ESC programming instructions were correct! I had the setting on a nicd battery not lipo, finally got it swapped and a good prop on there and that thing flew out of the water (litterally)! Great run times around 4-5mins, and doesn't cut out any more. Totally sick boat would reccomment this easy mod to anyone. There is a 300mah battery on Ebay done up by Great planes I think that is a small form factor and would give me about 10-12 minute run times but currently this setup is fine for me. plus I am too busy working on a 400 mah batter for my dnano (1hr 30min run time, not that I need it that long but still).

2008.06.01, 11:31 AM
Final product.

2008.06.01, 11:32 AM
If anyone is interested I have all the small parts to do this setup (servo milled ball studs) props trim tabs etc. let me know how serious you are and we can work something out.

2008.06.02, 06:38 PM
if you live by a body of water bigger than a bath tub....Well, I live by the Pacific Ocean......but I don't think these will work for me. ;)

Very cool though, thanks for the heads up. :D

2008.06.05, 10:23 PM
I like how you modded it, any chance for a video?

2008.06.06, 01:33 AM
yes just as soon as I get my camera back from Vegas where my wife has left it.