Australian RC Forums banner

Thinking about building a boat

4K views 22 replies 9 participants last post by  wobblygts 
#1 · (Edited)
I'm about to recieve $450 and would like to build a brushless boat.

Thinking maybe a 32" Pursuit mono hull.

These are the specs for the guts of it:

Leopard 4074 2000kv motor.
180 Hobby Wing esc.
4s 35c 5000mah lipos.
3/16 prop shaft and flex.
48mm carbon prop.
Water cooled motor mount.

Should get about 40/45mph out of it. :thumb:

What do you think?
 
#4 ·
I was thinking it's about time I tought myself how to use brushless and lipos, nitro is getting to be a pain. Good point though! I know someone who has a nitro boat engine I could get cheap enough. Then I would just have to get a hull and drive train. Thinking......

Why 2x 3s and not a 4s? I think that would cause heat issues with the setup I have. Please explain.
 
#6 ·
2x3S for a 6S total, 32" is a 800mm or there abouts, 4S would be the the smallest you would want to run, but for performance 6S or better is the way to go. High Voltage low KV motor is the way to go to keep temps manageable with a water cooled engine mount.

I have been looking at doing this myself for a long time now, I have designed a mono hull about 1m long that i would scratch build and fir it out with an 8S lipo and brushless setup. I knew one day those 4 years as a boat builders apprentice would come in handy eventually.

Looking over utube there is a lot of 5 and 6S setups using those leopard motors in the hull you are thinking of buying, they are the way to go.
 
#7 ·
use two packs Mainly for weight distrubution and 6s total as 4s will be a slug in the water with a 2000kv. 15volt max times 2000 is only 30,000 rpm.
That's not very fast, maybe alta your prop with less angle or a smaller diameter if temps are high on 2x3s, You will be running a 180amp esc, it should handle that load fine. Especially if it is water cooled.

for higher speeds on water I believe you need lots of rpm and a less agressive prop, if you want more tourque you go with a more agressive prop but gear it down, An agressive prop spinning too fast will lead to cavitation and the boat goes no where.

Cheers
 
#8 ·
I better re-think the setup. Thanks for the replies guys!
 
#10 · (Edited)
Not trying to pi55 on ya parade, but letting you know, I tried building my own boats a few times and could never get the prop/motor/power combo right. I was also trying my own hull designs made from balsa too, Lots of research first will make for smooth sailing! Pun intended!

What I thought would fly through the water just went at jogging pace, wouldn't even get up on a plane at all. I even tried air power using the prop motor ESC and batt from a Stryker f-27 brushless that flys at 80+kmh, the air boat went about 2kmh. Live and learn, and hopefully enlighten others along my way.

Your set up sounds good, just get a array of props and maybe 2 different battery setups if you can, to see what works well. If you buy 2s you can always use 3 to get to 6s, if there's room in the hull.
 
#12 · (Edited)
Not trying to pi55 on ya parade, but letting you know, I tried building my own boats a few times and could never get the prop/motor/power combo right. I was also trying my own hull designs made from balsa too, Lots of research first will make for smooth sailing! Pun intended!
I'm sorry you tried to build a boat and it didn't work. That's not Pi55ing on my parade, I have never built a boat that didn't work very well, I just need to learn more about the electric side of boating. I'm sure I could get an ice-cream container, with a rubber band paddle pop stick motor going faster than walking pace.

I will try one prop size either side of the suggested prop in carbon or alloy (balance and sharpened) and I recon the boat will be fast enough for me. I doubt I could catch it running flat stick down a mine shaft. lol

I will probably start with the two X 3s lipos, they are cheap enough.

Hey Matt, I'm doing all the hardware myself. I wouldn't trust such a close tolerance job to a little Chinaman that can't wait to get home cause he doesn't get paid enough.

I'm still looking for a hull at the moment. I will let you know who stands out. The Delta Force boats are well represented in the boat fraternity.

Cheers, Brett.
 
#13 · (Edited)
I'm still looking for a hull at the moment.
Thinking maybe a 32" Pursuit mono hull.
Nothing wrong with that hull at all, actually nothing really wrong with your initial plan other than not going 6S straight up. The motor will go 6S just put it with a ESC that can handle the power and you will be in business. On 6S you should be looking at 100Km/h +, and your budget, while tight should be able to accommodate a more powerful ESC, just go hobbyking for everything and you should be able to make a pretty lethal weapon.


The only mods to the hull i would do is the add some glass and resin in places to add a little more strength where its needed, from what i have been reading, thats about all anyone does to them, saw that hull on utube on 6S doing 85mp/h thats insanely fast.
 
#14 · (Edited)
Thanks for the Reply, I'm going to have a look at hobby king now for an esc that will handle 6s lipos.

Do you think a Turnigy motor of the same Kv rating would be as good as the leopard?

Cheers!
 
#15 · (Edited)
I can only comment on their car motors, i have a couple of 10T xcars and a 5T xcar and have had no trouble with them at all, the same with their car esc's performance wise, sure they are not LRP or REEDY but they do th job and are reliable, run cool and cost a whole lot less. If i get around to building my boat, it will use hobbyking motors, esc and batteries.

Turnigy Marine 180A Brushless Boat ESC $90

Would have to go the leopard motor to get 6S in an 36mm motor, that way you can get a water jacket for it to keep it cool. Something like AquaCraft One-Piece Machined Motor Water Jacket 36mm, looks like the best HK do in a 2200ish kv 36mm motor is 4S, they do a watercooled 1500kv in 6S 36mm, other wise you have to jump up to bigger motor diameters to get 6S+.
 
#16 · (Edited)
Offshore Electrics do the Leopard 4074 2200kv with a free water jacket for 95 bucks US. Thats a pretty good deal i think.


Found it S3665-1800 Brushless Inrunner (1800kv) will run 6S and is $33, and hobbyking also do a waterjacket to go with it as well, Purple anodized aluminum water cooling jacket for 36mm motor, $3.50, and the Turnigy Marine 80A-HV Brushless Boat ESC is $70, so as a package its just over $100 bucks.
 
#17 ·
Brett, pm me with what your after, I have a fully prepped MHz ea mono with neu 1515. Even an etti 150 and new Hyperion 45c 4s 5000 or 5s that has race pedigree in oval and saw. Murder anything mentioned above. Have too many props to mention but depending on 4or 5s.. Could even 6s for saw or insane speed runs? Got to run balanced and sharpened de tougned brass props for this boat.

Let me know if you want to oval race or have fun. This is carbon fibre and set for race, fully assembled..

Leopard are no where efficient enough. Neu or lehner will spin 50000 rpm..

I'm club racing now and getting ready for national saw in April.

You can have it for 400 less batt. Price goes up from there..
 
#18 ·
I remember in 1976 I had a day out with my parents to Ludenham Model Park. I was exited by the nitro boats. but someone brought out an electric boat, probably a brushed motor boat and did some laps of the pond.

I was so suprized at the speed from electric boats! I have had a soft spot for them ever since.
Steve Vaccaro on OSE is selling something similar to the one Id'e like to build for $400. He's in the states and postage is way to much.

Ide like to see more about your boat.


I guess all I need is pics for now. I'm baffled at the moment. lol
 
#22 · (Edited)
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top