New EDF powered boat project

[ajac63]

Any tips, advice for an EDF powered boat build? The hull is a 3-foot shallow V and although I have a rough idea of what to do, I will need pointers as to the power chain to achieve speeds of say 45-50 mph. So cell type, how many, what MAh and also ESC specs. I've seen a few youtube clips that proves an EDF setup will work. Anyway, that's basically it. Thanks

 

[LibertyMKiii]

I think the angle of attack and placement are some of the most key factors.
Is there a specific budget you want to stick with?

I have not built one, but I have looked into EDF setups for an outrigger boat setup.
My thought is that it would be a bummer if you spend lots of money and not have enough power to hit your goal.

For this reason I would go 6s versus some lower power level and probably a 70mm EDF or larger given the hull size you have.

 

[ajac63]

Yep, I agree angle of attack is a main factor, so I'm thinking of some sort of mount that allows me to adjust the position of the EDF. This youtube clip shows a setup using a 90mm EDF and it seems to run OK.
Here's a pic of the hull. Thanks for your help

 

[LibertyMKiii]

Yep, I agree angle of attack is a main factor, so I'm thinking of some sort of mount that allows me to adjust the position of the EDF. This youtube clip shows a setup using a 90mm EDF and it seems to run OK.
Here's a pic of the hull. Thanks for your help

That setup looks pretty good to me, but not near your 40mph goal.
It certainly gives you a good idea where to start.

I think 90mm would be plenty of size if it was a higher end setup that what he used. You will have to start comparing thrust values and see where you can find the best bang for the buck.

-Liberty

 

[ajac63]

No, maybe it's going 30-ish mph or so, but still something to gauge my attempt by. Anyway, how many cells can I go for with say a 70A esc and should they be LiPo's or NiMh's? Oh, and what MAh figure?

 

[LibertyMKiii]

No, maybe it's going 30-ish mph or so, but still something to gauge my attempt by. Anyway, how many cells can I go for with say a 70A esc and should they be LiPo's or NiMh's? Oh, and what MAh figure?

You would absolutely want LiPo and 5000mAh or 6000mAh.

I'd look for 6s EDFs, the esc power rating would depend on the fan motor.

The Arrma blx 185 esc is going to outperform most ESCs for the price point. It outputs 120-180 amps. (If the motor can demand that much)
They run in the $50-70 range on eBay new.
It also has the bec circuit to run the steering servo.

If you wanted something nicer you could look at Castle ESCs

You don't have to run airplane ESCs but you could. The one described above is for an rc car. (I find that car electronic hold up well with their built in cooling fans )

It would also then work easily with a pistol grip style car radio.

That's how I'd do it anyway...

-Liberty

 

[ajac63]

Right, so 6 LiPo cells (22.2 V) at 5000 or 6000 MAh and a 120-180 amp ESC with BEC. I now realise that a 70 amp ESC certainly wouldn't do it, and why it should be LiPo and not NiMh, so thanks for putting me straight on those things.

 

[tntpoof]

The edf powered boat is cool. Id go with a water cooled esc and id go A123 batteries .. they are a lot heavier than lipo.life or Nimh… and harder to build to a pack..I use a 250 watt solder iron for stained glass window.. Id also think about a small wing up from as a safety to push bow down like a boat fail safe . hold a switch and if it starts to fly .let go of the switch it pushes boat back to plane(boat term) or back down to water this will happen both ways in a fraction of a second..

 

[LibertyMKiii]

Right, so 6 LiPo cells (22.2 V) at 5000 or 6000 MAh and a 120-180 amp ESC with BEC. I now realise that a 70 amp ESC certainly wouldn't do it, and why it should be LiPo and not NiMh, so thanks for putting me straight on those things.

I have seen those EDF combo's where it includes the EDF fan and esc rated around 70-80 amps.
Honestly the price is pretty good and likely would get you to your goal. My setup mentioned might be more suited for higher speeds...

My largest concern about the cheap stuff is reliability. I have found you want to spend good money on the ESC and the motor can be cheap to some extent. Again thrust values are what you are looking for when looking at the fans. I believe the 12 blade designs output more thrust than the lower blade counts, but lack some of that "cool sound".

I like LiPo for the discharge amperage abilities over NiMh and charge time of LiPo is around 1/8 the time. I don't have first hand experience using A123 batteries so I cannot comment on that.

 

[ajac63]

@ tntpoof, thanks for your reply. The EDF will push the bow down a bit and I'm also thinking of using trim tabs to prevent bobbing or porpoising, but you think I would need a down-force wing as well? Near the front of the boat? As A123 batteries are a lot heavier than LiPo or NiMh one's, wouldn't this be a reason not to use them? Confused... Surely I want to reduce the weight as much as possible.
Also, is a water cooled esc a must? I was thinking of simple air-cooling by placing the esc near the EDF at the top of the boat.

 

[ajac63]

@ LibertyMKiii. Thanks again for your advice. Higher speeds would be ideal which is why I was erring on the higher-specs you mentioned, especially as you suggested that the setup in the youtube clip wasn't doing even 40 mph and I'm looking at 45-50 mph. Plus, once the weight of the deck, the batteries, esc and servo, etc is factored in, I'll probably need the increase in power anyway

 

[tntpoof]

The thing is this is your boat .You can do whatever you want. A esc under the top deck has no air movement that why I said a water cooled esc.. and the A123 sure there a slight bit heaiver than a lipo but will take more abuse..and the bow wing again its up to you..My 36" proboat miss bud runs at a easy 60 mph .I have a retrieval quadcopter setup with a hook and line to rescue my boat when I capsize it. happens 1 in 8 runs...even at 10 mph on water ,waves ,wind ,fish .just happens..Id rather throw the info your way at 1st .Then let you decide.its no biggy to me rather have you have info instead of spending time and money dollar after dollar.

 

[ajac63]

Water, waves, wind, FISH - LOL! I know what you mean. Another one is small leaves, blades of grass and such that seems to converge right in front of your boat for no logical reason and getting wrapped around the prop.
Anyway, by top of the boat, I meant having the esc outside on top of the deck just in front of the EDF secured with hook'n'loop pads and housed in a small angled bracket type structure - the esc will be waterproofed and the airflow should keep it cool enough.

 

[tntpoof]

hook n loop isn't the best.Id look at 3m dual as a fastener...

 

[ajac63]

OK, thanks for recommend - sorry for late reply...