Twin outboard center console build

[forescott]

What props did you end up with? Venom sells 32mm 3-blade aluminum counter rotating props that have a very scale appearance. They are fit a 4mm shaft.

[Darin Jordan]

The pitch on these 3 blades is 1.4 which appears to be identical to the stock 2 blades. The only difference seems to be the extra 2 mm in diameter and the extra blade.

So, 1.4 sounds more like the pitch ratio than the actual pitch... Take the Pitch Ratio (1.4) and multiply it times the diameter to get the actual pitch.

I just ordered some 3 blades with the same diameter and pitch as the stock 2 blades. We will see if they are better.

That might help. If you could give the exact specs of the props, we might be able to help more.

The motors....well I can see with these outboards the weak point is the lower unit gears. They seem impossible to get without buying an entire new motor for 75 bucks. So I don't think putting more power on those gears is a good idea.

That might be the case... I had a couple of these and the gears do get worn quickly. The real weak point is the stub-shaft, which is only 3mm and bends pretty easily.

If you decide that these units won't cut it, you can spend a few more $$ and get a VERY solid, and fairly scale looking unit from ProBoat:





This unit will take ALL the power you can throw at it and can handle some serious prop as well...

I just got my 7 cell Ni-MH batteries so the boat will be going a little slower anyway. These batteries are much heavier than the LiPo's and less volts. 8.4 as opposed to 12 volts for the LiPos.

That should help too... It does sound like you were turning those motors too hard for the application and pitch of the props.

BTW....should these Ni-Mh battery packs get warm when charging? I charged them right out of the package. Hopefully didn't over charge them.

Yes... when they reach their peak cut-off, they'll be warm... often around 120-degrees or more, depending on the cells...

[ScarabChris]

Oh and the water was getting into the motor cowlings through the seem where the cover meets the lower cowling. I put tape around it and no water.

[ScarabChris]

My experience with these outboards and those brushed motors (are you running the stock silver canned motors???) is that they are kind of "draggy" and use a lot of power to turn the prop. Any more prop than an X435 or so is really going to be pushing things. I played around with one of these on the original AQ Bass Boat and the brushed setups just go really hot, and really didn't deliver the performance I was after.

Do you know what pitch those 3-blade props are that you have on there??

You might have better luck, if you want to stay with those outboards, if you switched over to a suitable Brushless 1/10th scale sized car/truck motor. Something like a 17.5 or 13.5 T would deliver much more torque than the 550 can motors would, and should bolt right on.

The pitch on these 3 blades is 1.4 which appears to be identical to the stock 2 blades. The only difference seems to be the extra 2 mm in diameter and the extra blade.

I just ordered some 3 blades with the same diameter and pitch as the stock 2 blades. We will see if they are better.

The motors....well I can see with these outboards the weak point is the lower unit gears. They seem impossible to get without buying an entire new motor for 75 bucks. So I don't think putting more power on those gears is a good idea.

I just got my 7 cell Ni-MH batteries so the boat will be going a little slower anyway. These batteries are much heavier than the LiPo's and less volts. 8.4 as opposed to 12 volts for the LiPos.

BTW....should these Ni-Mh battery packs get warm when charging? I charged them right out of the package. Hopefully didn't over charge them.

[ScarabChris]

Chris,

What dimensions do you want these decals?

All the best,

Ray

Dude if you cam make them with the "Evinrude" 2 inches long and the rest proportionate that would be awsome!

Let me know if you can find "Scarab Sport" too! I looked all over the internet and all I could find was just "Scarab"

[Darin Jordan]

My experience with these outboards and those brushed motors (are you running the stock silver canned motors???) is that they are kind of "draggy" and use a lot of power to turn the prop. Any more prop than an X435 or so is really going to be pushing things. I played around with one of these on the original AQ Bass Boat and the brushed setups just go really hot, and really didn't deliver the performance I was after.

Do you know what pitch those 3-blade props are that you have on there??

You might have better luck, if you want to stay with those outboards, if you switched over to a suitable Brushless 1/10th scale sized car/truck motor. Something like a 17.5 or 13.5 T would deliver much more torque than the 550 can motors would, and should bolt right on.

[ScarabChris]

Damn, hoses are tight on the cooling coil and the motor cowlings are still filling up. And whats happening is the motors are sucking the water up and blowing it out the tops. They won't last long like that.

[ScarabChris]

OK I did a test run and its obvious these props are too much for these motors. Right away I can tell by the sound they make that they are loading up too much and the boat was slightly slower. The motors got hot and had that "smell" after just a few minutes of run.

The original 2 blade props are 1.25" diameter (not sure of the pitch) and these new 3 blade props are 1.5" (36mm) diameter and 1.4 pitch.

Anyone have a suggestion for props? I was counter rotating 3 blade cleaver props to keep with the scale theme. Or maybe some stronger motors? But then the gear will be the weak link. What a dilemma.

Also....the motors are filling with water, not good. But the hoses might have been lose so I'll have to test that again.

The upside is the trim tabs leveled the boat right out.

[ScarabChris]

Counter rotating props and trim tabs....




Charging batteries and will do a test run. These props are 2 mm larger in diameter so I'm not sure how it will run.

[BILL OXIDEAN]

That is just too cool! Can't wait to see it run!!

What's up Darin, Randy picked up a Spektrum yesterday!
He needs to know what receivers are compatible with what..

[BILL OXIDEAN]

This thing is close to THE most awesome project I've ever seen.
Its going to rip no doubt.

My imagination sees a servo activated trim for the outboards

[Darin Jordan]

That is just too cool! Can't wait to see it run!!

[ScarabChris]

Some new pics of the project....

Mercs to Evinrudes..



Console and lean post..


In water shots..I think it floats perfect. Waiting on trim tabs and props for final testing.

[westbeach]

BL - Brushless
Neu 1527 - Neu Motors 1527 series. Check out OSE for different winds/KV.

If you can't move the batteries too far fwd, you should add ballast to the front. Rather than extending your battery wires.

Your build looks great! Keep the pics coming.

What do you mean when you say "BL" and "Neu 1527"?

Also a question about CG on a boat like this. With so much weight on the back my CG is nowhere near that "30% of the hull from the transom" even with all the batteries way up front. Thats why I extended the ESC wires so I could put them up front. No worries I soldered everything and used a good marine grade wire.

[forescott]

That looks fantastic!