70" CRC Outerlimits Electric Build

[WheelMan]

Took the first onboard video a couple days ago.

[bogieboy]

looking great!!!

[WheelMan]

Had this thing out on the water a few times since my last post, with all this good weather we've been having. I've played around with a few different props. Taken some more videos. All in all, this boat is a blast, and I'm very happy with the results so far. Not too bad I don't think, for a first time boat build, and for the size it is.

My original prop for this build was a 1.4 pitch 62mm 3 blade. I quickly found out it was not enough prop for the boat. I bumped up to a 1.4 pitch 70mm 3 blade, which did better, but I still thought it needed more. I then went up to a 1.4 pitch 74mm 3 blade. This prop did much better than the 62 of course, but I still wasn't satisfied with it, as it was starting to run toward the hot side, and the cavitation on launch was bad. It just didn't seem to perform out of the hole like I expected it to with that massive powerplant, and I knew I couldn't go bigger on the prop. After some thinking, I remembered learning something interesting about 3 blade vs 2 blade performance on a much smaller single prop mono I have. I found on that little boat that 3 blade props could not match out of the hole performance of 2 blade props. The 3 bladers would cavitate horribly, and create more heat in the electronics. So I decided to give a 1.6 pitch 70mm 2 blade prop a try on this big Outerlimits, and boy did it come alive! I think I've landed real close to the perfect prop for this boat. Acceleration is much better, the electronics are happy, and I've met/exceeded my speed goal, as you can see from the photo below.

I have some cool video I'm working on putting together for a new YouTube upload. So stay tuned :)

IMG_20200613_171916.jpg

[fweasel]

Glad you found the sweet spot. 2 blades are more efficient than 3 blades, and it doesn't seem to be causing you torque roll issues with the diameter you're running.

[WheelMan]

Glad you found the sweet spot. 2 blades are more efficient than 3 blades, and it doesn't seem to be causing you torque roll issues with the diameter you're running.

Yeah I've been pleasantly surprised and very pleased with the lack of torque roll. During the build it seemed that many, including myself, thought it might suffer from that. However, I only notice it a tiny bit on hard, fast, full throttle launches. Maybe the large size and weight of the hull, combined with my battery placement being toward the outer edges, helps keep torque roll under control? Regardless, whatever it is that's keeping it in check, I'm very happy with it. I do think I will move the batteries forward a little. I believe it will benefit from shifting some weight forward just a touch more.

Anyways, I got my previously mentioned video compilation uploaded last night. Check it out. Hope you all enjoy. It was a fun couple of days running it on the river.

[nsrcboatguy]

That is a great looking boat you have there and you did a real nice job on the build.

If you don't mind me asking how much did it cost to build for parts? I am thinking about changing some of my gas boats to electric because of the noise factor and was wondering the cost difference. What kind of run times are you getting?

[WheelMan]

That is a great looking boat you have there and you did a real nice job on the build.

If you don't mind me asking how much did it cost to build for parts? I am thinking about changing some of my gas boats to electric because of the noise factor and was wondering the cost difference. What kind of run times are you getting?

Thank you, very much appreciated.

As far as cost into parts only directly related to it being electric, I'd say there's roughly $2,700 in it. That would be the LMT 30100 motor, MGM 40063 Controller, MaxAmps Batteries, custom motor mount by Peter Zicha (punisher_67 on here), motor collet/coupler, 8mm bullet connectors, and some miscellaneous hardware.

[nsrcboatguy]

Whoa! Thanks for the info. I guess electric isn't very cheap compared to gas parts!

[WheelMan]

Whoa! Thanks for the info. I guess electric isn't very cheap compared to gas parts!

Electric setups certainly do not have to be this expensive. They can be done for a fraction of that cost, with other brand components. About 70% of that $2,700 is for the motor and ESC I chose to use. There are much much cheaper alternatives out there, if you desire to keep the cost low, which still perform very well and have good reputations. My point being, do not use my build as an example of what electric boat setups cost. This is near the top end of the scale.

[nsrcboatguy]

Ok, thanks for the info. I will look into some options then! Keep up the great work with your boat!

[RubeBwoyFishman]

Travis,

Really love this build and thinking about doing on myself. Can you send me a list of the brands and part numbers for the hardware you used? Also, who do I need to talk to to get on of those motor mounts?

Franz

[Jesse J]

Post #52 gives you most of your answers.

[WheelMan]

Finished up the boat, before it headed off to it's new owner. Had no plans of selling it, but a regular customer of mine just had to have it, so I couldn't turn him down. I can (and will) build another, so stay tuned!

Anyways, as I said, I finished it up, getting the permanent battery mounts in. I learned a lot of lessons, do's and don'ts, etc with this build, which I will use to improve upon the next one.

A few photos below for those interested. And big thanks to those who followed along, gave advice, helped with parts, etc. Very much appreciated! This build was a blast, and I am excited to start another large mono build!

IMG_20200719_200206.jpg IMG_20200719_200058.jpg IMG_20200719_195941.jpg

[fweasel]

Trays turned out very nice. Can't wait to see the next one.

[WheelMan]

Trays turned out very nice. Can't wait to see the next one.

Thank you, I was happy with them. They're nothing fancy, but they turned out good, and work great.

Regarding the new build, something I've been pondering, but haven't found much info on yet: with a twin drive setup, or even single for that matter, can the rudder be ahead of the prop(s) or does it need to be behind (not directly, just further rearward) of the prop(s)? I've started collecting parts for the next build, and the length of the stingers + props gets out there a ways and am curious if I can use a rudder with a shorter arm that places it in front of the props vs using a super long arm to get the rudder out behind the props. I have no knowledge of the effects of placing it in front, just seems I have not seen it done. Seems the rudder is always behind the prop(s). Figure there must be a reason for this, but of course am questioning if its possible maybe everyone does it that way because they're all just following a trend, or if there's a real functional reason for it. Anyone with some knowledge on this, or experience, would be greatly appreciated.