Identical configuration on two different hull types...substantially different results

[fidelity101]

Zero water at full throttle? You have my curiosity on that one. But I have on occasion made a teardrop shape out of the holes. As long as you do not round the rear scooping part of the intake

I think I may have done exactly that to both of the rudders. I took a hobby knife and removed the sharp edge along all sides of the hole...even the back portion. Can I save the rudder by drilling the chamber a little deeper or did I screw it up permanently?

Any chance that Sparten has a offset rudder and at full throttle the intakes are out of the water?

No, the rudder holes are always in the water.

Here are a few pictures of the holes
display.jpgIMG_2578.jpgIMG_2582.jpgIMG_2581.jpg

Looking closely again at the pictures, I think I'm ok in terms of the rear portion of the hole...I didn't remove enough to cause a negative difference. (hopefully)

The blue rudder is from the Spartan. Water shoots out about 4-6" at 50% throttle depending on which way the rudder is angled. It seems to increase or decrease pressure based on which direction I'm turning the boat...weird I know. If I do a full throttle pass, I have yet to see water come out of the holes. Once I slow down again, the water comes shooting back out in a few seconds. I decided to try my luck at opening the holes on the rudder because of limited water flow out the side of the boat. Opening the holes did appear to help a little but I have zero flow at full throttle and I can't figure out why. All lines are new, water flows freely through the entire system as there are no obstructions or kinked lines.

[srislash]

Those don't look bad. The aluminum finish one being the better with the trailing 'scoop' still intact as far as I can see.
I would think the oversize drill bit should work to fix up the Sparten one. With a light gentle touch as that drill bit will want to bite into the rudder and tear it up. I will go see if one of my tear dropped rudders are handy

image.jpg

Not my best one but you get the picture. This one supplies two motors in my Geico twin

[fidelity101]

Thank you once again! That's exactly what I needed to know. I opened up the top and bottom of both rudders to make that same tear drop shape and it looks like I still have plenty of material between the rear scoop portion and the actual elbow inside the rudder (90 degree portion of the inner hole). I'll post again once I've had a chance to test the new modifications to the rudder.

[dasboata]

Thank you once again! Last question I swear. :)

Is it "ok" to open the water intake holes on the Aeromarine dual intake rudder? I used a hobby knife to remove some of the material surrounding the two intake holes, thinking it would increase the amount of water going in and up the rudder. I did the same thing on the upgraded dual intake rudder that's on my Spartan and I have excellent water flow at half throttle BUT zero water flow at full throttle.

Yes by all means open it up use a dremal or a file tapper the opening even more is the challanger pro a 43 or a 48?

[fidelity101]

I used a dremel 1/8" metal ball bit to open the hole a small amount and created the same "tear drop" shape that srislash pointed out. The boat is an Aeromarine Challenger Pro 48" hull.

I'm not sure why the stinger was set to a negative pitch but I have it back to zero degrees and a very slight bend in the trim tabs. I'll mark CG at 33" of the hull which should be approximately 16" from the transom. Hopefully I can dial this in before those new props arrive. :)

[dasboata]

[ATTACH=CONFIG]122564[/ATTACH][ATTACH=CONFIG]122565[/ATTACH][ATTACH=CONFIG]122566[/ATTACH][ATTACH=CONFIG]122568[/ATTACH]

I'm new to fast electric boats so I'd like to know if it's normal to have such a large different in power consumption.

Conquest: 150A and hitting 66mph. The entire hull is out of the water and I know catamarans are generally faster than deep V/mono hulls.

Challenger Pro: 200A and hitting 56mph. The entire hull is out of the water and I'm having problems with chin walking...I think that means I have to adjust the stinger or is it a CG/battery placement issue?

The funny thing is that BOTH models pull about 50 amps at half throttle. I'm not sure why the Challenger Pro is going so much higher in amp draw, but I may have to step down to a smaller prop if I can't figure out out as the temperatures were jumping into the 60C-65C range.

The 48 is just not going to handle well above 50 MPH the bow catches to much air pretty sure I told you to stay away from the 48 ? get a vector

[srislash]

Ahh, Chris is doing some props for you? Good show.
I would just try the stinger at neutral and then try the tabs. One thing at a time;-)

[fidelity101]

I purchased this boat as a ready to run boat minus the ESC as he didn't sell the Swordfish..which I purchased separately from OSE. The boat didn't come with a transmitter, receiver, spare parts, etc. Since this was the second boat I purchased from this seller, I figured this boat would arrive with the exact same items being they were both "RTR minus ESC". So rather than continuing to ask for help AND the missing parts, I figured OSE would be a better place to get assistance. I really appreciate everyone's help!!!

The stinger arrived with a slightly negative angle and the trim tabs were at different heights. So for the first few runs, I set the trim tabs to zero degrees and left the stinger alone. I focused on battery placement and noticed that moving my 6200mah 10S batteries even an inch resulted in some pretty large changes. I had the batteries to far forward on the first run and I was pushing 219A while the boat plowed through the water. I moved the batteries back about 2" and it ran better but I started having a lot of chin walking at full throttle...but max amp draw was 189A.

Hopefully I can get this out in the water a few more times before the snow starts falling. :)

[fidelity101]

The 48 is just not going to handle well above 50 MPH the bow catches to much air pretty sure I told you to stay away from the 48 ? get a vector

You did! :)

This boat doesn't need to be a speed daemon so long as it can handle rough water conditions. I'm going for better run times which is why I wanted to step down from the CNC 55mm prop. I think that 50mm 3 bladed prop will be the perfect prop to get me in the 50mph range at top end.

To date, it's been my experience that increasing speed is almost exponential to amp draw. This Challenger Pro runs 50A at 50% throttle. At 100% throttle, it pushes up to 200A. I've clocked speeds of 55 and 56.9mph with the stinger slightly negative and neutral trim tabs. With any luck, I can reduce amp draw by setting up the boat properly which will also increase the boats handling. Setting this boat up as a 50mph boat is my goal. Running beside my full size boat at 35-40mph would be ideal with the ability to step on the juice if needed. :) I was also running the boat in a 10S1P configuration so I'm sure the amp draw will change when I switch to a 10S2P configuration and add another 2.5 pounds of battery weight.

The Vector will probably be my next boat...but I'm going to built it myself. My friend Brian wants the Donzi I have so I'll probably buy some gear from you in the next month or two as I start that build process. :)

[iridebikes247]

I think you'll like 10s2p the extra weight may increase amp draw a tiny bit but not by much imo. 50 mph is a good goal but don't be afraid of amp draw and a little bit of heat the components you've got are very capable, the extra weight may sort out some of the handling problems you're having at speed as well.

[dasboata]

You did! :)

This boat doesn't need to be a speed daemon so long as it can handle rough water conditions. I'm going for better run times which is why I wanted to step down from the CNC 55mm prop. I think that 50mm 3 bladed prop will be the perfect prop to get me in the 50mph range at top end.

To date, it's been my experience that increasing speed is almost exponential to amp draw. This Challenger Pro runs 50A at 50% throttle. At 100% throttle, it pushes up to 200A. I've clocked speeds of 55 and 56.9mph with the stinger slightly negative and neutral trim tabs. With any luck, I can reduce amp draw by setting up the boat properly which will also increase the boats handling. Setting this boat up as a 50mph boat is my goal. Running beside my full size boat at 35-40mph would be ideal with the ability to step on the juice if needed. :) I was also running the boat in a 10S1P configuration so I'm sure the amp draw will change when I switch to a 10S2P configuration and add another 2.5 pounds of battery weight.

The Vector will probably be my next boat...but I'm going to built it myself. My friend Brian wants the Donzi I have so I'll probably buy some gear from you in the next month or two as I start that build process. :)

I have a beter feel for the boat now I might change the prop I am going to send you : )

[fidelity101]

Yes thats quite a bit of negative take that out and then put cg at about 33-35% and trim attitude w/ trim tabs

Based on this information, I was pretty far off! I went in the workshop tonight and checked my estimated CG location...it was 15" from the stern. That's about 31%. I was able to move the batteries all the way forward (about 4.25" further forward) and my CG is now at 15.75" which is 32.5%. Hopefully that will be close enough to start as I'm going to be hard pressed to move the batteries any further. It makes sense that my CG was to far aft as that would have raised the bow and lowered the stern. The stinger was at a negative angle which lowered the bow. I'm guessing the two incorrect adjustments were working together to mask the problem...making my hull run very wet? Time will tell as the weather is getting pretty bad here in Buffalo.

I found this video on youtube last night...his boat is running much better than mine!

https://www.youtube.com/watch?v=9057JzW1JlY

[fidelity101]

Prop differences! - Thank you DASBOATA

I spent a little time at the lake getting the Challenger Pro dialed in and the results seem to have paid off. The boat ran very well at various speeds with no bouncing, chin walking, etc. The stinger is set at 0 degrees, trim tabs are barely down and the CG is set at just about 31% or 15" from transom. Running some pretty heavy battery packs 10S2P with 5S 6200mah 30C lipo batteries from CHL (ChinaHobbyLine). They seem to be holding up "ok" but I'm definitely going with Revolectrix next year.

As you can see from the graphs below, the props make a HUGE difference.

CNC 55mm prop: Last clocked at 55mph top end and I didn't have a chance to retest but the speed is similar. I peaked out at 212A, 7891 watts and my temps him about 45C (given it was low 40's F outside temperature!)

ABC 2414/3 prop: I had trouble reaching 100% throttle as it had to be pushing high 60's-70's and the lake was small. This prop will be perfect for my AM Conquest! Amp draw hit 247A, 8982 watts and 49C. The swordfish ESC didn't even break a sweat so I could probably go even further but the speed scares me...almost to much to handle on this hull.

Prather 250 SS prop: This is the only prop I was able to speed test using my GPS. It came in at a perfect 50mph on the dot! 178.5A max, 6996 watts and it stayed below 42C. Run times are great, the prop bites into the water from a dead stop and acceleration is perfect! I found the perfect prop for this boat! Thank you DASBOATA.

Now I'm going to take the Conquest out for a spin with that 2414/3 and see if I can push it into the 80's. (Although it may have to wait until next year! :)

55mm CNC prop on 10S2P configuration in the Challenger Pro.jpg2414-3 Prop on 10S2P in the Challenger Pro.jpgPrather 250 SS on 10S2P in the Challenger Pro.jpg

[dasboata]

Excellent,, glad my prop picks put a smile on your face

[fidelity101]

do you have the factory single pick up Rudder. If you haven't already get a dual pickup rudder and plumb the esc and cooling jacket on their own circuits. Also pull that nipple of the rudder and inspect for burrs possibly being restricted there. I hope that helps happy boating ��

Thanks for the tip AMP EATER. I do have the upgraded twin intake rudder, but I foolishly went with one from ebay rather than buying the one from OSE. I'll remove the nipple and see if maybe there are some burrs which could be negatively affecting the waterflow. I also purchased the boat in this thread so I plan on using that rudder (hopefully it's the OSE version as I never bothered to ask) to see if it helps the water flow issue. It's a very strange issue as I haven't been able to find anyone else posting similar problems with the Spartan nor do I have this problem with any of my other boats. It's very possible that it's just a cheap rudder and the inside is full of burrs and defects which interrupt waterflow when under a certain pressure. (The one I'm having problems with is a HOT RACING rudder.)