VDub99AML

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Hey everyone, I just got back from running my Super Hawaii. I loaded a video earlier http://www.rcuvideos.com/view_video....bafb4acb29e344 of last summer's run with the stock hardware. Since then, I've installed the Speedmaster's hardware and a very lightweight piece of aircraft aluminum to the transom. Oh, and also a 42mm carbon fiber prop. With this setup, I should be getting even faster speeds than last year, but I am getting the exact opposite. I have played around with the prop angle quite a bit, and have been able to get it to just barely plane. If I make a left hand turn, forward propulsion is pretty much killed due to where I put the rudder-- live and learn. I am wondering if the rudder placement is killing the aerodynamics of the boat altogether? What do you guys think? Am I on to something, or am I missing something else? Currently, I have the prop angle pitched up to be even with the rear part of the hull. I have bought a piece of aluminum plate exactly like what the rudder mount is made of, and I was thinking of moving the rudder back directly behind the prop. Any suggestions/ideas will be greatly appreciated!!!

--Aaron

DuckOfDeath

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What motor are you running and the cell count?

Duck

VDub99AML

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Graupner 700BB Turbo on 12 cells in series

DuckOfDeath

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That's the same placement that I have on my Purple Light, and the same placement that my friend has on his Super Hawaii, so I don't think that is your issue. Both of our boats plane relatively quickly. Also, Rooski, who often posts here, has the same set-up. When I beefed-up my transom, I used ABS plastic and made sure that I epoxied it to a nice sharp edge on the botom, so as not to create drag. I cannot tell from your picture how the aluminum meets the bottom of the boat. It might be creating drag, it might not.
I run an 18 volt DeWalt drill motor on 21 cells, and my friend runs a 700BB on 14 cells., With turn fins on both sides and trim tabs, neither of us seems to have an issue with losing power in left or right turning situations.
I know this isn't much help, but if it eliminates the issues that are not your problem, then you might be able to pin point what is the problem.

Duck

rooski

Looks nice. As Duck says, I also have this set-up. I run 14 cells and the boat gets on plane in a < second and is waaaaaaay faster than stock (~26-28mph) and significantly faster than when I use 12 cells.

It would be helpful to also see the insides of your boat. Our Purple Light versions of the SH allow for the motor to be placed nearly in the middle of the boat which makes for nearly perfect balance. Your original SH has the motor compartment in the back so you may have to adjust to that a bit. Otherwise, I don't know why it would be only as fast as stock. There is something in the equation that is clearly wrong. As duck says, can we get a close up pic of the bottom of your transom from the side to check for drag and also strut alignment.

Have you checked the batteries? Put a voltmeter on them and make sure they are getting a peak charge. Also, you should repeak them right before you go boating. NiMh likes to be warm to be efficient.

How hot does the motor run?

Also, any boat with an offset rudder is hard to turn when it's not on plane. Don't move the rudder. When you get the boat to plane it will turn like a big knife

VDub99AML

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Alright, here's some pics as you requested. I have adjusted and tried different prop angles, and the way it is set up now had best results. I have not however tried different battery positions ( both across along the top), and I did not recharge the batteries before use. They sat for about 2 weeks since the last charge. After a run at WOT, the motor did not hardly get hot at all, and the batteries got mildly warm. They did not get nearly as hot as last summer when I was running the boat (like in the video) with the X445 prop. Thanks for your help so far, hopefully this will get figured out! I wanted to take video yesterday of the crappy run, but I could not get anyone to go with me.

n.h.schmidt

Hi

I have worked on a Purple Light. It was converted to 12 cells and a old type 8.4 700 motor. Using a CF 42mm prop it will run between 22 and 25mph ,depending on the batterys. You boat should be able to do at least as good.
You should use your batterys almost right off the charger or no more than a hour or two later. Waiting days or weeks will loose most of your charge. I race electric boats .Nobody I know would try to run with anything but a fresh charge.
You did not say what 700 turbo motor you have . 8.4 ,9.6 or 12V? If it is anything but the 8.4 you will have miserable results. Personally, I would recomend a 700sc motor from Offshore electrics. It could gain you several mph over any of the Graupner motors. It dosn't cost any more either.
One thing we have to accept is with surface drive is ,left turns will never be as good as right turns. Even with a central placed rudder.
The SH is a huge boat for a 700 and 12 cells .That means everything has to be right or the results will be poor. They will run though. 26 to 28mph should be possible when using a 700sc on 12 cells.
About your prop, could you give me the Graupner part number? Haveing the right one makes a huge difference.

That Astro ESC controller is a good one. Should be up to everything you need it for on this boat. I have several and there is one thing you should be checking on .Are you really getting full speed? Sounds dumb but, its easy to not be gitting full speed out of them. It all depends on where the neutral is on your radio and how much travel you have to full on.
Thats about it for now .I hope I haven't stepped on you toes too hard. I like to help whenever I can. until next time
n.h.schmidt

VDub99AML

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Hi n.h.schmidt, to answer your questions: I have the 8.4V motor. The prop I'm using is the Graupner carbon fiber prop (first ones at the top of the list on offshore's site.) As for full speed, I left the boat out of the water at the pond, and free reved the motor. It sounded like it was getting good RPM's, and in the water it sounded like it was cranking pretty good. Maybe with a load the batteries are not providing enough power after sitting so long. Once again, I wish I had a video from yesterday as it would prolly make a world of difference. I would like to get back to the pond ASAP with fully charged batteries and try that.

rooski

Two comments...first, I would get new batteries. Those Venom 3300's are ...I'm sorry to say, not that good. They also look like they have been thru hard times and are probably well past their usable life. Get some GP3700 7-packs (maxamps.com) with Deans connectors then of course change out all connectors to Deans. BTW...I just buried an even newer set of Venom 3600's after they died after about 25 cycles. As NH said...you should peak your batteries before each run to warm them up a bit. Knowing Venom batteries, you probably were under 7.18v for each pack when you started your run if they sat cold for 2 weeks. Not good, especially for a power hungry 700BB 8.4.

Second. I would back out the drive shaft about an 1/8" or so to free it up a bit. When power hits a flex cable, it shortens and your drive dog gets pulled into the strut bushing, which of course causes massive friction under load.

Strut angle looks OK.

VDub99AML

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Ok, I just took 3 batteries off the charger. All 3 of them measured from 8.68V - 8.82V. I am going to go to the pond here soon to take a test run. Hopefully this will show good results and the problem will be fixed. One other thing, some of you are saying that you're running 14 cells? Isn't that overvoltaging the motor? I read in the spec sheet that it is recommended up to 12 cells. I know that 14 cells is only 2.5V over, but I didn't want to take any chances of frying another motor (another being all the 500 size motors I killed by running them in parallel-who knew? lol.) Well, gotta get to the pond before it gets dark!

--Aaron

n.h.schmidt

Hi
Roosky is right about the cells and the Deans connectors. The low cost ones can't take it for long. I have seen cheap packs give it up after three runs .That was with a 12 cell mono and a 700 motor too. You don't have to use the best but the cheap ones aren't a worth it at any price. The gp 3300s are now old hat but, still good solid cells. I have seen them at Radio shack at good prices. n.h.schmidt

rooski

Let us know how it goes. Also, 700BB's love 14 cells. They need water cooling and perhaps brush cooling with 14 but they also need the extra power. Look on offshoreelectrics.com website under motors and read about the 700BB. 12-14 cells is fine.

VDub99AML

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I looked into deans connectors on ebay, and found some good deals as long as they're not some cheap off brand kind http://cgi.ebay.com/Deans-Style-T-Co...em270034762520 . I just took the boat out for 1 run. It went better, but still not as good as the previous video. I moved the driveshaft out 1/8" as you suggested rooski. I don't know if it helped or not, but I would imagine it did. The batteries were I'd say warm-hot to the touch (not unbearably hot), and the connectors themselves were hot to the touch, telling me I need to break down and buy those deans connectors. $11 shipped for 10 pairs is pretty good I'd say? I looked at maxamps.com and found those 7 cell packs- $110 for two 7-cell packs- wow. But I guess you have to pay for speed. Thanks again for your continued support!

--Aaron

VDub99AML

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Here's a video of today's run. There is no sound for some reason, but maybe someone can see something i'm not. Still not as fast as last year.