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View Full Version : First Run w/38x63



Drag Boat Bob
06-12-2009, 12:42 PM
The 38x63 performed better than the 38x55 (at least for me). Ride was a bit more loose (which I am looking for), but still not anything close to wild. GPS - 47.5mph.

It handled crossing the wake well without getting out of control. It is also much better at acceleration out of the turns. It has better bite on launch also. No torque roll (hospital hop or whatever you guys call it) except momentarily in rough water.

Temps are still not an issue, but then this is what I would expect at this load level. I expect the L40x57 and M445 to make temps a concern. I will most likely try the L40x57 next and I base that solely on what I have read here, as I am an old 2-blade guy.

I still have more testing to do with this prop.

More to follow... :thumbup:

bigpapa
06-12-2009, 01:27 PM
chine walk lol good luck keep us posted

Drag Boat Bob
06-12-2009, 06:07 PM
chine walk lol good luck keep us posted

Chine walk...ok. From my old drag racing days that term was only associated to boats with a chine, like flatbottoms. However, I am ok with that.

Odd thing today. While charging my batteries one of them appeared to secrete a clear fluid. Only a very small amount, but it was enough to cause the seal-wrap to start to come off (approx 1/2 in from corner).

Both cells charge ok and are equal. I balance every time at .5c. Has anyone experienced anything like this? :confused1:

I think I will call MaxAmps when I get back to my home.

Drag Boat Bob
06-12-2009, 08:50 PM
I shifted some weight and tightened down everything and made another run. The boat rode looser than before and I could hear the prop getting air when crossing a wake. Overall I am happy with this prop. GPS - 48.6mph.

I might make one more run (with adjustments) before moving on to the L40x57.

One thing for sure, I need more than one set of batteries.

bigpapa
06-12-2009, 09:48 PM
picked up mph thats good temps were ok

TCR
06-12-2009, 11:58 PM
What is your strut depth w/ the 38x63?

Drag Boat Bob
06-13-2009, 10:28 AM
picked up mph thats good temps were ok

The motor temp was 126 and the ESC cap was 112. Deans were 119. These batteries have never heated up (always <90). Could be that with the exception of the boat's first run (all the way to the LVC) all are relatively short runs.

Actually I don't know what a "reasonable" run time is. I seem to be putting back around 2500 mAh back into the batteries (MA 6500 mAh). I'm sure someone can say if this is "reasonable".

I hope to get more runs in before I have to leave this lake (on vacation), but with it being the weekend (and leaving Monday) more people are showing up with the big boats. We'll see...

Drag Boat Bob
06-13-2009, 10:34 AM
What is your strut depth w/ the 38x63?

I started at the stock depth of 15/16" and with the prop changes, needed to drop to 1". Have not needed to drop any further as the ride wasn't excessively loose.

Drag Boat Bob
06-14-2009, 12:48 PM
I realize that 4 consistencies do not constitute empirical data, but it is enough for me to conclude that there is a problem with one of my batteries. There is a 3+ mph difference with a particular battery series. Simply put, with no other changes to the boat, the speed changes when one of the batteries is used on a particular lead (1st in the series connection).

I am now certain that one of the batteries is leaking a clear fluid on discharge. I will take this up with the manufacturer when I return home.

I have decided to delay testing of the L40x57 until I resolve the battery anomaly.

The L38x63 is a great prop and I will continue having fun with it for now.

Thanks to all who provided guidance. I am learning at an exponential rate.

Drag Boat Bob
06-15-2009, 12:09 PM
I decided to get in one last run before leaving this lake. Water conditions were absolute glass and no wind. I think I found the sweet-spot setup for this prop. GPS = 50.2 mph. :thumbup1:

It was a 1.4 mi. run and leaky battery or not, this is the best I have reached with this setup. Temps: Motor 121, ESC Cap 119, deans 108, batteries 86 & 94.

I really love this prop… now if I could only drive…

I’ll be testing the L40x57 in a couple of weeks.

bigpapa
06-15-2009, 12:12 PM
the 38x63 great speed, no chine walk at all ??????

Drag Boat Bob
06-15-2009, 12:25 PM
the 38x63 great speed, no chine walk at all ??????

Only when crossing its wake and then it subsides to a perfect sponson skip. It looked as close to a perfect ride as I can explain. I am sure the water conditions had something to do with it.

I have found that placement of the GPS has been crucial. It has made the difference of 4 mph. I believe that 'balance' is key to the ride.

Lifter props, do just that "lift" the back end. When the balance is too far back or forward it hurts performance.

bigpapa
06-15-2009, 12:28 PM
i here ya tks for the testing info and happy racin

Brushless55
06-16-2009, 09:45 PM
Only when crossing its wake and then it subsides to a perfect sponson skip. It looked as close to a perfect ride as I can explain. I am sure the water conditions had something to do with it.

I have found that placement of the GPS has been crucial. It has made the difference of 4 mph. I believe that 'balance' is key to the ride.

Lifter props, do just that "lift" the back end. When the balance is too far back or forward it hurts performance.



where do you place your gps ?

Drag Boat Bob
06-17-2009, 07:11 PM
where do you place your gps ?

I ended up with it as far forward as I could get it, but still in the back of the boat.

Drag Boat Bob
06-18-2009, 07:02 PM
I ended up with it as far forward as I could get it, but still in the back of the boat.

Here is where it ended up.

Brushless55
06-18-2009, 09:59 PM
Awesome, that's where I run mine..

6S HYDRO
08-12-2009, 12:18 AM
Just got mine tonight, and ran it 41.1 mph on 4s and 46.0 mph on 5s but i did not have nearly enough lake. That was on the stock plastic. I picked up a 38/63 for this boat and i will run it tomarrow.

Drag Boat Bob
08-12-2009, 12:31 AM
Just got mine tonight, and ran it 41.1 mph on 4s and 46.0 mph on 5s but i did not have nearly enough lake. That was on the stock plastic. I picked up a 38/63 for this boat and i will run it tomarrow.

Be careful if you decide to run 5s... many have ended up with molten electronics.

6S HYDRO
08-12-2009, 01:49 AM
Oh believe me i know to be careful... Only saw type runs. Came back cool after the 2 passes

6S HYDRO
08-12-2009, 04:26 PM
Hey bob, what about your strut angle w/ that prop? Neutral

Drag Boat Bob
08-12-2009, 06:39 PM
Hey bob, what about your strut angle w/ that prop? Neutral

My strut is about 1 degree negative.
Rudder is about 1-2 degrees positive.

I think that the L38x63 is designed for a flat 0 strut, but for what ever reason, this seems to be working well for me.

Brushless55
08-12-2009, 08:18 PM
what whould you say is the best overal prop you have used sofar?
also what prop has given you the best top speed?

Thanks

Drag Boat Bob
08-12-2009, 09:31 PM
what whould you say is the best overal prop you have used sofar?
also what prop has given you the best top speed?

Thanks

I'm not sure if this question was directed at me, but here is what I have experienced so far with my stock setup...

Favorite prop: L38x63 .. best speed with this prop is 50.2mph.

I love the acceleration without noticeable cavitation. Great out of the turns, as I am not an experienced driver and sometimes turn too sharp and shed speed. I will admit that the boat was not turning to my expectation and I moved to the top hole on the servo arm.

Best speed overall: L42x66 = 52.3mph. I have only tested this prop a few times and speed was slowing each time (as with the other larger props). I found that my nicely tie-wrapped motor leads were melting the insulation together. The other temps were not out of spec however. I have now changed to the 5.5 bullet connectors, so we will see...

Lubrication tests will begin on Tue 8/18 and I will use only the L38x63.

After that its hammer time...

Brushless55
08-13-2009, 12:35 AM
yes I was asking you..
Thank you for your info, just what I wanted!
I'll have to order a 38x63

I have tried Amsoil grease on my boats, and to me I like it better than the speed grease

amishjeb
09-29-2009, 10:33 PM
So Drag Boat Bob, do you recommend using a two-blade? If so which gives better acceleration and speed ratio? I am thinking of changing to a two blade prop for reasons that is "more efficient" and provides less "drag" from reading sailing articles. As one lets off the throttle on a three blade prop, the water current forces against the blades with no escape. At least with a two blade, there is the chance that the water flows through and meets smaller resistance that the three blade prop.

Drag Boat Bob
09-30-2009, 11:06 AM
So Drag Boat Bob, do you recommend using a two-blade? If so which gives better acceleration and speed ratio? I am thinking of changing to a two blade prop for reasons that is "more efficient" and provides less "drag" from reading sailing articles. As one lets off the throttle on a three blade prop, the water current forces against the blades with no escape. At least with a two blade, there is the chance that the water flows through and meets smaller resistance that the three blade prop.

The debate of 2 blade vs. 3 blade is one of popular opinion and factual results. Each has its positive and negative attributes. I can only comment on my personal results.

My all time favorite prop (for the UL-1) is the Grim L38x63 (S&B). It is not the fastest in top speed that I have tried, but hooks up real well. This helps me when I turn too sharply and shed a bunch of speed. It also doesn't make the boat go spastic.

I have tried the L40x57-3 which went just as fast as the L38x63, but did not accelerate as well.

The L42x66 was faster, but the boat was not as controlled (seemed to increase the spastic factor). It also made the components run hotter (but not out of spec).

As always when trying larger props, make short initial runs and watch your temps

In my opinion, there are 2 things to watch out for on the UL-1:
1. The capacitor on the esc. It is not sufficient for larger props on extended runs.
2. The motor leads may need to be replaced to larger bullet connectors.

If you find the temps getting high you may want to do what I did here:
http://www.rcgroups.com/forums/showpost.php?p=12281523&postcount=487
http://www.rcgroups.com/forums/showpost.php?p=12282500&postcount=490

Bob

amishjeb
10-01-2009, 12:56 PM
I am going to give that a try today in boring out the fittings on the motor jacket. I wonder if it was intended as sort of a "low pressure" value to keep some of the water in the jacket.

L38x63 sounds definitely like a winner prop!! :iagree:

I don't know if that capcitor overheating is an "overvoltage" issue. However, I read some posts that involve UL-1 users running close to 20Vdc on the ESC. Using more voltage is never good because along with current is resistance. Resistance is the number one producer of electrical heat.

I will be sure to watch the ESC and the "hot cap" issue when I order the L38x63.

Thanks Bob!

6S HYDRO
10-01-2009, 01:13 PM
cant get my 38/63 to hook-up at all anymore, it hit something and i straighten'd it ou and re balanced and sharpened, now nothing

Drag Boat Bob
10-02-2009, 01:07 AM
cant get my 38/63 to hook-up at all anymore, it hit something and i straighten'd it ou and re balanced and sharpened, now nothing

I had that happen to my x640. It looked smaller after I re-sharpened it. Never was as good after that.

amishjeb
10-02-2009, 01:43 PM
I had that happen to my x640. It looked smaller after I re-sharpened it. Never was as good after that.

Cu-Be (Copper-beryllium) props are easily moldable and cupable, so I am getting a S220 Prather Stainless steel proper, which is better at preventing dammage.

Drag Boat Bob
10-02-2009, 10:21 PM
OK Amishjeb, looks like you have it all figured out.

Make sure you tell us how you do.

BTW, nothing will prevent damage when you hit something...

Bob

amishjeb
10-03-2009, 09:28 PM
Well, would you rather have a bent prop or a chipped prop? I think the stainless steel will chip more than bend. I usually run my boats on big lakes or the Great Lakes where nothing usually hits the props. I received my L38x55 prop, which looks beautiful. I am waiting on a prop balancer on e-bay. Hopefully, I get my new water jacket and prop from OSE, so I can run my boat one final time before it gets too cold to go in the water.

I will let you know my results Bob.

Brushless55
10-04-2009, 12:03 AM
I would take the bent over chipped..
the Stainless wont bend and could cause damage to the drive if something hard is hit with it..