Blackjack52

I asked because of the size of the prop.....a 54mm.
Isn't that going to be a bit too big?
"The bag stock X447 prop on my 800 powered boat is very nicely balanced. Maybe I just got lucky. I won't finish a metal prop for this boat till I find the right size. A 54mm CF prop is next, those are in stock."

You had to mean a 45mm.

rooski

It's a Cordite 820 motor...not a 700. It can easily push a 54mm prop...maybe bigger This is in my 41" SH boat. I was just referencing this boat because that is where I put the unfinished X447. Here's a pic comparing it to a 540 and a 700 motor. The thing weighs a pound and puts out ~3/4 HP. Sorry for the tangent off topic.

Blackjack52

My bad. I misunderstood. Thought you were talking about a SV stock motor pushing a 54mm prop and I didn't want some newbie to see that figuring it could be done.

Wheelnut

My Feedback: (81)

I finally had time to remount my new replacement motor but I could not remember which way the mount faces so I looked at some pictures on the water cooling thread and found that it was mounted the way I have it in now. See picture. But I don't remember the coupler being so close to the stuffing tube. Seems too close to me. Could everyone please take a look at this and see how your setup is and post some pics. This would be interesting to find out if maybe this had something to do with why some of us had binding problems.

Speederson

sorry no pic but that is how mine is also. About 1/16 space and no problems so far.

Waterlogged

Same here, like 1/16inch. And 1/16inch sticking out the back behind the prop. -WL

Wazool

Same here, very little space between coupler and stuffing tube. The same between drive dog and strut. I read here that you should cut a new flex cable 1/4 longer then the original o account for binding. I checked my strut and there is no scratch marks from the dog touching it.

Wheelnut

My Feedback: (81)

Thanks guys, that pretty much sums it up. Just wanted to make sure. Thanks again.

gunnut

Let's talk about trim tabs. Here is what I understand: Trim tabs DOWN will keep the boat in the water and the increased drag lowers the top speed. Trim tabs UP will allow the boat to get out of the water but will make the boat handle more loose. Correct?
I'm running with my tabs a few degrees down. A Graupner 42mm CF prop.
Another question: what happens when you change the angle of the turn fin?

Blackjack52

Your right on track with trims. But remember, the more chop will also dictate your trim. Glass (loose) water, trims at more pos to keep her from running too wet. The wetter you run, the more stress on motor and batts and the more heat in both. The more chop, the lower your trims will be to keep her stable, but she will run faster. You have to really find your own settings for the different water conditions. Start with very small changes and you'll see how much will be affected. Too much neg trim, she will submarine. Too much pos trim and she will flip bow over stern, backwards. If she starts to chine, try offsetting the trims about .25-.5deg down on one side.

Keep a log, unless your young enough to remember.

Hope this is helpful.

Oh, turn fins further back will negate the reason for having them. You'll have to play around with this position too. If the top of the turn fin edge is parallel with the brace, your good for starters.

gunnut

Thanks Blackjack for the helpful post. I will have to keep tinkering with the setup.

Are you guys taking the tabs off to adjust them every time?

Blackjack52

You're Welcome.
Go with adjustables.
http://www.rocketcityracing.com/pilot.asp?pg=products
pg 2, the smallest ones or wait for the OE ones.
Until then,
Be very careful adjusting on the boat. Good tip while I ran the OEM trims: get some silicon seal and put it in the bolt holes that hold the trim plates on. Then get some electrical plastic ties (the smallest ones=1/32 and 1/64 thickness, perfect for making 1-2 deg changes) and cut the beginning part off (the thinnest part). Use these as a "wedge" to adjust the pos/neg deg. Use different thicknesses for diff wedge. Any plastic will do. The silicon seal is to keep water from seeping into the holes from making the adjustments here and there.
Just a suggestion.

Blackjack52

Bump............

Orange Crush

You gotta lay off that stuff.....

SuperArnie

Yep, itll make holes in your brain!

SV27dayton

First I appologize as I have not read all the threads in detail (hard to do when they are growning faster than I read). Three questions:

1. What kind of thread locker was used on the oem rudder? I stripped two of the set screws trying to get them out. I couldn't belive how much torque I was putting to them.
2. Can I buy just the shaft for the rudder anywhere. Mine didn't come out in one piece. (ease to push in but rudder blocks ability to push it back out).
3. Has anyone sharpened their rudder? Mine has about a 1mm flat spot on the front of it. As much attention as the props are getting I'd think this would be "low hanging fruit". Just concerned about stability.

Ohio lakes are starting to freeze so it's time for some heavier experimentation.

Thanks

Wheelnut

My Feedback: (81)

I use blue locktite, it holds good and can be worked loose when needed.
Aboat sharpening the rudder, I guess you might see 1/4mph difference.

SV27dayton

Whatever he's putting on them during original assy is much stronger than blue. It looks white. I use blue too and that's how I'll assemble it after I re-tap the holes. I was thinking that if the water pickup was moved to the transom like some other have done the rudder could be made to be much thinner. Again I don't know if this will compromise stability or not. Maybe that last bit of resistance back there keeps the thing pointing forward.

Blackjack52

The rudder has it's particular shape for many different reasons. The basic of course is turning. If you do sharpen the rudders leading edge, be very careful as the aluminum will chip if sharpened too much. If you sharpen the trailing edge, you will undoubtedly decrease your performance. The rudder needs dull trailing edges to create a pocket of air behind it. The trailing edge shape and cut at the top leading edge also provides the lift needed when cornering. Or less lift, depending on how far under or behind the rudder is positioned.

Wheelnut

My Feedback: (81)

exactly

SV27dayton

OK. Sounds like I can proceed with teh sharpening. I've whittled plenty of Aluminum so I think I know where I'm going with this. But I know what not to do now. Thanks! Now where can I get the shaft? I think I'll be using a "modified" drill bit for the time being but would like to get backt o OEM if possible. Should I consult the great and powerful Grim?

Wheelnut

My Feedback: (81)

SV27dayton, what really would have been nice, is if you would have done a gps speed reading before and after with no other mods to see if there is a difference and exactly what that difference would have been.

Grimracer

SV27Dayton

The locker is some powerful stuff for sure. I have to tell you its about as close to red as you can get.. Next time use some heat ( i place the tip of my soldering iron on the part) and heat it up. The heat will help loosen the locker.

The shaft is 3mm.. a drill blank is your best bet.. hea.. have you designed boats before?? if not you have a good sense as to what to do..

To sharpen the rudder.. I use a file for starts, 600 wet to get a good edge and finish with a stone..

Keep us posted

Grimracer

SV27dayton

To wheelnut: Yea that would have been nice. Being an engineer, I'm data dependant type guy. Only trouble is I used my GPS fund but buy a SV27 . What's a good good GPS for what we're doing. (I assume lighter is better)

Grim: Thanks for the locker advice, I'll use it next time. No formal RC boat design experience but I went fast in full size boats and did pleanty of tinkering. Seems like alot of the same tricks work here. In '99 a close friend lost his life in an accident and I got out. Recently, my wife saw me getting the itch to do it again. SV is my passifier. So far it's working well.

Wheelnut

My Feedback: (81)

I have the Garmin Forerunner201 but I have not found how to make it log the maxx speed. I know other people have the Forerunner101 and they can record the maxx speed on it.