Finally Broke 40!!!!!

[scooterP]

I finally made it past 40mph today!!! It was actually 41mph on the nose. I honestly didn't think I was going to be able to do it with the stock motor. I had done many 37 to 38.9 or so on water with a little chop and smooth as well.

Currently I'm stock except for OSE cooling jacket and 42x55 Grim prop. Other self done mods were minor mods of the cooling system and just under 5oz of lead right in front of the motor. I also have a home made port turn fin.

I'm running 2s5000 Turnigys with the front of the packs mounted up to 1/2 of the motor can. If I go any further, it looks to run too wet. I tried to compensate by raising the strut. This raised the bow a little but no improvement in speed......usually 37 to 38 with the handling suprising really good.

To get the 41 today I basically took the strut back to neutral or just a smidge (technical term) positive. Front of packs were just past the motor mount plate, and tabs right on neutral. It was fast, but as the pond started to get choppy, not nearly as stable as with the batteries more forward.

Of course without my gps in the front of the boat, I can move the batteries a little forward and maybe keep the speed and have stability.

Thanks for listening Thoughts and suggestions are more than welcome

[tiqueman]

Congrats on breaking 40 scooter. I know how you feel w/ it. I struggled for quite a bit to get 40mph on 4S in a 32" cat. I finally got her to 41, then went to 5S.. now Im trying for the magic 50. Im 1.5mph off.

My SV is getting the work next. Im glad to hear it will get 40 on mostly a stock set up.

Congrats again... now go for 42

What C rating are your Turnigys? I ask becasue I went from 20C to 30C and that made my 32" cat go from 40.5 to 41.5.

[scooterP]

[QUOTEWhat C rating are your Turnigys? I ask becasue I went from 20C to 30C and that made my 32" cat go from 40.5 to 41.5.][/QUOTE]

They are 20c, but the packs state 20 to 30c. Since I'm just a sport runner, I just went with the cheaper packs

I've got some different size carbon props on the way to see how they run.......it is an obsession

I've just got to get someone else near me interested. I still enjoy it, but running alone just ain't good all the time.....

[tiqueman]

[QUOTE=scooterP;126500 They are 20c, but the packs state 20 to 30c. Since I'm just a sport runner, I just went with the cheaper packs[/QUOTE]

I just got mine from Hobby city a couple days ago. I was running 2 2S Reedy 5000mah 20C. I got the Turnigy 5000 2S 30/40Cs.. and that gave me the 1mph. But that was cheating.

Ive had quite a few evenings of sharpening, balancing, thinning and detonguing props over last few weeks. Ive learned A LOT. Some of what makes sense, some I still dont get. But keep trying, props, cog, added weight, take out weight, get your cog as low as possible, scuff the hull, anything you can do to squeak every little fraction of a mph out of her and improve the handling.

Maybe soon I will actually get to run my boat and say "hey, that was nice, Im not changing anything" .... not sure if that can happen though.

And I hear ya on the gettin someone close to you interested. My boat racing bud moved to Alabama. BUT, Ive got his gas boat in the garage for when he comes down which is pretty often.

Keep up on the tunin. Im sure there is more in there

[scooterP]

On balancing props....I've done the learning thing on that as well. I think I have my 42x55 pretty good. I guess that comes from 20 years of making sure all of my helis spinning pieces are well balanced.
Detonguing.......that is something that I haven't quite built up the nerve to take on yet. I can see the benefit, just want to make sure that I feel that I can do it without screwing up my one metal prop that I have. I have the prop as sharp as my pocket knife....so I think that "should" be enough on that.

I like the fact that there is always a little more that can be done based on water conditions, equipment, and race environment. I'm a tweaker....

[785boats]

Well done on the fine tuning to get that extra speed. Now I think you can go up a size in the prop. In my opinion you are not yet using the torque that the motor has to offer.
I would suggest an Octura X642. Or an X445.
Sharpen & balance them & see how it goes. Then if, as you say, you like to tweak things you could detongue them. Or you could try those props in the M series which are pretty much the X series already detongued.
I've run the SV27 package in a smaller hull (25") with an X645 prop with no problems. Not sure how it would go in the SV27 hull though.
Watch the temps for the first few runs, & run times will be shorter.
Cheers.
Paul.

[scooterP]

I'm expecting some "testing" props to arrive tomorrow, and one of them is a CF Graupner k series 45, also a 47.

I actually tried out a friends Octura x647 that he runs on his Villian. The hole shot was great, but speed suffered....37mph. I'm also pretty sure that the temps would have been pretty high if ran more than a couple of passes.

Hopefully this weekend I'll get a chance to do some testing. I ran today at lunch with my same setup but with my GPS more centered in the hull and the batteries right past the motor mount but only got 37. I'm using my Blackberry as a GPS with some really neat free software and it seems to work well. The only drawback is the weight added in the nose.

Taking the GPS out means that you have to tweak a little more to get the handling back on par.

[tiqueman]

Look at lots of pics of props that have been detongued. Then just do it. Take a little off, resharpen and balance it, try it, then take a bit more. Baby steps have not let me down yet. Get or make some play doh. It works great to make sure your blades are shaped exactly the same.
If you really want some good advice on prop work, ask egneg on this forum. He helped me out a bit with a wealth of info. Gave me the confidence I needed to start grinding... Check out this post, especially page 3 I think it is when I start to mod props... I learned a lot and am still moving forward with it. http://forums.offshoreelectrics.com/...t=10195&page=3

[scooterP]

Yep, that's what I did when I bought the 42x55 prop. I did a bunch of reading then just wnet for it. Measured and cleaned everything up and sharpened. Threw it on the balancer and worked it until I was happy with the balance. It runs smooth, but I think I could sharpen it a little bit more. I'm going to do some reading on the detonguing, and then see what happens.

[scooterP]

Well, I tried a Graupner k45 prop....I thought it was the m type, but was mistaken. Speed much slower and took a while to get on plane. What is the difference between the k and the m series of this prop?
I did detongue the 42x55 prop a little and rebalanced. It's been hard to tell if I'm doing any better since I did that becasue it has been windy here and the water was so rough that I could not hold it full throttle for any duration without everything getting out of shape in a hurry. I did get a consistant 38 to 39 with it. Hopefully the next outing will have smoother conditions. A little ripple would be optimum over glassy.....at least that has been my experience with the SV.
I've also picked up another motor with a 2085 kv rating that I'm going to work with. It's a 51 amp motor, so I'm going to watch the esc close.

[rockwerks]

Hey scooter have you scuffed up the bottom of the hull yet? It helps to break the surface tension on the water. Its usually good for another MPH or more. I use 220 grit sandpaper and lightly swirl over the riding surfaces of the hull

[scooterP]

I scuffed it a little right after I got the boat and started reading the threads here. I don't think it is "scuffed enough" because I did it with some 400 sandpaper....it's all I had at the time. I was checking it last night because it didn't seemed too smooth still. I had basically just knocked the shine off of it. I'm going to use some 220 on it this afternoon and see how it does this evening.

[6S HYDRO]

get rid of the weight and move the batteries flush to the front of motor

[scooterP]

Yeah,
I'm going to play around with that a little. I had the batteries up to that point just a minute ago testing out the new motor and it was still pretty wild......even with the 4 oz of weight. The pond was a little rough as well. If would start to chine walk at full throttle if I went across any cross current. I'm going to do a little tab bending....just a little and see what I get. I'll put the GPS in it this evening and see where I'm at.

The motor runs extremely cool, but the esc seemed a little hotter than with stock. I don't want to burn it up so a little bit of testing to see how it's going to do. I'm still very new to this, and my only electric experience is with helis.....which I don't think pull near the amps of a boat.

[785boats]

ScooterP.
Have a close read of Post #5 in the following link. These tips By Darin Jordan have settled many a Sv27.
I realise that it is for a Formula Fastech but the trim tab mod & setting is the main point for the SV I think

http://forums.offshoreelectrics.com/...Bend+trim+tabs
Cheers.
Paul.