Blackjack 26, time for an upgrade

[Shovelnoserc]

Not too long ago I purchased the blackjack26BL off a board member here.

http://forums.offshoreelectrics.com/showthread.php?33188-PROBOAT-Blackjack-26-Brushless-RTR-with-programming-card

It all went well til late this afternoon during my second run, the stub of the flex shaft broke off. Lost the prop.
http://i269.photobucket.com/albums/jj65/SR-1ION/0c79e76c.jpg

It was great, so now I'm taking suggestion on a new flex shaft and prop, it has the stock motor and esc.

I will be doing 80% of my boating on salt water
http://i269.photobucket.com/albums/jj65/SR-1ION/71a8dfb6.jpg

Also Ive noticed it's a bit unstable when going against the waves or while turning too fast. Most of the time I was able to reduce speed and level it back up, but a few times it flipped

[JIM MARCUM]

First of all, STOP running in saltwater! One bad flip or crash can destroy all things electrial & if the LIOPs fry it can ruin your hull.:flame42:

I live in San Diego and our only official boat pond is saltwater. I've ran my gassers there, but will never run my expensive FE boats there. The only freshwater lake that will let me run my boats is a 30 mile round trip - but it's well worth it.

As to flexshafe, put the largest one you can w/o being too snug. Maybe a 3/16" setup. I'm still running the stock Blackjack drive & haven't had a problem, yet.:Praying:

Second, get an offset ruder adptor from OSE or Pro Boat. With a strudder like yours the propwash will make your boat squirelly as Hell and lousy in turns. JIM

[Chuck E Cheese]

i wouldnt worry about the saltwater. im in hawaii and we dont have freash water. i have been running high end fe set-ups in the salt for years with no problems (outboards included). all it takes is a little extra maintnence when your finished. the blackjack is known for being unstable in the turns, thats just how that boat is. it is a great boat and fast on the straights but no mater what it will not corner wide open... have fun and enjoy it...

[Shovelnoserc]

Thanks, similar to Hawaii I am in Puerto Rico surrounded by saltwater I have found waterfalls, rivers and mixed salt/fresh "lakes" but no 100 fresh lakes yet. I'm visiting hobby shops to find new places but most run at the sea shore.

[Shovelnoserc]

What size and length flex cable do I buy to replace this one?

[Shovelnoserc]

I posted the above question, because when I looked at the fillers site it shows a .125 flex shaft, but I finnaly got home and it measures .130, so at least I know which one to purchase now w/ a 3/16 stub.

[Shovelnoserc]

Fullers

[JackBlack26]

I don't know why the strut is so far back. Looks like it broke apart due to the cable whipping since it looks to have no support from the end of the tube to the front of the strut. I would replace the stuffing tube and get something like this. This is my nitro to electric conversion that I have had in my garage for at least 4 years. Finally looking to get it done this week. The strut alone(no brackets) is herehttp://www.offshoreelectrics.com/proddetail.php?prod=ose-80975 I'm using 3/16 prop shaft with .150 cable in 1/4 tube with brand new teflon liner.
http://i157.photobucket.com/albums/t72/rlopez75/c3222211.jpg
http://i157.photobucket.com/albums/t72/rlopez75/90b8701a.jpg

[Shovelnoserc]

Thanks jackblack26. I've gotten that comment from everyone that has seen the boat. It seems that it is advertised by fullers as a catamaran upgrade

Here is the link:
http://item.mobileweb.ebay.com/viewitem?itemId=120375965842
Sorry I'm using the phone.

I bought it this way, it works all right. I've bee listening to a few guys here and on different forums, I'm considering changing the strut, maybe keep the rudder, although an offset one would probably turn better.

Btw is that shrink tubing?

[Shovelnoserc]

http://i269.photobucket.com/albums/jj65/SR-1ION/2a2d69f4.jpg

[JackBlack26]

Yeah, the shrink tubing helps to keep the water from rushing up through the stuffing tube, in to the boat.

Yeah, I know its a Fullers "upgrade" but my question of why it was so far back was more rhetorical than literal:tongue_smilie:. As in "why the h3ll is that so far back?!", lol. Looks good but dont see what the gain is from having the prop so far back from the boat. I always wondered that.

Also, the rudder OSE sells for the Formula Fastech bolts right up to the stock rudder holes.http://www.offshoreelectrics.com/proddetail.php?prod=dh-prb3756

[JIM MARCUM]

I think you're on the right track. I've sheared off flex shafts the same as yours did. It was caused by too much flex between the stuffing tube and the front of the strut. Depending on the strut, sometimes you can drill out the strut enough (but not so deep to hit the bushing) to slide the stuffing tub into it about 1/2" or so. Finish up with some shrink tubing to help keep the water out. You will likely need a new, longer stuffing tube. But make the bend gently - not like the sharp bend shown above - starting about 1 1/2" from the strut. Sharp bends cause more friction on the flex drive, and wears out the stuffing tube faster.

The reason FE people use an offset rudder is to keep it out of the propwash. In straightaways, a strudder rudder is in the comparitively high velocity counter-rotating propwash which makes the boat twitchy & overly sensititive to rudder input. In turns it causes the rudder to over react and hard to control. Some of my boats - Miss GEICO, Black Jack, Apparition & my 56" Segad - came with a strudder and all were so squirely the boats would twitch all over the place or roll over in the straights http://www.youtube.com/watch?v=IPZGtssIXyQ , and were lousy in the turns. After changing to offset rudders they were like entirely different boats. Steady in the straights and smothe in the turns. JIM:cool2:

[Shovelnoserc]

Thanks, to all.

I just ordered the .130 flex shaft with tubing so that I can do just what you said there (same thing my uncle suggested).

[Stephavee]

I think you're on the right track. I've sheared off flex shafts the same as yours did. It was caused by too much flex between the stuffing tube and the front of the strut. Depending on the strut, sometimes you can drill out the strut enough (but not so deep to hit the bushing) to slide the stuffing tub into it about 1/2" or so. Finish up with some shrink tubing to help keep the water out. You will likely need a new, longer stuffing tube. But make the bend gently - not like the sharp bend shown above - starting about 1 1/2" from the strut. Sharp bends cause more friction on the flex drive, and wears out the stuffing tube faster.

The reason FE people use an offset rudder is to keep it out of the propwash. In straightaways, a strudder rudder is in the comparitively high velocity counter-rotating propwash which makes the boat twitchy & overly sensititive to rudder input. In turns it causes the rudder to over react and hard to control. Some of my boats - Miss GEICO, Black Jack, Apparition & my 56" Segad - came with a strudder and all were so squirely the boats would twitch all over the place or roll over in the straights http://www.youtube.com/watch?v=IPZGtssIXyQ , and were lousy in the turns. After changing to offset rudders they were like entirely different boats. Steady in the straights and smothe in the turns. JIM:cool2:

Also you can use your offset rudder to fight prop walk instead of using rudder trim just move the rudder outboard of the prop (if off set to the right side of a counter clockwise rotating prop) the drag on a rudder in "clean" water is far less than dragging it through high speed prop wash!

[JIM MARCUM]

:iagree: JIM

[JackBlack26]

not like the sharp bend shown above
I assume you're talking about the picture I posted. The bend may look sharp but its not. This boat has very little deck height so a gradual bend is not possible without making the stuffing tube in to an "S", which is how the stock tube actually comes, or cutting a very oblonged hole for the stuffing tube to come through the bottom of the hull. But you wouldn't know that without actually have built one of these boats. It also has a Teflon liner so wearing out the stuffing tube is not an issue when you factor in that it will be well greased. And lastly, this isn't my first build. The App, Geico, and Segad have way more space to make a gradual bend than this boat does. I have owned all except the later.

[JIM MARCUM]

:iagree: some what. My Apparition Pro & Segad have enough room to park my Kia Soul in. However, I don't understand the concern of making an oblong slot for the stuffing tube to pass thru. Every FE catamaran I've seen - except bare hulls - have a slotted hull for a gently curving stuffing tube. Some use S shaped stuffing tubes, and some argue that an S tube has slightly less friction on the flex shaft than a gentle curve. But I don't think you will find much support from experienced FE builders that a sharp bend in the stuffing tube won't cause the stuffing tube excess wear & put unecessary drag on the flex drive. Friction is your :cursing: enemy.

Oval slots ane easy to make and make bending & aligning a new tube far easier. For a scratch build: drill hole in hull, form slot with a round rat tail file. If replacing a stock tube, it's probably already slotted.

As to using teflon liners or no liner, I've heard from people with 30 years of RC boating experience - including several FE SAW record holders - on both sides of that issue. My preference is no liner.

Because running w/o a liner, it will prematurely wear out thin brass tubes. I use seamless Stainless Steel stuffing tubes on my builds, and when replacing a worn/dammaged stock brass tube. In my experience, for full sized or model boats, Stainless Steel beats brass anytime. Maybe I just like shiny things.:biggrin: JIM

[JackBlack26]

For a sport build this works just fine. I'm not trying to break any SAW records, lol.

Good idea on running stainless on your builds. I like running Teflon because it's easier to swap out the liner rather than having to replace a tube.

As for the bend, whether it be 1, 30* bend or 2, 15* bends in an "S" bend, its still the same amount of friction. You cant escape physics. I know one long slit across the bottom of the boat would have fixed that but I didn't feel like cutting a 2 inch slit when I can just run the liner and call it good.

:beerchug: