27" carbon cat black edition build

[kfxguy]

My build threads have been slacking. I've been slacking. Had so unfortunate events in my life that have caused that but I'm trying to get back on track. I've been alternating builds as my new shop has much more room. I was limited to one build and maybe an inlay in another boat set up on a folding table before. Not now, much better work space and I'm thankful for that....makes me want to build even more. I've also been out fitting it with tools and things to make my life easier and boats better built and faster built. Anyways, on to the build....

This is my favorite smaller cat hull. I've done a build thread on one before or maybe two. But this one is going to be different. My last was was a huge success with it topping 91mph on just 4 cell voltage. Fweasel convinced me to regrettably let it change to his hands so I must build a replacement. I always try to outdo my last creation (whether it's mine or a customer boat) by making changes to better it in any way possible....and let me tell you it's going to be hard to top that boat. It was a masterpiece, I'll post a pic or two of it if anyone hasn't seen it....it's very meticulously built and hauls the mail. Anyways. My goals with the new one are to go at least as fast but hopefully be more stable (the previous one was very stable as it was) by concentrating the weight of the boat lower where I can all the while making it as light as possible but not too light. Also I need to make a little more room for batteries to fit in easier. So....follow along as I show you what I'm doing on this build.

I want the name either black edition or triple black. I'll cut some decals for whatever I decide. Let me know what you guys like better for the name and it might help me decide. The reason it's going to be a black edition is all the aluminum parts will be powder coated black by me.

Here's my parts list:

27" Tfl mini zonda (what they call it, I call it mini rivercat lol)
Tp power 3650 motor
Spektrum 6240 servo (one of my favorite! This is a bad azz servo)
Swordfish 220x (planned)
Billet rod ends on servo rod
1/8" heavy duty servo rod
Mbp collet
.187 custom made flex (by me)
Custom CNC cut Motor mount (mono Jeff)
Custom CNC Battery trays (mono Jeff)
Custom servo mount (me)
Custom made hardware and a Speedmaster strut and rudder
Ball bearing strut


On to the fun part. Pics and building.

Inlay. Carbon honeycomb




This is the type of motor mount I'm going to use. I have this in fiberglass but I'm gonna resize it and make some changes and make it more compact, made from carbon

[kfxguy]

I hand made this servo mount. It's going in the sponson for a lower center gravity.

[kfxguy]

Getting it lined up and tacked in





I'm using black dyed 5 minute epoxy on this. I've had really good luck with it.

[kfxguy]

So I made these transom brackets and machined the offset bracket for the rudder. Mounted it to the boat and I don't like it. I made them too short on the height and a step had to be cut in the rudder bracket. I did not like it. So I made some more brackets that are 22mm tall bed like 17mm tall so my offset bracket can accommodate a nice Speedmaster rudder, a tad bigger than the previous version. It can be cut down shorter but the extra width is what I wanted, in hopes that I can get it to turn well in sport mode (lower voltage for just zipping around)

I'll get more pics this evening

Notice the slot I milled to keep it lined up. That eliminates extra screws and acts as a nut for the strut. Ever have fun trying to adjust the strut by using an Allen wrench on one side, crescent wrench or wrench on the other and try to move and hold the strut precisely.....no? I didn't think so. This helps a lot!





This is a Daytona I'm building for someone. This kind of bracket is what will be going on the mini. Lightened as much as possible without worry of it bending in a crash.

[CraigP]

What's the material? It looks like more material could be removed for weight savings? Beautiful design, and yes, the strut adjustment is normally a bitch! That's a nice feature...

[kfxguy]

What's the material? It looks like more material could be removed for weight savings? Beautiful design, and yes, the strut adjustment is normally a bitch! That's a nice feature...

It's 6061 aluminum. It has a nice big slot in it, I'll take more pics from the rear, next version will be even lighter. I could use off the shelf tfl parts as their light but they are like pot metal aluminum and bend too easy.

[CraigP]

Oh, you got the right stuff! Just 6061-T6 is heavy, compared to 3003. I was just seeing that the oval that the steering push rod passes through could be taken toward the strut some. I got the same problem on my turn fin bracket, need to mill out some areas and rib it more to lighten it up a tad...

[kfxguy]

Oh, you got the right stuff! Just 6061-T6 is heavy, compared to 3003. I was just seeing that the oval that the steering push rod passes through could be taken toward the strut some. I got the same problem on my turn fin bracket, need to mill out some areas and rib it more to lighten it up a tad...

Im gonna give it some thought on making things lighter. I need to incorporate my gram scale in this adventure lol

[fweasel]

Travis, in terms of improvements over the last build, my suggestions are:

1) some type of flat spot or fixing screw on the rudder to push rod arm. The Speedmaster piece is just a clamp style over that pivot pin and the high speed crashes almost always tweak it out of alignment. Obviously a crash at 80+mph is extreme, but I'll be looking to modify mine to prevent it.

2) shortening or rerouting the rudder cooling hose. With the bulkhead nipple on the opposite side of the strut, it makes for a slightly longer run of hose. Again, in a high speed crash, mine got surgically sliced by the prop and it cost me my final run. Had I the opportunity to do it from scratch, I would route the hose through the rudder mount and into the hull right next to the steering push rod bellow. I might do that over the winter and use the original hole for a drain plug.

Can't wait to see this one progress. These little boats are real head turners at the lake.

[kfxguy]

Travis, in terms of improvements over the last build, my suggestions are:

1) some type of flat spot or fixing screw on the rudder to push rod arm. The Speedmaster piece is just a clamp style over that pivot pin and the high speed crashes almost always tweak it out of alignment. Obviously a crash at 80+mph is extreme, but I'll be looking to modify mine to prevent it.

2) shortening or rerouting the rudder cooling hose. With the bulkhead nipple on the opposite side of the strut, it makes for a slightly longer run of hose. Again, in a high speed crash, mine got surgically sliced by the prop and it cost me my final run. Had I the opportunity to do it from scratch, I would route the hose through the rudder mount and into the hull right next to the steering push rod bellow. I might do that over the winter and use the original hole for a drain plug.

Can't wait to see this one progress. These little boats are real head turners at the lake.

Thanks for the feedback! Helps to improve things a lot. The rudder was already decided on. No more clamp style, the one I'm using is a billet block with a billet arm machined into the block. If you like, I can update yours to this also. Text me if interested.

Cooling hose. Well maybe I can make it come into the top of the transom, or maybe in the transom on the same side as the rudder. What do you think?

Cooling hose length, unfortunately I don't see a way to shorten the run of hose, if you can think of something let me know. I want to not see the hose as it is now, makes for a cleaner install and I haven't had temp problems.

Cooling exit. Yes I agree. However, have you ever tried to slip the hose on the fitting in that tight spot say in the rear Of the transom? Omg the cussing it will involve! I had one of Keith bradlys boats in my possession and it had an exit at the top in front of the hatch. My opinion on that is it looks bad, the hose has to bend to much to make I turn into the fitting and it will be in the way of the esc on this boat because I'd want it in the middle. Plus I don't want to copy him either. So maybe I'll figure something out of the rear trans one but that will make the hose even longer lol. How about just higher on the side?

[fweasel]

Thanks for the feedback! Helps to improve things a lot. The rudder was already decided on. No more clamp style, the one I'm using is a billet block with a billet arm machined into the block. If you like, I can update yours to this also. Text me if interested.

Cooling hose. Well maybe I can make it come into the top of the transom, or maybe in the transom on the same side as the rudder. What do you think?

Cooling hose length, unfortunately I don't see a way to shorten the run of hose, if you can think of something let me know. I want to not see the hose as it is now, makes for a cleaner install and I haven't had temp problems.

Cooling exit. Yes I agree. However, have you ever tried to slip the hose on the fitting in that tight spot say in the rear Of the transom? Omg the cussing it will involve! I had one of Keith bradlys boats in my possession and it had an exit at the top in front of the hatch. My opinion on that is it looks bad, the hose has to bend to much to make I turn into the fitting and it will be in the way of the esc on this boat because I'd want it in the middle. Plus I don't want to copy him either. So maybe I'll figure something out of the rear trans one but that will make the hose even longer lol. How about just higher on the side?

Transom, same side of the rudder would better shield the hose from the prop, IMO. I don't know that the hose needs to be shorter per se, but that the loop is protected from the prop as best as it can be. I was only ever making about 4 passes per set of 4S packs, plus half throttle return trips. Nothing ever got hot, so cooling capacity is not even remotely an issue.

The more I think about it, a top exit on this hull would be tacky, and like you mentioned, difficult to plumb. I suppose as high on the side of the hull as the flat material affords you would be better than centered. I know you're putting the servo in the rear of one sponson, but you could potentially do a through hull pick-up in the other, that would eliminate the hose all together.

[kfxguy]

Transom, same side of the rudder would better shield the hose from the prop, IMO. I don't know that the hose needs to be shorter per se, but that the loop is protected from the prop as best as it can be. I was only ever making about 4 passes per set of 4S packs, plus half throttle return trips. Nothing ever got hot, so cooling capacity is not even remotely an issue.

The more I think about it, a top exit on this hull would be tacky, and like you mentioned, difficult to plumb. I suppose as high on the side of the hull as the flat material affords you would be better than centered. I know you're putting the servo in the rear of one sponson, but you could potentially do a through hull pick-up in the other, that would eliminate the hose all together.

Good idea. Glad you posted, I'm gonna do a through hull pickup. I know they don't cost any mph at all. I tested that. Never got around to testing the rudder unfortunately. Maybe you should do yours like that too. I feel pretty certain I can get the Speedmaster rudders with no pickup. I've talked to harry numerous times, and got odd stuff from him. I can call and not even tell him who I am and he knows lol. Stay tuned.

[dirtdummy]

Looking good!

[CraigP]

Travis, fill the rudder with JB Weld. I'm going to do that on my mono. Got the Promarine Skater today. I think I see the turning problem the guy was talking about. The leading edge of the rudder is behind the front of the prop by almost 1/4"... So I need to fix that. Looks like it came that way, the strut and rudder look stock. It's a surprisingly big and light boat!

[CraigP]

I'm going to put a thru hull water pickups on each side of the Skater, to balance any potential drag. I like two channel cooling...

[kfxguy]

Travis, fill the rudder with JB Weld. I'm going to do that on my mono. Got the Promarine Skater today. I think I see the turning problem the guy was talking about. The leading edge of the rudder is behind the front of the prop by almost 1/4"... So I need to fix that. Looks like it came that way, the strut and rudder look stock. It's a surprisingly big and light boat!

Yea I've done the job weld thing before but in my opinion it's not a very elegant solution to it. I'd rather have some rudders made than to do that. If I can't have them made then I may weld the hole shut (I have a tig welder).


Here's the bracket I originally made that I'm not happy with.

[kfxguy]

My motor came in today. Looking at it closely makes me wonder how anyone could buy a leopard motor over one of these. It's just made extremely well. Notice it has a 8mm shaft necked down to a 5mm. That allows some serious rpm and a better bond between the rotor and the shaft. This is a 36mm motor too. I'm not sure how much influence I had on this but I talked to junlin at tp power about using 8mm shafts in there motors necked down to 5mm for some applications and she told me they could do it custom for me. Then they just started doing it. Best motor you can by for the money or even double the money.

[kfxguy]

Looking good!

Thanks!

[kfxguy]

By the way, I thought I was going to be making a emergency room visit last night. I was cutting the brackets for the strut in my bandsaw, I had just changed the blade and it cut faster than I anticipated and I didn't move my finger fast enough. It bit me pretty good. In the split second it got ahold to my finger it cut over 1/8" deep and through my fingernail. Didn't even hurt, at first lol. Today it throbbed all day long. I thought it was going to give me troubles with bleeding badly because I'm on blood thinners but it didn't thankfully. I felt like a dummy and was not believing I did that. I cut a strip of shop towel, wrapped it around it and then wrapped with electrical tape and went back to milling on the brackets lol.

[Erroneous]

Savage level 9 acheived. Looking forward to seeing this done (with all digits intact). Party on.

[kfxguy]

Savage level 9 acheived. Looking forward to seeing this done (with all digits intact). Party on.

This gave me a good laugh. Yea I guess you right, injure myself and go right back to building boats. Lol I've gotten super glue in my eye and went right back at it.

[CraigP]

You're a boat buildin' Som'Bitch, that's for sure! You gotta slow up on that finger widdlin'!

[CraigP]

Yea I've done the job weld thing before but in my opinion it's not a very elegant solution to it. I'd rather have some rudders made than to do that. If I can't have them made then I may weld the hole shut (I have a tig welder).


Here's the bracket I originally made that I'm not happy with.

What's the matter with that bracket? Just looks like too long a bolt and shave some off the top. It would be beautiful with some 3/16" bull nose radius' all around... Talking about the side bracket..

[kfxguy]

What's the matter with that bracket? Just looks like too long a bolt and shave some off the top. It would be beautiful with some 3/16" bull nose radius' all around... Talking about the side bracket..

The height of it is too short in relation to the knuckle for the rudder. I don't want to have to make a step or angle the width of it. That was rough mockup. I will round it when I'm set on the one I'm using. I have some radius bits for the mill. I should have something whipped up over the weekend. Right now I'm contemplating my choice of flex cable.


This is a fairly small boat, I was considering a .078 wire drive, mbp billet collet and change out the steel screws in the collet in favor of titanium ones to save a tiny bit of rotating mass. Might help some at 45k rpm right? Lol

[golfito]

Very nice construction.

[kfxguy]

For my future reference, the mbp collet weights 15.2g I'll try and lighten it from there. More pics coming soon.

[kfxguy]

On to a new try at a strut and rudder setup. Found some thick angle stock in my stage. First step is to see if I can even machine a accurate slot for the rudder knuckle. The clearance was less than .0005. Pretty good for a first try

[kfxguy]

Then I had to drill and tap for the mounting screw. This had to be 100% accurate and straight. No drill press used for this, only the mill.




Perfect

[kfxguy]

Next it was on to the pivot hole for the rudder. Let me just tell you I was nervous. I already had some time in this thing and if it didn't drill straight then the rudder won't turn smoothly. Notice how short the drill bit it. No flex there so the bit don't walk.





Got that whipped now it's time to lighten it up

[kfxguy]

One hole. Steering rod goes through here.





And another hole just in case lol (Also notice I milked off the extra steering arm, there was one on each side...not using it so it had to go)









I'm