Sprint Cat 29 Build

This will be my 2nd build thread. First was a SV27 which was my first FE boat and it turned out great. Hope this one does too & I hope you guys can get something out of it!

I purchased the Sprint Cat 29 hull from Fightercat57 here on OSE. Awesome seller, btw!
Came with a water-cooled motor mount, strut, rudder, servo mount, and some other misc small bits to help with the build.

Fightercat57 also steered me in the right direction with a Leopard 4074 1050kv motor & 80HV esc. I'll be running her on 8s.

Here's the hull before I received it:
Attachment 58306

I got the hull and electronics in the mail yesterday, took a picture or 2 but haven't gotten them off the camera yet. It looks exactly the same anyhow.

The Hull definitely needs a lot of work. There are plenty of low spots and paint drips or something strange going on with the paint. Also, the rudder I received is a great part, but I think it only attaches with 2 screws. I may look into a different mount for it to line up with the 4 holes in the hull properly. But that'll be a while.

The "standard" hatch's paint is badly cracked and worn, that'll all need to be sanded off. I'm not a big fan of how it's shaped and it doesn't fit on the hull flat, so I may just do some heavy modification and create something new out of it. Might do something different with the turbine hatch as well, it's not 100% my style either. I'll try to end up with 2 nice painted hatches either way though. Stay tuned! :tongue:

This hull alone could take a week or 2 of my free time to get ready for paint, so don't expect a quick build. I'll try to keep it well updated however, so hopefully there will be something new to see every couple days.

So far, it just worked out that my other 2 boat's paint schemes matched the motors inside them very well. So I expect to end up with a cat that's got some red in it due to the Leopard motor.

And away we go!
-Jeff

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I guess that's the only good picture I got earlier. Still builds the excitement a bit.

I got a small bit of sanding done and checked over all my parts. Not much progress on the boat itself.
The PVC boat stand is all done & looks good, however.

Here is a link to my Sprintcat .21 build. Not the best thread, but you may find it a little helpful.
https://forums.offshoreelectrics.com/...=sprintcat+.21

Thanks for the link, definitely some useful info.
Hadn't even considered the troubles of taping down the turbine hatch. I don't like the looks of it though, so some major modification was going to be in the works - Now I get to add the taping issue into the thought process.

The classic hatch is also not a style that I can live with, so we'll be reversing it and doing some modification as well. Already started on that one last night, actually. Still trying to get my 28" mono painted up, so I haven't put much time into the sprintcat yet. But she is atleast started!
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Got some time in on the build over the weekend.

Removed a lot of old paint on the top/sides of the hull. Then I filled and straightened/leveled the top of the sponsons (if they're called sponsons on a catamaran?)

Also did some rough blueprinting of the steps on the bottom of the hull for now. My autobody metal filing tool works great for cutting straight and level, now I just need to find a nice level surface to help when finishing.

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You can see in the previous post the direction I'm going with the hatch. Running it backwards and rounding out the "front" of the canopy part.

Here's one last picture - took it last night before spraying a guide coat of primer on the top of those sponsons. I think I'll need to apply a light coat of glaze to get it perfectly even, still felt a little low in one spot on the left side.

Attachment 59528

I told you the progress would be slow! But with my 2nd boat's refinishing almost complete, I should be able to invest more time into the sprintcat pretty soon :)

Oh, and if anyone has a rudder or even just a rudder bracket that mounts with 4 bolts, please send me a pm if you'd be willing to let it go for a reasonable price. The rudder I got with this cat bolts to the hull with only 2. I'd much prefer a 4-bolt mount, especially if it might fit the existing holes in the hull. So yeah, let me know if you got one. Thanks!

I like the work you've done to the hatch, looks like it'll work well and look great at the finished stage. Well done!!!:thumbup1:

Looking good so far as for the hatch on mine I did a sub hatch which was a easy fix and works great the only isue with a sub hatch on this hull is the motor height what I did is moded the piece of lexan to fix that problem

Thanks for the kind words, glad you guys like the direction i'm going with it!

Here's a quick update, taking the body lines out of the center portion where it meets the hatch. Should be smooth and sleek when done.

Attachment 59722

Oh, also spent a little bit of time today building that pvc rig underneath it in the picture. Awesome work stand for the sprintcat, and should work with deep v hulls too!

Finally got out in the garage again for a little while. Removed lots more old original paint down to the gelcoat (time consuming and tedious work!) and then filled some low spots, finished evening out that front tunnel part, and the hatch modification is nearly complete. All paint is just primer to fill and seal for now:

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Starting to look good man!

Thanks :)

It's getting cold already here in MN, so I haven't been out in the garage much this week. Hopefully I can invest in a decent sized electric heater soon so I can keep going with this. This weekend is supposed to warm up again, but I fear it'll be the last warm weather we get this year, lol.

So, slow progress still. Glueing and painting in the cold isn't my favorite thing in the world. Need that heater!

Been chopping up the turbine hatch most recently, seeing what kind of hatch I can make out of it that looks sleek and not nearly as obnoxious. Pictures to follow soon.

Haven't given up on the project!
I did get the bottom of the sponsons done, removed all paint down to the gelcoat* and then filled a few spots on edges where there were actually tiny air pockets between the gelcoat and fiberglass (not terribly uncommon the way most fiberglass work is done with the gelcoat and fiberglass mat production methods. It's tough to get that fiberglass pushed in real tight in those molds. Same thing happened with some of my autobody panels on a project back in school.)

Anyhow, got the ride pads as straight and sharp as I think I could. Still removing the last of the paint off the bottom of the tunnel. Tough to get in there. I also did some more sanding and filling on that standard hatch. It's getting there. Haven't touched it in atleast a week, but wanted to get an update in here. I think it helps me get motivated to "talk" about it. I think feedback helps even more ;)

Oh! And I finally got that pesky rudder problem sorted out. Had to get some plane parts from hobbyking and so I went ahead and got one of their rudders:
http://hobbyking.com/hobbyking/store...75MM_BOAT.html
Was about $15 with my platinum membership :p
Might be a bit long, but I can always cut her down after seeing how the boat runs with it. I just hope it works well enough sitting back 75mm. Seems that Cat rudders are usually a little closer to the transom. There was another one that I liked better too, but it just ran out of stock before I was going to put my order in.
I'll need to plug the water pickup since I'll be doing in-hull pickups, worked good when I did on my SV27 rudder. It just looks so much cleaner to me when there's no cooling line coming out of the hull!

Finished paint removal & sanding the bottom of the hull & did some test fitment of my hardware & electronics.

Picture 1 I'm almost done with paint removal. This really was a pain in the butt, but I'll be much happier applying all new paint to the gelcoat rather than hoping all the old paint sticks. Little bits here and there flaked off pretty easy, so who knows what would have happened. Glad I did it right. Just REALLY delayed the progression of this build so far.
Attachment 62508

Here's the hardware on the back. I'm going to have to drill a new hole in the supports for that strut to get it to mount in the right place. You'll see that the bolt going through the supports is way behind where the strut needs to be attached. I hope that the rudder is okay that far back too. Cats usually have it closer to the hull from what I've seen. Guess we'll find out!
Attachment 62509

And here's the power setup. The motor sticks up quite a bit for the required angle of the stuffing tube, but luckily the way I've got my hatch setup, it fits under there with plenty of room. Whoohoo!
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I kind of forgot about this build once the cold hit, whoops. I think all I did since my last post was some smoothing and finessing of the hatch and the sponsons a bit. I haven't done any boating this year either!

Gotta get my butt in gear. I'm going to put this hull on the workbench this weekend and see what happens.
Maybe I'll get motivated that way and atleast fill the water exit in the bottom of the tunnel. Then perhaps I can install the pickups and the hull should be ready for paint, if I can come up with a scheme I'll be happy with.

...I did say this wasn't going to be a quick build, lol.

Success!

Got a little bit of work done over the weekend:
*Plugged the water outlet hole in the bottom of the hull
*Drilled the 2 other holes for the rudder bracket that I had previously neglected
*Filled all sorts of small blemishes here & there
*Dremelled out most of the old carbon fiber & epoxy hull floor reinforcement (the old material was softening and actually peeling up here & there)
*Laid a fresh coat of epoxy and fiberglass reinforcement around the floor of the hull where the stuffing tube passes through after grinding out the old material.
*Sprayed a coat or 2 of primer and re-sanded most of the hull exterior & H. Re-sharpened the sponson edges and such a little bit as well.
*Installed the 2 water cooling outlets, one on each side of the hull.

Still need to figure out the water inlets and lay down new hull reinforcement inside, but things are finally progressing again! Oh, and I need more primer...

There's not much to show of the progress this time, but here's the current state anyhow:
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Lots more work done...

Laid down a nice new fiberglass floor in the hull, strengthened the motor mount (still don't like not having a rear support with the large motor, may have to work on that), went ahead and primed everything and prepped it for paint.

I then painted the hull a base of white, and laid a really nice blue down on the sponsons. & then cleared the whole hull.
Of course right afterwards I realized I had yet to tackle the water inlets. So I might need to respray the rear ride pads after I put those in. I'd really rather not run any kind of external inlet system.

I had a few issues spraying the hatch next. The first design was wonderful, but the paint lifted and some of the white came up with the tape after I sprayed the blue. So I simplified the design and just shot the whole top blue. Not unhappy with it, but it makes me think I should have just done the entire top of the boat blue now. Instead the white just looks out of place.

But I had the hatch close to done, was just cleaning it and using a tack cloth to ensure there wasn't any last dust settling down on it when I dropped the stupid thing on my garage floor. Damaged the front corner of the hatch & scratched the top of the lid. Very upset. So I filled the missing corner and sanded the nicks out of the paint.

Need to go pick up a new can of blue and then respray the hatch. The white was unaffected, but I'm thinking about just doing the whole hatch blue now. I'd definitely do it if the hull didn't have the white on the front of the tunnel but I really don't want to monkey around with paint on the hull anymore. Thoughts?

Sorry there's no picture yet of the white on the hull, but the front of the tunnel is mostly white. Just use your imagination. It's there under the masking tape!

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Thinking about getting one of these.
Does anybody have any motor/battery recommendations for this hull?

As one option, I mentioned in the first post here that "Fightercat57 also steered me in the right direction with a Leopard 4074 1050kv motor & 80HV esc. I'll be running her on 8s."

I really want to try this setup because it'll run lower amps with the higher voltage. But I haven't got it put together yet, obviously. That guy really knows what he's talking about, so I'm pretty confident in those components performing great in this hull.

Otherwise I usually see 27"-30" catamaran or deep v hulls set up for high power with with a 4074 size motor in the 1800-2200kv range on 4s. I've been out of the rc boat world for a season now, but that's what I recall and have that size Tacon 2200kv in another one of my boats & I'm really happy with it.

Might be able to do a p-spec setup too for class racing, with a 36mm Aquacraft 1800kv or 2030kv on 4s? I don't know if there are other requirements for that or not.

I have a much harder time figuring out all the prop sizes and what's best for each application.
-Jeff

Puttzing around in the garage a little bit here and there. Haven't made it out to get new paint yet, sop the hatch is still unfinished. Took a few shots of the hull anyway though. Mounted some of the hardware too.

I still don't like how the white stops at the windshield. I may need to re-try the design that I messed up on the first time, then there will be some white on the top of the hatch too. Just need some more white and blue paint.

Definitely digging the color though.
I still need to tackle the dual water inlets too. Need a bunch of brass tubing for that. And some sandpaper & patience.

As for the prop, there's just a grim 42x55 (s&b) there now. No idea how That'll run. I'm guessing I need a larger prop with the low kv motor on 8s?

As always, thanks for looking! Hope someone else out there can get something out of this thread & all my efforts :)
-Jeff








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Oh! Dropped in a JR DS821 digital high-torque servo too & ran some linkage. Things don't really line up very well through the hull, but after a few carefully placed bends in the pushrod, I think it's working out alright.

Can anyone tell me if these servo specs will be enough for a boat of this size and speed?
Torque:
4.8V: 72.0 oz-in (5.18 kg-cm)
6.0V: 88.0 oz-in (6.34 kg-cm)
Speed:
4.8V: 0.19 sec/60°
6.0V: 0.15 sec/60°

Thanks!
-Jeff

I run 9kg Servos myself but they are readily available where i am. Those specs should be ok thou. Nice build BTW can you tell me what colour blue that is i love it :thumbup1:

It's a Duplicolor spray can, I think in the Perfect Match lineup. Tossed the can, unfortunately. Still need to pick up another one though, so I'll pay attention to the name for you.

Looking online quick, it could be either "Intense Blue Pearl" or "Newport Blue Pearl" or "Medium Quasar" too. Maybe even "Bahama Blue" but that's on the lighter side.

My Napa only had one real nice intense blue, but it's gotta be one of those. The photos here of course look a little different than how it looks in person. And until I polish that clear coat a bit, it won't really *pop* like it should.

There was also a really cool deep blueish teal that I had considered that you should take a look at if you go paint shopping.
-Jeff

Looks great so far. I need to just get started on a project myself.

Hey Jeff,

I would recommend this one bro. I used this on my SM29. The one in my Avatar. It's a 29" deep-V and I used the same rudder that you ordered from hobbyking. Never has a problem with it.

http://www.servodatabase.com/images/...axxas-2075.jpg

http://www.servodatabase.com/servo/traxxas/2075

Quote:

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Originally Posted by tagasagwan

Hey Jeff,

I would recommend this one bro. I used this on my SM29. The one in my Avatar. It's a 29" deep-V and I used the same rudder that you ordered from hobbyking. Never has a problem with it.

http://www.servodatabase.com/images/...axxas-2075.jpg

http://www.servodatabase.com/servo/traxxas/2075

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Yep, I like those servos too, have one in my TenaciousVEE. If you're patient, in the states, they're pretty easy to find brand new for $20 shipped on ebay. I figured I had a decent new servo sitting here anyway, so I dropped in the one I had. Plan on making this hull as waterproof as I can anyhow, so hopefully I won't need the servo to be waterproof.

The rudder still seems awfully long. We'll see how it works though!
-Jeff

Oh! And I bought another can of that paint, but can't remember what it was. I'll be in my garage today, so I'll try to remember and take another look at the name.