First Cat 36'' Sprint Cat

[bustitup]

I like your hatch mod....gives the sprintcat a whole dif look

[knpc]

Thanks
I finally found the motor, should have it within a week andthe build can continue.

[DISAR]

Beautiful hatch!

Can you please describe how you made it?

[Fluid]

I agree, beautiful hatch. It completely changes the character of the hull - for the better IMO. Good going.




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[knpc]

Thanks maybe I'll e-mail a pic to aeromarine to inspire them to update some of their designs. It would be nice if the hulls looked as good as they perform and they would sell more hulls.
I started by attaching thin plywood to the bottom of the hatch where I was going to cut. I did this first so it would hold the form of the hatch. I then cut out a large section of the hatch you can see in the pics below. I sanded down the area around the cutout and applied a few layers of epoxy finishing resin and fiberglass cloth over the ply and on to the edges of the existing hatch. Next I formed a cockpit out of a block of foam, attached it and applied epoxy and cloth same as before. After it was dry I cut out the bottom of the cockpit to make room for the motor. Last was sanding, filling, sanding, priming, more sanding, and paint.
Glad you guys like it

Kevin

[knpc]

I got my motor today thanks to Randy at BBY Racing, from CA to MA in three days . Now comes the challange of the stuffing tube. I imagine its a bit more difficult to get right than on a mono. I have five pieces of tubing, hopefully I don't need that many.
I hope to make some good progress over the weekend.

Kevin

[knpc]

I got a some more stuff done. Just a few little things left to do. I'll drop it in the pond tomorrow to do a leak test. I want to order a few props to test, a x645 was recomended. What other ones should I order? Right now I have a x440/x442/x445/m445/x637/x640. I think all of these would be too small. By next weekend it should be ready for its first run!

[Fluid]

Get an m645 and an x450 at least. A Prather P225 and P230 would be good ones to try as well. You can go broke buying a bunch of props to test, any other boaters near you to borrow from?






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[knpc]

Thanks Jay, I ordered a m645 and x450 to start. I'll sharpen and balance them and test this weekend. I weighed the boat tonight. Dry weight is 8 lbs. so the rtr weight with two 4s packs will be just over 10 lbs. I'm not sure how that compares to other cats of this size. I can't see a way to build it any lighter.

[knpc]

I took the sprint cat out today for the first time and made three runs. The boat ran well, very stable and in the mid 40s with the m645 and upper 40s with the x450. Temps were 130s on the motor and esc and 120s on the packs. I think I need to free it up a bit but I'm not sure what adjustments to make. Right now the cog is 33% and the strut is 0% and 9/16'' above the sponsons. I'll try to get a video next weekend to help with advise on setup adjustment.

[Fluid]

Those speeds are about right for those props, the temps are not bad depending on how long you ran. Free the hull up by moving the CG back to 31%-32%, raise the strut another 1/8" and angle it up 1-2 degrees at the prop end. That may or may not be too much, but it should gain you a few mph. The next prop up is a P230 - watch for heat, this isn't a hydro remember.



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[ozzie-crawl]

there is some good info here as i am about to start a sprintcat build
i really like the look of that canopy

[knpc]

Thanks Jay, I will make those adjustments and test again next weekend. I was on and off the throttle alot trying to get used to how the boat handles, I think that why the temps were higher that they will be in the future. By the third run I was more confident and held full throttle most of the time. The boat hadled great and turns on a dime. There is a learning curve driving the cat, especially in the turns. To this poind I've only had monos. I'm very happy with the boat and with some tuning it will be a great running cat.

Not sure if I would try, but could this setup be run on 5s2p ? or whould that be too much for the esc to handle.

[Fluid]

My P Sport Hydro racing setup pulls around 150 amps average with that motor on 4S. You could try running a smaller prop on 5S, but you are starting to get into SAW territory. That motor on 6S can run in the 80s...

You may want to consider dialing down the steering sensitivity, you should be able to run full throttle around 30-40 foot diameter turns. Racing turns are 70 feet in diameter........





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[knpc]

I had a chance to take it out today for a run after making the adjustments Jay suggested. The cog is at 32%, strut is 1/2'' above the bottom of the sponsons with 1deg kick up on it. This did seem to free the boat up. It ran 49mph and stable, when it came out of the water it stayed level and just kept going. Temps were all at 130+- on a timed 3min run. I'll keep tunig and order another prop or two to try. The wife agreed to take a video this weekend.