Project Fast Cat

[flraptor07]

Travis, I think you'll like those servos, I'm using 6.6v LiFe Rx packs so I'm probably about 230oz. on that servo. They do make a DS2509MG servo that's 347oz. @ 7.4v I use those in my bigger Hydros it's red anodized and silver. http://translate.googleusercontent.c...i30m1XTxlDLkAw

[keithbradley]

I tried the JB Weld on a battery tray that was holding a 6s lipo. I filed in V cuts every .125" on each of the tabs for more surface area, sanded it with 120 grit, wiped down with alcohol let it cure for a few days and it held up great for a couple months, but then crashed at 76mph and most of the JB weld joints failed some ripped from the hull but most as u can see sheared in the middle of the JB Weld joint. Just saying

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JB weld and other epoxies will work to a certain point, but because of it's inability to flex, it can always be broken off. The bigger your boat gets the more apparent this will become in crashes. Large surfaces will flex in crashes on even the strongest hulls, and when the epoxy can't flex along with it, it just cracks. The solution is to use something a bit more pliable. I have some stuff I can send you if you want to use it on your mono.

[kfxguy]

JB weld and other epoxies will work to a certain point, but because of it's inability to flex, it can always be broken off. The bigger your boat gets the more apparent this will become in crashes. Large surfaces will flex in crashes on even the strongest hulls, and when the epoxy can't flex along with it, it just cracks. The solution is to use something a bit more pliable. I have some stuff I can send you if you want to use it on your mono.

Man I came up with something on accident the other day. I bought some black epoxy dye to try....I mixed it in with jb weld and it stayed flexible. Well not not rubber but I put a mix of untouched jb next to it and let both cure. The jb was super hard and I could not bend it at all. Then the mix with the dye, I could bend it a little. I might be on to something accidentally for stuff that needs a semi flexible bond. Hmmm

[keithbradley]

Man I came up with something on accident the other day. I bought some black epoxy dye to try....I mixed it in with jb weld and it stayed flexible. Well not not rubber but I put a mix of untouched jb next to it and let both cure. The jb was super hard and I could not bend it at all. Then the mix with the dye, I could bend it a little. I might be on to something accidentally for stuff that needs a semi flexible bond. Hmmm

Interesting. How much dye did you put in it? With most of those dyes you could literally dip a toothpick into the dye, dip it into your mixture, and stir. If you put a lot, maybe that's why it had an effect on the hardness.

[rearwheelin]

Nothing in my opinion holds two surfaces better than JB . It's all about the what your trying to bond. It does like bigger surface areas that are being joined . It's what I use on my mounts but I make sure it has the biggest surface possible for bonding. Once setup it's hard to beet .

[kfxguy]

Interesting. How much dye did you put in it? With most of those dyes you could literally dip a toothpick into the dye, dip it into your mixture, and stir. If you put a lot, maybe that's why it had an effect on the hardness.

Yea I think that's how I found this out. I put 3 or 4 drops in it lol.

[flraptor07]

I mix milled Carbon Fiber (made myself) with 30min. Z-poxy and I've never had anything break loose with that mixture. Don't use it if you think you might ever want to take it back apart someday, or if you do you'll have to cut it apart.

[kfxguy]

Look fellas, need some experienced advice/opinions. I want a sponson water pick up instead of rudder pick up. I've heardits more drag, less drag, same drag. I don't want to do anything that would lose me mph. I plan on making a thinner stainless rudder. So my main question is with a bottom sponson pickup and a thinner rudder would I be faster or at least the same?

[flraptor07]

I doubt there's any difference in a rudder pickup or a sponson pickup. The difference would come in with a sponson or rudder pickup and a tube type transom mounted pickup. If you didn't want to do a sponson pickup or a rudder pickup, I think the next least amount of drag would be a prop wash pickup.

[flraptor07]

I've also done this pickup location that worked real nice if you're using a strut. DSC02500.jpg

[monojeff]

I'd use a prop wash pickup. Done deal KISS no drag no issues.

[kfxguy]

I was trying to get rid of the outside hose too

[TheShaddix]

Think of it this way, your boat is flying at 90 mph with the hull barely touching the water and the only drag is coming from the rudder which isn't much, overall it's like an airplane on water, that's what makes cats so great - the lack of drag. But then you introduce some vertical tube (even with a slanted edge) sticking out of the hull. Common sense suggests it would cause drag. And not only that, but it can affect your stability too when the hull/sponson lifts off and then comes back down, and instead of just smoothly gliding on the surface, the water will catch that pickup of yours. On top of that, it doesn't look that clean aesthetically.

Why not just do flush hull pickups, two on each side for motor and esc? Really easy and gets a LOT of water through. I do those even on mono hulls. They get no drag to speak of and look clean and are super easy to make.

[rearwheelin]

My vote for rudder pickup ! Less bubbles equal better cooling !

[Fella1340]

Travis, just joining in here. Insane motor choice, just crazy. I like it! I think sponson water pickups would be best, eliminate the outside tubing will really clean it up. As far as the other styles of pickups, some look better than others, the word "drag" really seems to get overused. With all the power you have I doubt any style of pickup would noticeably affect speed or handling. I like the stainless steel rudder idea. I have a good selection of 440c stainless and some of the more exotic types I use for knife making. My heat treatment furnace finally gave up and I have yet to replace it so heat treating one for you is out. I could send you some 440c in 3/32" and 1/8" (possibly 1/16" to)if you want to really make an ultra rigid rudder. You'd have to find someone local for heat treating. 440c stainless is pretty straightforward to heat treatment and shouldn't cost more than $10-$15. A good source state side for all your stainless needs is admiral steel. I have a couple blades I already made up somewhere around here. Rigid is putting it lightly! Of course a quality stainless knife blade can be used. Cheap knives just don't compare though. Pm me if you'd like some. I think you'd see some gains from the effort. You should use black epoxy pigment in your jb weld or west systems stuff. Getting everything black will really make things look cleaner inside. I use 2-3 drops for 3 ounces of epoxy, it goes a long way. You could always skim coat what you've already done. It's the one thing that I can think of to really make things look better. I agree the extra weight will help you stay on the water, not like your going to run out of power!! Excellent job, keep the build logs coming!