help with small boat

[craZaboutRC]

im building/ buying a small deep vee hull. i have a proboat esc, a 17t double motor , water cooling for everything. but i need to know if anyone has a good idea on how to get the power to the water and what prop i should use. i need one for all around good take off and decent top speed and i need one for insane high end. the boat is going to be between 18 -22 inches in length and have a 6.25 - 8 inch beam.

[Hydro Junkie]

Why are you looking so small on size? A boat that small will have trouble on anything worse than flat water. Also, you will not be able to carry many batteries due to the small size. You might consider buying/building something closer to 30 inches. It will considerably reduce the effects of rougher water and lack of weight carrying ability :)

[Maltrio]

I just picked up a boat on ebay and I can't wait to get started. Its 26" long with a 10" beam. I really wasn't going to get it at first but the auction included 2 nice 1700 batteries and a reversible ESC so I said what the hey and bid on it. I paid about $48 for the whole package (boat, batteries, esc, motor) and I can't wait for it to come. I'm just going to take the radio out of my Kyosho Ultima and stick it in the boat. I was just wondering if you thought a 26" boat would handle small to medium sized waves (2-6"). There is a small pond near my house that is always calm but I also have a camp on a large lake and I would like to run my boat in both areas.

[Hydro Junkie]

It should be able to handle the 2" stuff, larger may cause some problems. If the boat has a hatch cover to keep water out, you should be fine. Just remember, if the ESC and motor are air cooled, you need to be sure to make some way to get air into and out of the hull, without letting water in. In the rougher water, you may have to throttle back to keep from flipping the boat

[Maltrio]

Ya, I was just looking on ebay for some cooling kits and water pick-ups. I found some pretty cheap kits but I think I want to try out the boat alittle before I decide what I want to put in it. Also, my prop is under the boat, it isn't surface piercing so I waswondering if there would still be enough prop wash to push water through a cooling kit if I got one and how would I go about mounting the pickup to create as little drag as possible? Thanks

[Hydro Junkie]

As I don't know what it has for hardware, I can give a few possibilities. One option used by gas and nitro boats is a rudder with built in water pickup. Several companies make these, just a matter of finding one the right size for your boat. Another option is to solder a tube to the back edge of the rudder. With the bottom end cut at a 45 degree angle and soldered so the long end is at the rear, this also works. Make sure the top end sticks up high enough to attach a hose to it. Both these work if the rudder is behind the boat. If the rudder is under the boat, you can use a variation of the cut tube by clamping it to the transom with just the bevel cut end below the transom. There are also through the bottom water pick ups available on the market. Something else to think about is where to dump the water overboard. Be sure it dumps somewhere it can be seen. The reason for this is so you know the cooling system is working. If you are running full throttle and no water is visible at the dump, you have a problem. If you have a hidden dump, you could flood the boat or burn up the ESC or motor and not know it till the boat fails, or worse, sinks. Hope these ideas help :) Almost forgot, with all these type pickups, the forward motion of the boat forces water into the cooling system. Whether or not the boat has a surface drive or not doesn't matter :cool:

[Maltrio]

Awesome, thanks for all your help.

[Hydro Junkie]

Glad I could be of service :D

[Maltrio]

Just one more question (in actuallity there will probably be alot more, but oh well). Should I water cool the ESC too? I've seen kits on ebay where you have to drill through the heatshink and insert an aluminum tube and that is what the water flows through. Do people normally do this or is cooling just your motor usually enough? Thanks again.

[Hydro Junkie]

As I don't have any electrics, I can only answer part of your questions. If you plan on having a hatch over the motor, it would be a good idea. There are ESC's that have water cooling built right in. As for the drilling, I can't say. Water cooling the motor in an enclosed hull is also a good idea. There are cooling coils and cooling jackets available, depending on what motor you have. You have to remember that when electronics are used, they produce heat. Keeping the electronics cool will prolong the life of the ESC and motor. Many underestimate the effects of heat on electrical circuits. All commercially produced circuit boards are coated with a nonconductive sealant to protect them. When the board gets too hot, these coatings either melt or burn off. When this happens, the circuit is easily shorted and destroyed. This, and burned out components(due to overloading and heat) are the primary reasons ESCs burn out and fail. Hope this explains a little and answers your questions

[craZaboutRC]

you dont have to water cool the esc, but if you were looking to make your own watercooling i tried a method and it worked with only one small flaw. you get yourself a "D" size battery, some morton regular salt, and a 5/32 inch aluminum tube, aprox 3 foot in length. you crimp one end of the tube and fill the tube up with salt and tap the tube on the ground to pack it in as you go. when it is full you crimp that end and using a vice you clamp a d battery in. then being very careful wrap the tubing around the battery. the salt makes the tube become as if it were a solid piece of aluminum tubing and it works great. and it fits onto any 05 or 540 motor, with a nice tight fit. the only problem i had was getting the salt out of the middle of the coil. also you cut off the crimped ends with either a dremmel or a small hack saw. it works great and i actually bought a PROBOAT esc, it can handle down to 15t motor, up to 10 cells, and is completely water proof and has an aluminum case that you can wrap aluminum tubing around to make it water proofed. you can ge *** for around 30 bucks its awesome. good luck. im building a boat that is about 22 inch in length has a 8 inch beam, and is gonna fly on top of the water. anyone else have any info on setting up trim tabs??