To much prop and the wife says stick with this boat. Suggestions?

[Switch]

Well I got went to the pond this last weekend and tried out my MC with the new s/b X642 and I think it was just a bit to much prop for it in stock form. Oh well I am going to go and try a grim prop next and see how it does. Can't wait till I can mod this boat I'd rather build a bigger hull but I don't think thats gonna happen until I prove to the wife this boat won't get me where I wanna go. I know I'm playing with fire here and asking to completely destroy this boat but does anyone have a setup to get the MC over 60mph. I have read a bunch on this forum and plan on foam filling the hull and rienforcing the hatch and floor. On the good side though If it does blow over and go boom I can get a big cat lol. Thanks guys for sharing all you info it really helps us first time boaters.

[Fluid]

Why do you think that the x642 is too much prop? If you are looking for more speed it is there with a different prop (and perhaps an ESC), but with high speeds comes shorter run times. The record for a P-Limited Ofshore boat is held by a cat running a UL-1 motor and an ABC prop at over 67 mph. But at that level of amp draw it's two quick passes and back to the bank. The Limited motors are called limited for several reasons.....


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[Switch]

The prop seemed to much becuase it was noticably slower with the X642 the the stock plastic prop. I did sharpen and balance it on a top flite balancer. Didin't seem like the rpms where as high as before. My battery and motor temps were fine fairly cool to the touch but we have cold water here in Wyoming normally around low 60's. So you think just changing the ESC would get me more speed? I really would rather build a differn't boat to reach my speed goals (hydro Rigger) but the wife isn't to fond of the idea and I try to live by the old saying happy wife = Happy life

[hazegry]

got pics of your prop you worked maybe I can help you fine tune it?

[Fluid]

IME the m445 is a bit faster than the x642 but neither will get you close to 60 mph. You need to loosen up the hull somewhat. Move the packs back as far as possible - I set mine on edge to get them back against the aft wall. Set the boat on a flat table and adjust the strut so that the bottom is 3/16" above the table, angled up about 2 degrees at the prop end. Adjust as needed, but for top speed you want the cat to run on the last 6" of the sponsons (or less).

A higher-quality ESC may gain you a few mph, particularly if you advance the timing a bit....but don't expect a big change from this. Things like making certain the motor is perfectly aligned with the cable and reducing driveline friction will contribute to higher speeds. Also remember that all the power in an FE boat is in the packs. You will not reach record speeds with cheap packs. Lastly, blueprinting the sponsons bottoms can help; use a sanding block and 220 grit wet-or-dry (used wet) to flatten the riding surfaces of the sponsons - sand each step separately. Most hulls are not flat and have surface depressions which suck the hull down on the water. Flat and smooth with sharp edges is fast. Don't polish the bottoms, the finish left from the 220 paper is fine.





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[Switch]

you bet! I will post up some pics of the prop tonight I know its not perfect but its only my second one and with no one up here to ask for advice it's tough. I didn't detounge it just sharpen and balance.

I scuffed the bottom of the Sponsons with some 600 this weekend hoping that would help but to be honest I hear alot of you guys talk about flattening them out but I have to be honest and yes I am a dumb newb but Where do I want to do what on the sponsons? Are we talking about the flat stepped portion of them near the rear of the boat or the long flat front portion what about the side ridge? I know this seems dumb but I honestly don't know. Sorry for all the newb questions. Is there a sticky anywhere for hull design and setup basics?

[xlandguy]

I'm pretty much in the same BOAT as you Switch. (i'll bet nobody has used that joke around here before :olleyes:) I've been tinkering with my Motley for some time now and it's my first RC Boat. An idea for more speed that I got here was to run it on 5s, see a definite speed increase then!

[sanyijr]

Switch,

I'll bet you are running wet. As Fluid says, check your CG, strut height and angle. You lost rpms beacuse you are running the prop too deep is my guess. And check your strut angle as well. Go either flat or +1 to 2 degrees. I got a used boat and trim was all off. Strut was -1-2 degrees, pushing the nose down and just killing speed. And I set strut height at about 1/4" up from bottom...

[Switch]

I've thought about that just not real sure about hurting the electronics. The batteries I'm using in my boat are (2) Venom 5000mah 40c hard case 2s lipos in the stock parellel format. I know there not ideal for this boat so what would be way better? and where can I get them? I'm willing to do a motor and speed control upgrade to get some serious speed out of it just not really sure on what to get I am trying to learn everthing I can about understanding brushless motor sizes and ratings and winds but haven't been able to find a good resources to help me understand it all and what the hell the differnce is between a 1Y or a 1D. Another great idea for a sticky for you senior members

[Switch]

I was wondering if I am running to wet but without any base line idk how to tell lol. I'll try to adjust the strut. Also how do I check the CG i see guys say its at 30% or 40% but howl do they measure it?

[sanyijr]

CG measued from back of boat. So, 8"-8.5" from back of hull. Strut height is set of the bottom of the hull. Set the drive line about 1/8" to 1/4" above hull bottom. It will cavitate a bit on start, but once it plane, it opens up. Then, based on performance, porposing, etc, you adjust.....

[Switch]

so the boat needs to balance at 8" from the back of the boat? I feel so dumb asking this.

[xlandguy]

Figure it this way on a 30 inch boat the center of gravity at 50% would be at 15 inches. 25% would be at 7 1/2" and so on.

[sanyijr]

Ask away. But most of this is answered in the forum. Just takes some searching....

Cg-center of gravity. And, yes, balance point for hull. Pending personnal preferences, cg is typically around 30%. If you read through the MC forum, most people are setting theirs at 8-9 inches. Most leaning closer to 8. But if too far back with the cg, you will run "loose". So too loose is if the boat is in the water and you start bouncing or floating and possibly get air-borne. But the trade-off is loose=speed. too loose and you are up-side-down.

Setting CG, strut height and strut angle all effect performance. So first set CG at 8.25" to start. Strut angle to neutral=0-degrees and height at 3/16th above bottom. And see what that gets you.

[Switch]

Sweet I got it. I think harry said the same thing to Cole Trickle in days of thunder " loose is fast but on the edge your out of control" LMAO. I will go home and set the boat up that way. I went home at lunch and checked the strut hieght. Right now it is about 1/16th - 1/8th" below the hull right now so I bet the boat is running way to wet if raising the strut will pull it out of the water.

Thanks a ton for your time guys I really appericate it.

[Switch]

Well Guys I moved the packs to the back and raised the strut up 1/4" and wow what a differnce. Much happier guy now I'm still gonna play with the strut placement some more just to fine tune it but it is running like it used to. Thanks a ton guys. And for the record the wife lost I got two new boats this weekend!!!!

[sanyijr]

Switch,

I was running mine this weekend. Stock motor, SF 120 esc and 2 20C 5000 2-cell lipos. I started at 1/4" up on the strut and kept adjusting up. I am just under 1/2" up with a X640. Starting at 1/4" up seemed pretty fast cause I was at 1/8th originally. Added about 1 degree more to 2-3 degrees positive on the strut. Still made it faster/looser but gave great handling. Then upped the strut 1/16th every run till I got to about 7/16ths up. Runs GREAT. Super fast. And, at a certain point, you will hear the rpms really open up. at the (approx) 1/2 mark, my rmps really came loose and gained noticable speed.

Sean

[Switch]

I raised it way up at one point just to see what it would do and it ran horrible took it down from there gradually and bam now it runs great. I might try and add some pitch and see what that does? My strut in the stock position was below the sponsons.

[Fluid]

When I tested the prototype 2 years ago it ran very well with the stock prop when the strut was at or slightly below the sponsons. But the production hull with a more aggressive prop does run better with the strut raised. Glad it is working out for you...


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[sanyijr]

Fluid,

I was surprised by how high the strut would go up and still perform well. Yes, it cavitates for 10 feet, but once it plains, it absolutely rips even with a X640 balancedand razor sharp. The prop is barely touching water at WOT. It might just be my combination of things, but she runs great! Haven't run a 42 mm prop cause my esc and batt connectors are a bit warm and don't want to risk it.... (getting temp gun to measure soon)

Only weird thing (besides the fact that I have 1/3 of the prop in the water at WOT) is that the prop spray at WOT is very big. Don't know how to explain it. But it is all over the place. Big rooster and everything. But it is biting and holding high speed better than at 1/4 and up to 7/16th".