Ron Olson

My Feedback: (1)

Good to know that it does run so you did alright. Before hitting the water you might want to fatten up the needle a little more.

jac32224

Nick... Looked at the video. Glad to see it run for you. I tried to pay attention to rotation, and I'm not sure (hard to tell on video),but when the prop stoped it may have been backwards. Anyway, like I mentioned, with the output in the rear of the engine, not the front, the starter rotation will be backwards from what your used to... John

nickrummy

Will do Ron, Not enough smoke coming out of the exhaust? What do you guys recommend for fuel? I used some O'donnell %30 that I used for racing with my truggy. I believe it has around %12-14 oil which is fine for trucks.

John, which edge of the prop cuts into the water?

jac32224

Cupped side cuts first.. If you're standing behind the boat looking at the back of the prop... the prop will turn counter-clockwise. I think what Ron meant... Unlike aircraft engines (or maybe even buggy)... The common mistake (at first) is that most adjust the high speed needle to lean. Listening to your video the throttle seemed fairly snappy. Even though that sounds good on shore, you have to remember the engine / prop has no load on it. What he meant by "fatten up the needle" is to richen your needle. Basically, its getting enough fuel to carry the load now, but there is no load... It will starve for fuel once that prop hits the water... Hope that makes sense

jac32224

Nick... best advise I can give is to take your time with this project... Over the years I've flown everything R/C from 1/2 A to 1/4 scale... Heli's... Cars... You name it. I enjoy them all, but I respect the boats the most. I don't know if I enjoy the challenge (or frustration), but I find the boats "by far" the hardest to set up. Boats are truly a different beast. Since you don't have a RTR all the setup is left to you... I almost "promise" that there will be issues to overcome as you get this up and going. You are now just finding a few... Hull type, prop height... but wait till it hits the water... Prop size, prop angle, tabs, maybe a hopper tank... and so on. Just work out one thing at a time, and move on to the next if need be. There are A LOT of good people here willing to share their advise and experience. You have my email... ask away. I may not always have the answer, but someone here will.

nickrummy

I'm following you on richening up the needle. I didn't see to much smoke coming from the exhaust and thought that might be a sign. I know when I tune my off road vehicles you want to see a smoke trail.

I thought it was pretty darn snappy running like that too. I know it has no load. Kind of like running an off road truck off the ground. It all changes when there is a load on it.

I can definitely tell I have a lot to learn but that is why I love this hobby so much. These aren't just toys. They're miniatures of the real thing and that's what makes it so awesome! I've had about all there is to be had for vehicles on the land. Never had something that flew (besides a CX2 but those are easy to fly) so when I had the chance to get this I couldn't turn it down.

I appreciate all the help I've got from you guys so far. I'm trying to be a sponge and soak up all the info! I'm taking the boat to work tomorrow and on the way back stopping at a LHS. The guy is pretty big into boats and I'd like to just stop by with it to pick his brain a little.

scardina

My Feedback: (3)

i start my 3.5 outboard by spinning the flywheel clockwise. also, 14% oil is really too low to run in a boat, at least in my taste. most guys by me run at least 16%-18% if not more. there was apparently one guy who ran super low percents, like close to 5%, but they called him 3-lap, because thats usually all he ever got before his motors siezed up. moral of story, run a lot of oil. I'm using heli fuel at the moment. think about it this way: when you run a car or truck, your throttle goes up and down because of the track layout. in a boat, you are full out, balls to the wall, WOT pretty much the whole time. you may lose a tad bit of speed w/high oil, but motors are too expensive to go through any quicker than you got to

nickrummy

Valid point. I know using more oil can technically prolong engine life but I always thought to much oil could gunk up a motor too.

Ron Olson

My Feedback: (1)

I watched the video twice to see if it was spinning the right way and it was. Reversing the wires on the starter is the way to start it properly.
If and when you get to trying other props, the Octura X-447, X-448, X-450/3 and the X-646/3 are good choices.

nickrummy

Thanks Ron, I looked at it last night and it seemed as though it was going the right way. I was pretty sure the curved edge of the blade was the leading edge since it was sharper than the flat edge.

I'm so excited to get this thing in the water. I'm going to try and make sure someone is with me to take some video so you guys can see how it runs. I'm trying to plan a day where we have kayaks available so I don't have to go swimming if something happens to the boat.

Emcee_MadCatz

I usually run my boats with 16% oil. As for gumming, the stuff I use is 1% castor. The rest is synthetic and I find Synthetic burns cleaner in my two stroke Yamaha. I figure it would apply to models too?

I don't know if anyone has covered the height of the engine but I think the recommendation for fullsize boats is 1/4 to 1/3 of the way up the transom from the lowest point in the hull. Some people just eyeball it and set the hydrofoil (the horizontal fin above the prop) slightly below the surface at standstill. The problem is, this is where the hydrofoil should be WHILE RUNNING. This means as the boat gets speed, the hull will rise and pull the hydrofoil out of the water and you lose stability (not good).

Your best bet is to probably mark the waterline while running (eyeball it with respect to some point on/near the transom). and mount the hydro foil about 1/8" below that point. I would guess it's somewhere near the line created by the two lower rails on the hull. I could be wrong but I shouldn't be too far off?

coyv10

It is an early Dumas hull I have one also but has a gas g260 in it the hull is tough as nails.

nickrummy

Thanks guys. I stopped in at the hobby shop last night and spoke with a gentlemen there for a while who races boats and seems to have a wealth of information on boats. I left earlier than I wanted to because there was another customer but I plan on going back to pick his brain more. He also said it was a dumas model.

He mentioned that the motor is pretty close to where it needs to be. The pictures might throw it off a little. It has an adjustable mount on it and is as low as it can go so I can raise it about 3/4" if need be. We'll see how the first run goes.

I picked up all new fuel parts. Tank, lines, filter etc....

ryan_t888

How high or low is the prop shaft in relation to the hull?

Ryan

THEguzzler

Could you take a better picture of the motor please? Specifically the area around the prop. I believe optimum for most mono-hull o/b is close to where the prop shaft lines up with the lowest point in the hull (the keel I believe it's called?) The best performance is when the prop is as high as possible, which means as high as it can go without cavitation.

nickrummy

Sure I'd be happy to take some photos for you guys. I plan on putting in the new fuel parts tonight and will take some then.

I guess I don't see how the prop position is relative the hull height. I mean a larger boat is going to sit higher in the water than a smaller boat that uses the same running gear correct? I know there are more variances than that but generally speaking all heights should be set based on the waterline when the boat is at speed. I don't see how that can be done unless you just make a good educated guess at first then fine tune from there?

THEguzzler

In one word, yes. It generally is really hard to get it in the sweet spot at once. The main one is weight. A smaller hull and larger hull will have different variances as to where it sits in the water. The best way is to adjust on the fly. I'm assuming that the boat when at speed, runs with the water line close to the height of the two lower rails on either side as most boats do. But modifications will obviously change that.

THEguzzler

The horizontal plate on the engine is not called a hydrofoil. It is an anti-cavitation plate (usually just called a cavitation plate). The purpose of this is to prevent surface air from being pulled into the prop and causing cavitation. To be quite honest, I see no point in this on a model. I would assume it is only there for a more authentic "scaled" look, that and the fact that it's an awesome place to mount the water pickup. For one thing, our models rarely produce more than 1hp especially nitro engines thus, the thrust and suction produced by the prop would rarely be enough to pull air into the prop. The only time this would happen is when the prop is set too high in the water. Also, even on true scale boats, the prop is quite oversized thus further preventing cavitation.

Also keep in mind that a lot of nitro/electric boats run surface drives. In this case, a cavitation plate is useless and therefore not included.

-Nam

P.S. I'm not trying to flame you or anything. I apologize if it came out that way.

ryan_t888

Nick, when I said prop height in relation to the hull, I meant How high is your prop compared to the bottom of the vee or very bottom of the hull.

The prop's center line should be about an 1/8" higher then the bottom of the vee when setup for surface drive. It should be setup for surface drive, if not you are going to have to use a prop much smaller than what is recommended.

Also, the term cavitation must be the most improperly used term in the dictionary and in these forums. The plate above the prop certainly does not prevent cavitation, it prevents air from getting to the prop - aeration. Now aeration does prevent cavitation but that's another thread.

Ryan

nickrummy

Doesn't cavitation have to do with vapors forming in liquids while under pressure or something like that? From a prop or turbine or something accelerating the liquid? Aeriation is simply when air is brought into water?

After reading I see that surface drive is when the prop runs on the surface of the water. Being generic I'll say half in and half out of the water. Submerged drive would be the complete prop under water.

So what's to say this boat isn't just setup for submerged drive? I'm pretty sure the prop shaft is below the hull. The exact dimension I'm not sure. If I had to guess I'd say the plate above the prop is about even with or just slightly above the bottom of the hull.

Are you saying the prop needs to be smaller for submerged drive because of the increased load on it compared to when it's used on surface drive?

THEguzzler

Yes, cavitation occurs when water "boils" around the prop. Aeration is when air is sucked through. What I was supposed to say is aeration. It's just I'm used to talking about full sized boats where the two terms are generally used interchangeably (albeit incorrectly).

The boat could well have been set up for a submerged drive, but you won't get the speed it's capable of. The nice thing is that you will get a consistent run whether in smooth or light chop because the prop is always fully submerged. If you need a comparison, think about a yacht and a powerboat. the yacht is a submerged drive and the power boats are generally surface drives. And yes, the prop may need to be smaller, but you may get away with it. You just won't see the full potential. You'll have to run the boat to fine tune the prop.

-Nam

P.S. There is never a guarantee something is setup right... even when buying new sometimes.

ryan_t888

Yes it would have to be smaller as the load is much heigher since that extra half of the prop will be in the water instead of in the air.

Surface drive boasts better performance and top speed where submerged drive is good for acceleration and sometimes handling. If you look around, 95-99% of the electric, gas, and nitro hulls are setup for surface drive. There is a reason to this.

Did you wish to run it as is or lift the engine?

Ryan

THEguzzler

Haha I was going to ask that question too. Beat me to it. I think this debate started because someone had mentioned it was too low. You could run it either way but you may need to make some small changes, i.e. the prop.

nickrummy

My plan. To put it in the water as is and have fun

Honestly, I don't have a plan. This was such a spur of the moment purchase. Obviously we're all here because we like reading up on how to make these things faster and perform better so you better believe that making this boat perform as well I can with what I have is something that interests me. I'm such a fan of mechanical stuff that I just love seeing how things work and making adjustments from there. I think putting this in the water as is will be great for a reference point to see how the changes I make effect performance. I'll be sure to take a lot photos when it does hit the water. I really like hearing all the different opinions discussions on setups.

If surface drive is the best performing solution that is most likely the route I will take. Especially since it wouldn't really involve major changes. Hopefully the vertical adjustment on the boat right now is enough to setup the surface drive correctly. Judging from you guys and other things I've read on the forum the motor mount will most likely need raise a bit on the transom to be surface drive.

Testing will tell!

nickrummy

Well guys I'm not sure how much longer I'll have this boat but I thought I'd still share some pics and experiences.

I got the boat out to the lake yesterday ready to give it a run. I just got a 3PK so have still been learning how to set that up. Thought I had it all worked out but could not for the life of my get the idle setup correctly. Pulled the cover off the electronics and realized the throttle servo must have stripped an internal gear because it wouldn't center at all. So didn't get to drive it. I did set it in the water so that you guys could see the waterline and motor height. It's DEFINITELY sitting low in the water. I'd say it needs raised but I'm sure the boat will come out of the water quit a bit when it gets up to speed right?