Progress On the Boat Building Project

[DaveDude]

Hey Everybody,

I'm finally making progress again on building my 32" dee vee. I was held up for a long time looking for engine mounts that my recoil start engine would fit on and I finally gave up and made some up custom! In retrospect, I probably could have made the shape slightly different to get the engine slightly lower, but they look pretty good. I'll keep this thread updated and post some pics.

[DaveDude]

Here's some pictures of the mounts I made. I picked up the rubber mounts for $2 a piece on eBay, got the hardware for less than $2, and used some scrap aluminum from a boat yard.

[DaveDude]

Here's another one. The next time I make engine mounts :D I'll put the rubber mounts a little closer together to get the engine lower.

[DaveDude]

I got my engine rails sanded and drilled today, so I just stuck them in with the engine attached to see how it all looked. I'm a little concerned and would like some feedback on the engine angle. I'm thinking that I angled it down too much and it should be a little flatter to reduce amount I'll have to bend the shaft tube. I could always elongate the front holes in the engine rails to make a shallower engine angle. What do you think?

[DaveDude]

This one gives a better idea of the angle...

[DaveDude]

And this is one last closeup...

[Watercadet]

The curve in the stuffing tube will help to control the "whip" in the flex shaft. I would slot the REAR holes and bring the collet side of the motor down so it lines up with the shaft comming through the lowest point in the radio box bulkhead. Mounts look nice-BTW
Adam

[Doubledog]

You're showing us the fun part of modeling. Coming up with new ideas and sharing them with the rest of us.

[DaveDude]

Thanks! In response to Watercadet's suggestion to lower the rear holes, unfortunately I don't think I could do that very much because the nuts on the outside of the engine rails would hit the bottom. What's the best way to bend the brass shaft tube? Starting in the radio compartment and coming up gradually through the radio box bulkhead, or beginning the curve where the tube passes through the bulkhead?

[Watercadet]

I see what you mean. As for the beging of the bend, if you could get enough bend in it after the radio box then I would do that.

[DaveDude]

Thank goodness for 3/16" shishkabab sticks! ;) Anyway, this pic shows exactly where the engine is aiming.

[Ron Olson]

Keep in mind that you want some space under the flywheel to make getting the starting belt on and off and space between the collet and stuffing tube for the same reason. That will make things a lot easier down the road.
The shish-kabob trick is a good idea too!
BTW, what hull is that?

[DaveDude]

Thanks for the advice. Don't forget I have recoil start, though, so a starting belt shouldn't be necessary. This hull is about 35% plans and 65% messing around with a pencil and a ruler on some 36" x 36" graphing paper! I got the basic dimensions from plans I found in a book for a smaller boat and scaled them up, modified them a good bit, and voila... I wanted a project, so I found one. The only thing I'm worried about is the beam is a bit narrower than other boats I've seen with the same length, but I just figured I'd keep building and see how it runs!

Oh, I have one last question before I start bending my shaft tube. Is it usually necessary to put anything in the tube while bending it to keep it from crushing? I've heard that putting fine sand in there would work for that. My bend is going to be about 10 degrees over about 2".

[Micho523]

Anneal the tube first, then do the bending with the flex shaft in. That works best for me. If you don't have the flex yet, then yes fine sand will do the trick!

[ejp]

Don't forget to take the teflon out of the stuffing tube when you go to anneal it.:D

[Icman69]

OK I have to ask what does this mean?

[macleod]

Anneal the tube first, then do the bending with the flex shaft in. That works best for me. If you don't have the flex yet, then yes fine sand will do the trick!

Can you give us a quick lesson in annealing the tube.???

Im not using teflon but two tube inside one another.....

Thanks

Ross

[ejp]

All you do is heat the brass up red hot and put it under cold water. Look at this site and you can read up on how to bend and make a stuffing tube also, I just know you asked how to bend and make it.

http://www.offshoreelectrics.com/articlesmain.htm

[DaveDude]

Thanks for refreshing my memory ejp, I actually read that article in offshoreelectrics a long time ago and then forgot about it! Now I just have to wait for the weather dry up a bit down here in Florida so I can get back to work!

[Watercadet]

I don't anneal my stuffing tubes. Put the shaft in the tube and make your small bend. No big deal.
Adam

[spyderwebb]

Looks to me like your going to be putting a lot of stress on your engine mount ears as the motor mount is a 2 pc. unit and not connected from side to side. It seems to me the engine mount ears are going to absorb the flexing of the boat along with the engines torque .To much stress and you end up with a broken crank case. Just a thought.

[DaveDude]

Funny, I never thought about stress problems associated with 2 pc engine mounts. I guess all the rubber mounted engine mounts I've seen, like those from Aeromarine and Speedmaster are 2 piece...

Actually, I was thinking about putting a layer of fiberglass over my engine rails for reenforcement and stiffness. What is a reasonable weight of fiberglass mat to use? Can I get it from a marine store, or do I have to go to a model shop?

[DaveDude]

Well, I just got the engine rails epoxied in and I bent the shaft tube. I decided to skip the annealing and just give it a go because I had a spare tube, just in case it didn't go well. As Watercadet said, it's not a real sharp bend and I think it went almost perfect. Hopefully, I'll slap a little fiberglass on the rails for reenforcement in the next day or two and then put the sides on. More pics then...

[DaveDude]

I'm just waiting for some fiberglass I stuck on to harden and I'm trying to figure out what radio to get. I've bought a couple of radios before, but those where for electric models. What are some essential features for nitro running? For example, some radios I've seen have 70/30% throttle centering instead of 50/50%. Is that definitely worth having?

Can anybody recommend some decent 2-Ch radios that won't break the bank? (Say, under $75)

Also, should I use a standard servo or a mini servo for the throttle on my .21 engine?

How many people out there are using failsafe modules that bring the engine back to an idle when the radio signal is lost?

Pushrods and pushrod seals???

[Ron Olson]

Dude, you can use the radio systems that you already own, there is no difference in suface radio systems whether it's for electric, nitro or gas.
There are a lot of low dollar radios out there made by almost every manufacturer.
I use the Hi-Tec HS81-MG servos for thottle and remote needle operation. Use the MG servos only as the plastic geared servos can't handle any abuse.
Use of a failsafe is always a good idea.
What do you need to know about pushrods? I use 2-56 threaded rod for the throttle and for small boat rudders. On .21 and over boats I use 4-40 threaded rod for the rudder. For pushrod seals, it's your personal choice. I use Bru-Line but have also used Aeromarine and Du-Bro's.

[DaveDude]

I got the sides on today and the thing is actually looking like a boat now! The middle compartment looks a bit rough because I had to scrape out all the fiberglass I put in due to a bad batch of epoxy that wouldn't harden :( In the end, though, I decided that everything was stiff enough so I didn't need the fiberglass... But it should look spiffier after a good sanding and another coat of epoxy. I still haven't ordered my radio gear, but I've located nearly everything on my list. Next step is getting the running hardware ready to stick in and working on mounting my other gear. I have some nice 90 degree angle aluminum hanging around that would work for mounting servos...

[69dart]

dont go cheap on the radio trust me
get a jrxs3 its what i use and i love it
you have all the trims sub trims and everything you need
it cost about 150 and the best part
no crystals to deal with

[DaveDude]

dont go cheap on the radio trust me
get a jrxs3 its what i use and i love it
you have all the trims sub trims and everything you need
it cost about 150 and the best part
no crystals to deal with
That JR XS3 sure looks like the Cadillac of radios!

[DaveDude]

Since I'm using the instructions for the Wild Thing plans from R/C Boat Modeler as a guide, I decided to leave the sides a bit long so they would overhang the bottom and make chine rails when the groove is filled. How large do these chine rails need to be to create the right amount of lift? The boat is about 7" wide (fairly narrow) and I'm hoping it will go at least in the mid 30mph range. Also, is it best to align the rails horizontally, or angled slightly inward to improve tracking?

[DaveDude]

Hey Guys, I may have been quiet the last few days, but I have been busy! I got most of the faring done on my chine rails and I just epoxied the shaft tube in today.

I'm waiting for my servos to arrive and the challenge of the day is figuring out what is the best layout for my tuned pipe. I'd like to have the entire pipe below deck if possible and I anticipate drilling or making cutouts in my bulkhead and transom to fit the pipe through. I stuck the pipe on top today just to get an idea of how it will fit. I've got an O.S. engine and the header has a "high" and "low" position. I'm going to try to use the "high" position if I can to try to reduce the chance of water running back into the engine when the boat stops. As soon as I get the hull sealed, I'll weight it down and float it in a tub to get an idea of where the waterline will be. How does this layout look?

[ejp]

That pipe is going to be WWWAAAYYY long. You will have to add a extesion on the stinger or have the pipe hang out of the boat.

[Watercadet]

Don't send it through the boat. Just let it go out the top like the rest of us. I always heat the header and angle it up a little. As it sets, the header is like a "U" I just pull the outlet side up to help the pipe point out above the deck.

[DaveDude]

Yeah, thanks for shaking me awake! Sticking the pipe out the top is definitely going to be easier and it looks like my middle compartment will be open, anyway, so it won't cause any sealing issues.

[DaveDude]

I finished sealing up the wood on the hull yesterday and test floated it with the engine and some fishing weights inside to represent fuel, radio gear, and hardware. I was surprised to find that the thing floats level and quite high in the water! The water line is just above the chine. Well, I guess as long as the prop's underwater, I shouldn't worry about it.

Right now, I'm working on fabricating servo mounts and getting my control linkages all set up. I'm sort of confused as to how to install the Du-Bro rubber pushrod boots. first, do I jam the round plastic insert into the boot or glue it on? Second, do I put the O-ring on the plastic insert directly, or around the outside of the rubber boot? Oh, and is it usually better to have the boot on the rudder pushrod on the outside or the inside of the boat? Inside might allow water to sit inside the boot, but outside might interfere with the movement of my rudder?

[DaveDude]

I got another question for ya! Does it make any difference if I route the cooling water outlet straight out the side next to the engine or run it back out the transom? I'm curious because it seems like the water would flow out the back better than the side, but that would require another hole in the bulkhead.

[Ron Olson]

Dave, if you plan on racing or just making a lot of right turns, I find it easier to exit the water through the left side of the hull. It makes it easier to see if the water is flowing and won't be obscured by any spray coming off the back of the boat.

[Watercadet]

I believe the plastic part is glued in place through the bulkhead, then the pushrod goes through it and the boot. The O-ring then goes over the boot and seals the boot against the plastic insert. Run the water out through the side; or if you think you are going to go fast enough just send it straight up off the head. My Micoburst (white above) just has a 1/16 hole drilled in the top of the water jacket. The water sprays up and the boat moves out from under it.

[Ron Olson]

Spray WD-40 or put a little grease on the linkage when you slide it though the boot, it'll go on a lot easier.

[DaveDude]

Thanks for the feedback. Running the water out the side will be a lot easier. I'm working on making the steering servo mount out of two pieces of angle aluminum attached to a block of wood. Unfortunately, I haven't made much progress this weekend cause I was distracted by another building project (a full size one), but I hope to be able to devote my full attention to the boat again tomorrow or the next day! I'm also still waiting for a drive dog that is supposed to be in the mail. Until I get that, I can't quite put together my drive line. Still, I'm really hoping I'll have this thing in the water in the next 2 or 3 weeks! I gotta figure out what color to paint it, quick! ;)

[DaveDude]

Well, I just got my throttle servo (a HiTec HS-81) mounted today and I'm a bit worried because it often buzzes at the neutral position, like it's not quite centering. When I move the pushrod by hand, I don't feel any significant resistance and the servo does not have any trouble moving when I hit the throttle. I've never rigged up a throttle for a nito engine before, so I don't quite know what to expect. Do I need some kind of servo saver to get the servo to center properly without buzzing? :confused: Can anybody recommend one?

[Ron Olson]

Be careful when messing around with the HS-81 servo. The nylon gears are weak and won't take much abuse. The metal gear ones are a lot stronger. I use those in several of my boats. You might be getting some binding from the connectors that you're using as they can't swivel much throughout the range of travel. You can put a ball-link type of connector on one end or put a "Z" bend at one end, the cheap and easy way to do it, usually through the servo arm. It would be a good idea to do it now as later on when the engine is running the vibration will shake those loose, especially if you are using the plastic grommets. Don't ask me how I know. :D

[DaveDude]

Yeah, I was actually planning on using a "Z" bend to attach the pushrod to the throttle arm, but, as I discovered, the 2-56 pushrod does not fit through the hole! How does one deal with this problem? Would the screw on a 2-56 size ball connector fit through the hole on the throttle arm?

I'm having trouble with my fittings being too big for the hole in my aeromarine rudder too! I got a 4-40 size ball connector for that and the screw is way too big for the hole. I will have to drill out the rudder and must use the inner hole on the control arm because the arm is too narrow at the end to drill out the outer hole. Man, they ought to color code these things for us newbies!!! :D

[Ron Olson]

You can drill out the arms using a 1/16" drill bit or tap them if you can or have to.
I recently dscovered these locking ball-links from Sullivan, they are much better than the ones used on R/C cars and trucks as they won't pop off easily but by sliding a spring loaded piece back they come right off. http://www.sullivanproducts.com/ContSysAccMainFrame.htm
They have sizes for 2-56 and 4-40 rods. They can be placed at only one end if you still want to use a "Z" bend at the other.

[DaveDude]

Well, I finally broke down and drove to my nearest decent hobby shop (30 minutes each way)! I found a guy who worked there who makes a lot of custom boats for people and showed him what I had. He thought my setup was ok, but I bought a ball connector for the throttle arm anyway. I would have liked to use one of those nifty Sullivan ball-links as Ron suggested, but unfortunately, I'm a little short on clearance between the throttle arm and the screw on the engine mount and it wouldn't fit. Personally, I'm still not completely satisfied with the throttle linkage, but I do feel better with the ball connector on there.

The guy at the store also said that he would never run a nitro boat without glassing in the shaft tube. He thought the vibration would separate the brass from the epoxy. Is that acurate advice?

[Ron Olson]

I've only epoxied on stuffing tube in a boat. I did try a Shoo-Goo type of sealer but when I tore my sons boat down last week I found out that the stuff comes loose after a while. I repaired it using JB Weld hoping that it will hold it. you should have seen if he had a small piece that you could get from him as if you bought a package of it you'd have enough to 'glas the whole boat and then some. I've got a sheet of it around someone but couldn't find it when I needed it. It's a little extra added insurance but it looks like you've got it pretty well mounted. If you find out later that you have to raise the tube then you'd have a lot of fun trying to get it out.
You asked about a color. Bright colors work best for visibility. White shows every little drop of oil or greasy fingerprint, that's why none of my boats are white but other bright colors aren't a whole lot better.

[DaveDude]

Hello again! I'm here's the latest. It may not sound like much, but the thing's really starting too look great! I cut out the hatch holes in the deck, reinforced them with strips of wood around the opening, epoxied together the cabin/sprayshield, made the radio compartment hatch, aaand decided on the color scheme! Silver deck and blue hull. Unfortunately, I'm still being held up by the lack of a drive dog. I plan to order another one from Rocket City Racing tomorrow. Here's some pics I took tonight. The deck and cabin isn't attached yet, but you get the idea... Thanks to everybody on the forum for their help, you've been great!

[ejp]

That is looking awsome. I really like it. The windshield or whatever you call it looks sweet.

[DaveDude]

Here's how I want it to look following a few sessions with the spray cans:

[nighthawk355]

Nice looking boat!! Thats so tight! I like the sleek design, and how everything comes to gether very very well, nice work man. Also, is that drawing a CAD drawning????? If not, what program did you use to draw that?

-Garrett

[DaveDude]

Thanks for the compliments! I WISH I had CAD! I'm sure it would have made planning out the boat much easier, but I just used Adobe Photoshop to make the sketch. All I did was trace over the original photo on a few different layers, color fill them, and then get rid of the picture altogether, leaving the drawing in the foreground.

[nighthawk355]

oh lol well shoot! i would have done that too lol dang! i didnt even think about that! that makes it a ton easier! lol. But CAD does rule. you can dl it offline for free im sure.

-Garrett

[DaveDude]

Do you think I could find some kind of CAD program online that would allow me to lay things out in 3D and look at them from different perspectives? I've downloaded a few programs, but they only allowed me to lay things out in 2D. Does anybody know of one?

[DaveDude]

I have a question about where to mount my rudder. As it turned out, my rudder will be next to the prop, rather than slightly behind it. I know I should position the rudder pretty close to the prop, on the right side, but how close is too close? If I mount the rudder so it goes really close (like 1/4") to the prop on left turns, will the turbulance from the rudder interfere with the prop?
Thanks

[Chris LaPanse]

Do you think I could find some kind of CAD program online that would allow me to lay things out in 3D and look at them from different perspectives? I've downloaded a few programs, but they only allowed me to lay things out in 2D. Does anybody know of one?
Sure, but most are more than worth their weight in gold.

[Watercadet]

I have a question about where to mount my rudder. As it turned out, my rudder will be next to the prop, rather than slightly behind it. I know I should position the rudder pretty close to the prop, on the right side, but how close is too close? If I mount the rudder so it goes really close (like 1/4") to the prop on left turns, will the turbulance from the rudder interfere with the prop?
Thanks

My .21 rudders are 1" away from the tip of the prop. Depending on the hardware you use, that might be as close as you can get them any way. Most of my rudders leading edge is behind the trailing edge of the prop. Only my .45 mono is even.
Yes, the prop turbulance will effect your rudder. It can even strip out stering servos :rolleyes:

[DaveDude]

Well, I got a drive dog!!! -and there's another one on the way... I was getting impatient. Never know when you might need a spare... :) Anyway, I'm rigging up an aluminum spacer thingy to put my Aeromarine rudder an inch further away from the transom. Not exactly an elegant solution, but it will work for the moment and the rudder was way too close where it was (I couldn't even fit a pushrod boot in). Perhaps later I will come up with something that looks better; or just get another rudder. Hopefully, I will get my steering servo mounted tomorrow and maybe the deck on the day after. May the Force Be with me!!! ;)

[DaveDude]

Hey everybody,
I just got the deck on my boat yesterday! And today, I put on the windshield and filled a couple spots on the hull with West System Low Density Structural filler (aka "the brown stuff" :D ) Everything's going nicely and all I have to do is make some kind of pipe holder (I haven't received my pipe clamp from Rocket City Racing yet :( ), fit an antenna, and do one last coat of epoxy to seal everything! Two more days max before I'm ready to paint!!!(assuming I get my parts today)

I'm planning to attach the battery pack to the bottom of my sealed radio compartment using industrial velcro and the radio to the bottom using double sided tape and foam for vibration insulation. Does this sound like a good idea, or will the vibration and banging around cause everything to become unstuck and start flying around the radio compartment? Also, I'm using Dubro pusrod boots; is it a good idea to glue the end of the boot onto the pushrod with something like CA glue to seal it, or will this restrict pushrod travel?

[Ron Olson]

I Velcro my RX batteries in place and they seem to hold pretty well. I wouldn't CA the boots otherwise it'll give you fits if you have to replace them.
A little secret on the tuned pipe clamps. They originally are from securing wiring for trailers and some underhood hoses in cars. You can find the same things in auto parts stores or a trailer/RV dealership.

[DaveDude]

Thanks for the info! Yeah, I figured out the real deal with the pipe clamps about two days after I ordered them, because I saw the same thing holding up wires in the engine room of a big Hatteras I was working on. I'll know better next time!

[Ron Olson]

It's amusing to think of where a lot of our parts come from and when you find out, you can save some money over buying from the R/C supplier. I started getting my starter belts from a sewing machine shop that pulls off used ones when they do a repair or fix up a trade-in. There is nothing wrong with them and I get them super cheap!

[Watercadet]

Hmmm Hatteras.... HMMMMMM

[DaveDude]

Hmmm Hatteras.... HMMMMMM
Hahaha, they're not so much fun when your work includes helping to clean out the bilge!!!

[DaveDude]

I just finished painting the boat today and I'm busy putting hardware on for a launch tomorrow! Ahh, sealant everywhere... :D -Well, not tooo bad. I elected to use spray-paint from spray cans so the finish is fairly crappy, but the blue and silver colors look awesome.

I'm curious; the water cooled head on my engine (an O.S. RG-MX .21) is oriented so one of the water fittings points right at my header. I think my water hose will be kinked when I bend it around the header. Is it possible to unscrew the six hex-head screws on top of the header and rotate the whole thing so the water outlet points in a better direction? And, if I complete this operation, will I screw up the seal on the engine and cause it to lose compression?
Thanks

[Doubledog]

Paint job looks good, but that natural wood was something else! Can't wait to see how it does.

[Burkey1000]

you should be able to rotate the head without any worries the thing to check is when you remove it see if feed in and out have a clear path for the water to flow through, no cutouts in the jacket, other than that you will be fine.

[ejp]

Yeah, you can move it w/out a problem. I had mine off and you'll be fine. Tha paint looks cool too. Can't wait to hear how it runs.

[DaveDude]

Thanks guys! It's now 1:00 AM and I believe I'm finished after a marathon assembly session that started to crank up about 6:00 PM! I think I'll sleep in tomorrow! I did rotate the head with no noticeable problems and everything is ready to go other than greasing the shaft tube. Funny enough, I've never run a nitro boat before so I have no idea what to expect, but I imagine it'll be a good learning experience. I'll definitely post some pics of the boat on the water (assuming the rain holds off!!!!). Anybody have any final advice? :) :) :)

[ejp]

Just Have Fun!!!!!

[DaveDude]

THANKS!!! I actually just got back and I can't exactly say my first run was a blast, but I certainly learned a lot about running nitro engines and so far my actual hull design seems to be working great (although I think I only took it up to about 15mph).

When I first got to the lake, I gave the engine a few pulls and it came right to life for about 5 seconds and then died. After that, I flooded it (as I found out) and couldn't get it restarted again. So, after about an hour of frusteration, I broke down and went to the R/C airplane field (how convenient) and found a guy named Eddy who was my savior. Apparently, while the instruction book said to unscrew the needle valve 2.5 turns, the engine would only run with it about 1/2 a turn. hmmmm, what's with that? So, after about 3 minutes, he got the thing going great and off I went to the pond again. After that, I popped it in the water and took off about 1/4 throttle to warm it up. It seemed to go pretty well, although it stalled about three times when I slowed down too much and once when I tried giving it full throttle (???). (The water was delightful :D) Unfortunately, after that, I had all sorts of problems, like the engine would stop whenever I pulled the glow starter out, even though I hadn't riched up the needle any from where it was before. And I kept having my drive dog and collet losen up. So, I went back over to the airfield and my magician Eddy got it running just like before in about a minute. By this time, I had managed to spend about 5 hours and decided to head back home and sort out some issues with my shaft. Apparently I gotta solder the end of my flex shaft to make it more solid and file a larger flat spot on the shaft for the drive dog set screw to seat on. If I get everything done tonight, I'll see if I can get the engine running better tomorrow! Unfortunately, the batteries in my camera were dead, so I didn't get any pics I can post, but I'll put some on as soon as I get some.

[Ron Olson]

Dave, with it dying after pulling the ignitor off, it's one of two things, it's too lean (my guees) or you have a bad glow plug.
to make a flat spot for the set screw to sit in, I take a stack of 4 of those cheap Drememl cut-off wheels and make a notch. You have to watch it though as you can go too deep really fast.
Is that the LutreKote aluminum paint on the deck? I tried using some of that last week and had nothing but trouble with it. It ran and was splotchy.

[DaveDude]

Dave, with it dying after pulling the ignitor off, it's one of two things, it's too lean (my guees) or you have a bad glow plug.
to make a flat spot for the set screw to sit in, I take a stack of 4 of those cheap Drememl cut-off wheels and make a notch. You have to watch it though as you can go too deep really fast.
Is that the LutreKote aluminum paint on the deck? I tried using some of that last week and had nothing but trouble with it. It ran and was splotchy.
I'm a little mystified with the engine dying after I took off the glow starter cause I tried leaning AND riching without a noticeable improvement. After that, I changed out the glow plug and that made no difference either. Later when I went for help, we put the original plug back in and it ran fine. Too bad, I'm already beginning to get scared to adjust the needle valve after it's set because the engine always seems to get worse and then not recover when I put it back where it was originally! Maybe it just needs more breaking in; I didn't quite run a whole tank through it yet!

I just filed about a 1/32" flat spot on the shaft and loc-tited the set screw, so I have high hopes that it will retain it's position for more than 5 minutes!

Actually, the silver paint is just metallic silver Rustoleum spray paint from Home Depot. It looks good from a distance, but it did dry pretty rough with little flecks of metallic stuff on about half the surface. The smoothest parts seemed to come out when the can was only 6 or 8 inches from the surface. I'm beginning to appreciate the merits of finding a buddy in an auto painting shop. :D Still, this works for my purposes.

[Burkey1000]

if its dying at full throttle its to lean be carefull because if its running to lean you will destroy the engine. is it a new engine or secondhand etc, give some details of the history of it.

[DaveDude]

Well, the engine is a brand new O.S. .21 RG-MX with a recoil start. I've got 15% nitro fuel with synthetic oil and both O.S. #8 and McCoy RC9 glow plugs. Here's a breakdown of what I've done with it over the last two days:

-First time out, tried cranking with 2.5 turns on needle and untouched lowspeed screw as directed in the engine manual. Engine started up, ran for 5 seconds and died. After a few more tries it got totally flooded.
-Got help from someone who leaned up the needle valve to about 1/2 a turn and got the engine running pretty well.
-Cranked up and made a few runs around the lake with the engine running ok at medium-low speed but stalling at low (which I expected) and also high speeds.
-Engine started dying when I removed the glow starter. I believe this was probably a combination of the glow plug filiment getting black, my glow starter being a cheap alkaline one, and maybe the mixture being off still.
-I got help again and we got the engine running, but still were not quite sure if it was my glow starter or plug. Then I went home.
-Today, I got the engine started fairly easily, but could not get it to run without the glow starter.
-I went back over to the R/C airfield (where I've been finding help) and a R/C flight instructor there thought my lowspeed mixture screw was too rich (although I was a bit apprehensive). He leaned it slightly. Also, we found my glow starter was weak and discovered that the engine started better with a NiCd starter. Of course as soon as he left, the engine refused to run reliably without the glow starter again! Probably a bad plug???
-Now, we're up to the present and I just bought a HotShot 2 NiCd glow starter and a couple more #8 plugs. To date, I've run about 3/4 of a tank through the engine, about half of which was on various picnic tables. I feel like I need to rich up the engine some, especially after Burkey's warning, but I can't seem to get the engine to run at all when I try.

[Burkey1000]

the low end needs to be set first, as starting and low throttle response are down to the low end, i am worried about the 1/2 a turn on the high end if the book says 2 1/2. If its just flooding try leaning the bottom screw a little all ypu have to do is adjust it 1/4 turn and see if its any better make a note of where the needle is now so its easy to get back to where you started.

[DaveDude]

Thanks, I'll give that try. My low end has just been leaned slightly from factory settings and I'll try riching up the needle valve if it can handle it. I just tried out my new glow starter and it's about 200% better than my original one which completely drained two C batteries in an afternoon. I'm considering hooking up my cooling system to a hose and running the engine for a while on land til I'm more confident that it's tuned well enough to run up and down the RPM range.

[Burkey1000]

Just remember all engines be it nitro or gas all run a little unsteady until there run in then they settle down and need next to no adjustment other than a little tweak i summer and winter, good luck with it. :D

[ejp]

I put mine at the factory settings and ran 2 tanks through it on land giving it some burps. I tried taking it to the lake the first time just like you and couldn't even get my boat to go fast enough to run water through the cooling lines. So, i took it home and broke it in.

[DaveDude]

Thats very interesting, so you got your O.S. .21 to run with the needle valve out 2.5 turns? Mine kept flooding, big time. What adjustments did you end up with by the time it got broken in?

[DaveDude]

Here's some pictures of the final product!

[DaveDude]

Another

[DaveDude]

The business end:

[DaveDude]

And the radio compartment:

[Ron Olson]

You might find that the pipe may be a little long so once you get it running, shorten it a little at a time. It wouldn't hurt to bag the RX and battery pack.

[ejp]

To, tell you the truth, I have no idea. I think it migt have been somewhere around 1 1/2 but I'm not sure. I left the low speed alone and it ran fine.

[DaveDude]

Ok, I ran it again this afternoon and managed to get it running pretty steadily at low speed, although I had to keep the needle valve leaned up quite a lot to keep it going when I took off the glow starter. However, every single time I tried to rev it up, it cut out! What do you think is going on?
Also, I'm not sure if this is normal or not, but there seemed to be an aweful lot of brown crud (burned fuel) in the pipe and in the cylinder whenever I took the plug out to take a look. Does is this sound like the result of the engine being too rich or too lean?

Finally, I don't know too much about the inner workings of glow engines, but I have come up with a theory to explain the engine stalling as soon as I give it gas. Here goes: The low-end mixture adjustment is too rich causing the engine to stall when I remove the glow starter. At the moment, I have the needle valve quite lean, which counter acts the rich low-end adjustment and allows the engine to idle. However, when I open up the throttle, the low-end adjustment ceases to affect the mixture and the engine dies because the mixture becomes too lean. Does this sound realistic or am I going off in the wrong direction? If this does seem likely, I would have to lean up the low-end adjustment while riching up the needle valve.

[ejp]

Sounds like you know more then you thought!!! That would have been what I would have said:D

[Ron Olson]

You may be rich on the low end but still lean on the high end needle.

[DaveDude]

I really appreciate your sticking with me on this one! Well, I'm determined not to be one of those people that walk away from the whole nitro boating hobby after the first totally frustrating day!

I tried running the engine again after my last post. I leaned up the low-end mixture screw about 1/3 of a turn. At least part of my theory was correct because the engine now runs with the needle valve out where it should be - between 1 and 2 turns out. The engine is also running cooler and spitting a very healthy amount of clear fuel out of the exhaust pipe. However, the brick wall at about 1/4 or 1/3 throttle is still there. It just dies past that point. Anywhere slower than that is excellent; I can slow it right down to an idle. Now, when I give a little kick of gas, the engine begins to speed up, seems to falter, gives a little puff of smoke and a spray of fuel, and then slows down again. Any attempt to hold the throttle up for longer than fraction of a second has the same result: an immediate stall. I guess today I'll double check that it's getting enough fuel by taking the tube off the pressure fitting and blowing on it. If that has no effect I'll just have to keep working on the mixture! Gerrrrr I'm open to any suggestions!

[Watercadet]

This may not be new news to you but nitro engines don't like to idle. There are some, especialy in cars and planes that will but I am yet to find an engine in a boat that will idle for any period of time above 3 seconds. Longer than that the carb will load up and the motor will shut off. Our motors need to be "throttled" to keep them alive and cleared out while on the beach. It sounds like you are tuning your motor to run at idle and that would be excessive leen due to the loading up condition above. Remember to only make mixture adjustments after the motor is at opperating temp, like after a lap on the pond. On that motor I believe the low end needle should be flush with the brass ring that it sets in. And the main needle should be at about two turns out. Hot and humid days will be leaner as the air is thinner and cold days will be a little fatter to mix with the thicker air. I would start at those settings and start to run a few laps to break in the motor.
Also remember that a engine won't die from too much fuel while you are at speed; they die from being too lean.
Another thing to think about is that the LSN is like the idle/curb mixture screws on a automotive engine, that any speed above idle they are not in play. The main needle is just that, as it meters ALL the fuel comming into the motor. Most high end nitro boat motors don't have a LSN because they are ment to scream, not idle.

[Ron Olson]

Frustration? Welcome to Nitro boating! :D Once everything gets dialed in it isn't so bad, it's just getting there that's the hassle. I've come to expect this with every new boat that I build.

[DaveDude]

Thanks for the encouragement! I'll try riching up everything some more and making sure the idle speed is high.

[Ron Olson]

These little buggers like to idle at around 2 Grand. It sounds kind of high if you figure that full-sized vehicles are now idling at less than 1,000 RPM, some as low as 600-800. Too slow and you could get the loading up of the glow plug like you described earlier with the brown plug.

[DaveDude]

Well I hate to be premature, but I ran the engine again yesterday, and all of a sudden, it started working properly. I put in 2/3 of a tank and ran it connected to the hose again. Most of the time, I couldn't get it to speed up, regardless of my needle valve setting. But finally, when I was almost out of fuel, I riched up the needle valve a couple clicks (as I had done about 10 times before) and all of a sudden I couldn't get it to idle. However, I COULD get it it go fast! Excellent, maybe it's finally getting broken in or something. I'm feeling very positive, however, I still can't be 100% sure it will run the same next time because I only had about a minute of fuel left in the tank. It's possible that the sudden change in behavior has something to do with a change in fuel flow. Unfortunately, I'm getting some of those famous south Florida thunderstorms this afternoon, so I can't crank it up, but I'll definitely have to give it another try tomorrow to reassure myself! We'll see what happens!

[Watercadet]

Forgot one more bit of info. Boat motors act like they lean out under load on the water when they get near opperating temp. In otherwords, on the beach it might be blubbering rich, but when it completes lap one it will be acting more normal. That is why making adjustments to the needle must be done after warm up on the water.

[DaveDude]

Thanks for that! In fact, I did try the boat at a lake today and it conks out every time about 15 feet after I toss it in. I assumed that I needed to rich up the needle valve, but doing so actually resulted in the engine dying by the time the boat reached the water, even when I rev it up during the process. After about 7 of these false starts, the engine was plenty hot (I was actually worried that it was too hot because it was burning my fingers when I cranked it up and, of course, not getting any cooling water). I know the glow plug that's in there is a bit cruddy, so I'll try putting in a fresh #8. Do you think that could explain these symtoms? I was also reading the engine manual again and it said that if the boat begins to speed up and then the engine cuts out after a few seconds, the low speed mixture adjustment might be too lean. Worth a try, I guess???

[DaveDude]

The saga continues!!! I just got my last chance to run my boat today. I'm leaving for college next week and I can't bring it with, initially. Today, there was good news and bad news. First, I got the boat on the water and managed to adjust the needle valve so it didn't die. However, I'm still not getting proper throttle response. At the moment, I have a nice new #8 plug in there, the needle out about 2 1/8 turns, and the idle speed screw at about the factory position. When the boat is tossed in the water, the engine maintains a fairly constant, slow, speed regardless of what I do with the throttle!!! I don't get it! Leaning the needle a few clicks results in surging, although no better throttle response. The engine will speed up to high RPMs for a few seconds, then falter and slow down again (or even stall). Riching to above 2 3/8 turns also causes the engine to stall soon after I toss the boat in. In general, the thing still runs better slow than fast. This time, though, the needle's definitely not too lean. Maybe the low-speed adjustment again? Any ideas???

Well, even though it hasn't really gotten going, it was still pretty exciting carving turns around the lake I was at! Hopefully I'll get to see the boat's true colors during winter break. In the mean time, I'll have to start up an R/C Boating club at Rochester Institute of Technology! There's a great icy winter for building boats up there in NY! :D

[DaveDude]

Hey everybody,

Man, it's been ages since anything happend on this thread! It's too bad I left for college in NY in September last year without ever reporting any good news or even getting any pics of the boat in the water.

Well, this summer, I was ready to renew my efforts, and thanks to some expert assistance by a few participants at the NAMBA Nationals held in District 3 at Markham Park, south FL, I got the boat running and almost broken in. I also had to replace the Aeromarine Posi-turn rudder I had on there. The water pickup simply didn't work well and I almost burned up my engine before I realized it. That was probably one of my problems earlier on; I couldn't lean up the engine enough because it would overheat. Right now, I have a cut down Speedmaster 40 sized rudder blade with a much bigger inlet on the left instead of on the right like the Aeromarine one, and I get ample waterflow.

For all you guys who gave me so much help and support, here's a little video I took last weekend and some pictures of my project.

The Video (Hosted @Myspace) (http://vids.myspace.com/index.cfm?fuseaction=vids.individual&videoid=1040533722&n=2)

[DaveDude]

Here's another picture. Seems to be running quite well! I think I could get a good bit more speed if I had more lift in the bow to raise it more out of the water and reduce drag at high speed. I'm thinking of epoxying on some planing strakes along the bottom in the front to serve that purpose. Still not quite sure how to get strips of wood into the correct 30-60-90 degree wedge shape to lay along the bottom. Any ideas?

[Doubledog]

<sits back & smiles to himself> :)

Good job.

[Burkey1000]

Its good to see one go from plans to on the water running. good job and enjoy. :)

[Ron Olson]

Tilt up the strut just a little or raise the trim tabs if you have them to get it looser on the water. Go just a little at a time to see what happens.

[DaveDude]

Tilt up the strut just a little or raise the trim tabs if you have them to get it looser on the water. Go just a little at a time to see what happens.

I have a fixed shaft angle and no trim tabs installed at all, at the moment. Would you see any advantage in installing some, or would they only be useful in lowering the bow, not raising it?