R.J. West

Today I received my Dumas kit #1301 Atlas van lines U-71. Dumas discontinued this boat, I dont know how long but this one and the Miss Thriftway is also gone. You can sometimes find these on ebay. I paid $70. Dumas still offers a handfull of other small 18" boats designed either for electric or .049 Cox engines. I have a 18" Dv-10 "short-Stuff that I'll be working on later. I also received my running hardware from Dumas same day I got my boat! The Dumas hardware for the Atlas is kit# 2306, cost me 21 bux. I will be using a rebuilt Cox Babe bee .049 with a throttle sleeve, and the boat shall be made to be radio controlable. I may add a small fuel tank in the nose, cause the babe bee only holds 5cc's fuel..
I plan on building the hull as stated on the plans except maybe drilling some small holes in the bulk heads so to allow water to drain out in case some gets in.
I'm not sure how old the wood is in this kit, it appears to be 1/16 mahagony. Also included is a decal sheet and plastic full length cowl and instructions printed on both sides with lots of pictures.

Any questions, comments, concerns are always appreciate

Ron Olson

My Feedback: (1)

The Cox .049 is going to be a big disappointment in that boat, I don't know why Dumas tried to use it in the first place. I built their Deep-Vee 10 boat many years ago with a TD .051 and it barely moved. For the price you might want to upgrade to a better engine like an Aquacraft or Pro Boat engine. You can find them dirt cheap. I'd also update the running gear if you want to see any speed out of this boat.

R.J. West

This evening I spent it sanding down all the wood in the kit and very slowly and carefully scoring the parts out with a pen knife before attempting to remove the parts from their carrier sheets. Very tedious job cause some of the stamping was hard to see.

I have a small collection of Cox engines I like to try out first. There are alot of parts online to upgrade them to coax more RPM's outa them.
I do have a Cox .74 queen bee....I was thinking about sticking that in a 22' scratch built 69' notre dame hull just to see what happens.

EngineCrazy

I echo Ron's post. I myself had an Atlas Van Lines hydro back in the early 90's. It was my first RC boat. I to was going to retrofit RC gear into her but only one channel for the rudder. I used a new TD .051 in mine. with the extra weight it would hardly get up on plane. As for using a Cox 1/2a engine in these. I bet as a free running boat it would be fine but with any extra weight at all and it's just to much. I design and make many performance upgrades for the Cox .049/.051 engines myself i.e. 1/2a TurboHead, performance cylinder/piston sets, modified cranks, I even do a complete rear drum valve conversion so I know what a guy can get out of a Cox 1/2a engine and even with that said I advise against the Cox engine in a RC fitted boat. As for the Cox Queen Bee .074. It is one of Cox's biggest flops at engine design. Looks good on paper, RC throttle, .074 size...in real life it puts out power of a good running .049 at twice the weight and larger footprint...bad engine to say the lest.
Now I think JetPack has a thread started about the Dumas 1/2a hydro's. With aftermarket hardware and a different choice for an engine i.e. Norvel you might get somewhere. Another problem with the Dumas 1/2a hydros is there just isn't alot of room for radio gear. Just my 3cent worth

LAter,
Tim

R.J. West

What do you guys think of this one?

Thunder TigerGP .07abc w/muffler. From Tower Hobbies $48.99

Hydro Junkie

Can't say on the GP .07, but I will comment on the wood in the kit. If you haven't started the assembling the hull yet, you need to replace the wood with aircraft ply. The mahogany supplied is junk and will add almost it's own weight in filler due to it's being so porus. You also need cut large litening holes everywhere you can to eliminate weight as well as to drain water in the underdeck framing. This is what I'm refering to:

Ron Olson

My Feedback: (1)

Honestly? Stay away from plane negines as for one thing they're hard to cool and they don't have the timing needed to get that hydro up on plane. Boat engines on the other hand are timed for more bottom-end grunt.

Hydro Junkie

I didn't know boat engines grunted Ron. Did I not get the memo?

Ron Olson

My Feedback: (1)

They grunt just before they scream! I was just like that last week myself but I won't go into the details, it wasn't pretty.... [X(]

R.J. West

O.k. folks.

The build is going along pretty well, I'm just taking my time....The construction techniques is similar to the 36" Miss Unlimited in that you build the rear bulkheads and stringers first on the hull bottom, then assemble the outside stringers and front bulkheads that form the sponsons in two separte assemblies that come together to form the hull.
I would suggest anyone building this one or the Thriftway to first center the bulkheads and use a square to make sure they are perfectly straight on the bottom. They may not be perfectly lined up on both sides of the bottom, just center the pieces as best you can. Assemble the sponson stringers and forward bulkheads and then sand the bottom first before attaching to the hull bottom. Test fit first before glueing.
Today was spent cutting out lightening holes w/ Mr. dremel in the rest of the bulkheads. I noticed a big difference in weight loss after the cutouts were made.....But will be gained back after the hull is finished. I plan on using a mixture of slow setting epoxy and denatured alcohol to seal the inside and sanding sealer on the outside, then a couple coats of white "LustreKote" paint.
I'm not going to use the dumas hardware, nothing wrong with it, its just that the type of performance that i want to coax from the boat you cant do because the way the boats setup in the plans comes from a different era.
Pics coming soon.
Funny how a full grown man would put so much time in such a little boat, I just noticed on the box that its "for builders 8 years and up"...

jetpack

My Feedback: (1)

If I remember that kit right, some of the bulkheads are not very symetrical at all. I had traced them on paper, and fliped them end to end and laid them over the tracing again and you could see how different they were. I suppose the inaccuracy has to do with how good of condition the stamping die was when it stamped the parts.

Measuring and marking the center of them is a VERY good idea, and work off of a drawn centerline with all of them during the glue-up like you mentioned. If you're brave, and have a perfect picture how the parts should be, sanding them to shape over the tracing helps at this point because once the bulkheads are glued up you have to edge sand them which can be a hassle and you risk breaking them.

I never did like having to sand over the top of bulkheads to get shape or size. The sanding block always likes to catch, or the parts chatter more than they get sanded, but thats how it goes sometimes and you can't avoid it. I've been using those "KISS" brand wet/dry fingerboards you find at Walgreens for sanding. They come in coarse grits too, good for this kind of wood.

Sounds like you have a good idea how you want to seal and finish the hull. If you're going to thin the epoxy I would suggest you look for the 90% alky so you cut out as much water as you can from it.

For sealing, the thinned mix should be okay, I just worry about it turning to rubber because it's happened to me before so if you haven't done it before, take a day and do a test on some scrap first. LusterKote has mixed results sometimes. I've used cans that worked okay, others ruined the whole job. That stuff is a crap shoot for me so I've stayed away from it.

Appliance Epoxy spraycan works okay too, but only comes in like two colors. White and usually something else bland. I've used it on my field box and works good.

Sounds like your putting a serious 8 year old attempt at things with Mr. Dremel but I cheer that stuff on and will be doing the same thing to mine. I can't wait to see some pics. It's been probably 30 years since I built the one I had.

Ron Olson

My Feedback: (1)

Hey JP, one thing on the appliance paint. I got some from a big department store up here and they do have a lot of colors. I'd only use that stuff outdoors as it has some nasty solvents in it. I don't know how anybody could rattle-can a stove or fridge inside a house with that stuff!
Speaking of LustreKote, I'm heading down in a few to shoot some sponsons with it. The old lady doesn't like me shooting that in the house either so I'm going to do it while she's sleeping.

jetpack

My Feedback: (1)

Always be sure to wrap the can in a large towel for extra measure for shaking. They know the sound.

R.J. West

Hi Jetpack,
Oh so you havent started your Atlas yet, thats good.....Remember "measure twice, cut once, cause it doesnt grow back after you cut it"....
Again I'm trying my best to get the parts to fit flush and tight against each other. And if you follow the plans exactally as its worded, you may end up with a shelf piece instead of a high performance boat...Sand & test fit every part before gluing. The wood in the kit is kinda flimsy however once you start building it gets easier to work with. I'm kinda brave. I used a rubber sanding block from walmart w/220 grit.  however yeah, you gotta use very light presure if any, and take your time....The notches in the parts are there, but nowhere to being precision cut. Thats why I suggest building the main sponson stringers and forward bulkheads seppartly so your able to sand the bottoms before attaching to the hull bottom and make sure the bulkheads sit evenly on the stringers.I used a small machinist ruler to be sure all parts are even w/ each other.  Be carefull with bulkheads 3 & 4...Test fit, sand test fit rinse and repeat if necessary...#4 is a fragile one! The sponsons side and bottom today went on without any problem.
I may add 1/8 square balsa along the sponson/side stringers to allow more surface area for the deck....
bulkheads 6 & 7 will be the radio box...I'm using those mini cox servos. It will be mounted on its side..
The radio I'm thinking about is the Tower hobbies system 2.4
I added a 1/16 sponson doubler on the inside of the right sponson for the turn fin. Going to use mini blind nuts if I can.
Right now the hull is completed, I'm still working gingerly on the cutouts to lighten her up. and I'm going to order up the parts from "Head of the river r/c".
I got my NIB Cox medallion in the mail today. It brand spankin' new with a throttle ring on it....Once I have my hardware I'm going sort things out, check on how its balanced, before instaling the deck....
Pics on da way.....

Ron Olson

My Feedback: (1)

She sleeps a lot with the TV on or a noisy fan running. If I'm on the other side of the basement I can run my Dremel. The problem is that I'm building the boat under our bedroom, not in my usual workshop area. I'm finishing up the laundry for her so the dryer is also going.

R.J. West

I've been reduced to going on the back porch with my dremel.....damm mosquitos....

Ron Olson

My Feedback: (1)

It's 37 here now, no worries about mosquitoes!

jetpack

My Feedback: (1)

I bought nine of those hot red servos myself to use in my 1/2A boatworks. I hope they work okay. I'm trying to stay with as much Cox stuff as I can on these because I'm hooked on the whole Cox Power scene. Good looking servos. The plastic color reminds me of the tons of squirt guns we had as 8 year old kids.

I'm still waiting for my ebayer to mark "ITEM SHIPPED" but it hasn't happened yet for the Atlas and Thriftway combo deal of the century to get here. I sure hope your good at tracing parts. I'm crazy about building that Thriftway now that its actually more than a dream to have one. This one was sort of an unexpected surprise to have. Too bad it's vapor below the deck line on parts.

R.J., Here's what I can feed you right now on cylinder identification. You started me on having to organize all this stuff I've collected on it.

You might be able to peer inside the throttle sleeve and see a small stamped number in the wall of the exhaust cut out. Some are not marked however which just adds to all the fun. There was always strange goings on with these engines inside the factory(s) even though nothing really apparent changed on its looks. One has to know these things if they are to scavenge parts.

Your newer double slit exhaust engine you've mentioned in the past I believe do not have sub-port induction (good for engines with an added rc carb) but low on power being cut with only one port. I'm guessing on this.

Ron you better wait till the dryer dust settles out or your boat is gonna come out looking like the pink panther after a blow dry. She meant to start clothes so you wouldn't paint down there while she was sleeping. She'll know by the paint job for sure.

R.J. West

I hear ya on keeping it all Cox. I went so far as to obtain Cox and Dumas boat decals...Some came with the engines I've been purchasing.
Heres some pics. the brand new medallion w/ the exhaust throttle ring has a #2 stamped on themounting base.I believe it to be a post '96.the one with the slit exhaust ports has no spi inside the cylinder & no number,I dont think they came like that from the factory & my guess is the former owner may have changed it in an attempt to get more rpm's. it has good compression but not the same "pop" as the newer engines. the original owner told me it was from the early 80's. I'm trying to locate a replacement piston & cylinder for it. I'm curious about the engine with the brass carb. It has a #5 on the cylinder. I was told it may be a .051.
my thriftway shipped on the 8th & this mondays Columbus day, I'm expecting to get it. and the rest of my stuff this week.
from what I've learned from my Atlas build will be applies to the thriftway. I sand the partsin their carrier sheetsand score over the stampings w/ a xacto knife before removing the parts. I will carefully trace the parts either on cardboard or paper or both...and contact you mr. jetpack.

R.J. West

Heres a few pics of my build so far. I'm just taking my time....A part of me wants to keep the bulkheads air-tight to keep it afloat in case of a flip, then another part want to keep it light and be able to drain out water....I could add styrofoam in between the bulkheads to keep it from sinking....

EngineCrazy

R.J.,

Your TeeDee is in fact an .051. Couple of hints...the TD .051 had a red venturi mount while the .049 was black. They both interchanged so it's common to find a "red" .049. But the #5 cylinder is a .051 cylinder. The TD .049 is a #4 cylinder. Also last but not least the .051 piston has a small id groove at the bottom of it's pistons skirt. The engines both put out the same exact power rating as you are looking at only a .002 difference in displacement. The reason Cox made them like this was the .049 and .051 where in two different engine size classes in free flight flying and using the TD .049 and .051 allowed the flyer to fly the same plane without any needed trimming changes in two different flying classes.

LAter,
Tim

jetpack

My Feedback: (1)

The pics make me want to build. I spent a long time looking and thinking back on what I went through building mine. I remember the instructions telling you to use a book as a building board to clear the sponsons when gluing the bulkheads or something.

There's lots of room to stash a radio in that hull. I'm thinking of making small compartments and hatches for each servo, and running the wires open to the reciever and battery box. Maybe even a hatch under the hull for the tank.

I would say this much about keeping the compartments air tight. It also keeps them oil tight. These boats get messy and keeping them easy to clean at the end of the day is a help, so I'm going with a "deep well" approach for the engine bay and radio compartments where its just a pocket in the deck all sealed. Use foam in the hull either way it doesnt really weigh anything thats my thought.

If you're worried about water getting trapped inside a sealed deck, you can always drill drain holes in the back of the sponsons. They dont have to be big, just enough to let the humidity out as it dries. A small brass eyelet and a cork (yep they make them that small at the hardware) can be used. This trick also applies to the transom plate.

R.J. West

Well its nice to know. Thanks for the info, Now I got myself a .051 TeeDee.. I'm trying to get myself some throttle rings.

These are my thoughts so far. I'm keeping the engine bay intact to make cleaning easier. The front cowl will be pernament and my 3/4 oz wedge tank will be made so that the nipples would protrude in the engine well, keeping it a permament instalation...unless theres some way to replace the backplate of the engines with a mount tank....that would be cool....
I'm going to use presure from the engine for the fuel tank....

Well heres some pics of my build so far....Today I started to make some cut outs up front, but not done yet....I noticed that after I skinned the front sponsons the hull sat forward on the sponsons....with the stern about an 1/2" up....after I made these cut outs as seen in the pics, it now sits on the stern....

I'm still considering installing aluminum tubes along the sides for the water cooling but havent decided if I want to do that or use my Cox buggy heatsink....

jetpack

My Feedback: (1)

I always wondered about this setup.

Perfect makes small wedge tanks along with their rectangular kind. By resoldering the pickups in the tanks you could fit two 1/2oz or so tanks right on the sponson bottoms on each side and run pressure from one to the other, letting the outside sponson empty first.

That would really clean up the center section of clutter and keep the balance lower.

I would definetly bench check the setup first to see if the engine does okay with that kind of layout.

R.J. West

Interesting idea, I like it.
I did order an assortment of Perfect tanks....I'm only concerned about balance as the fuel empties one tank first. unless someone else tried it before.
using the hardware that was discussed before would probably lower the engine alittle bit, being a much shallower shaft angle. As soon as my gear/tanks etc comes in, I'll have a better idea of the layout....but will definately explore your idea.
the center of bulkhead #4 really serves no purpose, and after decking it will be cut out. Its just excess weight that goes thru the engine well.....

I'm going to start refinishing my 1/16 hydro and prep it for retrofitting a Cox engine as well....I'm going for a TeeDee .09 or .15 being a 22" hull....
heres some pics of that one.....wadda think?