PT109

Gentlemen; I found, at the curb, being discarded a old Dumas wood boat kit (kit 1312), a 36" model of the Atlas Van Lines U-76 hydro-plane! The kit was started up to the begaining of planking and all of the wood and plans were in the original box! I have built Dumas boats before and I knew exactly what it was when I found it and it was all there!

I am now planking the boat and the original plans call for a K&B .40 size engine. Is K&B still around? Anyway, I would like to marine nitro power it and this model will not get a lot of running, probably like my other boats and I will not be racing it either. Any suggestions on a up to date power plant for this model??? Thanks much, Karl

piper_chuck

My Feedback: (12)

You can find K&B engines at http://www.mecoa.com/kb/index.htm . Another choice for a reasonably priced .45 engine is OPS, which you can find at http://aeromarinerc.com/ . My source for much of my nitro hardware is G&M models (Gary Preusse) at 630-279-2451. He doesn't have a web site, you have to call to order. Gary sells K&B and OPS as well as the other parts you'll need to get your boat built. You didn't say if the hardware kit came with the boat, but even if it did, Gary would be able to suggest much better choices for you.

Hydro Junkie

Can you post a few pictures of the boat as it is now? I would like to see if any mods were done or, if possible, what you should do to the boat before you put the decks on it

Sean Bowf

I wonder how the OS .46 fits into the mix of motors mentioned here...For the $240 list price, and the fact you can normally get 20 or so dollars off an order in the price range, I would think (no personal experience) it might be a decent engine to try.

Sean

Hydro Junkie

doesn't it need a 180* header?
If so, there may not be room for the header and pipe without some serious mods or hack job

stempak

Gas Has really become popular, it was suprising to me that they are what's pretty much the thing these days compared to when it was unheard off pretty much. But nitro is still around for those people that havn't completly given up/swithced on them they still make twice as much power to cc ratio to gas. but you can pickup a .40 K&B for nothing on ebay or any other .40. I've seen K&B's as low as 50bucks but average is probably 60-100 You can findem with pipes without em, Just depends on what the person is selling! You can findem brandnew aswell.


As a matter of fact there is won right now with a pipe for 50bucks with 2days left.

Sean Bowf

Makes sense, thanks for the explanation.

Sean

jetpack

My Feedback: (1)

The front intake/side exhaust K&B marine engine (#8060) would be a great economical engine for it. It is basically a convered ringed airplane engine, very easy to wait for a new one in the box for under 65-75 dollars on ebay and comes with carb, flywheel and basic muffler.

The one in the pic has a perry carb. some come with that, but earlier ones have the cast one with fins.

The second one is their current version.

Ron Olson

My Feedback: (1)

According ot the very old instructions way back when the boat began production the K&B .40 Torpedo's were one of the hot engines of the time, not so any more. I talked ot Gary Preusse around 6 weeks ago and he said that the K&B .45's were supposed to be going back into production again soon.
You can find some .45's around on places like eBay from other manufacturers that will do the job better than the old Torpedo.

K&B also had what they called a Sport .40 engine, a very cheap basic mill. The last one that I saw went for just under $80.00 new.

Hydro Junkie

Forget the side exhaust engine as well. The boat will need more power than that engine can put out. If you want to go with a K&B, wait for the front exhaust .45, kinda like this one, which is mounted in basically the same boat, the 1973-75,77 Pay N' Pak U-1/25, 1976 Atlas Van Lines U-76, 1978-1988 Miss Madison U-6. You can see how little room is available around the engine, and why a rear or side exhaust won't fit

jetpack

My Feedback: (1)

$276 vs. $80 dollars, not much running and not being raced I would choose the old ring version and it still would be a fun boat. Macs might even have a tuned muffler for the side exhaust which would help. It would distract from the scale look but that might not be a concern(?)

PT109

Wow! That was fast! Thanks guys for your thoughts and recommendations on my Dumas Hydro-plane U-76 wood boat! It looks to me that this model as I will build it to the original plans and materials will be a heavy one! I was kind of wondering if the recommended .40 size (K&B) engine might be big enough to get it out of the water! Again, I just want it to for a little fun, no racing planned with it. I am 72 years old and I don't think that I can re-act quick enough at very high speeds!

I also have a four year old gas boat, the Prather Fun Cruiser for a nice running boat. I have a nearly complete Dumas wood PT-109, about 33" long that will be electric powered. A nitro engine in this model would probably vibrate all of the deck details right off of it!

As for the engine for the U-76, I think I would rather buy it brand new rather than one off of E-bay that might be less than perfect (messed up). Also, I want to add the very latest running gear.

If you guys have any other thoughts on this, let me have them, please! Karl

jetpack

My Feedback: (1)

Hi Karl,

I would have to go with Hydro Junkie's setup then with the newer K&B engine. There's other brands but will all start at the same price and only skyrocket from there, and some can be beasts to tune proper. A decent "middle of the road" engine would be OPS which you can find at the Aeromarine website. They are the older technology competition motors, but very strong runners and enjoyed the spotlight for quite a few years.

The long-standing hardware such as the driveline setup and props, is still Octura Models with Speedmaster products being the high end of the spectrum for struts and rudders, ect. There's a couple companies in-between that also can be looked at for other items such as turn fins, pipe mounts and radio hardware. Aeromarine will fit that catagory, Marine Specialties also.

[link=http://www.aeromarinerc.com/]Aeromarine Laminates[/link]

[link=http://www.rossisales.com/]Speedmaster (Rossi Sales)[/link]

[link=http://www.marinespecialties-rc.com/index.htm]Marine Specialties[/link]

This last link is a master link to many companies that are involved with nitro boats. There you can find companies that supply their own hardware or ones that have already been mentioned, plus some regular hobby distributors such as Tower Hobbies that will carry your paint and glues.

[link=http://www.wrcpbc.org/id7.html]Web Links[/link]

All this is a decent start on getting your Atlas going, I am sure you will have more questions as you go, and others will have more to add.

The Atlas you have there is a very historical boat and one of the most favored designs, it should be a fun one for you.

Ron Olson

My Feedback: (1)

PT109, you'd be surprised. We have some racers about your age that drive some fast boats that race in your neck of the woods. There's one that has I think Parkinson's Disease that once he has a transmitter in his hands shows the young-un's the way around the course.

gooycheese

I race with alot of people over 60yrs old, I never asked there ages but I would bet there are a few that are over 70 for sure and maybe some closer to 80. Don't let age slow ya down, wont hurt to try racing if ya feel up to it ..................... could always race sport tunnel.


Paul


I race for fun , winning would be great but I have fun just being there.

PT109

Fellas, you have all been a great help and I thank you all so very much! I "tried" to upload a photo that I took of my "curbside find" just as I found it, the boat had been built up to the point of being planked. The builder used CA in its construction, so I re-glued all seams with epoxy. Now let's see if my photo attachment is attached! Now, I am going to the Web sites that you guys sent me to see what I can spend my money on! It is cold now in Michigan and it is an ideal time for this project to continue! Thanks, CUL, Karl

Hydro Junkie

Okay Karl, are you ready to start shedding some weight?
You can drop probably 25-40% of the weight out of that boat very easily at this point. If you go back to the pictures I attached back at post 10, you can see all the glue blocks I've installed. You can easily add them to your boat as well, by first removing any extra epoxy at the bottom edges where they are glued to sponson insides. At this point, you can epoxy in some 1/8th " square spruce stock for the full length of the bottom. This is important since the butt joint will not handle the stress while running. Also, add them at the top of the lengthwise frames in between them, as well as on the outside of the sponson inside from the sopnsons trans to the tip of the sponson. I would recommend notching the top of all the cross frames and installing the glue blocks as a continuous stringer. This will force the top of the lengthwise frames to stay straight. Next and finally in the adding department, add a 1/4" doubler to the inside of the right sponson transom. Be sure to get as much doubler as you can in there as this is where the skid fin will be mounted and you want that transom to be as strong as possible

Hydro Junkie

Now that you have had the cance to beef up the hull, you need to figure out where the exhaust, water tubing, fuel tank and radio are going to go. As you can tell, my tank is going to be under the deck beside the engine with access through the bottom. I did this to leave room for my radio gear in front of the engine. I know your boat is designed to have the radio box under the cockpit, so it's up to you which location you want to use.

When you get that all figured out, it's time to start removing unwanted and unneeded wood.You need to cut lightening holes in all the framing that will enclosed be under the deck. As you can see in my pictures, all the cross frames have a large round hole cut through them. This removes around 40-50% of the weight of each frame, as well as giving water a way out and air a way to circulate inside the boat. The full frames trap any water that gets in right where it is, and trust me, it will get in. A Dremel Tool is good for this, especially if you have a 90* drive attachment for it. This needs to be done inside the sponsons and in the small triangles outside the frames as well. You can see in my pictures all the wood that was removed from the outboard lengthwise frames, you need to do this as well. Be sure to leave at least 1/4" of material beween the holes and the edges of the frames.
Now we get to look at the sponson framing. Besides cutting lightening holes out of the cross frames, you need to cut or even drill them in all the large areas of wood in the front of both sponsons. Be sure not to remove material where the lower frame is attached to the bottom of the sponson sheer. Also, remove about half of the material on the inside of the sponson sheers and the lower frame AFTER you epoxy the skin to it. It doesn't need to be nearly as wide as it was cut.
One last thing before you start puting skin on the framing, anyplace that will be closed off prior to the deck going on needs to be sealed with epoxy before installing the covering skin. This is primarily in the front of the sponsons. If you do all fo thins, your boat will be at the same stage mine is in the pictures I posted. If you have any questions, don't hesitate to ask.

I have reposted my pictures, along with some from other boats to make it easier to see some of what I was refering to.

stempak

Lucky find and cool build. I would personaly put a K&B in there definately for the nostalga and plenty of good running power. OPS is also a good way to go. You will definately want rubber engine mounts because possibly the last time you were hobbying they weren't used like in the pic.s above. I would also personaly use speedmaster everthing running gear. Anyways have fun, I will post a picture of rubberized motor mounts for you. I would use them because I have seen a boat hit a dock at around 50! from not having rubberized motor mounts. The vibration caused the servos 2 lock up. That is also why I have model insurance which covers up to a million I believe.

These Are 1 of the best motor mounts available. They are speedmaster and a type of (rubberized)motor mount you should use.

Ron Olson

My Feedback: (1)

I think that after today we're officially in the boat building season in Michigan as we got snow today on this side if the state. Last week it was official up north when they got 6-8 inches of the white stuff.

Hydro Junkie

Actually, I was going to get into engine mounts later, but since it was brought up, better still, than using what was pictured, is to use the inserts vertical from the boat bottom. Most people building scale boats run them that way as they still absorb vibration and at the same time, don't sacrifice power do to extrame flexing as the horizontal dampers will. Above all, DO NOT USE THE DUMAS BLOCK SET UP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Stempak, while the engine mounts pictured are of high quality, they do have drawbacks. The biggest being they are designed to go through the engine bay rails, or in this case, sidewalls. IF the engine/mount assembly is too wide or narrow, it won't fit in the boat. That's another reason why going through the bottom is a preferred method. Even my boat will be retrofitted to the damper-through-the-bottom set up and the hard mounts removed. The hard mounts were used as, like the rudder assy and strut, they were what I had on hand at the time.

TheRealDeal

PT109,
Nice find!!, I would defenitaly go with K&B or OPS for the nostalga of that kit and Speedmaster for good
upto date hardware

Hydro Junkie,
Is this not the 1312 kit that was avalable with a plastic cowl at one time but only in wood now?

I was going to order it and put it on the to do shelf,but I'm a little confused now with PT109 showing the
kit he has as a 1312,,Can you share some history of these kits with us?

Thanks,Joe

stempak

Yes, retro fitting can be a pain as mentioned. but as long as it is not metal to wood. You should be fine. What you are describing, mounting to the botom would work fine and be cool too. I think I,ve seen it that way before, Also in a hydro? I have never done a hydro just deepvee's, mono's and tunnel hulls.

Hydro Junkie

I built the 30" Pay N' Pak kit #1310 back in 1982 and built the 36" Blue Blaster kit #1314 in 1986, both of which had wooden cowlings. I can only assume that the 1312 Atlas, 1321 scale 1982 Atlas and 1322 scale 1985 Miller American also had the wooden cowling, based on my knowledge of the 1310 and 1314 kits and seeing the picture of the 1312 frame. I know that Dumas had smaller models of the generic roundnose Miss Unlimited and U-70/71 Atlas from 1971-1974 that had plastic cowlings, not to mention the Circus Circus kit #1325, which also has/had a plastic cowl. What you have to remember is Dumas put out boats that were die cut and fairly simplistic on their design, but did not take into consideration system placement, balance and width. This made them, for the most part, unsuitable for racing unless modified.
I found out how much they needed to be modified upon meeting the late Troy McIntire back in 1987. I had taken my Atlas out and was going to try and run it at a park in Arlington WA, only to discover there was an R/C Unlimiteds race going on. As I walked past the pits checking out the boats(or should I say pieces of artwork), I passed Troy, who saw my boat. After checking out my boat, he proceeded to tell me about his experience with the same kit and his problems trying to race it. I went home that day, heavily schooled on R/C hydros from several of the racers, a few new friends, and a set of plans for the 1980 Dr. Toyota on order. My boat never got wet that day, but it was a great day at the lake.

Hydro Junkie

Time to build a hydroplane Stempak. Since my boat is still open, it won't be that hard to do any retrofitting. If I had already installed the deck, however, it would be a whole different ball game.
Getting back to the engine mount, going through the bottom actually does a couple of things:
1) It can lower the engine for a lower CG
2) Lets the builder have more options on where the engine will go, not to mention making engine bay widths a non factor as long as you have room to work on and tune the engine
3) Puts all the stress on the bottom of the boat, rather than the internal framing. If a mounting screw fails for some reason, it's easily fixed, unlike through the engine bay side which would require removing either part or all the the bottom or a complete deck to repair