IMPBA 6 scale gas rule change proposal

[ChrisHerzog]

Not quite finished yet but this is what I did to my two hulls that I’m building.

 

[Marty Shallenberger]

Wish I had gotten into gas scale a long time ago. I love the boats and the class. Huge bummer that rear exhaust motors are no longer available.

I was just curious as to why 1/6 scale was selected. Not that I am advocating for larger hulls, but would a 1/5 scale size have the dimensions to allow side exhaust motors to fit into more hull designs? Is that a direction to go to grow or save the class also?

Late to the party - Doug

Hi Doug - Since I was the one the created the Gas Scale rules for NAMBA let me explain the rational why we chose 1/6th scale. It was that if we had gone to 1/5th a majority of the hulls would have been illegal to run under NAMBA insurance - NAMBA Max boat length is 60 inches - I know its not easy to fit all the hardware in a Gas Scale but if you look at the RCU group out of the Pacific Northwest there are plenty of hulls from different years running side exhaust engines by using different techniques to hide the pipe and carburetors.
Marty Shallenberger --- Past NAMBA Scale Chairman

 

[DPeterson]

Thanks Marty. Would love to scan some pictures to get some ideas. I googled RCU Pacific Northwest and don't get much. Is there a link you could point me towards?

Doug

 

[LohringMiller]

So this is illegal under IMPBA rules?

Lohring Miller

 

[scottmeyers]

Here you go Doug. Go to the "Boats" page to see some of the currently registered gas boats. Note that all of them have no bumps, holes, or other provisions to accommodate the motor or carb and all have concealed exhaust that exits the transom. The super-simple trick is to build an engine well and lower the motor slightly. Everything fits just fine.
https://www.rcunlimiteds.com/

 

[Marty Shallenberger]

Thanks Scott - I want to point out that the Gas Scale Rules were written to mimic 1/8 Nitro Scale Rules so bumps in the cowling and pipes running out past the dummy turbine tube is not accepted in the NAMBA rules....

Marty

 

[Bradley Maglinger]

So this is illegal under IMPBA rules?

Lohring Miller

View attachment 301765

C.
3c. Gasoline engine and complete exhaust system excluding up to 1" of exhaust outlet must be concealed with fake engine or cowling as per prototype boat.


Answer #1 as the person if I had to tech it, ***I would have to argue to say that the Carb is not "concealed" which is part of the Gasoline engine. You can see part of the dummy motor is cut out for the carb and now that part of the motor is showing. Then technically the coil is part of the engine right? however I like how you painted it black but technically I can still see the coil wire. I would like to see the other side of the dummy motor bc if, I can see any part of that exhaust it would be illegal because the rule states "excluding up to 1inch of "EXHAUST OUTLET". If the rules were like the 1/8 scale rules it would be legal no problem.

Answer #2 as a racer and one that runs 1/8 scale religiously, or one that is on the sidelines, I would say he attempted to conceal to the best of his ability, the boat measures correctly, the strut is in the proper area, and when its on the water it looks like a scale boat it should be legal,

BUT reading the rules there is no wiggle room.

Lohring Miller that is one beautiful build and you went over and beyond to conceal to the best of your ability and it shows, great work man, but do you see the questions that are raised if you had to be the actual one to tech it?

 

[ChrisHerzog]

Wesley,
I just went and looked at both the 1/8th and 1/6th Scale rules. I would suggest that you change your proposal to read something like this. Keep in mind I don’t have your submission in front of me.

pg I-13 Gas Scale Unlimited
C, 3c from what’s there to…

Effort must be made to conceal gas engine with fake engine or cowling as per prototype boats.

“then add this”

d. Minimum 50% of gas engine crankcase must be concealed with fake engine or cowling as per prototype boat.

—————————————————

1/8th Scale says nothing about the exhaust so I wouldn’t deviate from them on that and I would remove it from the 1/6th rules all together. It’s stupid that it was ever added just in the 1/6th rules and not the 1/8th at the same time when the 1/6th were voted in. If pipes become an issue down the road then sec 3e can be added to both 1/8th and 1/6th at the same time to address that.
This will be my suggestion as Dist-5 Scale Director to both the Dist-5 Director and to the Gas Director who is also in Dist-5.

edit:
Stupid might have been a little harsh. I just can’t stand that it’s one way in 1/6th and different in 1/8th. Make them both as similar as possible.

 

[Wesleys Custom RC]

Wesley,
I just went and looked at both the 1/8th and 1/6th Scale rules. I would suggest that you change your proposal to read something like this. Keep in mind I don’t have your submission in front of me.

pg I-13 Gas Scale Unlimited
C, 3c from what’s there to…

Effort must be made to conceal gas engine with fake engine or cowling as per prototype boats.

“then add this”

d. Minimum 50% of gas engine crankcase must be concealed with fake engine or cowling as per prototype boat.

—————————————————

1/8th Scale says nothing about the exhaust so I wouldn’t deviate from them on that and I would remove it from the 1/6th rules all together. It’s stupid that it was ever added just in the 1/6th rules and not the 1/8th at the same time when the 1/6th were voted in. If pipes become an issue down the road then sec 3e can be added to both 1/8th and 1/6th at the same time to address that.
This will be my suggestion as Dist-5 Scale Director to both the Dist-5 Director and to the Gas Director who is also in Dist-5.

edit:
Stupid might have been a little harsh. I just can’t stand that it’s one way in 1/6th and different in 1/8th. Make them both as similar as possible.

You can see my proposal in the reply to Brian Schymik and it is almost word for word what you are proposing and almost mirrors the current 8 scale rules which have worked for years. In my opinion there needs to be a small deviation from 8 scale some due to gas motors being more than 20 percent larger and the motors and pipes get hotter requiring better and more air flow to cool and run properly. The miss dollar bill in the previous pic is a great example. The carb and probably header are exposed and allow good airflow. It also looks cool ! if you completely seal off the motor as some suggest you will overheat the motor and it will look less scale.

 

[ChrisHerzog]

(Wesley Ellet IMPBA #9911S would like to propose to amend or change a rule for VI - GAS SCALE UNLIMITED

I would like to remove rule C-3-c which says:
c. Gasoline engine and complete exhaust system excluding up to 1" of exhaust outlet must be concealed with fake engine or cowling as per prototype boat

I would like to replace it with:

c. Effort must be made to conceal glow engine with fake engine or cowling as per prototype
boats.

At least 50% of engine and at least 50% of header/pipe/silencer combination must be concealed as per prototype boat.")

Again, I would not bring up exhaust at all since it is not mentioned in the 1/8th Scale rules. Make the proposal as similar to 1/8th scale as possible and you will get it through. If the exhaust becomes an issue then a rule can be added and inserted with the same wording in both the 1/8th Scale rules and the 1/6th Scale rules at the same time with one proposal to do so.
I would also consider changing the percentage of engine exposure from 50% to maybe 25 or 30% but when you do this also make the same change carry over to 1/8th Scale so you keep some consistency between both 1/8th and 1/6th Scale rules. Like me, I think most of the Scale guys have concerns about the class becoming just another Sport Hydro class. Keeping the wording and rules as close to the already in place 1/8th Scale rules will suggest that is not the intent here and gain more support from all the Scale guys.

 

[LohringMiller]

"Lohring Miller that is one beautiful build and you went over and beyond to conceal to the best of your ability and it shows, great work man, but do you see the questions that are raised if you had to be the actual one to tech it?"

Thanks. I don't have a good picture of the other side with the cowl on, but you can see that the pipe is exposed somewhat like the carb. By the way, the boat was quick enough to hold the NAMBA 2 lap record at 24.56 seconds. It does tend to blow off, though.

Lohring Miller

 

[Mike Cathey]

I'm building the 82 Pak and I made full use of the legal belly pan rule to drop the motor as low as I can. As heavy as the gas motors are, there's also a performance increase in cornering stability by lowering the CG. Also, in full cowling applications Bill Brandt of Rattlesnake RC is selling the H&P motor mounts that allow you to roll the motor over 5 degrees to the left side get the pipe lower. The H&P stuff is top quality stuff.

 

[Wesleys Custom RC]

Here you go Doug. Go to the "Boats" page to see some of the currently registered gas boats. Note that all of them have no bumps, holes, or other provisions to accommodate the motor or carb and all have concealed exhaust that exits the transom. The super-simple trick is to build an engine well and lower the motor slightly. Everything fits just fine.
https://www.rcunlimiteds.com/

That's interesting scott. Almost no modern hulls. Also, I would be curious to actually see the engine well of the round nose boats. If they completely conceal the header and carb I would like to see how they did it and still let the motor breath and stay cool. I know you chose a boat with a inclosed cowl. What if someone wanted to build the turbinator (U3) with an open engine well and a 3/4" transom?

 

[DPeterson]

Spent a good deal of time looking at the R/C Limited site. Love the boats. Would be most helpful however to see pictures of the engine compartments for understanding and ideas.

Doug

 

[scottmeyers]

It's four weeks until our first race for this season, and with racer's permission I'll take pics and shoot some video of the interior of our gassers.
Quick note for Wes; a 3/4" gas scale transom translates to only 5" in full scale. Waaay too small! Fix your boat design and everything will fit.
Never really thought about it before but you're right that we have only one Bud style hull in gas, though I think a few are in development now. I'll be sure to get an inside look at Jeff Snell's beautiful Graham Trucking for y'all.

 

[Wesleys Custom RC]

It's four weeks until our first race for this season, and with racer's permission I'll take pics and shoot some video of the interior of our gassers.
Quick note for Wes; a 3/4" gas scale transom translates to only 5" in full scale. Waaay too small! Fix your boat design and everything will fit.
Never really thought about it before but you're right that we have only one Bud style hull in gas, though I think a few are in development now. I'll be sure to get an inside look at Jeff Snell's beautiful Graham Trucking for y'all.

You are correct on the outside dimensions of the transom scott. Unfortunately you are not taking into account the double wall floor of a glass hull as well as the thickness of the top making it virtually impossible to run a 7/8ths pipe out the back without catching something on fire. I have seen a thunderboat run the exhaust out the bottom. That may be an option. Just trying to make it easier for a newbie like me. Although I have learned ALOT from you my friend. Thanks for your "how to" blogs. They are a great way for people to learn and avoid big mistakes.

 

[Don Ferrette]

You are correct on the outside dimensions of the transom scott. Unfortunately you are not taking into account the double wall floor of a glass hull as well as the thickness of the top making it virtually impossible to run a 7/8ths pipe out the back without catching something on fire. I have seen a thunderboat run the exhaust out the bottom. That may be an option. Just trying to make it easier for a newbie like me. Although I have learned ALOT from you my friend. Thanks for your "how to" blogs. They are a great way for people to learn and avoid big mistakes.

Well..... not trying to be argumentative but gotta disagree Wes. I had no heat or fire issues on the fiberglass U-7 Dame I built, it worked great. Sadly at the time gas scale just wasn't catching on yet in D12 and it sat on a shelf. Brian Schymik wound up with the boat and basically cleaned up with it from what I heard. If you'd like to chat sometime about some ideas I'm working on to ease things a little let's share a phone call.

 

[Wesleys Custom RC]

Brian Schymik? !! That wuss! I beat him going backwards! He had to sell it kuz he was so embarrassed!

Seriously, that was an easy conceal job. Others, not so much. I have built a bubble bud, 7-11 and a griffin bud. All because they were easy to conceal the motor. It's time to evolve!?

 

[SayMikey]

Heat was a issue on Your boat Don. We figured out the vennom cc exhaust will pull the heat out with the exhaust after he ran it with out the cowl

 

[scottmeyers]

I get your point Wes, and it makes some sense to be sure. Scale is tough man!
The thing y'all need to determine is whether you're ok with having your scale classes tip toward 'sport' and away from the original intent of 'scale' or not.
Here in the NW where scale is King, we hold the line despite the difficulties. You'd be surprised how creative you can be when you must!
I guess I'd just encourage you to be as conservative as you possibly can with your proposals, recommending only what you feel you MUST, while avoiding changes seeking only to make it easy.