1:8 SAW rules , Aronow UL Tunnelhull

[Christian Lucas]

Hi,
I have a few questions about 1/8 Unlimited Hydroplanes rules. Specifically SAW racing.
The IMPBA rule book says that any unlimited hydroplane that was built according to the rules can participate, with a driver, cockpit, dummy engine and drive as in the original. I would love to build Don Aronow, Gary Gabrecht's catamaran. But the boat had 2 propellers, which would be allowed according to the rules like the prototype, but the rules also only say one motor? Okay can also drive two geared propellers with one motor. Is that ok then?

Happy Amps Christian

 

[LohringMiller]

The NAMBA rules don't allow either twin motors or gearboxes.

Lohring Miller

 

[Mike Mulligan]

As I recall, the Aronow Unlimited ran with outdrives (stern drives) as opposed to shafts and rudders. Not sure if that would fall under the "original drive" clause or not...

 

[Christian Lucas]

Hi Lohring,

IMPBA say under Section J Fast Electric
at E. Scale FE Unlimited Hydro , number 4.
4. Motor, Boat and Battery Specifications
a. All boats to be modeled after Unlimited hydroplanes from past or present.
b. All boats to be built to a scale of 1- 1/2" to 1'0" (1/8 scale) plus or minus 10% of the beam and
5% of the length
c. Boats will look as scale as possible and meet the following requirements for racing and scale
judging:
I. Cockpit with driver.
II. Complete all major lettering and paint schemes.
III. Effort must be made to conceal the motor with fake engine or cowling as per prototype
boats.
d. Hull bottom and running hardware will not be judged or checked. However, hull must not deviate from conventional 3-point hydro (unless prototype was a different design).
I. Hull bottom must be scale appearing.
II. Belly pants are acceptable to clear motor.
III. Secondary front sponson running surfaces are optional.
IV. Air traps are optional.
e. Only one brushed motor of any type or one brushless motor from the following types, Lehner 22xx series, Neu 15xx series and Plett 370. Any other brushless motor is subject to technical approval.
f. Boat shall use same number of propellers as the prototype.
g. The drive dog must not extend beyond the transom unless the prototype boat did so.

under f. f. Boat shall use same number of propellers as the prototype. So the Original Boat has twin Z drives , two propeller.
How to drive them ? Gear ? or two motors ?
NAMBA is clear.

Happy Amps Christian

 

[Mike Mulligan]

I guess putting two props on the same shaft would come across as being a bit snarky...

 

[Christian Lucas]

Hi Mike,
yea, but never say never . Two props on one shaft , posible with flex cable. And have you ever seen a full size UL Hydroplane with
flexcable drive . They have all straight solid shaft. Modelboater , most have flexcable driveshaft for easy adjusting. I have straight shaft on my hydroplanes and never had problems with them.

Happy Amps Christian

 

[Mike Mulligan]

I kind of figured that the outdrive issue wouldn't be a problem, especially considering the flex cable point that you mentioned. Reading through the rules you posted confirmed that.

I am still very curious about the "only one motor allowed but must run the same number of props ruling" though. I feel like the issue must have come up at some point since the rules mention it at all. I can only think of a few real unlimiteds with more than one prop anyway.

BYW - I saw the Aronow unlimited run in San Diego back in the day. Made fantastic noises but didn't seem to be as impressive as everyone was expecting it to be. Neat idea, but I think it would have been better suited to tighter courses that were typically run by the Unlimiteds.

And please tell us more about that twin drive rigger!!

 

[Christian Lucas]

Hi Mike,
thanks for your thoughts about the Catamaran and how it performs. To build the Aronow catamaran i got the idea at the Munich SAW last week. The fastes boats during the competion are catamaran L20 class. around 250 km/h that are 156 mph with a similar powerplant like the unlimited hydroplane 1:8 class.
And when you see this tunnelboats runing you will see that the water condition was not as flat as a rigger need it. So this catamaran are offshore style cats but we know how to set up such power bomb. Thatˋs the reason wy, and i love tunnelboats with outbord and inbord and one prop and twin contra rotating and so on. So wy not to try ? The current record from Don Ferrette is 100,1 mph .

Happy Amps Christian
the front twin proprider , see other tread.

 

[Mike Mulligan]

I really like your idea, Christian! I had forgotten just how fast the offshore cats were running these days, it makes the idea of the Aronow as a scale unlimited SAW boat sound pretty viable.

The Aronow was based on F1-type tunnel boats of that era, which are quite different to the more modern offshore cats, so there will be a few issues to address, but with allowable mods it could be made to work.

The boat was pretty wide for its length, compared to modern cats, and had a very shallow tunnel, but looking at the rules posted above it seems the tunnel could be made a bit deeper and still be considered legal. Also, you can run your props quite far back, as the original's props were far behind the transom.

I will be following along with your project for sure!

BTW - Have you seen this???

http://hyperprod.bizhosting.com/transfer_case.html
There is this on &bay as well. I saw that there was someone running one of these in a 1/6 scale drag hydro, so it would most likely be strong enough for a 1/8 SAW boat.

https://www.ebay.com/itm/1651562669...1291&msclkid=91a8a93d7e3a145c3fc1ca06de9d8abd