21 Hydro on a diet

[akilbar]

I am looking to lighten up my 21 rigger ( Jag 2 with CMB 21). My question is what should I shoot for. I have spoken to people that say "nothing over 3 pounds with fuel". Currently with everything but fuel mine is real close to 4 pounds. I am heat racing the boat. I currently have 2 standard size servos in the boat so going with mini or micro is my first step. My pipe mount seems heavy also. Anyone got a slick mount for a 21 CMB quiet pipe that is light??

What does your 21 weigh??????

Thanks for your time.

 

[user 115]

If you boat is 4lbs then you have a great boat.. Leave it alone.. Some of the bigger named racers have boats 3lbs 10oz to 3lbs 14oz but you will not be left in the dust by them. Setup will be key.

Thanks,

Charley

 

[nitro junky]

I have a scratch built 21 that weighs 3lbs 10oz. and run in the low to mid 70s. I would only change to smaller servos and maybe the pipe mount as you mentioned and leave it at that and work on setup.

 

[jaso]

Not being an expert by a long shot, from what I've seen of late seems if you go too light with a oval heat race boat you can cause yourself more trouble than good.

What I mean is I think too light often means a lot more susceptable to the water conditions,wind and the wash from other boats. Light is fast for sure but you got to be able to keep your boat on the water and running to finish. Just my 2 cents.

I have a very light .21 boat that is made from balsa/ ply sandwich on tha sides of the tube and sponsons covered in very thin ply except on the inner surfaces, this boat is roughly 10 years old and I've just started playing with it again. With little more than some new high nitro fuel a head shim adjustment ot suit the fuel , a couple of props that weren't around 10 years back, it's up and running with the current competion in speed but, the speed has brought out some bad traits in the design of the hull. Now I'm thinking it's time to build a new one and weight isn't going to be my biggest concern. Just my thoughts, anyone else have any ideas on the little riggers?

 

[Don Ferrette]

I am looking to lighten up my 21 rigger ( Jag 2 with CMB 21).  My question is what should I shoot for.  I have spoken to people that say "nothing over 3 pounds with fuel".  Currently with everything but fuel mine is real close to 4 pounds.  I am heat racing the boat.  I currently have 2 standard size servos in the boat so going with mini or micro is my first step.  My pipe mount seems heavy also.  Anyone got a slick mount for a 21 CMB quiet pipe that is light??
What does your 21 weigh??????

Thanks for your time.

"Nothing over 3 pounds with fuel??" Do you want to fly it or race it??? Whoever's been telling you that needs to put away the crack pipe. A properly set up 21 with a weight between 3 1/2 & 4 pounds will work just fine. The standard servos could go in favor of minis (like Futaba 3101's) to save a couple ounces. My 21 SGX weighs 2 lbs. 10 ounces without the motor.

 

[ampba 237]

at 4 lbs your boat is what i consider to be light it should run fairly hard at that but if your looking for more speed i think you need to look at your set up . also what fuel & prop are you running , whats your pipe length etc. is the motor tired that thing should haul arse?

 

[Scott Schneider]

:huh: I too have and race a JAG-2 .21 rigger. 3 years old now and has been set up with a CMB red head, then the Green Head and this last year a Mac .21.

Boat RTR - fuel is @ 4 1/4#'s and does run quite fast, But DOES NOT run any of the bigger props that others use, Won't launch with em! I have to run the smaller wheels with a short pipe amd get the RPM up into the +/- 30 K range to get it to run fast enough to be competitive. Lighter weight won't make that boat run any better, It's the boat !!

:angry: Scott

 

[ampba 237]

IF I WAS YOU I WOULD EITHER MOD SOME PROPS OR GET ONE FROM ANDY BROWN OR WHO EVER YOU CAN GET TO DO IT FOR YOU .

A BIG PROP IS NOT ALWAYS A FAST PROP THEY CAN EITHER MAKE OR BREAK YOUR BOATS PERFORMANCE.

 

[jaso]

Scott,

What size props will your boat run to be competive? I think I seen Don say some where that the hot prop was a 1450 cut down to a 46 dia. for a .21 rigger?

 

[Guest]

A properly set up 21 with a weight between 3 1/2 & 4 pounds will work just fine. The standard servos could go in favor of minis (like Futaba 3101's) to save a couple ounces. My 21 SGX weighs 2 lbs. 10 ounces without the motor.

Don,

The MAC 21 with pipe and pipe bracket will add 1 lb - 1 oz.

Putting you at 3 lb. 11 oz.

Just weighed John's SGX... 3 lb, 5 3/4 oz. Mini servo on Rudder, Micros on throttle and mixture, 5 cell 350 mA pack. Finished with West Systems epoxy on tub and K&B on front sponsons.

The MAC 21 has the Aluminum Drum valve I am testing. Saves only 1/2 oz.! For the boat that means nothing, for the engine could mean a lot.

 

[AndyBrown]

Trying to stay a Newbie as long as possible. LOL

 

[TomMoorehouse]

A properly set up 21 with a weight between 3 1/2 & 4 pounds will work just fine. The standard servos could go in favor of minis (like Futaba 3101's) to save a couple ounces. My 21 SGX weighs 2 lbs. 10 ounces without the motor.

Don,

The MAC 21 with pipe and pipe bracket will add 1 lb - 1 oz.

Putting you at 3 lb. 11 oz.

Just weighed John's SGX... 3 lb, 5 3/4 oz. Mini servo on Rudder, Micros on throttle and mixture, 5 cell 350 mA pack. Finished with West Systems epoxy on tub and K&B on front sponsons.

The MAC 21 has the Aluminum Drum valve I am testing. Saves only 1/2 oz.! For the boat that means nothing, for the engine could mean a lot.

hey Andy..... you have to login to get that post count up

and please modify your email address in your "My Controls" i get a lot of bounced messages for ya

 

[Joe_Knesek]

Props are not universal for all boats. The Jag 2 is far differant than say a Road Runner or an SGX. The cut down 1450 may work well on some but from what I've seen, the Jag 2 can't turn as much prop as some of the other boats because it seems to drop down into the water in the corners which really loads the prop. Trying to run the same prop as other types of riggers may cause you to chase your tail. I agree with Scott that it's in the boat more than the prop. The Jag 2 runs much lower in the water than an SGX or any other boat if seen. The tub spends a lot of time touching the water compared to most boats.

If you are under 4 pounds, you're in the ball park.

 

[shoboat]

Boaters,

A 21 Hydro in the range of 3 1/4 to 3 3/4 lbs. seems to be extremely

fast and a competitve weight. I have always tried to get mine under

4 lbs. for the last ten years or so. I think the hardware is a GREAT

PLACE to lose some weight also. Setup is always CRITICAL on a 21

so you definitely need to do your homework. Anyone trying any new

props on their 21 hydros this year? I have just recently tried a NEW

PROTOTYPE from ABC a 1714/3 and it really worked WELL. I couldn't

believe a three bladed prop on a 21 Rigger,but it really seemed to like

it. It was in the low 70's on a 21 SG and I know there's more in it still.

When Jim gets the 1714's done that will be a GREAT 21 PROP I think.

Thanks,

Mark Sholund

PROPS-4-U

[email protected]

 

[TomMoorehouse]

got a pic of the prop? what are the specs?

can i get one to "test"

 

[Joe_Knesek]

Boaters,
A 21 Hydro in the range of 3 1/4 to 3 3/4 lbs. seems to be extremely

fast and a competitve weight. I have always tried to get mine under

4 lbs. for the last ten years or so. I think the hardware is a GREAT

PLACE to lose some weight also. Setup is always CRITICAL on a 21

so you definitely need to do your homework. Anyone trying any new

props on their 21 hydros this year? I have just recently tried a NEW

PROTOTYPE from ABC a 1714/3 and it really worked WELL. I couldn't

believe a three bladed prop on a 21 Rigger,but it really seemed to like

it. It was in the low 70's on a 21 SG and I know there's more in it still.

When Jim gets the 1714's done that will be a GREAT 21 PROP I think.

Thanks,

Mark Sholund

PROPS-4-U

[email protected]

Mark, did you fly south for the winter? All the water around here has ice skaters on it.

 

[Don Ferrette]

"I think I seen Don say some where that the hot prop was a 1450 cut down to a 46 dia. for a .21 rigger?"

Yes I did say that in the Hummingbird rigger thread because that's a great prop for that boat. Also works really well on Roadrunner Ultralites & Extremes & Eagle SG & SGX. B)

 

[Don Ferrette]

Don,

The MAC 21 with pipe and pipe bracket will add 1 lb - 1 oz.

Putting you at 3 lb. 11 oz.

Just weighed John's SGX... 3 lb, 5 3/4 oz. Mini servo on Rudder, Micros on throttle and mixture, 5 cell 350 mA pack. Finished with West Systems epoxy on tub and K&B on front sponsons.

The MAC 21 has the Aluminum Drum valve I am testing. Saves only 1/2 oz.! For the boat that means nothing, for the engine could mean a lot.

That sounds about right Andy. I'm running standard size steering servo, mini's (3101's) on throttle & third channel, 600 mah 6 volt pack. Plus a "full body" paint job!

 

[[email protected]]

IF YOU NEED TO REDUCE WEIGHT FROM THE PIPE BRACKET, YOU CAN DO LIKE I HAVE on my Rossi pipe and JB weld or aluminum solder a small O-ring collar and lock it down with a wire and second O-ring collar to the hull. That's a very light weight set up. My CVEC pipe comes stock with a similar but better looking set up.

 

# 1/2 to 4 pounds should not make you worry to go lighter.

 

[[email protected]]

I was thinking about what else could be reduced for less weight any chance you can lighten up the motor mount, get a lighter square drive or collet? How about dropping down from a 3/16th cable to the one a slight smaller, what's that the .187 cable? Take the teflon out of the tube, go to a micro Receiver, take the on/off switch out of the casing, cut 3 or 4 threads of the back tip of the prop shaft assembly, and finally mill down the water cooled head if possible.

 

Hey you asked!