JAE 21set up/prop recommendations?

[Terry Keeley]

My F.A.S.T buddy Mike Nowicki built a nice JAE 21 and after getting the bugs out we were trying to make it go fast but were having a heck of a time with the handling.

It would run great with 1450's in the low 60's and even got up on a 1650 but it was too much so we tried some ABC 1819's, one that was cut way down that was too little and another that was full blade was too much. We started trimming back the TE kicker (progression) on the full blade one and it just threw water in the air, shoved the nose down and pulled hard right.

He tried the stock Zipp fin and it was "twitchy" as hell, trimmed it back some and it helped. He made a thin ti fin (similar to Dave Preusse's) that was better but it was still way too touchy, 1/8" rudder travel would put it inside the buoys. Rudder is Speedmaster mini, strong Savox servo and solid pushrod, boat alignment good. He started with the sponsons parallel and later towed the right one in 1/4" or so, no difference. Booms are solid 5/16" CF.

The CMB Beta 21 was running good after a careful break in, AB quiet pipe and OPS 3280 at 8", 60% fuel, various plugs.

Any suggestions?

 

[Buckshot]

I have been running an ABC 1816-17-45 with good results. (K-21)
Pruesse fin
Yes they are ultra sensitive and require VERY LITTLE rudder throw. My transmitter EPA is around 45 on the right and 20 on the left with as much of the mechanical throw taken out as possible (Closest hole to center on the servo horn and as far out as possible on the rudder horn).

 

[Mike Hughes]

Big prop on a light boat. Prop walking the back end to the left. Couple of solutions. Add weight to the bait box. Planting the prop and get rid of the walk. Add shim to strut. 1-2 degrees to the left changes thrust angle. Pushing back end to the right and correcting the walk. Tuck wedge rudder. Will plant the back of boat.
Mike

 

[ricwally]

Do what the instructions say! Square everything up. Strut down against the ski and neutral. I have three Zipp 21 hydros. One long one and two short ones with narrowed sponsons. No issues with prop walk or turning issues with Preusse or Zippkits 21 turn fin. I have an old long stroke Nova Rossi in the long hull. It will pull a 1450 prop with ease. I have found that the CMB Beta motors will not pull a 1450 in a Zipp hull. Not very well anyway. We have started using an H-5 for the most part. I have anyway. Some others are using 16 series and maybe a 1715-19-38 I believe. CG must be causing the sensitivity in your turning. Check it and if needed make a mounting plate and shift the turn fin aft a little.

 

[Terry Keeley]

Anyone know when they switched to the new style sponsons?

 

[Olly]

I bought mine last October and it had the new sponsons.

 

[Roxyflash]

When I ran a 21 I used a 1445 or h5 or h 7 if it was cool ran 70 using these props on a good day ran 73 mph with the h7

 

[SayMikey]

Best practice start with a 1715,19,38 baby steps. try the Zipp pipe it works well. A Preusse fin works great. CMB Beta head at or around .008 60 % nitro. Sneak up on larger props

 

[Tom Foley]

Bill Gibson ...

 

[Bill Gibson]

Alan Elzer did up a couple for me......i believe im running a 1719 that he worked and the boat runs great with it! Maybe Alan will chime in and elaborate more on what he did! I also took out just a little bit of cup from the bottom of the turn fin which seemed to help the boat turn not as aggressively, but still turn well.........the boat needs so little rudder to turn well!