JAE21 OB rigger

[XtremeRcBoats]

A long time ago I only ran tunnels, then I saw the sundowner OB hydro and that got me interested in outriggers. I bought a Sundowner from Joe Monohan and ran it with great pleasure, it was a fun boat to drive. After that a lot more conventional outriggers followed (21, 45, 90, twin 90 and gas) but when the JAE21 OB hydro got released at around 2012, I got to have it. I bought the kit but then (familiy) life got in the way.

So I finally unpacked it last year and started to built it.


Anyone has recommendations for improvements or upgrades? I discussed it with Tom David last year if the his mods he did on the normal JAE21 would work, but he wasn't sure. Since my time is limited I'm not going to try it.





For power i'll use an OSmax 21 V1 outboard with irwin pipe. I got the engine from a friend. It came with the header and I don't have the muffler.
Last year I already got a lower with the fin cut off from Kris Flynn and a conversion kit for the lower from Mark Scott to put the skeg next to the prop.

Can anybody tell me the reason why this works best instead of a normal skeg on a outboard rigger?
Shall the skeg be on the right of left side (have seen both)?





I'll post some updates now and then, but they will come slowly.

 

[MichaelDornbusch]

Paul in the 90's and early 2000's I raced 3.5 and 7.5 Prather OB hydros. Both lower units the skeg was cut off with offset rudders to the right side. Cutting the skeg off allows more undisturbed water to reach the prop. More bite, more speed. Hence why OB tunnel hulls cannot match the hydros speed. As far as which side the offset rudders are on, not sure it really matters. People mount rudders on inboard rigger hulls on both sides. Probably just your personal preference or what seems to work the best on your particular boat. Both engines were set up with exhaust throttles (i.e. Butterfly plates on exhaust header) and venturi carburetors. No tuned exhaust. Hope you continue to enjoy building your project! Look forward to your updates!

 

[RaceMechaniX]

All the O/B hydro's I have seen have the skeg on the right. Most used a very thin knife style rudder instead of a water pickup and kept the prop blast on the cav plate or had a water pickup in the center ski.

 

[XtremeRcBoats]

Tnx Michael and Tyler. Will have a look on the knife rudder. What kind of knife did you use for this?
I've ordered a small single water pickup that i'll laminate in the ski.


Was finally able to do some glueing. Have added some extra 1/4" triangluar wood strips in the tub, glued in the reinforcements at the back and the front tub bottom.


Will start on the ski next week.

I noticed that in the JAE21OB there is no foam in the nose section, in contrast with the conventional JAE's. Do you use this section, othewise i'll add some foam in there.

 

[Mike Hughes]

I would put foam in there. It add strength and floatation. Cant have enough of either.
Mike

 

[XtremeRcBoats]

Tnx Mike, was thinking the same.

 

[HTV Boats]

As for the lower I have run stock lower and offset skegs left and right side and not a big advantage either way. What did improve turning was to extend the tub about 2 inches. You can move the boom tubes forward and or move the mounts on the sponsons to accomplish the same.
Mic
PUT ALL THE FOAM YOU CAN FIT. Watching your sponson tips slowly sink while the retrieve boat is getting others is a bad feeling. That one went to Davy Jones Race Team

 

[HTV Boats]

 

[XtremeRcBoats]

Thanks for the tip Mic. What did improve with moving them forward? I'll add some extra set of boom tubes, same as you did, to test.

Have laminated the boom tubes in the tub and closed of the nose compartment. Next time i'll add some 2 component foam in there.

 

[HTV Boats]

Steering in the corner unproved. less oversteer.

 

[XtremeRcBoats]

Thanks for the info Mic. Did you also play with the turnfin for that? Or change to other turnfin. I know there are different versions available for the normal JAE21, like for example one the David Preusse.

I started with assembling the ski. There are not too much pictures on the internet about the JAE21OB. Can you post a good picture of the end of the ski, having some doubts if the waterpickup can fit in. Tnx again.

 

[XtremeRcBoats]

see example below where i put 3 turn fins side by side.