Hey Ladies and Gents,

I am currently designing a couple of nitro riggers and am in the process of beging assy of the 1st one. After seeing some of the gas riggers out there and the size of them, I have decided to build a gas rigger. After much though I have come to the conclusion that just scaling up my current design may not be the best idea. I would like to see if you guys could offer some advice as to dimensions and such and I will be glad to keep you all posted. I will get up a first draft of the plana soon and you guy can offer your opinions if you don't mind. I notice that there are not many people building gas riggers and I think a few different boat designs may help the class.

I thankk you in advance,
Zach Vought

not alot of people with ideas???? ???

I would help you but I don't have a rigger. I built one a couple years ago...similar to a Cajun Bullet. Had Cajun Bullet sponsons (originals) and tub was 44" long by 5" wide (inside). I hope some others will chime in with better information, but for some reason the Gas rigger guys are usually pretty quiet about sharing details!

I think a .90 size rigger is a good place to start... pretty sure sponson attack angles need to change though.

Thanks Marc.

;D Zac, Welcome to MGB.

Rigger from scratch huh .....

Not going to be that easy sorry to say, you have lots of dynamics involved that require trial & error building.

That is unless you copy someone else's design R&D .... : Best idea actually.

"GAS" riggers because of their weight need either wider or longer front sponsons ( For weight carrying and easy launching)

A.O.A. on front ride surfaces a tad steeper than a nitro of same size.

Sponson stance (Width) should be wider too so prop torque does not cause boat to rock side to side at speed. O.A.L. needs to be a minimum 45" if using a mod 260 or better engines.

*** You should design a cowl that TOTALLY covers carb from water spray. Little covers that attach to carbs intake NO NOT WORK !!

Just food for thought

Scott

PS. You might want to contact Tom Morehouse over at the International waters site.
He markets plans for his " Firefighter" riggers that need to be built from plans.
Get his R&D on the cheep, then redeign your own from there :o

See: www.intlwaters.com

Thanks Scott,
I kinda figure that I would have alot of work cut out for me. I have designed smaller nitro riggers the next is a larger 90 size boat and i figured I would work with that design but I was also looking for advice and general measurements of other boats that people own. Measurement like sponson length and width, and depth and depth of the tub. I know that 5" seems to be the width to go with for gas riggers I was wanting to make the tub as narrow as possible. Any suggestions?

Thanks Again,
Zach

5 inchs is easy to do, and enables you to use rubber mounts between engines mounts and rails.
Going narrower you have to hard mount engine into tub .... Engines vibration will shake the boat apart, cause major radio issues and generally not be a good design.

What you need to also under stand, pending on sponson designs, a rigger does require some degree of aerodynamic lift along with Hydrodynamic lift from ride surfaces.
Build it with all down force and you will have a glued down boat that will require radical A.O.A on front sponsons that only leads to blow off's as speeds increase.

Tub depth relative to sponsons ride surface and hulls "After Plane" control the pitch angle changes hull will have going from slow to high speeds.

A 3 point design requires a flat bottom tub, while a 4 point requires an up swept bottom to create suction at rear of boat.

Confused yet ???

is there any way to approximately calculate the lift in a hull? Or do i need to find someone with a wind tunnel? lol. This is exactly why I posted I find that there are many people out there with a tremendous ammount of knowledge such as youself that can aid me in this process. The smaller designs he proven to be pretty successful thus far so I was wondering if as a base design if i should just scale up one of my smaller boats? Good idea or bad idea?
Thanks,
Zach

A wind tunnel would be nice, but understand that a boat like a hydro does operate to a degree within the realm of "Ground Effect"

The ride surfaces and tub being in very close proximity to a rippling changing surface (Water) will differ from that of a hard smooth wind tunnel.

Again, 99% of the R&D others have developed have come from trial & error.

Well..... I suppose i will have alot of boats that don't work well.lol