Sponson span

[Bill Eilers]

Building an f rigger w/cmb 91rs Evo any help on what the spon inside span should be. Tub 40"

 

[Danny King]

18” - 20” works

 

[Chris Wood]

wider can help. but to narrow of sponson ride pad and wide spacing did not work well for me.
just keep that in mind

 

[Bill Eilers]

View attachment 302072

wider can help. but to narrow of sponson ride pad and wide spacing did not work well for me.
just keep that in mind

 

[Bill Eilers]

Thanks CRISS. It's now at 22" thought it was to wide. Got whittle away some front end weight. C/G is way fwd w/ cmb91 rs Evo. Originally was built around an ops small block 1.2 c/g comes in with cmb 80. The 91rs is going 2 require surgery for proper c/g

 

[Bill Eilers]

18” - 20” works

18” - 20” works

Thank you it's now at 22 thought it was 2 wide. Got whittle away front weight(cg to far fwd) originally built around an ops 1.2 small block. Cg is in with a cmb80.. 91rs is heavy. MAy need surgery to move it back

 

[Bill Eilers]

View attachment 302072

 

[Bill Eilers]

What do u find to be narrowest spon heal that works. It's now at 3"

 

[Bill Eilers]

wider can help. but to narrow of sponson ride pad and wide spacing did not work well for me.
just keep that in mind

Criss I heard your running an 80 in a hyd. If so how do the bngs hold up when motor is spun hard. And is it competitive against the 91 and 101's

 

[Bill Eilers]

PS thanks for the help some years ago. Getting that 27 alpha. Set up. Pretty sure your the one that helped me. We talked on the phone

 

[Walt Barney]

PS thanks for the help some years ago. Getting that 27 alpha. Set up. Pretty sure your the one that helped me. We talked on the phone

Yep it was me in Fl. at the Ft Myers pond.
Walt

 

[Chris Wood]

Criss I heard your running an 80 in a hyd. If so how do the bngs hold up when motor is spun hard. And is it competitive against the 91 and 101's

i have not run boats for a few years now. I used to run 80's and i never felt they had issues or not competitive. I won my fair share of races and events over the years with 67's and 80's. I ran 67's in f hydro with no issues. The main issue becomes props and twins chewing up the water. Torque helps that is why 91's and 101's are popular. but 80's are not popular anymore and most go to a 91. but the 80 weight a little less and weight is speed.

multiple ways to skin a cat. just pick what you like and move forward.

 

[Bill Eilers]

i have not run boats for a few years now. I used to run 80's and i never felt they had issues or not competitive. I won my fair share of races and events over the years with 67's and 80's. I ran 67's in f hydro with no issues. The main issue becomes props and twins chewing up the water. Torque helps that is why 91's and 101's are popular. but 80's are not popular anymore and most go to a 91. but the 80 weight a little less and weight is speed.

multiple ways to skin a cat. just pick what you like and move forward.

Thanks. A light boat spinning hard in clean water. (Good luck) or something a bit bigger to pound thru thru the holes. Thanks again!

 

[Marty Davis]

i have not run boats for a few years now. I used to run 80's and i never felt they had issues or not competitive. I won my fair share of races and events over the years with 67's and 80's. I ran 67's in f hydro with no issues. The main issue becomes props and twins chewing up the water. Torque helps that is why 91's and 101's are popular. but 80's are not popular anymore and most go to a 91. but the 80 weight a little less and weight is speed.

multiple ways to skin a cat. just pick what you like and move forward.

Chris:

As wide as you can run them without "Tip Toeing" between the sponsons.

Marty

 

[Wasted wages]

I always felt that 80's were dogs... they never seemed to RPM as hard as the .67's.
And if you were dealing with a heavy hull, it made sense to go to a .91....


Just my .02,, I know my twin rigger ran faster on .67's than .80's and throttle response was always nice and crisp with the 67's.

80's do seem to work well in a mono though, can pull a little more prop, and has better torque out of the corner..

 

[Bill Eilers]

I always felt that 80's were dogs... they never seemed to RPM as hard as the .67's.
And if you were dealing with a heavy hull, it made sense to go to a .91....


Just my .02,, I know my twin rigger ran faster on .67's than .80's and throttle response was always nice and crisp with the 67's.

80's do seem to work well in a mono though, can pull a little more prop, and has better torque out of the corner..

Thanks. One I know said also, his twin crapshooter seemed faster w/ 67's in it. I have a 91 in it now. But that eng weight has moved c/g to far fwd. I'm just going to have to perform some surgery, and move eng back. Thanks again for your response

 

[bzubee]

If you check the speeds of saw records most of the time a 67 will be faster than 80s or 90s engines or even twins.

 

[Jeff Lutz]

Thank you it's now at 22 thought it was 2 wide. Got whittle away front weight(cg to far fwd) originally built around an ops 1.2 small block. Cg is in with a cmb80.. 91rs is heavy. MAy need surgery to move it back

I wouldn’t worry much about a super slight CG change, you may would want to move your turnfin a little though. It’s location versus CG is more critical than the CG versus sponson ride pad location. With some mods, your big block .91 will be consistently faster than 67/80’s. How did the OPS 1.2 hold up for you ?

 

[Jeff Lutz]

If you check the speeds of saw records most of the time a 67 will be faster than 80s or 90s engines or even twins.

E record is 120. F record is 134/135 .

 

[bzubee]

E record is 120. F record is 134/135 .

I qualified my statement Jeff with "most of the time." Same goes with twins most of the time single engine powered boats are usually faster than twins at RTs.