Don Ferrette or Nitrocrazed please help!

[Mark]

I would like to know what front sponson setup and prop to run with a Mac 84 in my Hummingbird. Yes I FINALLY got one.

The setup says from rear of front sponson forward 5 7/8 inches and then a 3/8 spacer to set the angle with the tub height at 11/16. Is this what Don used with his 84?

What strut angle? I was thinking of running the strut a 0 degrees but it says to run 1 degree negative. ?????????

HELP!!!!!!!!!!!!!!!!!!!!

 

[Preston_Hall]

I don't think Don ever had a Mac in his. But the setup given is the typical starting point. Minor adjustments may be necessary as with most boats.

 

[Don Ferrette]

Mark-

Ok here goes--

First level tub to your set up board, this is first & foremost. Measure just behind rear boom tube & just in front of forward radio box wall (engine compartment). Use the strut to set level. BTW- I never ran any negative in the struts on the Hummers, all were "0". Any neg in the struts & they would try to stuff on me in the corners. Using a 3/8" square metal stock, slide under each sponson & measure from back of stock to trailing edge of sponson. I ran 5 7/8" on left & 5 3/4" on right (turn fin) side. Every adjustment you make to achieve these angles you must check & re-level the tub as needed. Lastly I ran the rear sponsons 3/16" up off the set up board (made 3/16" shim stock to set them) with the front tips 1/8" up from tub bottom. Make sure your turn fin is dead parallel with tub both from top & side views. This should get you very close to optimum but as Preston said you might find a minor adjustment or two to get you where you want to be. B) B)

BTW- what's the measurement from the rear boom tube hole to the back of transom??

 

[Mark]

Don,

Can you remember what prop you ran with the Mac. I bought a 1667 and a H32 as a starting point. I think that the H32 will be a bit small. Your thoughts?

 

[Don Ferrette]

Don,
Can you remember what prop you ran with the Mac. I bought a 1667 and a H32 as a starting point. I think that the H32 will be a bit small. Your thoughts?

The H32 will be ok to break in motor but too small to race with, go with the 1667, always one of my favorites. I didn't run a MAC in my Hummer but the 1667 should work fine. B)

BTW- don't forget , measure the distance from rear boom tube opening to transom for me.

 

[Mark]

Don,

Thanks, my boat is at work so I'll measure it today and get back to you later on.

 

[TimD]

Ian's 'bird was a custom one so his setup will not be of much relevance to you!

 

[Don Ferrette]

Ian's 'bird was a custom one so his setup will not be of much relevance to you!

Not true. I set them all up the same coming off the set up board. Then tweak 'em at the pond. Ian will be using these same specs next outing........ B)

 

[TimD]

I think the next time Ian's bird hit's the water it will probably be in the 67 class with different front sponsons on it. He is very happy with his new 90 boat (CHD sprint) especially in the rougher conditions we race in here in Oz. Picked up 2nd place at the Nat's with it with very limited setup time on it! (must have been that highly modified prop of mine - hey Ian!) :lol: :lol:

The 'bird was too hard to run in the chop but holy S#!t was it fast!

 

[Don Ferrette]

Why does he want to change the sponsons?????

 

[TimD]

The ride pads are huge compared to the 67 /80 'bird sponsons! Very very very wide!

 

[Don Ferrette]

Hmmm, wider is not always better.......... :blink: :blink:

 

[TimD]

Exactly my thoughts Don,.

The 67/80 bird sponsons have same basic geometry and should be a straight swap.

The longer afterplane and tub length should make it a real nice boat with a strong 67 in our conditions.

Tim.

 

[Don Ferrette]

Get Ian to try it first with the set up I gave him. I think he will find it to his liking......

 

[Ian Inverarity]

I am going to try 67/80 type front sponsons because I am running the larger front sponsons at much less angle than recommended. I am hoping that the smaller sponsons at the corect angles will fix some of the issues I currently have.

I am also thinking a 67 may be better due to less torque at the prop. With the 90 the prop blows out of the water too much in the rough. The props dont last long.

I will try re-setting the rear sponsons. But I dont have a 67 at the moment and most of the hardware etc got pinched from the boat for my CHD Sprint 90! So it may be a while before I get it running again.

The 90 Hummingbird is still the fastest boat I have had, and I know it had a lot more in it because I was no where near the limits with the props I had to use! If I can turn it into a package I can race well with it should be awesome!

Hey Tim,

Yep, killer prop! Pity I didn't have about 2 more weeks development on the boat, it goes a lot better now!! B)

Got any ideas for a strong 67?

Nitrocrazed racing: Time to make more hardware again.

 

[Mark]

TimD,

"The 'bird was too hard to run in the chop but holy S#!t was it fast!"

That's exactly what I wanted to hear. Insane speed is what it's all about for me.

Hopefully the Mac 84 turning more RPM with a smaller prop might help the handling problems.

Don,

I'm still getting that measurment.

 

[Ian Inverarity]

Mark,

One of the more interesting aspects I found about my boat is I could launch practically any prop I tried, which is certainly not the case with my new hull. You may be able to run surprising large props. Good luck!

Ian.

 

[Ian Inverarity]

Don,

I wonder if I messed up the weight ditribution of my hull, do you what sort of percentage of the weight should be at the strut?

Ian.

 

[Don Ferrette]

Well did you change anything drastically like motor placement? Where is your batt. pack in radio box?? How heavy is it? :blink:

 

[Ian Inverarity]

Don,

I put the radio gear all in the front half of the radio box as Jim suggested to me that the CG should be close to the rearmost point of the turnfin, and even with the radio gear all in the front my CG is further back than that.

From memory the boat weight was about 8 1/2 pounds and the strut weight was about 18% of that.

Ian.