Questions

[gooycheese]

Hi All,

I have a 7.5 Hawk, basically built right out of the box. On my Table I use either a .380 or .135 block for measuring AOA. On my front sponsons I know there is a slight arc to the bottoms will this cause my AOA measurements to be different ? I will slide a measuring block under the sponson until it touches the bottom of the sponson and then measure from that point to the trailing edge, this is how I get these numbers.

Here is an example: Block size @ Distance to TE

Right sponson:

.380 @ 5.812 = 3.579

.135 @ 2.718 = 2.764

Left sponson:

.380 @ 5.875 = 3.541

.135 @ 2.906 = 2.645

If anyone can figure this out Please Help.

Thank You,

Paul

 

[gooycheese]

Hi All again

I just checked the bottoms of my front sponsons for flatness. About only the first 3" from the TE is flat , at 5" the sponson has arced about .046 and at 6" its about .093 . So based on this I am guessing this is why my AOA is different with the larger block? Am I correct in thinking I should measure AOA on the flat of the sponsons?

Thank You,

Paul

 

[Ron Zaker Jr]

Hi All,
I have a 7.5 Hawk, basically built right out of the box. On my Table I use either a .380 or .135 block for measuring AOA. On my front sponsons I know there is a slight arc to the bottoms will this cause my AOA measurements to be different ? I will slide a measuring block under the sponson until it touches the bottom of the sponson and then measure from that point to the trailing edge, this is how I get these numbers.

Here is an example: Block size @ Distance to TE

Right sponson:

.380 @ 5.812 = 3.579

.135 @ 2.718 = 2.764

Left sponson:

.380 @ 5.875 = 3.541

.135 @ 2.906 = 2.645

If anyone can figure this out Please Help.

Thank You,

Paul

Paul,
I would just stick with 6 inches and use it as a BENCHMARK. Is this what your asking???

 

[gooycheese]

That is sorta what I am asking. The more I work with a setup table the more I see variables. If I use 6" as a set point then I will need to use a exact block for 6" is that what you are saying? Or should I try and be as close to 6" as possible? The arc of the sponson which starts around 3" has no bearing on this or is this just for a general point to work from (on my particular boat)?

Paul

 

[Ron Zaker Jr]

That is sorta what I am asking. The more I work with a setup table the more I see variables. If I use 6" as a set point then I will need to use a exact block for 6" is that what you are saying? Or should I try and be as close to 6" as possible? The arc of the sponson which starts around 3" has no bearing on this or is this just for a general point to work from (on my particular boat)?

Paul

It's a general point to start at.

 

[gooycheese]

Ron,

Thank You,

Paul

 

[Ray Sametz]

Example, Right sponson 5.812 div. by .380 = 15.294736 which = 3 degrees 45 min. Left 5.875 div. by .380 = 3 degrees 42 min. Need to refer to a Trigonometric Table for the answer to equation. B) B)

 

[Terry Keeley]

Hey Paul:

IMHO, no matter what you hear it is impossible to apply a "generic" set of numbers to a hull and and have it fly right off the set-up board (so to speak). :blink:

When people mention sponson angles they should really give the whole picture, ie: 3.2* on the right, 3.0* on the left, measured in relation to the flat part of the hull under the motor mount, taken from the flat area 3" from the TE. Which BTW works for me when I set the tub level with a Speedmaster strut on the table (shaft C/L 3/8" above table), rear sponsons 1/8" above the table with the last 2" at 1* relative to the table and a balance point of 25% of the afterplane....you get the point. :lol:

Most important (again IMHO) is that you use a system that is absolutely repeatable for you. In other words if you took your hull all apart you should be able to get it back together exactly as it was, including sponson angles, depths, off-set and toe, and fin and shaft angles.

 

[moparbarn]

i have to agree with terry on this. even though i don't run or know squat about riggers (that may change soon), you need a system that is easy for YOU to understand & is repeatable. doesn't matter what measurement you use, ie: angle of attack, inches, millemeters, minutes, yadda yadda. set it up, measure it. take it off the board, remove any leveling or measuring devices. set it back up, should be the same EXACT measurement. doesn't matter how you measure, as long as you understand what you're seeing. the important part is keeping records, so you know where you've been, & where you're going. develope a system that works for YOU, then you can evaluate the effectiveness of any changes you make. but, if you can't get repeatable measurements, no system in the world will help, until you do get consistent, repeatable results.

 

[Norm Doerr]

Get digital level ....then go to RC Boat.com and read the paper on using it to set attack angles.

 

[Terry Keeley]

Get digital level ....then go to RC Boat.com and read the paper on using it to set attack angles.

Here it is:

http://rcboat.com/setup2.htm

Note he uses only the rearmost flat sections of the sponsons...

 

[Ron Zaker Jr]

Hey Paul:
IMHO, no matter what you hear it is impossible to apply a "generic" set of numbers to a hull and and have it fly right off the set-up board (so to speak). :blink:

When people mention sponson angles they should really give the whole picture, ie: 3.2* on the right, 3.0* on the left, measured in relation to the flat part of the hull under the motor mount, taken from the flat area 3" from the TE. Which BTW works for me when I set the tub level with a Speedmaster strut on the table (shaft C/L 3/8" above table), rear sponsons 1/8" above the table with the last 2" at 1* relative to the table and a balance point of 25% of the afterplane....you get the point. :lol:

Most important (again IMHO) is that you use a system that is absolutely repeatable for you. In other words if you took your hull all apart you should be able to get it back together exactly as it was, including sponson angles, depths, off-set and toe, and fin and shaft angles.

TK,

That is exactly what I am saying.

 

[Terry Keeley]

Hey Paul:
IMHO, no matter what you hear it is impossible to apply a "generic" set of numbers to a hull and and have it fly right off the set-up board (so to speak). :blink:

When people mention sponson angles they should really give the whole picture, ie: 3.2* on the right, 3.0* on the left, measured in relation to the flat part of the hull under the motor mount, taken from the flat area 3" from the TE. Which BTW works for me when I set the tub level with a Speedmaster strut on the table (shaft C/L 3/8" above table), rear sponsons 1/8" above the table with the last 2" at 1* relative to the table and a balance point of 25% of the afterplane....you get the point. :lol:

Most important (again IMHO) is that you use a system that is absolutely repeatable for you. In other words if you took your hull all apart you should be able to get it back together exactly as it was, including sponson angles, depths, off-set and toe, and fin and shaft angles.

TK,

That is exactly what I am saying.

Except you did it in 50 words or less! :lol:

 

[Ron Zaker Jr]

Hey Paul:
IMHO, no matter what you hear it is impossible to apply a "generic" set of numbers to a hull and and have it fly right off the set-up board (so to speak). :blink:

When people mention sponson angles they should really give the whole picture, ie: 3.2* on the right, 3.0* on the left, measured in relation to the flat part of the hull under the motor mount, taken from the flat area 3" from the TE. Which BTW works for me when I set the tub level with a Speedmaster strut on the table (shaft C/L 3/8" above table), rear sponsons 1/8" above the table with the last 2" at 1* relative to the table and a balance point of 25% of the afterplane....you get the point. :lol:

Most important (again IMHO) is that you use a system that is absolutely repeatable for you. In other words if you took your hull all apart you should be able to get it back together exactly as it was, including sponson angles, depths, off-set and toe, and fin and shaft angles.

TK,

That is exactly what I am saying.

Except you did it in 50 words or less! :lol:

Yeah, you know how quiet goalies are.

I made up some document sheets and handed them out. This way you can always go back to base line numbers.

 

[gooycheese]

Thank You All !!!

I understand, I will keep records of how this works for me. I need to know what and how things change, and what and how to return those changes to past points. Doing this so I understand and can repeat as often as I feel needed. Thank You guys for not trying to over explain this, I know with too many people giving suggestions a person can be totally lost. I am pretty sure I got my plan of attack down so all is in my court now.

Thank You,

Paul