20 boat prop weight

[Ron Zaker Jr]

What kind of prop weight numbers are out there on your 20 boats, just curious. Please list hull brand,thanks

Ron Jr

 

[K-ZAM]

Ron,

My HummingBird has a tail weight of 1lb1oz.

Kentley

 

[Ron Zaker Jr]

Ron,
My HummingBird has a tail weight of 1lb1oz.

Kentley

Thanks KP.

 

[Marty Davis]

What kind of prop weight numbers are out there on your 20 boats, just curious. Please list hull brand,thanks

Ron Jr

My boat has 14 oz.

What is yours?

 

[Ron Zaker Jr]

What kind of prop weight numbers are out there on your 20 boats, just curious. Please list hull brand,thanks

Ron Jr

My boat has 14 oz.

What is yours?

Thanks Marty, 15.75 (jap21)

 

[Marty Davis]

What kind of prop weight numbers are out there on your 20 boats, just curious. Please list hull brand,thanks

Ron Jr

My boat has 14 oz.

What is yours?

Thanks Marty, 15.75 (jap21)

I believe that this is a SUPER IMPORTANT factor in any highly competitive 21 hydro. You can see that each is close as far as their strut weight. Not many people pay attention to this...

Has a great deal to do with the amount of strut angle that you have to run, the type & pitch props that will work on the boat, amount of acceleration, launch, etc.

Strut weight has a HUGE influence on the way a boat runs.

 

[Ron Zaker Jr]

What kind of prop weight numbers are out there on your 20 boats, just curious. Please list hull brand,thanks

Ron Jr

My boat has 14 oz.

What is yours?

Thanks Marty, 15.75 (jap21)

I believe that this is a SUPER IMPORTANT factor in any highly competitive 21 hydro. You can see that each is close as far as their strut weight. Not many people pay attention to this...

Has a great deal to do with the amount of strut angle that you have to run, the type & pitch props that will work on the boat, amount of acceleration, launch, etc.

Strut weight has a HUGE influence on the way a boat runs.

I thought I would throw it outhere,it's interesting.

 

[longballlumber]

I will throw myself out there and expose my inexperience.

Isn’t the strut weight a direct relationship to the COG front to back on the boat? As your COG moves forward your Strut weight will lessen, and adversely as you move the COG towards the rear of the boat.

 

[Buckshot]

Are you getting these numbers using the front sponsons as the fulcrum or the CG?

-Buck-

Edit:

I just realized the answer, if using the CG than the strut weight would = 0 as the whole boat would be balanced at that point. :blink:

 

[Ray Sametz]

Are you getting these numbers using the front sponsons as the fulcrum or the CG?
-Buck-

Good ? Dr. Buck B) B) That makes sense!!!! :wacko:

 

[Buckshot]

Are you getting these numbers using the front sponsons as the fulcrum or the CG?
-Buck-

Good ? Dr. Buck B) B)

I think I answered my own question. :blink:

-Buck-

 

[gooycheese]

I am not real sure how you guys measure this? I measured mine by putting a pack of smokes under the trailing edge of both front sponsons and puting my scale under the strut. My first reading was 9.2 ounces but the I figured I should put my driveline in and my next reading was 11.0 ounces. Is this to light? I have an issue with the front of the boat seaming a little light, atleast while its running its always a little too loose for me. If needed I can show a picture how I got this weight. This is dry weight ready to run.

Paul

I use a digital Ohaus LS2000, which weighs to the 10th of an ounce.

 

[Buckshot]

I am not real sure how you guys measure this? I measured mine by putting a pack of smokes under the trailing edge of both front sponsons and puting my scale under the strut. My first reading was 9.2 ounces but the I figured I should put my driveline in and my next reading was 11.0 ounces. Is this to light? I have an issue with the front of the boat seaming a little light, atleast while its running its always a little too loose for me. If needed I can show a picture how I got this weight. This is dry weight ready to run.

Paul

I use a digital Ohaus LS2000, which weighs to the 10th of an ounce.

The more I think about this the more I believe that the surface where the front sponsons are sitting would have to be the same exact height as the scale where the strut is setting in order to get an accurate weight.

I would set a pair of 1-2-3 blocks on a flat surface and shim them to get the same height as the scale and that would be where I’d set the front sponsons then rest the strut on the scale.

Just thinking out loud here.

-Buck-

 

[gooycheese]

I did make sure my tub was level if that helps and a block of wood and all level, scale was tared after the block added.

Paul

 

[dwilfong]

The point you use at the front of the boat would make a difference.

At what point do you support the boat in the front. where the ride pad touches the water?

And would the total weight make a different optimal prop weight? If so is there a percentage of total weight to prop weight ratio?

 

[Buckshot]

I did make sure my tub was level if that helps and a block of wood and all level, scale was tared after the block added.

Paul

I think it would be more important that the sponson contact point and the strut contact point be the same rather than a level tub. I.e. the ride plane

Think about it like this if the boat is stood on end and set on the scale it would register the weight of the entire boat, the more you go from vertical to horizontal the less weight the scale will see. Vice versa, the lower the front of the boat to the scale the more weight is transferred to the front of the boat and away from the scale registering less.

-Buck-

 

[Charles Perdue]

I will throw myself out there and expose my inexperience.
Isn't the strut weight a direct relationship to the COG front to back on the boat? As your COG moves forward your Strut weight will lessen, and adversely as you move the COG towards the rear of the boat.

The strut weight should be taken from the very rear of the sponson ride surface and level with the strut.

It is also possible to get the strut weight too light.

One other thing to throw into the mix is the thrust line( an imaginary line that is the same as the strut angle extended forward to the front of the boat). When setting up an airplane, this makes a lot of difference, especially with a pusher set up and our boat system is a pusher. What effect, if any, does it have on a boat? Something to think about.

Charles

 

[Marty Davis]

I will throw myself out there and expose my inexperience.
Isn't the strut weight a direct relationship to the COG front to back on the boat? As your COG moves forward your Strut weight will lessen, and adversely as you move the COG towards the rear of the boat.

The strut weight should be taken from the very rear of the sponson ride surface and level with the strut.

It is also possible to get the strut weight too light.

One other thing to throw into the mix is the thrust line( an imaginary line that is the same as the strut angle extended forward to the front of the boat). When setting up an airplane, this makes a lot of difference, especially with a pusher set up and our boat system is a pusher. What effect, if any, does it have on a boat? Something to think about.

Charles

Charles:

I agree with you about the thrust line. That is in effect the angle of the strut. The less strut weight, the less angle that you need on the strut. The prop will become super efficient at lifting the rear of the boat the less strut weight you have and thus the less angle required. On my current boat I have to run .8 degree of strut angle. IF I had more or less strut weight that would change.

I had a roundnose 1/8 scale that was a good boat. It had almost zero strut weight. I couldn't run a 1400 series prop because the prop would blow the back end up and out of the water and cavitate. But, it sure would work well with a de-tounged X series prop. I didn't have to run ANY strut angle. So , I am really not sure that you can get too little strut weight. Maybe???

 

[Bob Morton]

What kind of prop weight numbers are out there on your 20 boats, just curious. Please list hull brand,thanks

Ron Jr

Hello Ron,

Humming Bird strut weight is 14.9 OZ

 

[carlnoki]

Hey Ron;

Strut weight on my Basta _ _ d 21 is 16.4 oz. strut angle set at .8 degrees.

havent checked the strut weight on the new JAP and Hybrid 21 (standard hull and rear sponsons with JAP fronts) as yet.

am also building a 90 JAP at the moment.

Carl