Is there a formula for pad design ??

[spybot]

As the title says
is there a formula using the dead rise and angle of attack to work out the length and width of a pad ?
The boat in question is a very close copy of a Sidewinder ss16 mine was made in the 70/08s its a Dateline Bikini.
Now i know that they are unstable boats Chine walk kicks in around 40mph !!!!

Some of the 16' sidewinders had a pad that at the transom is 8-10 inches wide, but i cant find the length for the start. Another thread from 2013 says they handle better with 12" trim tabs on them.

I can add the trim tabs but as i have the hull stripped and upside down ( Trying to blue print ) aka making the keel as straight and parallel as i can, i thought it would be a good chance to add a pad to help over come the 40mph wobble.

Any info on the pad for the sidewinder or how to work out the dimensions would be great

Andy

[Risco]

As the title says
is there a formula using the dead rise and angle of attack to work out the length and width of a pad ?
The boat in question is a very close copy of a Sidewinder ss16 mine was made in the 70/08s its a Dateline Bikini.
Now i know that they are unstable boats Chine walk kicks in around 40mph !!!!

Some of the 16' sidewinders had a pad that at the transom is 8-10 inches wide, but i cant find the length for the start. Another thread from 2013 says they handle better with 12" trim tabs on them.

I can add the trim tabs but as i have the hull stripped and upside down ( Trying to blue print ) aka making the keel as straight and parallel as i can, i thought it would be a good chance to add a pad to help over come the 40mph wobble.

Any info on the pad for the sidewinder or how to work out the dimensions would be great

Andy

there might be formulas probably hard to get hold of.

The other factor that I don’t see you mention is weight. You can’t just look at width and length and not factor in weight. The very very general rule of the thumb is a 10-12 inch pad is usually very stable and fast but there are a lot of variables and weight is a huge one another thing is the ride will suffer some.


also Trim tabs are like training wheels no fast padded v bottom has the or needs them.

[CUDA]

8 to 10 sounds right, should be no need for trim tabs on a 16ft speed boat, set up is key.

You get too wide you will spin in corners, Ron Baker told me not to put a 12" pad on my 1981 20 ft

Hydrostream ex factory Havasu MVP boat, well my motor prop guy was part of the OMC race team and he

said go with the 12, It was a huge mistake, No one could beat me on the straights but she would spin like a

top as I started the turn, I actually became use to it when not in a race I could run strait for shore spin the

wheel and I would be going back the same way crazy.

[Greg G]

I would not go more than 8" if you are going raised. Then learn how to drive it.

[spybot]

The boat weigh 680lb the motor 360lb
Fuel 99lbs me 140lbs
so total is 1279lbs

If i make the 8" pad where would it start from ??? 4' from transom ??? More or Less ???
What height are we talking about from start of pad 0 to 1" ???? over the full length ??

Motor is a worked 140 V4 Johnson (1980)

Total rebuild balanced conrods pistons, all casting defects removed.
Port matched from carbs to transfer ports. Plunged port flaws removed. Carbs are 1 5/16" (cant find a set of 1 3/8" over here) jetted to one size over factory (think 67C ??? Will check tomorrow)
Sport reeds ect ect
All new electrics.
This motor is better than when it left the factory.
So i just need to blue print the hull add the pad and take it from there.

[FUJIMO]

8 to 10 sounds right, should be no need for trim tabs on a 16ft speed boat, set up is key.

You get too wide you will spin in corners, Ron Baker told me not to put a 12" pad on my 1981 20 ft

Hydrostream ex factory Havasu MVP boat, well my motor prop guy was part of the OMC race team and he

said go with the 12, It was a huge mistake, No one could beat me on the straights but she would spin like a

top as I started the turn, I actually became use to it when not in a race I could run strait for shore spin the

wheel and I would be going back the same way crazy.

...yet the original 22 Velocity had a 12'' wide pad, a transom step, and curled down chines, handled excellent, and was the APBA national champion 3 consecutive years in a row... Its all about the "entire" boat bottoms design as a whole.

[CUDA]

Yes first it's a bigger heavier boat, second they don't make 100 mph turns like a MVP boat, we never backed out just trimmed in a little for turns

Back in the early 80's MVP had no weight restrictions, 400 lb boats were common, no driver protection but helmet and jacket.

[David]

Aeromarine Research has software. He posts here as Jimboat
https://www.aeromarineresearch.com/