Boat Balls..

JJ_BPK · 08-29-2010, 06:12

Ok, all you junior pirates, miscellaneous swabbies and recalcitrant math
majors.

Whip out your protractor's and trigonometry tables.

How do you get an 80ft mast under a 65ft bridge??

http://www.youtube.com/watch?v=epz6B...layer_embedded

Here are some hints:

PI = 3.141592... (approximately 22/7 = 3.1428)
radians = degress x PI / 180 (deg to rad conversion)
degress = radians x 180 / PI (rad to deg conversion)

Extra points for the 1st to name the musical score..

**Peregrino** · 08-29-2010, 07:32

Interesting use for 2000lb lift bags. It'll take a while to drain them through the dump valve though.

nmap · 08-29-2010, 11:14

H = 80
O = 65

Theta = Arcsin(H/O)
Theta = 0.9484

Degrees = Theta * 180/Pi

54.34 degrees

Or about 35.66 from the verticle

For those disinclined to do the calculations, there's always LINK

**Bill Harsey** · 08-30-2010, 10:22

That was some good logging.

nmap,
Here is how the math would have looked if I did it:

80 - 65 = how much to cut off.

nmap · 08-30-2010, 10:26

Quote:

Originally Posted by Bill Harsey

nmap,
Here is how the math would have looked if I did it:

80 - 65 = how much to cut off.

Said the man who makes really good, sharp knives.

Dozer523 · 08-30-2010, 10:55

What was the pulley mechanical advantage needed to hoist those 2,000 bags? Or do they have winches (Not wenches, Richard. If I had a boat that nice I bet I could trick lots of wenches to come aboard) on board sail boats?

I'm guessing it was a steering maneuver that caused the boat to lean, do you steer into the weight or away to increase the lean?

**Bill Harsey** · 08-30-2010, 19:04

Quote:

Originally Posted by Dozer523

I'm guessing it was a steering maneuver that caused the boat to lean, do you steer into the weight or away to increase the lean?

Hard right stick and some left rudder.

JJ_BPK · 08-30-2010, 19:24

Quote:

Originally Posted by nmap

H

Or about 35.66 from the verticle

I'm going to declare nmap the 1st, 2nd, & 3rd place winner...

I'm think this guy has worked this process out more than once. I think he has a ballist pump system to shift water to the starbard side. It would only take maybe 30 gals to start the lean. The bags would compound the lean until they touch the water, at which time they are neutral.

I don't think steerage is involved. If it was, the boats track would be a arch. Watch the line the balls follow, as seen from the rib that's taking the video.

He might also rig the balls with a snap link that can be released, dumping the balls up-side down.

**Bill Harsey** · 08-30-2010, 19:45

JJ BPK,
Didn't think of the ballast thing. The arc would work if it was placed right but that boat seemed to track straight.

Also, once the balls hit the water, wouldn't that add to the (dragged) weight and continue to pull the boat over?

**Ambush Master** · 08-30-2010, 19:46

Quote:

Originally Posted by JJ_BPK

I'm going to declare nmap the 1st, 2nd, & 3rd place winner...

I'm think this guy has worked this process out more than once. I think he has a ballist pump system to shift water to the starbard side. It would only take maybe 30 gals to start the lean. The bags would compound the lean until they touch the water, at which time they are neutral.

I don't think steerage is involved. If it was, the boats track would be a arch. Watch the line the balls follow, as seen from the rib that's taking the video.

He might also rig the balls with a snap link that can be released, dumping the balls up-side down.

Not steerage or Ballast/Bilge Pumps!! It has a Lifting Keel that can be raised or lowered depending on your Sail Loading and Tack!!

Grew up on the Texas Gulf Coast and have spent MUCH time on the water!!

Later
Martin

JJ_BPK · 08-30-2010, 19:54

Quote:

Originally Posted by Ambush Master

Not steerage or Ballast/Bilge Pumps!! It has a Lifting Keel that can be raised or lowered depending on your Sail Loading and Tack!!

Grew up on the Texas Gulf Coast and have spent MUCH time on the water!!

Later
Martin

Live & Learn,, I have never seen a blow-boat that size with a lifting keel. So, I'm guessing that with the keel up, you need only move one person (150-200 lbs) to starboard to start the lean??

Tx Martin

**Bill Harsey** · 08-30-2010, 20:19

This ship, the Lady Washington, did not have a lifting keel but I was honored to be handling the tiller, yes, manual tiller, a few years ago as we took her up the Coos Bay River, turned it around and came to dock. Nothing was scratched bent or broken.
It was easy, all I did was follow the tillers orders from the ships master and use about every last bit of horsepower I could muster.

GratefulCitizen · 08-30-2010, 20:55

Quote:

Originally Posted by JJ_BPK

Ok, all you junior pirates, miscellaneous swabbies and recalcitrant math majors.

I resemble that remark!
(All too much...)

Quote:

Originally Posted by JJ_BPK

Whip out your protractor's and trigonometry tables.

How do you get an 80ft mast under a 65ft bridge??

http://www.youtube.com/watch?v=epz6B...layer_embedded

Here are some hints:

PI = 3.141592... (approximately 22/7 = 3.1428)
radians = degress x PI / 180 (deg to rad conversion)
degress = radians x 180 / PI (rad to deg conversion)

Extra points for the 1st to name the musical score..

Ummm.....

Why not just tie the weight/float to a rope which is slightly less than 65 ft combined length?
(Adjust rope length to allow for whatever margin of error is desired.)
Just keep tipping until the water is reached.

Don't even need to know the exact height of the mast.
The vector of gravity will address the rope alignment.
(Any drag on the float will just result in extra clearance.)

Going under a 62 ft bridge?
Use 3 ft less rope.

Good mathematicians are exeedingly lazy.

**Ambush Master** · 08-30-2010, 21:13

Quote:

Originally Posted by JJ_BPK

Live & Learn,, I have never seen a blow-boat that size with a lifting keel. So, I'm guessing that with the keel up, you need only move one person (150-200 lbs) to starboard to start the lean??

Tx Martin

Without a Lifting Keel, he could, by way of steerage, cause the Mast Ballast to swing out and once you got it there adjust it with a combination of the winches and steerage until you gain a stabilized track!! If you lifted the bags upward, you would eventually cause the list, at which point you control it with steerage and winches.