Efficacy of Water Ballast

[Russ]

All valid and legitimate tests.

Go on.

[OverEasy]

So the simulated calm water video was nice…. What about the storm tossed 3 footer seas version?

[opie]

OverEasy,

3 ft seas and higher! Video coming.....per your request.

Also, I am refining my model and getting way too serious..... maybe...

There are a few different values of Macgregor 26X specs found on the internet, (the M model is similar), so I picked out these rounded values for the new modified experiment:

Mac 26X Sailboat with engine and batteries and fuel : 1250 kg or 2750 lbs
Ballast: 545 kg or 1200 lbs
Total : 1795 kg or 3950 lbs

The ratio of 545 kg to 1250 kg is 0.436.

My model’s ballast, when full adds 240 ml of water, or 240 grams. Using the same ratio, my model empty weight should be 550 grams. Since my model only weighed 90 grams on my first test, I now had to add 460 grams of fixed ballast to simulate the engine, batteries, other structure, etc. I used about qty 20 of smaller 1/4” drive sockets in the hull bottom to achieve the 460 grams of added weight. Laying the weighted model in the kitchen sink tonight after added weight showed that the empty water ballast in the model was now below the waterline rather than over the waterline as previously.

My bad weather test outside in the hot tub ocean to follow soon.........it should be over easy.

Opie

[OverEasy]

Hi Opie!

Personally I think what you’ve been doing is a grand thing!
The reweighting of your model is putting it much more in line with an actual Mac26X.

Can’t wait to see the revised calm and rough seas trial of the model!

Best Regards
Over Easy

[opie]

So this completes my water ballast efficacy experiment. My boat model is now in the recycling bin.

Before I show the next video, a couple of comments.

1. The "permanent" ballast that I put in the model boat bilge were metal sockets. They moved around when the model boat rocked. A lesson to be learned here is when the boat rocked severely the sockets rolled to one side and sunk the boat. To prevent that from happening I stuffed in three plastic produce bags inside the hull to secure the sockets ballast.

2. The water ballast experiment conclusion is that the model will rock and roll both with and without ballast. It rocks and rolls less with the water ballast in.
The previous video showed that the model boat also heels less comparably with wind load when the water ballast is in as opposed to ballast out

3. Conclusion: The original poster in this thread asked a question about "how?" The answer lies in the fact that when the Mac heels leeward one inch down into the waterline, maybe that represents 5 gallons of water ballast that has risen one inch to windward. That represents about 40 lbs of weight out of the water providing a righting moment. Further heel produces more ballast "up" on windward side.

On edit, one more comment. Even though my model had 3 inches of freeboard, it was open at the top as compared to a closed top hull in the real Mac.
The Mac doesn't have sealed hatches in the cockpit of course, but the hatch cover and hatch board do keep out splashes. I thought it interesting that I could not sink my model with the waves I gave it even though the model was "open."

[OverEasy]

Hi Opie!

Great work!
Perfect demo of the water ballast system!!!

Really enjoyed the “heavy seas” videos with/without water ballast.
You must of had a good time at this!

Best Regards
Over Easy

[Russ]

That was fun to watch and gain confidence in ballast. Thanks.

[Drifter]

"I built a sturdy mast from chopsticks"

That's something you don't read every day...

[opie]

Drifter,
Your good humor is always showing. You have put Borneo on the map for us all!

[OverEasy]

Wasn’t there a scene or two where Jackie Chan was fighting with chopsticks?

[Be Free]

To scale, what size would those waves be?

[kurz]

Would be interesting to make a video with a simulated deep lead keel!