Theory:

     Everyone round the table stared at me in horror. I thought to myself, ‘Oh, these adults, they’ve no sense of adventure. How dull they are!’
 
     The storm didn’t break, but in the evening a strong wind started blowing. The ship rocked to and fro, rocking and rolling to the music of the wind. Huge waves were dashing against it. Even though the deck was slippery, I was running around. That’s when I noticed Uncle leaning over the railings. I ran up to him, thinking he too, was enjoying the experience. “Good morning, Uncle, isn’t it lovely?” I asked him.
 
     But he wasn’t well at all. He was retching over the rails and looked rather blue about the mouth. I felt sorry for him. “Can I be of any help? Shall I call the doctor?’ I asked him.
Explanation:
 
While having conveyed Vasantha's imagination and expectations, people around the table were shocked and looked at her weirdly; but, Vasantha did not care. Vasantha's thoughts were a bit odd. She thought to herself that they didn't have any sense of adventure since they were adults. For Vasantha, the elders seemed to be dull ones; they did not like to look around nature's works as they were afraid of it.
  
Although there was no heavy storm as predicted, there was a powerful wind in the evening. The ship swayed back and forth as if it were tossing and rolling to the music of the wind. Huge waves were striking the ship. Vasantha was running across the ship's deck, even though it was slippery, admiring nature's work. During that time, Vasantha happened to notice a person on the deck. He was leaning against the railing.
 
Vasantha ran toward him, believing that he, too, was enjoying the strong wind's work. She wished him a pleasant morning. Also, she inquired as to whether being on the deck in a strong wind was a pleasurable experience. He didn't reply.

The real fact was very different. He wasn't feeling good. His movements confirmed his seasickness because it seemed he was inclined to it. He struggled to breathe over the handrails, having been hit by the cold and struggled with vomiting sensation.
 
Railings.jpg
Railings
 
His condition was pathetic. Vasantha felt sorry for him and asked if he needed any help. She asked if she should consult a doctor to help him feel better from his illness.
 
Meaning of difficult words:
 
S.No
Words
Meaning
1.
Stare
To look at something for a long time, especially when surprised
2.
Railing
A fence made of metal or iron bars
 3.
Slippery
Causing people or things to slip or slide
 4.
Blue
Feeling sad and unhappy
5.
AdultA fully grown person
6.
Retch To behave and make noise as if you are vomiting and feeling sick
7.
Weird/Unusual Strange and unusual
Reference:
State Council of Educational Research and Training (2018). Term-3 English Standard-7. Man Overboard - Vasantha Murthi (pp. 125-130). Published by the Tamil Nadu Textbook and Educational Services Corporation.