Beneteau Boats

The boat was hit and got stuck on a sandbar and I'm sure he has struck off the paint and did some damage.
What happens if you do not fix it, it does not rust? I do not know what it is made from.
Do you think it will take on the platform, it costs £ 100 and is a lot.

It is a very good idea to do so. In the long term, you probably spend much more if you do not deal with him.
It is a fiberglass boat and you really want to have at least one qualified person to see if you have no damage to the glass.
Once the gel coat is compromised and the glass is exposed you have to deal with it.
If you crush the glass, you have to deal with it.
You do not want to allow salt water to seep into the glass. It can travel very far from the point of impact and create problems that can cost a fortune to repair.
Spend a little now to save many more later.
Sorry, but I saw this way too often.

Sailing ships aground on the sandbanks regularly. You did not mention the boat or wade the sea with a list of boarding. Did not you mention the boat dragged along the side of the hull to make him leave. If this is not the case and you've had the boat in the water for more than two shipping seasons you probably bottom of the keel for a scrape and a few anemones and other parasites that have been riding here. I do not get the boat if I had good reason to suspect damage or hard it was due for new paint. Try sailnet.com: there are people on the forum maintenance that offer practical solutions given the circumstances.

If it was sand and rocks do you have probably been lucky. You could take some goggles and dive in and check it out. In the old days, when the pirates had to repair the hull, they would run close to the shore at high tide and wait for low tide. Tieing the boat to trees that keep it from rocking back and forth. Then, just patch and paint quickly before the tide comes in. If it's someone smaller than you might be able to fit under a tarp, and bring around him, pumping water around the boat and then make repairs in a narrow ... if you can find a canvas large enough and strong enough. We used to get ours about every three years to scrape the barnacles and primer and paint.

Most bowling alleys will be solid steel and can be filled with lead to a max. While it is not puncture and lose water integrity I think it's ok ... but I would like to crawl under and check it.

Peace ... sailors

I fully agree with Mr No Name ...
But I would certainly go for a swim first, and take a look myself ...
I do not know where you are, I do not know how the water is clear ... but in general, you can see, feel and see if the damage ...
Who knows, you might really lucky ... I ran a number of things in my time too, and sometimes - where I thought that there would be major damage, nobody was there.
If you do not feel qualified to say what kind of damage there, ask someone you trust who does, and ask them to check it for you. I certainly would ... but if you can not see, and / or if it does not feel "perfectly smooth" everywhere and in ... Then I got out of the water. Beneteau is a good boat ... if you want to make sure you take good care of her.
Good luck!