how do boats take the ground

[tim_ber]

Like a bilge keeler or a catamaran.

I used to have a bilge keeler on a drying swinging mooring. I never really observed how she took the ground except to ensure she never tipped too much. Wasn't too worried because it was deep soft mud.

We all know that grounding is bad - leads to pounding in any waves on sand etc.

So how do all these drying moorings work? I saw a nice catamaran in the Channel Islands on a drying swinging mooring on hard sand.

AND if I ever get a decent sized catamaran, do you only run it onto a beach if you have no swell and know that she will float with no swell?

 

[alahol2]

Kept a 30' cat on a drying mooring for 10 years or so with no problems. It was a 'mud' bottom, but the boat soon scours itself a 'saucer' with a harder bottom. Went through THE hurricane on its mooring without damage.
As for the beach, I never put it on in any kind of swell, nor if swell was likely, but I have needed to get off in a light swell. Again, the boat shuddered a few times but there was never any damage done.

 

[snowleopard]

Ditto. My mooring dries to soft mud so it never bumps as it settles. The main problem is that the mud contains lots of sharp shell fragments that scour off the antifoul.

I will dry out elsewhere when I know the bottom is flat sand but won't chance it if there is any significant swell or the risk of rocks. My keels are hollow GRP (they also serve as holding tanks) and I don't currently have reinforced 'shoes' to protect them.

If you get caught by worsening conditions when re-floating it can be a frightening experience to be pounded on the bottom until you can get away.

 

[tim_ber]

thanks guys.

I was on the right lines then.

So what happens with boats moored over drying sand? Surely they are going to be knocked about a lot?

In Jersey I saw bilge keelers and a Woods 24' cat that took the sand twice a day - I am at a loss as to understanding how the boats survive - I wanted to sit and watch as the tide receeded on a rough day, but didn't have the time (or patience?!)