Yacht Delivery and Near Miss Keel Grid Failure (Bénéteau First 47.7 )

[RunAgroundHard]

This is a summary from Sailing Zingaro who delivered a Bénéteau First 47.7 from the Bahamas to Cartahena. In the video the skipper describes a situation with a keel grid failure that was causing flooding and compares it to the Cheeky Rafiki incident. Contains insights into the grid construction and offers an opinion that such designs are at risk of age related failure. While Sailing Zingaro doesn't actually state that if such a design is raced hard its whole life, then grid failure is inevitable, it is sort of implied, I thought. There is no statement that the yacht had ever been grounded. The construction method is praised for its contribution to build and production efficiency, allowing owners to select an internal layout that suits the type of use the owner wants. The video also praises the type of glues used to bond the grid and their general reliability in industry. So, it's not a grid, fin keel bashing, all praise encapsulated keel video. Rather it is a sobering look at age related risks for this type of construction.

It is an interesting video.

 

[Keith 66]

Having spent too many hours grinding fibreglass repairing yachts I have repaired quite a few damaged hull to keel joints.
Westerly Centaurs, UFO 31's, Carter concubine, Sigma 38, Jeaneau & Sabre. Out of them all the best designed & built one was the Sabre 27. Her fin keel stub was wide with high tensile steel bolts staggered heavily torwards the sides. Big thick washer plates to spread loads, her Internal floors were heavily glassed in.
The UFO's were by two builders & internal wooden floors & stringers were detached from the hull completely & the grp tabbing was shockingly light. The Carter had a ladder style keel matrix that also had detached from the hull completely. That took a lot of grinding & glassing to fix!
The Sigma 38 had lost her keel completely & a new matrix had to be made & bonded in. This construction method is equivalent to the modern french boats with the internal matrix providing stiffness. Trouble is the bolts are down between the floors & though some may go through the matrix flange some dont & loads are carried by the hull skin itself. In this case you are relying totally on the bonding paste between skin & matrix which to any sensible person is a bad idea. The slightest crack anywhere will propagate outwards detaching matrix from hull. Then it might as well not be there.
One would have thought the RCD might have prevented such construction but obviously not!

 

[RunAgroundHard]

The RCD isn't associated with repairs and post usage of the boat. The RCD does mandate an instruction manual which will probably state that in the event of grounding the boat has to be inspected. As far as design is concerned, it is obvious that the grid design works, hence a certifying authority would have approved for the RCD to be issued.

I do not think the RCD is relevant.

 

[westernman]

Does the RCD provide for any oversight that the boats are actually built to the design plans??

 

[ylop]

Does the RCD provide for any oversight that the boats are actually built to the design plans??

Some.

 

[bikedaft]

Interesting - thanks.

 

[fredrussell]

Sobering video that. I like that Zingaro guy. He’s a good communicator.

 

[Graham376]

Expedition Evans early videos are worth a look at, this gives an idea of the work needed to reattach the grid -