Interesting vid about keel grid

[Wansworth]

 

[Keith 66]

Good video. Takes me back to my days repairing write offs! Biggest was a Sigma 38 that had hit a reef off the Channels isles at night in a gale, keel ripped right off & sank.
Boat was salvaged. The grid matrix was totally shattered & the builders wouldnt supply us a repair section. And so we came up with a cunning plan. The grid matrix was cut along the cracks & breaks & repaired roughly with timber & self tappers. Chopped strand filler & bodyfiller made it good. We then cut the damaged bottom of the boat out & dropped the bodged grid matrix out. It was then cleaned up & polished & a light one shot splash mould made from it.
A new grid was then laminated & when finished lifted into the boat & hung from the ceiling of the saloon.
Hull then ground out & repaired & the new grid dropped down on bonding paste & tabbed in properly, Joins to the frames & stringers made good & furniture reinstalled.
I remember the fin was in two parts with an iron top & lead lower section, the lead was bent 3" out of true to one side at the front end with a spear of granite rammed into it. I dug a lot of it out but the last bit was left in there.
It took two of us 2 days to beat the keel straight with sledge hammers.
When the surveyor came to look at the job he couldnt believe how we did it.
As far as i know she is still out there racing.

Another similar one was a Carter 33 that after repair did the arc a while back.

I spent a long time in a powered respirator but sure dont miss the grinding fibreglass bit which has to be the poxiest job ever!

 

[RunAgroundHard]

Another interesting grid video. These videos are very useful for those contemplating buying a second hand boat with this design feature to aid a basic understanding. This one is very bad damage.

 

[Tranona]

It is important to remember as in post#2 this sort of thing is not new, nor confined to "modern" boats - indeed stretches back to wooden construction.

 

[Skylark]

The second video is very informative. Not so convinced about a few of the comments made within the OP video. Both boats have undoubtedly suffered hell of a bang.

 

[Snowgoose-1]

Just a thought. Many older designs had swept back fin keels rather than the modern vertical types. I believe it was thought that swept back fins were more hydrodynamic but later proved to be minimal if at all.

I do wonder if the older style keel would be less damaging if grounded. I was languishing in my boat one time close to a marina sill. An older style yacht charged the sill at some speed and literally rose up in the air. Perhaps a vertical keel would not have fared so well.

 

[RivalRedwing]

Just a thought. Many older designs had swept back fin keels rather than the modern vertical types. I believe it was thought that swept back fins were more hydrodynamic but later proved to be minimal if at all.

I do wonder if the older style keel would be less damaging if grounded. I was languishing in my boat one time close to a marina sill. An older style yacht charged the sill at some speed and literally rose up in the air. Perhaps a vertical keel would not have fared so well.

especially if you have a nice big bulb at the bottom....

 

[lustyd]

Perhaps a vertical keel would not have fared so well.

That depends, are you certain no damage was done? There are a lot of half sunken long keelers around our coast in rivers and it stands to reason that some have suffered impact damage.

 

[RunAgroundHard]

Just a thought. Many older designs had swept back fin keels rather than the modern vertical types. I believe it was thought that swept back fins were more hydrodynamic but later proved to be minimal if at all.

I do wonder if the older style keel would be less damaging if grounded. I was languishing in my boat one time close to a marina sill. An older style yacht charged the sill at some speed and literally rose up in the air. Perhaps a vertical keel would not have fared so well.

Personal experience:-

Sigma 41, hit rock under sail, web at front of keel, flange snapped clean through, significant internal damage to frames, stringers and hull.
Sigma 33, struck rock under power, cracked frames and stringers inside, no damage to keel.
Contessa 34, struck a boulder strewn leeshore under sail, big dent in lead, frames and stringers damaged in hull.

The above all have fins that slope backwards and do not have grids. In general terms, when the keel decelerates rapidly, the hull tries to pivot over the front of the keel flange as well as reacting against a keel driven upwards by shoaling water.

Encapsulated keels can have faired sections that are hollow and if grounded can cause flooding and sinking with no access to void space. Also damage to encapsulated keels, with no hull stringer and frame damage, can expose steel ballast to salt water and corrosion. This can cause significant secondary damage down the line and be a very expensive repair.

All yacht keel styles have inherent risks associated with grounding. I think, like Osmosis, grids and potential damage, will become accepted as a potential issue with second hand, older boats and be routinely reflected in potential buyers concerns. I do not know how much of an issue this is in the second hand market.

 

[Keith 66]

The old UFO 31's were quite prone to internal damage, i repaired two, deep lead fin with narrow base at top staggered keelbolts, very similar to a lot of modern production boats. Both had been raced hard & had significant damage, effect of a grounding at speed is for the rear of the keel to rock upward, both hulls were split at this point along the centreline & the transverse floors had come away from the hull. Distortion of the keel line was such that i had to jack the stern up about 300mm before the keel line was straight again.
I have seen modern boats distort this way just by taking the ground on a drying mooring.
First thing any buyer should do is look along the keel & see if the rear of the keel is deflecting the hull upwards.
Any signs of cracking in the bonding paste or matrix / floors & it will be expensive to fix.
One of those UFO's had recently had an insurance survey & the buyer swallowed that congratulating himself on saving the £300 for his own survey. He then had to fork out again for a massive repair job.
Caveat emptor!

 

[Snowgoose-1]

Personal experience:-

Sigma 41, hit rock under sail, web at front of keel, flange snapped clean through, significant internal damage to frames, stringers and hull.
Sigma 33, struck rock under power, cracked frames and stringers inside, no damage to keel.
Contessa 34, struck a boulder strewn leeshore under sail, big dent in lead, frames and stringers damaged in hull.

The above all have fins that slope backwards and do not have grids. In general terms, when the keel decelerates rapidly, the hull tries to pivot over the front of the keel flange as well as reacting against a keel driven upwards by shoaling water.

Encapsulated keels can have faired sections that are hollow and if grounded can cause flooding and sinking with no access to void space. Also damage to encapsulated keels, with no hull stringer and frame damage, can expose steel ballast to salt water and corrosion. This can cause significant secondary damage down the line and be a very expensive repair.

All yacht keel styles have inherent risks associated with grounding. I think, like Osmosis, grids and potential damage, will become accepted as a potential issue with second hand, older boats and be routinely reflected in potential buyers concerns. I do not know how much of an issue this is in the second hand market.

Interesting. Thanks.

 

[Snowgoose-1]

That depends, are you certain no damage was done? There are a lot of half sunken long keelers around our coast in rivers and it stands to reason that some have suffered impact damage.

I'm not sure what damage was done to the yacht .
I wonder if keels will ever have crumple zones like cars. Where I sail , it's nearly all mud which is very forgiving. Not the sand banks though.

 

[doug748]

I wonder if keels will ever have crumple zones like cars....

Looks like they already have.

 

[LittleSister]

Personal experience:-

Sigma 41, hit rock under sail, web at front of keel, flange snapped clean through, significant internal damage to frames, stringers and hull.
Sigma 33, struck rock under power, cracked frames and stringers inside, no damage to keel.
Contessa 34, struck a boulder strewn leeshore under sail, big dent in lead, frames and stringers damaged in hull.

Remind me not to sail with you.

 

[bluerm166]

Coincidentally RAN sailing has just posted a video of the beginnings of the keel grid within the empty shell of their hull with some interesting setting out involved.