# Grid system repair



## davidpm (Oct 22, 2007)

The following pictures are from a Beneteau 32s5 that suffered some damage. As you can see it uses a structural grid system.
What would be the process to repair this damage and can it be repaired well?
How is that grid connected to the hull.
As you can see the keel may be pushed up a little bit. It is very subtle but I would think that it should bow down not up as the ruler acting as a straight edge shows.
The first picture shows the grid system
The second picture shows how the aft end of the keel is pushed up a little
The third picture may be easier to see without the straightedge in the way.
The fourth picture shows a structural crack.


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## davidpm (Oct 22, 2007)

BoatUS.com: Boat Reviews by Jack Hornor, N.A. - Alberg 30

This guy says they glue the floor grid system in place.


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## hellosailor (Apr 11, 2006)

A grid is usually "bonded" to the hull. Beneteau-US can tell you on Monday but I'd expect this is structural adhesive or epoxy of some kind.

The repair to the grid would be a conventional fiberglass repair, i.e. grind back the edges of the crack at the correct angle, layer in new layers of glass, build it back up, same as working on a hull just more complicated when you're trying to work around right angles. Still, small area, simple enough to overbuild the repair. Aesthetics aside.

That the keel has stayed pushed up may mean the grid was pushed up more than it seems, or the hull pushed up and the grid is now holding it in the wrong position. I suspect that Beneteau would say a "proper" repair means removing the grid entirely, checking for hull damage and keel alignment, then reinstalling a new grid or repairing and reinstalling the old one, after checking it for proper shape. And since it is the keel, that really might be the only proper way to do it. 

An oscillating saw might allow you to cut the old grid free without damaging it, but I'm almost afraid to ask what B would charge to supply a new grid if they still can. As opposed to taking this one to the local auto body shop. (G)


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## Stumble (Feb 2, 2012)

I am not familure with this in Beneteau's but I have seen it repaired on some significantly larger boats. Basically they took off the deck, remove the entire interior, then removed the grid, fixed the grid, then working backwards reinstalled everything. The problem is that when it separates like this there is often grid damage that destroys the stringers. The only way to repair this is to cut out the bad, and replace it. 

The boat I am thinking of had a quote for the repair of $135,000 on a vessel worth about $160,000 in good shape. I was involved with a potential buyer that wanted to try and fix it for cheap to take cruising. Thank god they didn't. This however was a 46' boat with very limited access to the damaged grid.


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## SloopJonB (Jun 6, 2011)

Faster is currently doing a very similar job to his Fast 345 and doing a very nice job of it. I asked him to post pics & the process when he's done.

He is not repairing damage though, just putting in additional reinforcing for his own peace of mind but the process is much the same.


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## Minnewaska (Feb 21, 2010)

Ran aground at high speed? 

I understand the structural grid system can be a very sturdy design, but have always wondered about cutting access for tubing and piping, as in these pics. The factory themselves does it.

I'm sure it is uneconomical to fully repair correctly. It may be one of those that is repaired to be safe, but is never right again.


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## tommays (Sep 9, 2008)

Been through the 20000 dollar version on Zzzooom and at best it was necessary to cut out the liner to even assess the full extent of the damage

Its really unlikely that if you flexed the hull enough to crack the grid and debonded it from the hull that the hull does not have hidden delamination issues as this was a significant issue on Zzzoom 

Its really hard to see the delamination when its covered it paint as it turns the glass a milky white color


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## jimrafford (Jan 7, 2011)

Probably caused by the event you posted a while back. "Best boat ever built" as I recall.
Jim


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## davidpm (Oct 22, 2007)

jimrafford said:


> Probably caused by the event you posted a while back. "Best boat ever built" as I recall.
> Jim


It also came ashore during a storm a couple of weeks ago.


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## davidpm (Oct 22, 2007)

To do a repair I suspect the boat would have to blocked up some how to take the weight off the keel and restore the shape. Not sure how that would be done safely as blocking is usually done with most of the weight on the keel.


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## svHyLyte (Nov 13, 2008)

The yacht’s hull is solid, hand-laid, glass reinforced with an epoxy bonded partial hull liner extending roughly two feet above the bilges that was installed while the hull remained in the mold and still “green” to ensure a chemical as well as adhesive bond. The liner is comprised of a grid system designed to reinforce and stiffen the hull, particularly adjacent to the keel; mast-base; and where chain-plate loads are transferred into the hull. The liner keeps locker bottoms isolated from wet bilges and, during manufacturing, ensured the exact positioning of bulkheads. Before installation, the liner is partially cut-away between "ribs", and the resulting edge flanges tabbed to the hull with layers of bi-axial glass. This technique retains the strength added by the liner yet allows near full access to the inner skin of the hull. Penetrations along the undersides of the "ribs" for hoses, wiring et al are akin to penetrations in the webs of structural beams and of no consequence to the function of the sections.

Having "run aground", the keel would have attempted to rotate down and away from the from the keelson at the leading edge of the keel root, forward, and up and into the hull at the trailing edge. The keel bolts--16 or so--would have prevented separation of the keel from the hull hence the yacht accordingly rotated forward and down immersing the forward sections of the hull and raising the aft sections until the energy consumed matched the energy required to bring the yacht's forward motion to a halt.

The resulting torque introduced into the hull beneath the structural grid would have actually introduced transverse compression in the top of the ribs ribs forward of the centroid of the keel--hence the edges of the "cracks" in the forward ribs would likely show an upward ridge along the length of the cracks, while the ribs aft of the centroid would have been bowed upward, placing the top faces of the ribs in tension and cracks there would merely be "lines". The the corners of the intersections of the fore'n aft stringers and transverse ribs would have been likewise compressed or tensioned showing similar characteristics.

Despite the surface cracks, so long as the ribs/stringers did not separate from the hull--and the photos reveal no evidence of that--hull integrity would not have been compromised and the cracks would merely be cosmetic so long as they are merely surface cracks. One can determine that by releasing the tension on the shrouds and fore and back stays, relieving the tension on the yacht's hull and probing the cracks with a very thin probe. (Knowing the construct of the yachts, however, I doubt one will be able to insert a probe deeper than the depth of the gel-coat covering the ribs.) So long as the actual glass fibers in the section have not ruptured you have no issue other than cosmetic--which I suspect is the case. Merely clean up the glass, remove a very small area around the cracks--and I do mean small, no more than the thickness of the gel coat as you do not want to cut through the glass fibers, and full the cracks with Marinetex. If any of the glass fibers have ruptured, you'll want to remove the surface of the ribs to only the depth of the rupture along the tops and sides of the ribs and "splint" them by building up layers of biaxiel glass length-wise across the line of the cracks. This repair is actually better done while the yacht's afloat than on the hard as the yacht's weight is distributed and supported over the entire water plane rather than concentrated on the keel which will cause some distortion of the shape of the hull. If you do not have skills with glass, hire someone that does. Note, however, I doubt the foregoing will be necessary.

FWIW...

PS: It would be wise to clean up your bilge. Grime makes it very difficult to see what may have happened to a yacht's hull during a grounding and it makes a yacht smell bad.


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## davidpm (Oct 22, 2007)

svHyLyte said:


> This technique retains the strength added by the liner yet allows near full access to the inner skin of the hull. Penetrations along the undersides of the "ribs" for hoses, wiring et al are akin to penetrations in the webs of structural beams and of no consequence to the function of the sections.
> 
> Despite the surface cracks, so long as the ribs/stringers did not separate from the hull--and the photos reveal no evidence of that--hull integrity would not have been compromised and the cracks would merely be cosmetic so long as they are merely surface cracks.


You certainly seem to know your boats. Are you a builder or surveyor?
Not sure I under stand the first paragraph above. "allows near full access to the inner skin of the hull" It seems to me that the inner skin of the hull is covered by the liner. I suppose you could say there is access for snaking hoses.

So you are not worried about any potential damage to the hull just aft of the keel where it apparently got pushed up and is deflected now while on stands.
I'm concerned about delamination of interior layers in that section or maybe even of the inside of the hull which is covered by the liner.

I like your answer better though.


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## svHyLyte (Nov 13, 2008)

davidpm said:


> You certainly seem to know your boats. Are you a builder or surveyor?
> Not sure I under stand the first paragraph above. "allows near full access to the inner skin of the hull" It seems to me that the inner skin of the hull is covered by the liner. I suppose you could say there is access for snaking hoses.
> 
> So you are not worried about any potential damage to the hull just aft of the keel where it apparently got pushed up and is deflected now while on stands.
> ...


David-

I am neither a builder nor a surveyor, although I did stay at a Holiday Inn Express the night before I answered your post&#8230;.

Beyond the foregoing, I am a semi-retired Structural Engineer which does give one some insight into how structural systems operate. And, I own a Beneteau First 42, as does a close friend of mine-who does happen to be a surveyor-and because of that we have made a close study of Beneteau Yachts including on-going correspondence with German Frers, the designer of the First 42 and other Beneteau's as well as discussion with the technical staff at Beneteau's Headquarters and Ferenc Mate's research on Beneteau yachts which are prominently featured in his book "The World's Best Sail Boats". (The foregoing was the basis of a piece I penned on the First series of yachts for a magazine a few years ago.)

N'any case, my earlier comments were predicated on the impression that you were merely concerned about apparent cracking in the lateral and transverse members of the grid system in the hull liner. Perhaps you mentioned the "indentation" in the hull on the aft end of the keel but if so, I missed it. A persistent concave indentation in the hull abaft the keel indicates that the grounding was hard enough to have rotated the back of the keel up and into the hull far enough to have exceeded the elastic limits of the hull. If so, the bond between the liner and the hull probably ruptured for some length and the glass fibers along the inner surface of the hull will have-probably did-ruptured. With that, the hull would not be able to recover its original shape as it would with strains within the elastic limits of the material. Given that, I suggest a detailed inspection of the yacht by a knowledgeable surveyor and/or marine engineer (and likely a call to your insurer). I would expect such investigation to include cutting a hole through the hull liner above the area of the "indentation" to determine the extent of the separation of the liner and fracturing of the keelson. I suspect that although the hull skin may be intact, the keelson may have ruptured with the broken edges bearing against one another, preventing the recovery of the hull-shape. Unfortunately, proper repairs will require that the rig and keel of the yacht be removed and the hull be supported on for'n aft rails, similar to the bunk-boards on a trailer, to relieve any stress on the hull during the repair efforts.

I'm sorry that the foregoing is not the relatively simple repairs I described earlier but, evidently, your grounding was much more serious than I first assumed. Unfortunately, one cannot simply ignore the damage as groundings are inevitable and while the water-tight integrity of the hull may not now be compromised, the weakness in the hull would certainly risk a catastrophic failure of the hull with the next grounding.

FWIW&#8230;


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## davidpm (Oct 22, 2007)

svHyLyte said:


> David-
> Perhaps you mentioned the "indentation" in the hull on the aft end of the keel but if so, I missed it. A persistent concave indentation in the hull abaft the keel indicates that the grounding was hard enough to have rotated the back of the keel up and into the hull far enough to have exceeded the elastic limits of the hull.


Thanks for the explanation, makes perfect sense.
Would you take a look please at the two pictures in the first post of this thread.
I actually missed it the first time I looked as the concave effect is very subtle.
Probably only a 5/15" inch or so.

That being said I would have guessed that the design shape would have been at least 1/4" convex. If that is right then the full deflection is 1/2" which might be significant.
Then again maybe their is some normal deflection with the weight of boat sitting on the keel.

What are your thoughts?


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## svHyLyte (Nov 13, 2008)

davidpm said:


> Thanks for the explanation, makes perfect sense.
> Would you take a look please at the two pictures in the first post of this thread.
> I actually missed it the first time I looked as the concave effect is very subtle.
> Probably only a 5/15" inch or so.
> ...


David-

Relying upon an all but anonymous technical consult via the internet is likely not the ideal way to go with your situation. Never-the-less, if the apparent hollow that seems to appear above the straight edge of the tape measure in the photograph below is the distortion you refer to, I suspect that is merely a consequence of the concentration of the yacht's weight on the keel alone, which was likely blocked slightly bow up when she was hauled out. The yacht's hull is/was designed to carry it's weight distributed over the immersed water plane, not concentrated in a relatively small area around the keel as it is when out of the water:










You will be able to ascertain with situation more effectively with the yacht in slings and some, if not all, of it's weight lifted off the keel. Also, you might call BeneteauUSA and discuss the issue with one of their technical guys. You can start with Ward or Todd at 843-629-5300. Either of them can refer you to one of the technical/engineering staff whom I suspect will second my original thoughts on the matter ('tho' perhaps not) but offer you rather more valuable advice than I.

FWIW&#8230;


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## mitiempo (Sep 19, 2008)

David

In the past few months 2 different Beneteaus - a 331 and a 40 - locally have hit rocks and the damage was extensive in the floor grid area although it did not look bad outside. The 331 repair was about 28k and the 40 repair was about 40k. 

Get a good surveyor, possibly recommended by your insurance company, and with a proper survey you will know what is needed to repair the damage.


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## davidpm (Oct 22, 2007)

Thanks for your comments. I'm using this as a learning example. I was able to get pictures but the insurance is held by others so they are handling the final disposition.

I did talk to the yard manager and he has not finished his estimate yet. He is thinking that he should drop the keel to check to see if their is any damage around the keel bolt holes.

By the looks of the keel boat heads they will have to be broken to be removed. 
How are keel bolts replaced once they are broken in a steel keel?

I'm familiar with catalina lead keels where they just drill a hole and screw in a giant lag screw but what do they do in iron?


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## hellosailor (Apr 11, 2006)

david, what you are calling the keel bolt heads, aren't those conventional hexagonal NUTS that are simply screwed onto the actual keel bolts?

If they are nuts, a nutcracker or penetrant (like PBlaster) and a torque amplifier (Spinal Tap joke, turn the amp up to "11") should spin them off or crack them off.

If the bolt actually has a hexagonal head on it, then it is some type of lag bolt or threaded bolt (Beneteau style, a bolt maybe 4-6" long) and again, penetrant to soak in, maybe a carefully used torch to encourage them, and turn the torque amplifier up to "11".

If they are hex-headed bolts and they snap off, you're looking at options like a cobalt drill and retapping. OR, quite seriously, drop the keel, clean the joint out surgically clean, rebed the keel in 3M 5200 when you jack it back up and give it a week to cure. It will be permanently attached, no bolts needed any more.

Remember, these days combat aircraft are _glued _together. The trick is, good prep and the right glue.


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## CalebD (Jan 11, 2008)

David,
Can you lower the bow a tad and raise up the stern Jack stands a bit to see if the 'hollow', or deformity comes out? (Assuming boat is on Jack stands).
If you can't get the 'hollow' to disappear by shifting the weight around a bit with the Jack stands then it is time to call in the French Army as suggested above.


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## SloopJonB (Jun 6, 2011)

davidpm said:


> By the looks of the keel boat heads they will have to be broken to be removed.
> How are keel bolts replaced once they are broken in a steel keel?
> 
> I'm familiar with catalina lead keels where they just drill a hole and screw in a giant lag screw but what do they do in iron?


Keel "bolts" in an iron keel are actually studs threaded into the keel. To repair them you simply remove them, chase the threads in the keel to clean them up and thread new studs in.

Much simpler than the same job in a lead keel.


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## svHyLyte (Nov 13, 2008)

davidpm said:


> Thanks for your comments. I'm using this as a learning example. I was able to get pictures but the insurance is held by others so they are handling the final disposition.
> 
> I did talk to the yard manager and he has not finished his estimate yet. He is thinking that he should drop the keel to check to see if their is any damage around the keel bolt holes.
> 
> ...


Your keel is held on with (essentially) galvanized bolts. (See photo's attached--I hope!) If you will send me a PM with your email address, I will forward a file produced by Beneteau to address your questions.


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## svHyLyte (Nov 13, 2008)

I realized I could copy the Beneteau technical notice as a text file (absent photos) and thought that might be worth while. I regret the formating of the tables, below, isn't perfect, but should be understandable.

Background Information
• Cast Iron keel use galvanized bolts - There are threaded sockets cast into the keel
• Lead keels use stainless steel nuts - There are threaded rods cast into the keel

You can use stainless steel bolts in a cast iron keel, but you should remove and inspect the threads for galvanic corrosion yearly. 
A bolt only has to engage the threads 1½ times the diameter of the bolt to be effective. 90% of Beneteau Keel bolts are 3 inches or less in length.

Replacing Information
Use a battery powered drill with a wire brush wheel. Clean the heads down to new metal. Tip: use a shop-vac to clean rust dust and flecks as you clean the heads.

Remove 1 bolt and inspect. At this point you should be able to make a determination if the bolt is structurally sound or needs to be replaced. A complete set of the bolts and washers can ordered from the Beneteau Spare Parts Department. We will need the Model and Type of keel on of your boat.

14mm bolt uses 22 mm socket 
20mm bolt uses 1-3/16 socket
30mm bolt uses 1 7/16 socket

If you have water entering the boat through the bolt hole, replace the bolt and make future plans with your local boat yard to haul, separate and reinstall the keel.

If the head of the bolts are so degraded that the socket will not back it out, use a side grinder to grind two flat sides on the bolt. This should allow you to remove the bolt with a wrench. Worst case scenario: Remove boat from the water, grind the heads completely off and remove the keel from the hull. Then using the remaining shaft of the bolt, remove the bolts and reinstall the keel.

Coating the heads of the bolts with a rust preventative paint will prolong the life of the bolts. Tip: I have used Trailercoat from West Marine with success.

Do not use sealant on the bolt threads; only use sealant around the bolt heads to keep bilge water out of the bolt socket.

The keel to hull joint and exterior seam should be sealed with Marine Adhesive Sealant 4200.

Keel bolt Torque Specifications.
DACROMATISED STEEL BOLTS TYPE 8-8.

DIAMETER M14 M20 M24 M30
TORQUE in M.Kg - minimum	5	13	23	45
TORQUE in M.Kg - maximum	9	27	46	90
TORQUE in ft.lb - minimum	36	94	166	325
TORQUE in ft.lb - maximum	65	195	333	651

TABLE 6.5.2
STAINLESS STEEL BOLTS TYPE A4-70 and A4-80

DIAMETER M14 M20 M24
TORQUE in M.Kg - minimum	5	16	28
TORQUE in M.Kg - maximum	11	32	55
TORQUE in ft.lb - minimum	36	116	203
TORQUE in ft.lb - maximum	80	231	398

TABLE 6.5.3
STAINLESS STEEL BOLTS TYPE A4-55

DIAMETER M30 M36 M42
TORQUE in M.Kg - minimum	19	33	52
TORQUE in M.Kg - maximum	38	65	104
TORQUE in ft.lb - minimum	137	239	376
TORQUE in ft.lb - maximum	275	470	752​
FWIW...

PS: Keel bolts can be replaced, one at a time, while the yacht remains in the water. And, when I replaced our keel bolts, I coated them with Petit RustLoc primer--several coats--to good effect.


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## SloopJonB (Jun 6, 2011)

svHyLyte said:


> Your keel is held on with (essentially) galvanized bolts. (See photo's attached--I hope!) If you will send me a PM with your email address, I will forward a file produced by Beneteau to address your questions.


SV - does Beneteau use cap screws to attach their keels? I've never seen that done - it's always been studs threaded into the keel and attached with nuts inside the bilge.

Except for small keels that is - Thunderbirds keels are held on with countersunk flathead machine screws through the flange of the root of the keel.


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## svHyLyte (Nov 13, 2008)

SloopJonB said:


> SV - does Beneteau use cap screws to attach their keels? I've never seen that done - it's always been studs threaded into the keel and attached with nuts inside the bilge.
> 
> Except for small keels that is - Thunderbirds keels are held on with countersunk flathead machine screws through the flange of the root of the keel.


Beneteau's cast iron keels are secured with "DACROMATISED STEEL BOLTS TYPE 8-8" which are essentially galvanized bolts as discussed above (see photo attachments to my earlier post #21). This manufacturing process is evidently not uncommon with European performance yachts. Beneteau's Lead keels are fastened with nuts tightened down over stainless steel studs cast in place in the keel during manufacturing. One can use stainless steel bolts (in cast iron keels) but, if so, they must be inspected annually for crevice corrosion and getting them out (and there are 16 of them) is a serious PITA. After 26 years, I needed to replace 8 of 16 bolts because of the corrosion of the bolt heads due to the failure of the water-proof coating and some water having made its way into the bilge (which is normally so dry it's dusty). In fact, upon extracting the bolts we found that only a small portion of the bolt heads had actually deteriorated and that the shafts, threads et al were dry, clean and as shiny as the day they were installed in 1986.

FWIW...

PS: Interesting that you should refer to T-Birds. Our first real yacht--other than a sailing dinghy--when we lived in San Francisco was a late 1950's era T-Bird with the cast iron keel fastened as you described. Believe it or not, I still have the plans. Great boats.


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## davidpm (Oct 22, 2007)

svHyLyte said:


> if so, they must be inspected annually for crevice corrosion and getting them out (and there are 16 of them) is a serious PITA. After 26 years, I needed to replace 8 of 16 bolts because of the corrosion of the bolt heads due to the failure of the water-proof coating and some water having made its way into the bilge (which is normally so dry it's dusty).


So from your point of view putting a wrench on a keel boat, even if it is in water, extracting to take a quick look is a fairly routine project?

That takes yacht maintenance to a new level. I've always thought of extracting the keel boats as a once in a lifetime exercise.
Maybe because I'm more familiar with the Catalina system where the bolts are cast into the keel and the keel has to be dropped to check anything other than the nut and a inch or two of the top of the bolt.


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## svHyLyte (Nov 13, 2008)

davidpm said:


> So from your point of view putting a wrench on a keel boat, even if it is in water, extracting to take a quick look is a fairly routine project?
> 
> That takes yacht maintenance to a new level. I've always thought of extracting the keel boats as a once in a lifetime exercise.
> Maybe because I'm more familiar with the Catalina system where the bolts are cast into the keel and the keel has to be dropped to check anything other than the nut and a inch or two of the top of the bolt.


David--

The lead keels on Bene's that have cast in studs would be akin to the Catalina design although more robust. If you look at some of the other postings/threads on the subject, several members have posted photo's of what their keel studs looked like once the keels were removed and some are quite frightening. That is not the case with Beneteau's cast iron keel design. Removing a bolt while the yacht is in the water is not a big deal as there is no distortion of the hull due to the weight of the yacht sitting on the keel alone, hence the seal between the keel and the keelson is not compromised. If one does observe water seepage upon the removal of a bolt, it will be minimal but it will also be a telltale that one needs to drop the keel, clean up the top of the keel and the underside of the hull, and rebed the keel. There should not be any water penetration between the two as rust can/will form and force the two apart--just as rust on re-bar will blow the side out of a concrete column or beam, frequently seen on old bridges or retaining walls. The resulting stress in the keel bolts will further compromise the seal admitting more water and the cycle will continuously repeat itself until there is a failure although that would take a very long time absent an exogenous shock load.

In any case, I have never heard of anyone pulling a keel bolt and having water intrusion on a Bene. I'm sure it may have happened, but I have personally not heard of such a case. The only situation where I could see that happening might be where the bolts were not torqued sufficiently (see the torque tables in my earlier post). For our part, I torque the bolts to 150 ft-lbs and our bilge is as dry as a bone. And, I will not pull a keel bolt unless there is some evidence that it is necessary as I do not use stainless bolts in an oxygen deprived environment. (In fact, save for rigging, I don't think much of stainless.)

FWIW...

PS: David. Note that only the Stainless Steel Bolts need be removed for annual inspection (per Beneteau's recommendation). The galvanized bolts do not.


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## SloopJonB (Jun 6, 2011)

As I alluded to a while back - this is one of the benefits of iron keels. Keel stud problems on a lead keel are a major headache and big expense to fix but in most cases they are but a minor job on an iron keel.

As to removing individual bolts at the dock, keep in mind the huge safety margins designed into keel mountings. When my 10,000 Lb keel was off to be blasted, sealed & remounted the yard moved it around with a sling that was only attached with *two* of the 10 keel bolts - no problem.


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## hellosailor (Apr 11, 2006)

" this is one of the benefits of iron keels."
All in perspective. This system is AFAIK used on iron keels simply because the simpler cheaper traditional j-bolts aren't feasible in cast iron. If using studs to attach a keel really was a better way to do things, it would be simple to insert a metal plate in the top of a lead keel as it was cast, and then drill down into it so the same type of replaceable studs could be used. But designers seem to prefer J-bolts, probably for a reason. Of course the use of stainless may be a mistake but that dates back to the WW2 ear when "STAINLESS!" was marketing magic. And so many people still think it is.

I give credit to B for thinking outside the box in many ways but they also seem to think routine replacement of those keel studs is normal. J-bolts in a lead keel? OK, so you replace the nuts if you need to, rarely the bolts. PITA if you have to but that's what owner neglect causes, RFPITA.

Why folks don't do a little routine maintenance, apply some oil, grease, put a collar around the bolt head and pour in hit beeswax, just SOMEthing once or twice a year and the whole question of corrosion should be a non-issue, regardless of the metals or keel type.

I'd still prefer a lead keel over iron, which may be a great budget helper, but iron is still fat and cheap no matter how you look at it. Of course my real choice of ballast is the same one that NASA used on the Mars Rover shield: Tungsten!

Makes _lead _look fat and cheap.

Please save up all your tungsten incandescent light bulb filaments from burned out bulbs, I'm building a proper tungsten keel, 1/10th of a gram at a time. (VBG)


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## SloopJonB (Jun 6, 2011)

hellosailor said:


> If using studs to attach a keel really was a better way to do things, it would be simple to insert a metal plate in the top of a lead keel as it was cast, and then drill down into it so the same type of replaceable studs could be used.


That's more or less what they are doing with the current razor blade keels with bulbs 12 feet down. Drilling and tapping takes time which = $$. Usually the builders go for the cheaper option whenever they can.



> my real choice of ballast is the same one that NASA used on the Mars Rover shield: Tungsten!
> 
> Makes _lead _look fat and cheap.
> 
> Please save up all your tungsten incandescent light bulb filaments from burned out bulbs, I'm building a proper tungsten keel, 1/10th of a gram at a time. (VBG)


Why not go for depleted uranium? It's actually been done. There's probably lots of it in the desert in Iraq and Kuwait.


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## hellosailor (Apr 11, 2006)

Other than toxicity and restrictions on civilian ownership? 

IIRC it was Bertie Roos who literally borrowed enough spent uranium to make his keel in one of the Volvo (?) solo global races maybe a decade ago. And when the keel broke off and sunk in the Southern Ocean, I'll bet Bertie had a lot of 'splainin' to do.


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## SloopJonB (Jun 6, 2011)

hellosailor said:


> Other than toxicity and restrictions on civilian ownership?
> 
> IIRC it was Bertie Roos who literally borrowed enough spent uranium to make his keel in one of the Volvo (?) solo global races maybe a decade ago. And when the keel broke off and sunk in the Southern Ocean, I'll bet Bertie had a lot of 'splainin' to do.


If it's depleted it isn't really radioactively toxic, only chemically (ingested) but so is lead. It's actually used for radiation shielding. The first time I heard of it was back in the 70's - IIRC it was Alain Colas who did it on one of his OSTAR boats with help from the French Navy. It was quickly banned by making everything denser than lead illegal as ballast.


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## Faster (Sep 13, 2005)

I thought it was Taberly in one of the Pen Duicks that used uranium ballast... but could have been both, I suppose.


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## SloopJonB (Jun 6, 2011)

Faster said:


> I thought it was Taberly in one of the Pen Duicks that used uranium ballast... but could have been both, I suppose.


Could be - it was a long time ago. 

Edit: I did some digging - it WAS Tabarly. I guess his naval career should have been a tipoff.


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## svHyLyte (Nov 13, 2008)

hellosailor said:


> " this is one of the benefits of iron keels."
> All in perspective. This system is AFAIK used on iron keels simply because the simpler cheaper traditional j-bolts aren't feasible in cast iron. If using studs to attach a keel really was a better way to do things, it would be simple to insert a metal plate in the top of a lead keel as it was cast, and then drill down into it so the same type of replaceable studs could be used....


"J-bolts" are used in lead keels for two reasons. Firstly, because of the relative "softness" of cast lead, an extended length of embedment is necessary to allow the "studs" to develop the tensile loads required to properly support the keel (similar to the development length of reinforcing bar in cast concrete). Secondly, because of the relatively low melting temperature of cast lead (621º F) compared to steel (2600-2750º F), the studs can pretty easily be positioned while their physical properties (strength, ductility, et al) remain unaffected. This is not so with cast Iron as the meting temperature of the iron (2200º F) is great enough to adversely effect studs but also unnecessary as a cast-in plate machined to accept bolts is essentially homogeneous with the balance of the keel and only 1-1/2 bolt diameters of thread penetration is required to develop the load in the bolts necessary to support the keel.

Beyond the foregoing, of course, is the question of material costs with iron being relatively less costly than lead allowing relatively more affordable yachts. Frankly, however, the yacht really doesn't care what it's ballast is made of so long as there is an adequate amount that functions properly for the design objectives of the yacht and, at least in our case (First 42), it seems to do so.

FWIW...


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## davidpm (Oct 22, 2007)

svHyLyte said:


> Frankly, however, the yacht really doesn't care what it's ballast is made of so long as there is an adequate amount that functions properly for the design objectives of the yacht and, at least in our case (First 42), it seems to do so.
> 
> FWIW...


There is the issue of surface rusting of the iron keel.
I'm sure you have that solved. What have you done?


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## svHyLyte (Nov 13, 2008)

davidpm said:


> There is the issue of surface rusting of the iron keel.
> I'm sure you have that solved. What have you done?


David--

We haul out at roughly 2-1/2 year intervals and from time-to-time do find some rust. Basically, I grind back the bottom paint and surface coating to reveal the underlying iron, wire brush the rusted areas to remove surface rust, acid wash the underlying metal and then burnish the metal with a fine drill mounted brush, dry it all with Acetone, treat the exposed metal with several coats of Pettit RustLok primer and then fill any indentations with thickened epoxy and fair the surface. The fairing surface is coated with a layer of Epoxy and the whole business primed and repainted with bottom paint. Frankly, the foregoing almost takes more time to describe than to perform. The good news is that over the last 10+ years, areas treated in the foregoing manner have not required retreatments on subsequent haulouts.

Unfortunately, iron in contact with water will eventually rust (entropy always wins). Except in very rare circumstances, however, the rust is a minor issue and invariably looks far worse than it actually is as the volume of rust one sees is, roughly, 600 percent the volume of iron oxidized to produce it. So long as one keeps up with the maintenance, these keels will last virtually forever. Even with lack of maintenance, they will last a very long time (in human terms) as evidenced by the number of iron bridges constructed during the 1930's that are incredibly poorly maintained yet continue to "hang in".

FWIW...


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## SloopJonB (Jun 6, 2011)

svHyLyte said:


> Even with lack of maintenance, they will last a very long time (in human terms) as evidenced by the number of iron bridges constructed during the 1930's that are incredibly poorly maintained yet continue to "hang in". FWIW...


Or the iron bridges built by Brunel in the *18*30's that continue to hang in.


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## SloopJonB (Jun 6, 2011)

svHyLyte said:


> the volume of rust one sees is, roughly, 600 percent the volume of iron oxidized to produce it. FWIW...


I had no idea the oxide expanded THAT much - no wonder it can burst things when it's enclosed.


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## davidpm (Oct 22, 2007)

svHyLyte said:


> David--
> 
> acid wash the underlying metal and then burnish the metal with a fine drill mounted brush,


What exactly is acid wash? Product link?
Metal mounted brush like this?: 
4'' Stringer Bead Wire Wheel / Stainless Steel 5/8''-11 Arbor .020 - DW4927

or something else?


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## svHyLyte (Nov 13, 2008)

davidpm said:


> What exactly is acid wash? Product link?
> Metal mounted brush like this?:
> 4'' Stringer Bead Wire Wheel / Stainless Steel 5/8''-11 Arbor .020 - DW4927
> 
> or something else?


I have used both Wink and Navel Jelly. I think the Navel Jelly is somewhat easier to use because it is fairly thick but I don't like having to wash it off with water (if you use that, follow-up quickly with Acetone or 90% Alcohol). I prefer Wink soaked paper towels, that will "stick" to the keel and can be followed up with a wash of 90% Alcohol. The wire brush you show will work. Mine is very old and somewhat cone shaped. My drill is also very old and heavy/powerfull but is fitted with a side grip so it can easily be used with two hands and it does make quick work of burnishing.

David. Note that my approach is only one. I am sure there are others here about with somewhat different approaches that will work equally well.

FWIW...


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