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OZWILD 12-09-2019 12:27 AM

Keel Damage Repair 1986 H40 Legend
 
1 Attachment(s)
He All,
I have sustained some keel damage. I am not confident I know when it happened, but I suspect it was during multiple squall fronts one afternoon whilst at Dry Tortugas. Not a real issue when it happened. It's been that way for a couple of years and I haven't had any issues, but I want to repair it.
Given the Hunter has an iron keel, it should be a relatively easy repair, right?


It's time for a full bottom job so it's a good time to do it. My basic plan is:
a) Square off the damaged part so a corresponding part can be fashioned to fit without too many angles
b) Make a template from the damaged area for marriage to the keel
c) Fashion the missing piece from iron
d) One or possibly 2 metal dowels to provide for a bit of extra strength between the keel and the new piece
e) prep and join with suitable material
f) Fair the added piece to suit shape at front of keel
g) Seal the two parts in readiness for anti fouling.


Question for the knowledgeable here:
1. With regards to c) above, what kind of material should I use? Iron I'm thinking, but what quality and where can I get it in Florida?
2. What procedure / bonding agent can be used for e)? Can it be welded?

I would appreciate any advice. Remember I'll be doing this myself, and am no expert.

That's enough for now, and thanks.

PhilCarlson 12-09-2019 07:53 AM

Re: Keel Damage Repair 1986 H40 Legend
 
Can't really tell the scope of your damage without pics, but here are some things to consider:

-If the CI has been exposed for a couple of years then salwater intrusion and corrosion will have traveled and you will have a lot of rust to grind/blast away. It may not be limited to the keel either.
-Epoxy is the usual method to fill and fair. How big a chunk is missing and do you need the ballast it provided. If not, scabbing in a chunk of CI sounds like a difficult solution to a non-problem.
-If you do need to use a piece of CI, welding is difficult at best, if it's even possible... Pins and epoxy would be my first thought.
-Any impact sufficient to damage an Iron keel could very well cause other problems that may remain hidden. If it's a bolt-on, you might want to have a look at you keel bolts.

Fortunately you are not the first guy trying to figure this out. Google turns up tons of 'How to's,' including this from sailnet:

https://www.sailnet.com/forums/gear-...iron-keel.html

Jeff_H 12-09-2019 11:51 AM

Re: Keel Damage Repair 1986 H40 Legend
 
If you have damaged a cast iron keel enough for it to be visible, then you have have probably done a lot more damage than simply the visible part that you can see. Cast iron imparts much higher stresses into the fiberglass than lead in a hard grounding. Most keel losses occur long after the initial hard grounding. The hard grounding typically weakens the laminate in the area of the keel and the bonds between the internal framing and pans. Over time the weakened structural components allow the damage to migrate into adjacent areas of the hull until ultimately there is a failure of the hull and the keel drops away. (A good case of this is the Cynthia Woods, and the Cheeki Rafiki incidents (Google them to find the reports). Both of these boats were built to a much higher standard than a Hunter 40 with much higher engineering and quality control measures in place than most production boats, and yet both lost their keels killing crew members after an impact that sounds much lighter than the one that you are describing.

As far as the repair, I would make the repair with lead rather than cast iron since lead is much easier to rough cast to shape and then do a final fairing on, and can be gotten for almost free from a shooting range. No matter which material you use, I would drill and tap the cast iron keel and bolt the filler piece in place. You should not try to weld to the cast iron since its very difficult to reliably weld to cast iron and there will be a void left behind the weld. I would probably bed the joint in either 5200 or thickened epoxy. I would cover it and the surrounding keel area in glass and epoxy and then fair with an epoxy based fairing material. (Or as an inferior but cheaper and easier material to work with, fair with a thickened vinylester resin and apply a barrier coat.)

Jeff

olson34 12-09-2019 12:24 PM

Re: Keel Damage Repair 1986 H40 Legend
 
Some friends of ours recently completed a rebuild of portions of the interior "grid" on their Hunter 37. Big (!) insurance job, all from a hard grounding on a rock. The shock damaged the laminate mid ships and up into the shroud support on one side. Rig had to be replaced due to shock loading. There were no leaks, post grounding. But cracks were apparent.
You would be wise to pay attention to Jeff's advice.

OZWILD 12-09-2019 06:08 PM

Re: Keel Damage Repair 1986 H40 Legend
 
Thanks. Good advice.

OZWILD 12-09-2019 06:09 PM

Re: Keel Damage Repair 1986 H40 Legend
 
Thanks. I'm hoping no other damage has occurred. I've been keeping an eye out for signs and symptoms.

Minnewaska 12-10-2019 06:53 AM

Re: Keel Damage Repair 1986 H40 Legend
 
Sorry for the trouble. How did multiple squall fronts damage your keel? It reads like you completely broke off a piece of a cast iron keel. Afraid it's guaranteed there would be more transmitted damage from an impact that hard, if I'm understanding this correctly. I'd want someone to find it and identify a repair, not just monitor.

SanderO 12-10-2019 07:04 AM

Re: Keel Damage Repair 1986 H40 Legend
 
Without photos it makes no sense to propose a fix. Of course small missing bits can be replaced/filled in with epoxy fairing as Jeff noted. I suppose the question might come down to how much of the missing feel can be replaced with lighter fairing material with a negligible impact on performance. I suggest you do some math and compare the weights of the mass as iron and fairing. Consider that the dynamics of the boat are also based on how much superimposed dead load is on board.


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