hit a rock in the keel

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Fabian

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Sep 27, 2016
2
Hunter 320 YCU
Hi, I have a Hunter 320 and we hit a rock in the keel and it twisted one of the fins. Has anyone had to repair something like that? How do I fix it?
It is really necessary to fix it?
Thanks for the help


keel.JPG
 
jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
22,122
CAL 35 Cruiser #21 moored EVERETT WA
Does it need repair? Yes. The fin design affects the movement of water over the keel. The bent fin will effect the water movement.

How to do it? Depends on the material. Based upon it bending rather than shattering I am guessing it is metal. Metal can be bent, shaped and returned to its pre crash condition. Or it can be removed and replaced with a new piece.

To bend the fin I would guess the boat hit the rock with a lot of force. Careful inspection both inside and out is warranted to assure additional damage was not done to the boats hull and keel.

Good luck.
 
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tfox2069

tfox2069

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Apr 8, 2011
768
Hunter 40 Deale, MD
Agree with JSSAILEM above. Also, its hard to tell from the angle of the photo, but it looks like a large chunk is missing from the leading edge of the bent fin. That's probably going to need to be addressed as well. Its obviously not structural, but will definitely affect efficient hydrodynamic flow.
 
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F

Fabian

.
Sep 27, 2016
2
Hunter 320 YCU
It is of some kind of metal. And the question is: what material is exactly and what would be the correct way to fix it? Fortunately the structure of the ship was checked and it is fine.
 
rgranger

rgranger

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Jan 19, 2010
12,543
Hobie 16 & Rhodes 22 Skeeter Charleston
Is it lead?

If so, it does not take a lot of heat to soften it some. You might be able to lay it on a flat block of wood and using a heat gun (or blow torch if you are very very careful), gently warm the fin. Then I'd use a 5-lb sledge and another block of wood to gently tap the fin back into the right shape. The second block would be to prevent hammer blow imprints. Go very slow and be patient. Warm-Tap-Repeat.

As @jssailem said. You might have other damage. So you might want to drop the keel for the warm-tap-repeat operation. That would let you lay the keel out on a flat surface and inspect the hull-keel joint at the same time. Once you get the fin back in the right shape, you may find a few gouges or dings that need filling with epoxy. Then fair, paint and put it back on your boat.
 
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BrianRobin

BrianRobin

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Dec 31, 2016
319
Beneteau Oceanis 351 Charlottetown
To have a bend like that it almost has to be lead, cast iron doesn't bend. I agree with Don above, only maybe place a few wood blocks tight underneath the keel and bend slowly from the inside out :)
 
kjretlaw

kjretlaw

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Aug 3, 2010
150
Hunter 326 Charleston SC
Had the same thing happen to my keel grounding on a packed sand with high winds. I was able to bend it back by putting blocks under the unbent portion of the wing, then I warmed the lead using a small grill and charcoal. I then used a 5lb sledge and boards to hammer it back straight. Do not hammer the metal directly. Took about 30-45 minutes of low heat to soften the lead.
 
P

Project_Mayhem

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Sep 24, 2018
3,019
Catalina 30 MKIII Chicago
If it's lead I would be apprehensive to use heat as it's too easy to turn it to liquid. Lead is soft. I'd try to use a 2x4 on top and bottom of the fin and a couple of large c clamps to "sandwich" it into shape. If that doesnt work then I'd use a large hammer
 
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Justin_NSA

Justin_NSA

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Jul 7, 2004
8,450
Hunter 30T Cheney, KS
The trend in commercial aircraft has been to add winglets similar in look to that damaged keel. I wonder if the latest research in fluid dynamics wouldn't say that was a better shape. Just a thought. :huh:
 
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tfox2069

tfox2069

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Apr 8, 2011
768
Hunter 40 Deale, MD
Justin_NSA said:
The trend in commercial aircraft has been to add winglets similar in look to that damaged keel. I wonder if the latest research in fluid dynamics wouldn't say that was a better shape. Just a thought. :huh:
Click to expand
Wellllllll...yes, winglets on aircraft do help develop beneficial lift. But they're carefully designed to do so, lest a poor or "accidental" design produce a winglet that is NOT beneficial. I suppose its possible the "accidental" design produced a more beneficial keel design, but my money is on that NOT being the case - particularly since the keel wings are now asymmetrical. Though I suppose you could go back and hit the rock again with the other winglet to make them identical. I dunno. :)
 
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Apex

Apex

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Jun 19, 2013
1,209
C&C 30 Elk Rapids
go hit the same rock on the other tack, then you will have symmetric winglets.

or take your time and work it back flat.
 
RussC

RussC

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Sep 11, 2015
1,592
Merit 22- Oregon lakes
Justin_NSA said:
The trend in commercial aircraft has been to add winglets similar in look to that damaged keel. I wonder if the latest research in fluid dynamics wouldn't say that was a better shape. Just a thought. :huh:
Click to expand
I doubt if wing tip vortices are strong enough on this sailboat to gain any benefit from winglets. unless it has one of the new turbo fan outboards. :biggrin:
 
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shemandr

shemandr

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Jan 1, 2006
7,367
Slickcraft 26 Sailfish
It's got Manta Ray appeal.
If the boat is in the water I'd go out and tack back and forth. If one side isn't clearly better I'd be inclined to leave it. The fact that there doesn't seem to be damage to the hull or tabbing is probably due to the deformation of the lead which absorbed much of the energy of the collision. Another nod to lead keels.
 
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C

Capt Robbie

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Jan 24, 2017
669
Hunter 34 Toms River Nj
most hunters had steel keels instead of lead. Lead is a soft metal, I would be surprised hunter would have made a wing keel at of lead. One way to be sure is to try to drill a small hole into it. Steel is a much harder alloy then lead and is very difficult to drill. Lead on the other hand is soft and the drill bit will easily bore into it.

I would consult a black smith or metal forger and seek there recommendations.
Steel or lead loses a lot of its strength after it's been bent. I believe the metal needs to be heated to a extremely high temperature or it can break off if you ate onto bend it back.
 
jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
22,122
CAL 35 Cruiser #21 moored EVERETT WA
If it does crack and the tip comes off you can talk about it as a “keel with stubbie”. Of course you would cut some off the other side to balance the wings

Just be careful.
Don’t do it like my barber. He had finished my haircut just wanted to trim my sideburns. He did one side. Then he steps around the chair and did the other. Stepped back to admire his work.
Darn.
There not even.
So he did it again.
Rats there still not even.
Third time’s the charm.

Hell with that let see the mirror.

As I raise the mirror, he and the other barber start to snicker. April fools.

Moral don’t get your hair cut on April first.
 
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RussC

RussC

.
Sep 11, 2015
1,592
Merit 22- Oregon lakes
jssailem said:
If it does crack and the tip comes off you can talk about it as a “keel with stubbie”. Of course you would cut some off the other side to balance the wings

Just be careful.
Don’t do it like my barber. He had finished my haircut just wanted to trim my sideburns. He did one side. Then he steps around the chair and did the other. Stepped back to admire his work.
Darn.
There not even.
So he did it again.
Rats there still not even.
Third time’s the charm.

Hell with that let see the mirror.

As I raise the mirror, he and the other barber start to snicker. April fools.

Moral don’t get your hair cut on April first.
Click to expand
Thats what I tell people when they ask why I'm bald headed now.:laugh:
 
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A

artboas

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Jun 1, 2009
1,796
Hunter 49 toronto
Capt Robbie said:
most hunters had steel keels instead of lead. Lead is a soft metal, I would be surprised hunter would have made a wing keel at of lead. One way to be sure is to try to drill a small hole into it. Steel is a much harder alloy then lead and is very difficult to drill. Lead on the other hand is soft and the drill bit will easily bore into it.

I would consult a black smith or metal forger and seek there recommendations.
Steel or lead loses a lot of its strength after it's been bent. I believe the metal needs to be heated to a extremely high temperature or it can break off if you ate onto bend it back.
Click to expand
Hunter was one of the last builders to change to cast iron. My guess is the keel is lead. I’m not sure why you would drill holes to see if it’s iron versus lead, when a magnet would show the same thing?
 
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Will Gilmore

Will Gilmore

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Oct 19, 2017
7,801
O'Day 19 Littleton, NH
This is now a puzzle to figure out or is it a pool?

Who's for lead?
Who's for iron?
Who's for steel?
Aluminum?
Glass?
Other?
Maybe we can give odds for each?

I bet on steel. The wing seems too thin to be lead. I think lead that thin would bend on a soft grounding, so not the best design choice for wings. Iron doesn't bend well, but steel bends better.

Capt Robbie said:
I would consult a black smith or metal forger and seek there recommendations.
Steel or lead loses a lot of its strength after it's been bent. I believe the metal needs to be heated to a extremely high temperature or it can break off if you ate onto bend it back.
Click to expand
:plus: not sure about the "extremely high temperature" part (at least 800 degrees, is that evenly high?), but it's lost strength and will loose more from bending back unless annealed properly.

Project_Mayhem said:
I'd try to use a 2x4 on top and bottom of the fin and a couple of large c clamps to "sandwich" it into shape.
Click to expand
Maybe a heavier timber, 4x4? But that's essentially the idea I'd favor. You can even do it slowly, over days.

-Will (Dragonfly)
 
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