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DEFENDER 12 QUESTION, NEED RECOMENDATION FOR CAULKING KEEL TO HULL


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I AM LOOKING FOR ANY RECOMENDATIONS REGARDING BEST MATERIAL TO SEAL LEAD KEEL TO HULL JOINT ON A DEFENDER 12. I HAD THE KEEL OFF AND COATED THE HULL WITH AN EPOXY BARRIER COAT.  THERE WAS SOME SILICONE CAULKING RESIDUE IN THE JOINT WHICH I REMOVED BRIOR TO PAINTING. DOES ANYONE KNOW IF SILICONE WAS USED AT FACTORY ASSEMBLY?  ALSO, SHOULD I LOOSEN AND DROP THE LEEK AN INCH OR TWO IN ORDER TO GET THE CAULK DEEPER INTO THE JOINT? 

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8 minutes ago, WOODFIELD AIRPLANE said:

I AM LOOKING FOR ANY RECOMENDATIONS REGARDING BEST MATERIAL TO SEAL LEAD KEEL TO HULL JOINT ON A DEFENDER 12. I HAD THE KEEL OFF AND COATED THE HULL WITH AN EPOXY BARRIER COAT.  THERE WAS SOME SILICONE CAULKING RESIDUE IN THE JOINT WHICH I REMOVED BRIOR TO PAINTING. DOES ANYONE KNOW IF SILICONE WAS USED AT FACTORY ASSEMBLY?  ALSO, SHOULD I LOOSEN AND DROP THE LEEK AN INCH OR TWO IN ORDER TO GET THE CAULK DEEPER INTO THE JOINT? 

5200

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1 hour ago, Dex Sawash said:

FTFY

5200 to bed the keel.  Then use a thickened epoxy like Flex-Tec or ART with a 1/2" radius plastic paddle to skreed out the keel hull joint.  Been 3 years and no crack on 5800 lb keel. The product has some flex to it (as per the name) and takes about 24 hours to dry.  It has the consistency of polyethelene when dry and can be sanded, but it's difficult.  Just do a good clean skreed and scuff and cover with antifoul.  http://www.advancedrepair.com/architectural_epoxy_flex_tec_hv_info_instructions.html  .  It's great stuff.  I use it to filet/bond most anything.  

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Defender 12?  I didn’t realize they have keels!  Oh, the boat, Defender 12!  I prefer to use Polysulfide sealant on my keel studs.  It stays flexible like bubblegum.  It doesn’t shear, it doesn’t tear.  It doesn’t tear the bottom of the boat out when you need to remove the keel in the future!  3M had 101, but it’s been discontinued for quite a while.  Life-Calk has a polysulfide sealant!  

2C9F42DC-5FB4-4C77-9CC2-EB0A6CC47EE3.jpeg

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2 hours ago, Fleetwood said:

Two general approaches, discussed in exhaustive (exhausting?) detail in a previous SA thread:

I prefer the epoxy approach.

Fleet I got a notification you quoted...came looking...

I finished that OP (which was restricted to GRP boats) to generate views;

"Can anyone "who knows what their talking about" shed some light on this subject?"

The trend towards narrower connection interface makes the subject even more important.

6 years on I remain of the view there should be ZERO movement between keel flange and the hull/structure, providing it is properly bolted and bedded. The hull/structure flexs WITH the keel, the keel DOES NOT flex independent to the hull/structure. 

This combo technigue takes that one step further and while more time consuming and costly is even a better outcome as there is a very little sealant and the above objective of keel and hull structure being one is not compromised. 

From Longy who knows his shit

A combination technique: use epoxy and fit all pieces together with a defined joint made with thin plastic sheet. This is to ensure all surfaces mate up perfectly, keel is vertical to hull etc, slop taken out of bolt holes. Backing plates checked to ensure that they are normal to the bolt. All alignments checked/adjusted. After proper cure time, Keel separated from hull than final assembly done with sealant for waterproofing.

Then ditto Leo    

Longy got it, never use goop to hide a bad joint, never use epoxy for keeping water out in a flex joint. Many people over goop :) Its only meant to be a small bufferzone between parts.

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Strangely I'm putting the keel on my 16ft boat, which is a sit in boat sailed in a similar style to the Defender 12.

I would say this.. 

It's a little 12ft boat that is going to be put in and out of the water almost every time she's sailed, very inshore /  on lakes / on rivers, she's not going out in an ocean..

She is likely to  be bounced around on a trailer regularly .. If you use Epoxy it will crack.

 It would not surprise me if the original sealant was something off the shelf and not fully marine..

 

For my boat I will be using a sealant, ... Why?

It's my design, probably the only ever one and I wouldn't be surprised to have to take the keel off and alter it.

She will get bounced around on the trailer at the start and end of a season.

We run aground regularly, when you're tacking  / racing on a river you try to use ALL the river to your best advantage and when the tides against you, you want to get in close to the bank. Sailing 6 inches from each other and the quay headings / river banks is not unusual.

 

So my method..

The hull is a glass plywood glass sandwich, with hardwood bearers where required.

The holes will be oversize, 

The threaded rod keel bolts will be greased, then taped to stop the grease touching the holes edges..

 keel top covered in sealant.

Boat dropped onto keel,

Tape removed,

Resin poured into holes to ensure a perfect it, and seal the ply edges.

BIG washers then the nuts tightened down to about 50% 

Left for several days before  excess length of keel bolts cut off, and nuts fully tightened down..

Finish rest of boat, then check bolt torque before launching..

 

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I did the same to my Defender 12.  I loosened the nuts on the keel bolts to lower the keel enough to clean the old sealant out.  I think I replaced it with Lifeseal and tightened the keel back up.  Filleted the "squeeze out".  I'm sure the last thing you'd want to do is glass the joint after.  Surely will fall out over time/flex.  Haven't sailed the boat in years, but it was watertight last time she was in the water.

226323_1025260753661_7915_n.jpg

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On 5/4/2021 at 10:38 AM, WOODFIELD AIRPLANE said:

I AM LOOKING FOR ANY RECOMENDATIONS REGARDING BEST MATERIAL TO SEAL LEAD KEEL TO HULL JOINT ON A DEFENDER 12. I HAD THE KEEL OFF AND COATED THE HULL WITH AN EPOXY BARRIER COAT.  THERE WAS SOME SILICONE CAULKING RESIDUE IN THE JOINT WHICH I REMOVED BRIOR TO PAINTING. DOES ANYONE KNOW IF SILICONE WAS USED AT FACTORY ASSEMBLY?  ALSO, SHOULD I LOOSEN AND DROP THE LEEK AN INCH OR TWO IN ORDER TO GET THE CAULK DEEPER INTO THE JOINT? 

Don’t not use a structural adhesive  to bed the keel 

use a low strength , non structural , bedding compound 

keel bolts hold your keel to the boat ... not adhesive 

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