Dropping Keel to Rebed ?
 

I have to drop my keel after a hard grounding this past season. The
boat is a 34 fin keel boat with a glass keel sump that the keel is
bolted to. Lead keel, S.S. bolts 1". I have a couple of question.

Having never done this before I am looking for advice, not abuse. So
Glenn if you are listening...

What bedding compound should I use?

Should I leave the seal flexible? Or could I Glass over it with a
couple of layers of biaxial cloth and epoxy?

Any other tips would be great.

Thanks,

"Basil P" wrote in message
...
I have to drop my keel after a hard grounding this past season. The
boat is a 34 fin keel boat with a glass keel sump that the keel is
bolted to. Lead keel, S.S. bolts 1". I have a couple of question.

Having never done this before I am looking for advice, not abuse. So
Glenn if you are listening...

What bedding compound should I use?

Should I leave the seal flexible? Or could I Glass over it with a
couple of layers of biaxial cloth and epoxy?

I have no experience dropping a keel other than as sidewalk supervisor
removing a fin from a Hunter. One thing I did learn was not to use 5200.
The boat was on well braced stands with a fork lift holding the keel.
Everyone thought that once the nuts were removed from the bolts it would be
a simple matter to just lower the forklift. Not So! The 5200 held the keel
firmly. After much nerve wracking wiggling they finally had to saw through
the 5200 and then spend the better part of a day scraping the joint
surfaces.

The sealant should be a little flexible. Maybe 4200 or one of the other
sealants that is not quite as tenacious as 5200. The hull/keel joint is
going to flex minutely no matter what you do so glassing over sealant is
probably not a good idea.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Glenn Ashmore wrote:

"Basil P" wrote in message
...
I have to drop my keel after a hard grounding this past season. The
boat is a 34 fin keel boat with a glass keel sump that the keel is
bolted to. Lead keel, S.S. bolts 1". I have a couple of question.

Having never done this before I am looking for advice, not abuse. So
Glenn if you are listening...

What bedding compound should I use?

Should I leave the seal flexible? Or could I Glass over it with a
couple of layers of biaxial cloth and epoxy?


----------------------

I MIGHT SUGGEST USING A FLEXIBLE EPOXY BEDDING COMPOUND AND NO CLOTH. JUST MY
HUMBLE OPINION....

PAUL OMAN

On Tue, 2 Nov 2004 12:09:54 -0500, "Glenn Ashmore"
wrote:

I have no experience dropping a keel other than as sidewalk supervisor
removing a fin from a Hunter. One thing I did learn was not to use 5200.
The boat was on well braced stands with a fork lift holding the keel.
Everyone thought that once the nuts were removed from the bolts it would be
a simple matter to just lower the forklift. Not So! The 5200 held the keel
firmly. After much nerve wracking wiggling they finally had to saw through
the 5200 and then spend the better part of a day scraping the joint
surfaces.

Hi,

Might be handy for an offshore boat, as it's not unknown for keel bolt
studs to snap at the nuts.

cheers,
Pete.

I'm with Glenn.

The only cases of keels falling off that I know of we
- Ultra go-fast boats where the designer was trying to save the last gram and
left .01% safety margin
- Old boats whose maintenance (including keel bolt inspection) had been sorely
neglected.
- cases where the wrong bolt material had been used.

Use the right bolt material and a non-permanent sealant and pull a bolt every few
years to see how they're faring.

Pete C wrote:

On Tue, 2 Nov 2004 12:09:54 -0500, "Glenn Ashmore"
wrote:

I have no experience dropping a keel other than as sidewalk supervisor
removing a fin from a Hunter. One thing I did learn was not to use 5200.
The boat was on well braced stands with a fork lift holding the keel.
Everyone thought that once the nuts were removed from the bolts it would be
a simple matter to just lower the forklift. Not So! The 5200 held the keel
firmly. After much nerve wracking wiggling they finally had to saw through
the 5200 and then spend the better part of a day scraping the joint
surfaces.

Hi,

Might be handy for an offshore boat, as it's not unknown for keel bolt
studs to snap at the nuts.

cheers,
Pete.

Fully take that story of the 5200 holding the keel up under consideration.
This is not a job you do often and once done right it may never have to be
done again.
So how long do you expect to keep this boat for? Are you sailing in an area
where hard grounding is a common occurence?
I had an 18year old Pearson once, a racy one, and it had 5200. Never leaked
a drop, nuts were never found loose, although the table wiggled a little
under
heavy loading. If you ever have to separate something with 5200 plan in
cutting right through 5200 and then sanding or even grinding it off (still
very hard to do).
When keels are installed they are not lifted into the boat, the boat sits
(is lowered) on the keel. Measure the area of the keels top flange and the
weight of the hull in pounds and square inches.
Multiply that by 150% (wiggling and flexing under load) and get a psi rating
for the bedding compound. Most silicone based sealants will not even handle
half that much fully cured.
i.e. 10000lb hull (weight - balast/keel) keel attachment area 40"x5"
average=200sq.inches. 10000lb/200sq.in = 50psi x 150% = 75psi
Will your household grade silicone goop handle that? Rememember you have
10-15 bolts that are tightened till your 1/2" 3' long wrench bends.
The compound should at least half way cure before you release the maximum
weight and tighten the keel bolts. If the bedding compound is not up to the
job it will deform, squize out and make a poor seal, while it will have
little flexibility left between keel and hull. If a big hand grabbed the
boats kill and try to shake the boat around the boat will remain attached.
If the same hand grabbed the masthead and try to wiggle the rest of the hull
off the mast, he would again fail. That is a true minimum integrity of an
ocean going boat.
Again, use 5200 for anything you have no intention of ever redoing. For
everything else use plumbers goop or what have you.
Inflatable dinghies. When they've reached the stage where they leak so much
it is not worth patching them, do your last patches with 5200 and see if it
ever leaks again.

All that said, I would use 5200 so the keel would break in half before the
seal will be jeopardized.

KoZ

? "Basil P" ?????? ??? ??????
...

I have to drop my keel after a hard grounding this past season. The
boat is a 34 fin keel boat with a glass keel sump that the keel is
bolted to. Lead keel, S.S. bolts 1". I have a couple of question.

Having never done this before I am looking for advice, not abuse. So
Glenn if you are listening...

What bedding compound should I use?

Should I leave the seal flexible? Or could I Glass over it with a
couple of layers of biaxial cloth and epoxy?

Any other tips would be great.

Thanks,

I have no experience dropping a keel other than as sidewalk supervisor
removing a fin from a Hunter. One thing I did learn was not to use 5200.
The boat was on well braced stands with a fork lift holding the keel.
Everyone thought that once the nuts were removed from the bolts it would be
a simple matter to just lower the forklift. Not So! The 5200 held the keel
firmly. After much nerve wracking wiggling they finally had to saw through
the 5200 and then spend the better part of a day scraping the joint
surfaces.

I expect that are situations where 5200 is an appropriate choice... but I have
not come across any myself in 30+ years of sailing and working on small boats.
Alexander "Ali" Meller
http://www.sailing.org/int505/

All that said, I would use 5200 so the keel would break in half before the
seal will be jeopardized.

I am sorely tempted because I laid up my own hull and built my own support
frames. 5200 would add a layer of comfort. OTOH, the strength of a
structure is limited by the weakest component. If the 5200 bond is stronger
than the glass layup or the core material a small wiggle might cause more
damage than a simple leak.

Besides 5200 has a magnetic affinity for human flesh and any bright white
surface. :-)

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Glenn Ashmore" wrote in message
news:H%Aid.60577$UA.17462@lakeread08...
All that said, I would use 5200 so the keel would break in half before
the
seal will be jeopardized.

I am sorely tempted because I laid up my own hull and built my own support
frames. 5200 would add a layer of comfort. OTOH, the strength of a
structure is limited by the weakest component. If the 5200 bond is
stronger
than the glass layup or the core material a small wiggle might cause more
damage than a simple leak.

Besides 5200 has a magnetic affinity for human flesh and any bright white
surface. :-)

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Seems to me the deciding factor would be what is the basis for the design?
And I'm not talking about loads, stresses etc. I'm more interested in if
it's designed so that it can be maintained, designed on the basis that
maintenance will not be required ( and if that's the case, is there any
point in asking the question, it's a boat ... ) , or on the basis that
maintenance is either something to be dealt with when required, or will be
someone else's problem. Sort of an informal failure mode analysis....

So if I was absolutely certain that I'd be removing the keel to check in say
5 year's time, I'd use something I could remove rather more readily than
5200. If I wasn't going to check, or had confidence in the design and
perhaps a non-destructive testing method ( x-ray or ultrasonics ?) or
thought that in 5 years ( or whatever inspection period the designer or good
practice recommends.. . ) I would no longer care ..... I'd use the damned
stuff.

And this tempered by the idea that "a small wiggle" which was not so small
would perhaps have totally unforseen consequences, and that cutting out a
5200 bond might be the least of the issues.

Of course none of this helps anyone in making a decision ......

DF

While people are on this subject..... would anyone care to give their advice
when they think a keel should be rebedded?

I have a Cal 28 with a bolted on fin keel. About 5 years ago I grounded the
boat. It was nothing serious, but over time the keel has shown more and more
signs of movement. Initially the crack between the keel and the fiberglass
stub extended back about 1 foot from the front of the keel on the port side.
The second year it was about two feet and so on. This year the crack extends
the length of the keel and I'm thinking I need to have it done now.

When I'm sailing, I live by the motto "If you THINK it's time to reef, It's
time!" I'm wondering if I should do the same for the keel. I think it's time
but wanted to know what others thought. Also, if anyone knows how much I
should expect to pay my boatyard to do the job. All reply's would be much
appreciated.

Frank


"Basil P" wrote in message
...
I have to drop my keel after a hard grounding this past season. The
boat is a 34 fin keel boat with a glass keel sump that the keel is
bolted to. Lead keel, S.S. bolts 1". I have a couple of question.

Having never done this before I am looking for advice, not abuse. So
Glenn if you are listening...

What bedding compound should I use?

Should I leave the seal flexible? Or could I Glass over it with a
couple of layers of biaxial cloth and epoxy?

Any other tips would be great.

Thanks,