Bet You Didn't Know This About Hunters! - SailNet Community
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post #1 of 43 Old 09-02-2014 Thread Starter
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Bet You Didn't Know This About Hunters!

My wife and I are the happy owners of a 2000 Hunter 340. Boat surveyed almost flawlessly a year ago. Had a good season, saw a little rough weather on the Chesapeake and spent the winter in the water. Come the spring, we noticed water kept appearing in the bilge. We'd dry it out, it would come back.

Over a couple months, we progressively eliminated sources until we finally began to realize the water was coming from the #4 and #5 aft most keel bolts. Out of an abundance of caution, we hauled the boat, brought the surveyor out and revealed that we likely had a crack in the keel bedding that was letting water in via the keel joint. Recommended repairs was to expose the joint and fill it. Most yards stated the only sure way to repair such an issue was to drop and rebed the keel.

After much hand-wringing, the need for safety won out. We contracted for a yard in Annapolis to do the work and got the boat in the keel stand. They pulled the keel nuts and backing plates and we saw water in the tunnels. That cinched it.

Hunter owners out there, do you ever wonder why you rarely hear about issues with Hunter keels?

Here's the reason:

Bet You Didn't Know This About Hunters!-100_1102.jpg

That's air. Air from the gap from the saw required to cut away the keel joint to drop the keel. Air across 90% of the joint save for the first 3 keel bolt holes. That is all that is holding 4600+ pounds of lead in the air still attached to the boat.

All courtesy of Hunter's preferred bedding compound for keels: Epoxy.

I learned a lot that day. The main thing being that Hunters don't have keel issues because the bond is so strong it takes a very hard grounding to damage them. Even the factory was surprised to hear a 340 was getting the keel done.

For some reason, lots of builders are putting keels on with epoxy nowadays. It makes sense from a maintenance standpoint. Trouble-free when it works and beyond incredibly strong. The keel bolts are an afterthought. You don't need them. I have 5 keel bolts, 4 of them 1 1/4" monsters and in an epoxy joint, they are superfluous. All five nuts were off and the keel was hanging on the boat from three plugs of epoxy that had formed around the forward 3 keel bolt studs.

But epoxy creates stiffness along a joint of dissimilar materials that can and does flex. Hence why you're supposed to bed with something flexible to allow for that motion. As long as it holds up it will be fine.

But, as my experience shows, once a little fatigue happens or the joint flexes beyond the tensile strength of the epoxy, it doesn't bend; it cracks. That's what we think happened in our boat. That probably combined with a day at the factory where not enough epoxy was put on the day my keel was bedded on.

And when you need to fix it, here's where you wind up:

Bet You Didn't Know This About Hunters!-100_1110.jpg

Enjoy that view (or cringe in horror) and see what happens when epoxy as a joint compound fails you.

The end result, though, was a keel rebed that was better than new. The keel stub was repaired to perfection, the keel was rebedded with 3M 4200 and allowed the keel bolts to be actual bolts to hold the keel on and faired so beautifully you can't find the joint even if you knew where to look.

Hunter has apparently been doing this forever. And with few problems to their credit. Until you have one like mine. And so are a lot of other makers which leads me to wonder where they will be once sailing stresses take their toll on what is a butt joint to the bottom of their hulls rather than against a dedicated sump like on my boat.

But feel free to share this little tidbit with friends and fellow surveyors. Even our surveyor never knew this about Hunters.

I have plenty of pictures of this experience if anyone is curious about the process of dropping an epoxy bedded keel and putting it back on. The end result for us is peace of mind.

Matt

SV South Paw
2000 Hunter 340
South River, MD
Star #6100
Annapolis, MD

Last edited by mpickering; 09-02-2014 at 10:30 PM.
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post #2 of 43 Old 09-02-2014
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Re: Bet You Didn't Know This About Hunters!

Well, I guess keel bolts have now joined depth sounders in the growing list of stuff there's no reason to have any more...

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post #3 of 43 Old 09-03-2014
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Re: Bet You Didn't Know This About Hunters!

So why did you use 3M 4200 instead of 3M 5200 for re-bedding the keel?
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post #4 of 43 Old 09-03-2014
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Re: Bet You Didn't Know This About Hunters!

Many builders use an epoxy based keel putty with an elastomeric around the bolts. Hunter is not unique in this regard. Catalina & Sabre are two that spring to mind....

Course the keel sump & stub, while thick, is often very poorly wetted out so when the keel does need to be dropped there may be a lot of repair work re-laminating the lack of factory wet out..



And then there is always the possibility you lose the entire sump..





The strength of the keel bolts or keel to sump/stub epoxy is irrelevant if the hull can't hold onto the sump...

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post #5 of 43 Old 09-03-2014
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Re: Bet You Didn't Know This About Hunters!

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Originally Posted by Maine Sail View Post
Many builders use an epoxy based keel putty with an elastomeric around the bolts. Hunter is not unique in this regard. Catalina & Sabre are two that spring to mind....

Course the keel sump & stub, while thick, is often very poorly wetted out so when the keel does need to be dropped there may be a lot of repair work re-laminating the lack of factory wet out..



And then there is always the possibility you lose the entire sump..





The strength of the keel bolts or keel to sump/stub epoxy is irrelevant if the hull can't hold onto the sump...
Is that the super shallow draft version? I hear that is an expensive option!

To me it does seem to be strong, but only if there are no air gaps. But of course it is not exactly making for easy maintenance. Seems to me to be a more of a budget cutting measure as I am sure the epoxy that they buy by the tanker full is cheaper than 3M 5200, but is not made for any kind of repairs or maintenance. Kind of like the new "sealed for life" transmissions. Sure fine for the first owner, but not so much so for the second who has to have it rebuilt because they made it so you could not have the fluid changed as part of the scheduled maintenance.
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post #6 of 43 Old 09-03-2014 Thread Starter
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Re: Bet You Didn't Know This About Hunters!

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Originally Posted by Maine Sail View Post
Many builders use an epoxy based keel putty with an elastomeric around the bolts. Hunter is not unique in this regard. Catalina & Sabre are two that spring to mind....

Course the keel sump & stub, while thick, is often very poorly wetted out so when the keel does need to be dropped there may be a lot of repair work re-laminating the lack of factory wet out..

The strength of the keel bolts or keel to sump/stub epoxy is irrelevant if the hull can't hold onto the sump...
Can't do much with bad engineering or a thin layup. O'Day 30s are another boat with a thin layup at the sump.

Here's my sump:

Bet You Didn't Know This About Hunters!-100_1115.jpg
Bet You Didn't Know This About Hunters!-100_1124.jpg
Bet You Didn't Know This About Hunters!-100_1125.jpg

The holes are the #2 and #3 bolt holes and the hardened epoxy that flowed into them and had to be drilled out is clearly visible. The layup here is a shade over 1 1/2" thick. The layup color is very consistent throughout which tells me they did a good job at wetting it out.

The hacked up stub from the saw work was rebuilt with a bed of epoxy to create a perfect mating surface for the keel. The keel was put back on with the weight of the boat on it and allowed to cure to make sure there were absolutely no gaps. Then the boat was lifted off and the keel was then rebedded and reattached to the hull.

Bet You Didn't Know This About Hunters!-100_1128.jpg
Bet You Didn't Know This About Hunters!-100_1132.jpg

If the sump was weak, there'd be evidence of it by now due to the original bond flexing the sump laminate. What little I've found about H340s and their keels indicate the joint is quite strong. I've only found one other report of a keel drop on an H340 and it was a boat in Maine that went hard aground. Sliced the front of the bulb off. The joint didn't crack or open up. They dropped the keel (alas, didn't report the bonding material in the details), recast the lost lead and put it back on.

I'm not terribly worried about the thickness of my sump as the surveyor nor the folks I contracted for the work expressed any issues or concerns. Just the opposite. They were cursing the toughness of the boat in getting this work done.

Matt

SV South Paw
2000 Hunter 340
South River, MD
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Annapolis, MD
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Re: Bet You Didn't Know This About Hunters!

So, in all this, I'm still wondering what caused the damage in the first place. If it was cracked and leaking toward the aft end of the keel - that sounds like a pretty good grounding.


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Re: Bet You Didn't Know This About Hunters!

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So, in all this, I'm still wondering what caused the damage in the first place. If it was cracked and leaking toward the aft end of the keel - that sounds like a pretty good grounding.
We exposed the joint and it appeared to be a hairline crack towards the aft on the port side. Barely visible. There is no evidence of the boat ever having gone aground, we've never been aground since we bought it and the boat has spent its entire life on the Chesapeake Bay. Not impossible to ground and do damage but one of the safest places in the world to do it.

I've seen keels with grounding damage. No scrapes, no dents, no chunks removed, nothing on ours. Only evidence of an issue on the keel was the cracking fairing compound and that is a common problem on externally ballasted boats. Inspection found no evidence of any keel damage at all.

Our best speculation is given the thinness of the keel profile at the aft is more prone to flex and there isn't a lot of surface area there to bond to. And after putting the keel back on the long keel studs made it hard to get good torque on the nuts. Probably a combination of the long bolts, thin keel and perhaps a light amount of epoxy contributed. We sailed the boat in heavy conditions during a day race and we think that it started the crack to open just enough as the keel flexed in 30 knots of wind and short 4-6 foot chop.

The amount of water was negligible. Perhaps a paper towel's worth a day after we splashed following our two weeks on the hard for inspection. I checked the boat twice a day for the six weeks leading up to the repair date. Even the surveyor said it was a long term problem and recommended against repair unless we planned to keep the boat a long time (more than 5 years). Just live with it, sell it and make it someone else's problem.

This we obvious did not do. There was no corrosion on the studs and virtually no delamination in the glass in rearmost stud tunnels. So we caught it very early before it had a chance to damage the studs or wreck the rear sump laminate. Crevice corrosion on the bottom of the #4 backing plate but that is not uncommon given the shape of the sump in this area.

As I said, speculation at best. Since the repair, the boat is back to being bone dry in the bilge.

Matt

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South River, MD
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Re: Bet You Didn't Know This About Hunters!

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So why did you use 3M 4200 instead of 3M 5200 for re-bedding the keel?
On the advice of people far more experienced that I. We considered 5200 but there is ever another problem with the keel, getting it off is as bad, if not worse, than an epoxy bed. 5200 gives the flex but is still a cast-iron bastard to get off if something goes wrong.

Since the bolts are there to provide the mechanical attachment to the boat and the bolts on the 340 are 4 1 1/4" and 1 1", they had plenty of strength. 3M 4200 is an adhesive and is still insanely strong.

So we accepted it as a compromise to retain a lot of the original bond, allow the keel to flex like it is supposed to and make it actually possible to drop the keel in the event damage is done. And not at the cost of two solid days in the slings and damage to the keel stub in getting it off. 4200 will actually separate.

They were recommending a straight bedding compound like they do on race boats. 4200 was the middle ground from a 5200/epoxy bed.

Matt
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post #10 of 43 Old 09-04-2014
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Re: Bet You Didn't Know This About Hunters!

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On the advice of people far more experienced that I. We considered 5200 but there is ever another problem with the keel, getting it off is as bad, if not worse, than an epoxy bed... 3M 4200 is an adhesive and is still insanely strong... 4200 was the middle ground from a 5200/epoxy bed.

Matt
You really need to do some more research Matt. You are throwing statements around that are not correct. You should not rely on the yard "experts", who may not know any better than you do. In addition, the yard experts may not have your best interests in mind. Some yards do things to generate continuing business for themselves.

You are equating 5200 with epoxy, which is an erroneous comparison. The tensile strength of epoxy is more than 10 times stronger than the tensile strength 3M 5200.

The tensile strength of 5200 is 705 p.s.i. http://multimedia.3m.com/mws/mediawe...ant%205200.pdf(twice the strength of 4200).

The tensile strength of epoxy resin is 10,500 p.s.i. (aeromarine plastics brand http://www.aeromarineproducts.com/pa.../30021-tds.pdf)

3M 4200 is designed to cure faster, at a loss of some strength compared to 3M 5200. There is no difference in flexibility with 3M 5200.

A keel should not be bedded with epoxy, period. 3M 5200 would be the correct adhesive for bedding the keel and would allow the keel to drop after the bolts are loosened.
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Last edited by jameswilson29; 09-04-2014 at 10:48 AM.
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