Stress cracks at hull to bilge (keel pocket) joint, H376.

[Diablito]

Hello sailors,
Has anyone else experienced this problem?
For lack of a better name I’ll use “keel pocket”. The H376 has a bilge that is about 2’ deep, to which the keel is bolted. The keel does not bolt to the “bottom” of the hull.
Does anyone know if the “keel pocket” is a separate lay-up which was, subsequently, fiberglassed to the hull? Or is the “keel pocket“ part of the actual hull lay-up?
My boat is full draft. 5,000 lbs of lead keel bolt to the “keel pocket” roughly 2’ below the “bottom” of the hull.
She is a California boat, originally purchased by a doctor and birthed in Dana Point. To my knowledge, including inspection when on the hard, she has never been aground.
I had her hauled, for bottom paint, etc., last week. I inspected her and found, what I suspect, are stress cracks at the “keel pocket” to hull joint, while she was in the slings.
The cracks are across the leading and trailing ends and extend for 2” to 3” along the sides of the joint. They extend,as hairlines,approximately 14” from the trailing edge Forward. The cracks at the leading and trailing edges, are a maximum of 1/32”. The cracks extending from the trailing edge, forward, along the sides of the joint are hairline. No hairlines from the leading edge toward the stern.
It’s easy to believe that the hairlines are only in the gelcoat. There are several places around “sharp” corners, above the waterline (around windows), where no fiberglas to gelcoat bond exists.
Inspection after setting her on the hard, with a 2 x 10 x 48 under the keel, the hairline cracks can’t be seen. The leading and trailing edge cracks remain obvious.
The fore and aft keel pocket to hull joint cracks are of concern.
I’ve instructed the yard, and one of their fiberglas men, to grind out the cracks (including hairlines) lay-up with the proper Fiberglas material combinations for strength, fair and blend for my inspection, before continuing with bottom paint.
I’m confident that the repairs I’ve ordered will leave “Mer-Sea Beaucoup” safe and sound. I hope this post encourages other Hunter “big boat” captains to personally inspect this hull to keel pocket joint the next time they put their boats on the hard.
Fair seas, following winds.
Tim (Diablito) Hollar

 

[Diablito]

Good morning all,
Correction of terms and good news from a local Hunter very knowledgeable person.

1. Standard keel, rather than full keel.
2. Keel sump, rather than keel pocket.

The local Hunter very knowledgeable person ic Steve Curran of California Yacht Company. Mr. Curran's knowledge of the layup process of the H376 has allayed my concerns about stress cracks. The process of layup was explained to be as follows:

1. The keel sump layup was part of the hull layup. That is, it was not an separately layed up and fiberglassed to the hull unit.
2. Because the layup was accomplished in the hull mold the leading and trailing edges of the keel sump had to be within the radii capable of being formed by the chopped strand/woven roving process.
3. This necessated addition of leading and trailing edge inserts, to the keel sump, post hull layup. The purpose being clean hydrodynamic shapes for flow around the kayak sump. Edges conisitant with the leading and trailing edges of the lead keel casting.
4. The concerning cracks are at the attach point of the edge inserts to the bottom of the hull.
5. Therefore, no structural impact.

Ahhh!!!

Photos attached.

Best Regards,

Tim

 

[Terry Cox]

Hi Tim, good information to know. A puzzle, however. Your pictures show external keel cracks around the stub joint, which may or may not be an issue. In your post you refer to keel sump cracks. Those might be a different issue. It seems though that you have given your yard instructions to clean them up, a good thing.

 

[fantasyskipper]

I also have similar cracking on my 2004 H36 deep lead keel. I have researched the settings and torqued the keel bolts as necessary (no movement on nuts) and do not have any leaking but I am concerned that this may prove problematic if and when I sell. I had the cracks ground out, fared and covered by a yard only to have them reappear as soon as the hoist lifted the boat to relaunch. I have had the boat from new and have never had a hard grounding. Thoughts would be appreciated.

 

[Jerry Clark H356 SV Persi]

It’s common and called the Hunter smile! I have never had a hard grounding - 2003 Hunter 356 - and have it too in the front. Torque your keelboats and fill. I used 5200 last time out.

 

[Terry Cox]

Had a Hunter smile back in 2004. Hauled the boat, dropped the keel, yard cleaned and fared the stub joint. Used 3M-5200 to re-bed the keel. Smile never returned. Joint still solid as a original after several thousand miles cruising PNW waters.

Trying to repair a crack like that from the outside may/may not solve the problem. Perhaps something else going on.

 

[Diablito]

Hello all and thank youfor your comments.
I ‘m afraid lacking drawings it’s a bit tough to clearly present the issue. Information directly from Hunter, now Marlow Hunter, regarding layup of the H376 is. essentially, nonexistant.
So, here goes:
1. Inside of the boat, keel sump (misnamed by me as keel pocket) extends from just aft of the compression post to just forward of the forward edge of the galley sunk cabinet. It begins (at the bottom of the insige of the hull) as an approximately 10” wide, tapering fore and aft from the center.
2. This “sump” extends for, again, approximatley 24” below the internal hull bottom to sump joint.
3. The keel bolts enter the boat at the bottom of the sump.
4. No crack, of sny sort, are present at this keel to bottom of keel sump joint. No concern about re-bedding the keel.
5. The cracks are evident, on the exterior (only) where the keel sump meets the hull (about 24” above the joint between the lead keel and the bottom of the keel sump).
6. There are no cracks internally, between the bottom of the hull and keel sump. There are no leaks, from below. From above, throught the mast step, is a different issue and easily resolved with caulking between the mast step and the deck.
7. I’m having Windward grind, glass and fair the affected areas, replace the affected strut bearing,
drop the rudder and replace teflon bushings, replace one valve, put her back together and paint the bottom. 2 coats antifouling on the bottom plus a third at the waterline.
8. I sm no longer concerned about stress cracks and I know alot more about my boat!
Cheers Captains.
Tim

 

[Terry Cox]

Hi Tim, thank you for your nice writeup. A couple of comments.

1. Likely no cracks in the keel sump because the keel stub joint on our boat (probably yours, too) is well below the sump bottom.

2. Our crack appeared at the stub joint due to over stress. Yours appear to be the same, but I'm not there. Repairing it from the outside may fix it, then again maybe not. Cracks like that normally result from striking a solid object causing the stub joint seal to fail. Hunter did a good job building their boats. We fixed our crack by what I described above, which was recommended by our yard. In our case that repair has worked out quite well.

 

[Gypsy Wind]

I was at the Hunter factory in 2011 when they were building my e36. Here are two pictures that I took of the keel area while I was there. Not sure if it will help or not. Cheers!

 

[Diablito]

Thanks to all of you!

Jerry, thanks for the pictures of your boat’s “smile”. I been told there is something else going on with the leading and trailing edges. Both are much to sharp of contours for mat and woven roving. Again, I’ve been told there are glasses in filler pieces tor the sharp entry and exit contours.
I would love to see pictures of such “fillers” being glassed in, if they truly exist!

Terry, there was no evidence of grounding on the keel. We checked it out while in the sling. The yard glassed and faired the stub joint, per my request. Pic. Below.
Additionally, inside the keel sump there is a glassed in marine plywood crossmember. This crossmember may have been a Hunter fix to issues with the first few boats. I beefed that up with mat/roving/mat/roving/mat to double the strength in that area.
No cracks on ficerglass structural crossmembers.

Gypsy Wind, many thanks for the pictures of layup of an H356. The keel sump is similar, but not the same. Layup procedures would have been identical, I believe, but the keel sump is much deeper on the H376. There is also a rectangular configuration, part of the hull but below the “bottom”, to which the keel sump is glassed. I’ll take a picture next week, when she is back in her slip.

Once again, many thanks to all of you.

Tim

 

[Diablito]

Hello again captains,

I just had an “aha moment”, or a jeez Tim, really, how dumb are you?

Okay, pictures will show my point, but, the keel sump is surrounded by the hull liner, which is, of course, glassed in. The liner includes all of the nooks and crannies where through hulls reside, storage places below the sole and structural ribs. The “rectangular configuration”, referred to earlier is part of the liner, which is, again, glassed to the hull. See the pics, you’ll see what I mean.

Next, the mat/roving/mat/roving/mat job on the plywood crossmember in the keel sump. Again, pictures.

Lastly, pictures of the depth of the keel sump and the 4” or 5” radii at the leading and trailing edges. These pics make it clear that there is some sort of a fiberglass structure that accounts for those sharp edges seen in the exterior pics.

They’ll splash her Wednesday. They’ll paint the underside of the keel when she’s in the slings. They’ll let her hang for a day and night so the paint can dry.

Next project, a Tides Marine Sail Track. Mer-Sea Beaucoup is 22 years old and the track in the mast extrusion is just about done. The sail is herky-jerky going up and about the top 20’ of the sail has to be dragged down.

I've used SailCote, with reasonable success. But now is the time to do it properly.

All the best to all of you.

Tim