Keel Doesn't Quite Match Hull - Cherubini H36

[rardiH36]

Just wondering if any other Cherubini H36 owners (or other Hunter Cherubini owners of the +/- 1980 era) have noticed the same as my boat.

That is the keel doesn't quite line up in size with the hull stub -- as in the attached pictures.

In the pictures, while it may look like there is a camouflaged gap between the hull and the keel, this is not the case. The appearance is only from shadows of fairing with life-caulk. At the haul-out during which the pictures were taken, I checked the actual mating surface of keel to hull. Spot on. No "smile" or gap what-so-ever.

I've owned my 1980 constructed boat now for seven years. I did DIY work on the hard for the first 5-6 months of ownership and certainly noticed the misalignment at that time. And I have since hauled twice. Never have I found evidence of new FRP layup or cracking that would indicate a possible hard grounding which required a change of the original keel. The keel bolts and nuts and bilge are in great condition with absolutely no leakage of seawater into the bilge. Certainly the keel bolts match up with the original holes drilled into the bilge base. There is no indication of other previous alignments.

My thought is that Hunter at the time of manufacture might have miscalculated the actual keel dimensions vis-a-vis the keel stub shape for the H36. Or maybe took a short-cut and installed a H33 keel?

Any other conjectures?

 

[ggrizzard]

My 80 H 30 C 's lead keel didn't match the stub exactly either. I fared the seam and chalked it up to the vagarities of suppliers and costs of rejection on Hunter's part...
Lead is heavy!

 

[Benny17441]

That is close enough. Not a precision instrument.

 

[rardiH36]

thanks the input. just wondering since during all my various yard crawls, i don't think i ever noticed keels that didn't line up perfectly with the mating surface of the keel stub.

 

[rufus1138]

that is odd, ill have to try and remember to post some pics when i haul out, ill try and take some dimensions too so you can compare and see if yours measures the same as my 33, if you wanted to get rid of the seam you could lay glass up there and fair it out so that the hull flows better to the keel body??

 

[rardiH36]

that is odd, ill have to try and remember to post some pics when i haul out, ill try and take some dimensions too so you can compare and see if yours measures the same as my 33, if you wanted to get rid of the seam you could lay glass up there and fair it out so that the hull flows better to the keel body??

Thanks for the input. No not important enough to try and glass over. Would be a lot of work for .1 kt. And who knows what problems might arise in the future when my DIY fairing job starts peeling away! I didn't take measurements of my keel. So no need to remember to measure yours. I couldn't make the comparison!

 

[DianaOfBurlington]

What Grizzard says is very true. Judging from your photo I'd say the boat was misaligned on the keel from the start-- looks like they set it a little too far forward on top of the lead when they drilled the mounting-bolt holes.

I faired mine like crazy using milled fibers, Microlight and various other glop (basically anything I had left over when I was working on other boats in the yard). This tends to be a mistake as there is always a crack developing here. The dissimilar materials, coupled with the usual flexing of all fiberglass boats, means any hard-and-fast expectations of fairing compound here are futile. It WILL open up. Just use something flexible and neaten it as well as you can.

I have used 5200 and a putty knife to good effect in this application and elsewhere.

 

[RTB]

Rardi,

Sorry, no photos that would be helpful to offer you, but our keel matches up on my 1982.

Ralph
http://www.sailblogs.com/member/brogdon/

 

[rardiH36]

Rardi,

Sorry, no photos that would be helpful to offer you, but our keel matches up on my 1982.

Ralph
http://www.sailblogs.com/member/brogdon/

Hi Ralph:

Probably doesn't really have any logical bearing on the particulars, but what is your Hull number? Mine is #36 so quite early in the manufacturing run = Hunter still on a learning curve?. On the other hand, I think that only a couple of hundred 80-82 Cherubini 36's were made.

 

[RTB]

My HIN:HUN36115M82D

Ralph

 

[rardiH36]

What Grizzard says is very true. Judging from your photo I'd say the boat was misaligned on the keel from the start-- looks like they set it a little too far forward on top of the lead when they drilled the mounting-bolt holes....

John:

Thanks for jumping in on this. When I bought my boat, the hull too far forward (or the keel to far aft) on the keel stub was the main thought as well.

But with your comments, got me visualizing some more. And began to realize that if this was the case, at the point where the lead keel is the widest, and if the mounting is a bit too far back, wouldn't the widest point (of the keel profile) then be a bit wider than the matching location of the keel stub .... since the stub would be narrowing towards the stern direction? The second picture of my opening post shows the keel also too narrow along the hub width. More so than might be expected for the keel mounted only 1.5" or so too far back? The keel matches the stub on the aft end, so mounting the keel too far aft would imply that Hunter ground some lead off back there.

I'm getting more convinced I've got a mistake keel -- or my keel manufacturer botched the measurements.

Maybe I'm sailing with a few hundred pounds too light down there! And the weight balance is farther aft than it should be! Oh well, the boat does fine in any event.

Next time I haul, I should measure from the waterline mark to the keel bottom. Compare that to the 4'11" draft in the specifications.

I am posting more as a curiosity than needing to do anything about it.

 

[Alctel]

I am having trouble remembering but I'm pretty sure mine matched (1980)

 

[H33CRich]

I had the same problem. I faired it this spring with a 2 part epoxy fairing compound. I am curious about the weight and it's distribution lengthwise.

 

[rardiH36]

Possibly 690 lbs of Lead Too Light

... I am curious about the weight and it's distribution lengthwise.

The other day I did do a back of the envelope calculation of possible reduced weight of my keel due to dimensions being smaller than the stub face. This morning I attempted to do a little better. Still a very rough estimate though.

I have come up with about 690 lbs which is about 11% short of the specified 6000lb "ballast weight" for the Cherubini Hunter 36. Whether I've got a 6000 lb keel or a 5300 lb one, the difference most certainly would affect performance better or worse.

Looking at the photo's (included with my opening post), looks like the keel is 1/2" too narrow on each side on the forward strike of the joint. But from memory, the keel width does pretty much match up with the stub on the aft end. So let's say the 1/2" only applies to 50 percent of the length. Counting both sides equals 1". So for the average length, the keel averages 1/2" too narrow. Also I assume that applies right down to the bottom. From Hunter's drawings, I scale estimated that the side area of my keel is 22 ft. Per the internet, weight of 1/2" lead sheet is 28.8 lbs per square foot. So about 630 lbs light for being too narrow.

Then there's the missing volume on the leading edge of the keel. 1.5" missing say x 2 " x 4.5 feet length calculates to another 60 lbs.

So total possible shortage of lead weight on my keel is 690 lbs!

Bolting on a six inch thick slab of lead 3 ft long to the bottom of my keel would add back about 400 lbs of the missing weight. Not quite as much as the missing 690, but all of the 400 being at the bottom of the keel would add a lot to the stiffness of the boat against heeling.

Not that I plan to do it, but is it possible to add new lead without too much fuss to a bottom of a flat bottomed keel?

 

[rufus1138]

i would take this to sailing anarchy, some good naval architects there.

 

[rardiH36]

I am having trouble remembering but I'm pretty sure mine matched (1980)

Hi Alctel:

Thanks your response.

Something triggered in my visual memory that you might have posted pictures of your boat's bottom. Yes! A quick search yielded your thread about a crack at the keel joint: http://forums.hunter.sailboatowners.com/showthread.php?p=1103950&highlight=

Looking at the pictures, while the joint certainly looks to have been faired, I also noticed that the forward leading edge of your keel is essentially a straight line from the keel bottom to the hull joint. If the keel had been set back on the hull the same 1.5" as mine, while I see a bit of a (fairing) bulge in your picture, I would think it would be more noticeable (or even concave) at the the hull/keel joint section. Also in you picture, it appears that a small chunk of the fairing compound broke loose, showing the lead underneath looks to be positioned quite a bit more forward than on my boat.

 

[Alctel]

Hi Alctel:

Thanks your response.

Something triggered in my visual memory that you might have posted pictures of your boat's bottom. Yes! A quick search yielded your thread about a crack at the keel joint: http://forums.hunter.sailboatowners.com/showthread.php?p=1103950&highlight=

Looking at the pictures, while the joint certainly looks to have been faired, I also noticed that the forward leading edge of your keel is essentially a straight line from the keel bottom to the hull joint. If the keel had been set back on the hull the same 1.5" as mine, while I see a bit of a (fairing) bulge in your picture, I would think it would be more noticeable (or even concave) at the the hull/keel joint section. Also in you picture, it appears that a small chunk of the fairing compound broke loose, showing the lead underneath looks to be positioned quite a bit more forward than on my boat.

Good memory!

I just compared the two pictures and my keel is definitely a lot more forward than yours.

 

[rardiH36]

i would take this to sailing anarchy, some good naval architects there.

Good suggestion. Will probably do. But might take me a while.

 

[RTB]

I forgot about this thread, or I would have taken some close up photos....

There is a good bit of fairing compound on the keel/stub joint. Some was chipping off, so we did some filling at the joint. As you might see, the keel does line up on my boat though.





Ralph
http://www.sailblogs.com/member/brogdon/

 

[Blaise]

Midnight Sun's keel was so off one side to the other that it took seven gallons of epoxy to fair it to match. Not wanting to throw stones at anybody over what has been a fabulous boat, I will say I believe the problem was with the supplier that cast the keels. They just did a crappy job.