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Cptnsiroco

Cracked bulkhead

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We found a reef off the coast of Wisconsin and noticed a crack in the bulkhead that is closest to the mast. The crack is on the radius where the bulkhead goes from vertical to horizontal near the floor. The crack is about 1.5 inches long and at its widest point about 1/8 inch wide. I would like some ideas on how I could draw the crack back closed and then repair.

 

Bill

 

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Pictures? Boat type? More info needed.....

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Perhaps that b'hd is also closest to the keel? Still in the water? Is there a chance that the weight of the keel is pulling crack open? May want to haul and survey as mentioned prior to tabbing crack.

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The crack in itself is probably nothing to worry about. However, it is an indiaction that forces has been in action, resulting in some bending (otherwise no crack).

As Charlie said, careful inspection. Very careful. Look on the area around the bulkhead, both inside and outside. Sometimes very fine spidercracks has developed in the gelcoat - typical sign of bending, cracks develops as gelcoat has no glassfibre reinfocement -it is just a thick paint. Small, onetime cracks are often not serious, but should be treated - below waterline with epoxi, obove with some new gelcoat.

 

You want to mend the crack? Why? Looks? - hide it. Strength? - if it is close to a corner in the bulkhead, then it doesn't matter (disclaimer: difficult to know 1with this limited info given)

 

/J

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Yes, it right at the bottom bend where it goes from vertical to Horizontal. Why do you say no big deal if it needs to be carefully inspected? I would like to draw it back together, (i.e.original post), to repair / strengthen it. Checking for other less conspicuous damage is good advise.

 

Bill

 

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If I had a bulkhead that had cracked during a grounding, I'd cut it out and replace it - no if's, and's or but's.

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I doubt you need to replace the whole bulkhead - but as others have said careful inspection (and tap sounding) of associated bunk fronts, stringers, keel floors, etc is certainly worthwhile.

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If the crack is on the inside radius of rhe bulkhead you pull it closed with shroud tension, keep cranking till it closes up!

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Boat manufacturer and model is critical missing information. Fin keel or shoal. Liner or stick built? Tabbed in bulkheads or not? Chain plates to knees or bulkhead?

 

It's either cosmetic or fatal. Without critical information we can only guess.

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If you hit that hard, check the hull and floors at the aft end of where the keel meets the hull, especially if it is deep fin.

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If you hit that hard, check the hull and floors at the aft end of where the keel meets the hull, especially if it is deep fin.

Pull those cracks together by backing down really fast on the same rock.

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PICTURES!! Both wide angle of whole area and closeups. Otherwise we're just guessing.

 

And +1 to checking any transverse floors at the back of the fin. If you hit a rock with a keel the top front of the keel pulls down and top aft pushes up into the hull. Very common to find more damage aft.

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Yes, it right at the bottom bend where it goes from vertical to Horizontal. Why do you say no big deal if it needs to be carefully inspected? I would like to draw it back together, (i.e.original post), to repair / strengthen it. Checking for other less conspicuous damage is good advise.

 

Bill

Sorry, other things in between.

In the point / area where it goes from vertical to horizontal, there should not be much force. Many boatbuilders doesn't fasten the bulkhead in that area on purpose - the hull should be able to flex, around a corner it is easy to get point stress.

That is why the crack in itself is no big deal.

 

From this,

- it is probably difficult to draw it back again. As it is not coming back by itself, there is probably some stress in the area, from when the boat was built.

- do not make it stronger ... if you really want to do this, you have to be extremely careful. Making it stronger in one point would change the stress balance. What you have now may be an improvement from stress point of veiw.

 

The careful inspection should be in all places where the hull could have been distorted. Other ersponses have covered some of this. Sometimes one is suprices how a grounding has affected areas far from the point of impact.

 

Did I say one should inspect inside and outside? Remove some of the paint, aft of the keel and really inspect. As well as propellor shaft installation (when grounding, usually the engine moves around a bit - usually possible to see in spider cracks around the engine. )

 

/J

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The boat type, construction, and photos are really needed to provide any meaningful advice. You say the bulkhead goes from vertical to horizontal near the 'floor'. Is it joined to the sole (as in the cabin) or the hull (maybe in a forepeak compartment)? If it is joined to the hull, the fact there is a crack means that the hull experienced stress beyond the design loads. We don't know if the bulkhead is structural or not. If the bulkhead is glassed onto the hull then it is probable the boat builder went to the time and expense of laying up composite, which means that the bulkhead is likely structural. In some boats the chain plates are attached to forward structural bulkheads, which adds a whole other dimension of stress and loads. If you have a composite failure in a location that is intended to support structural loads the completed repair should be able to withstand loads equal to or exceeding the original design. Adhesives or filler in this area will not provide that strength. The crack must be widened or cut out and repaired - the method all depends upon the original construction methods of which we know nothing from the info provided.

 

The larger concern, since the grounding resulted in loads exceeding the design, is what unseen damage there may be. Subsurface delaminations will not be visible but 'may' be found with a thorough inspection of other structural members. Deformed keel bolts may only be apparent after removing the nuts. Was the rudder involved? Any failure in a structural component should be a cause for concern. Stress cracks around your stanchion - not so much, but a failure at the joint of a structural bulkhead and the hull - you betcha.

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Fosh, you make some good points. The pictures are not available at this point and they will only show 1/8 X 1.5" long crack near one of the corners. The bulkhead is the one in the center of the boat near the mast and the chain plates are tied into it, so it is structural. I am not sure what the bulkhead is made of, it is a laminate and I think it is balsa core like the hull and deck. It looks like the bulkhead is one piece from across the top around the sides and across the bottom of the boat. The keel is attached to a aluminum grid which is tied to the hull. As you can read there are varying answers to my question, my sense tells me that my initial question and my initial concern is founded in your remarks.

 

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Banged a hard one years ago. Lifted the boat immediately and transported it to a yard. Surveyor went thru it and scheduled the repairs. Yard performed the work and insurance minus deductible , covered it. All is good? No,The following spring the commissioning revealed faults in the repair and faults in the survey. Yard replies " bring it up in July, "We'll take care of it"! !/2 a racing season gone in July! We slaved over the issues we found and thought we had it. Two owners later sent pictures recently the work he's doing to fix up what a surveyor (and I) missed. Get a yard you don't like and a surveyor you don't know!

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I got on the boat today, it looks like the crack has closed about 50%. It is now about 1/16 th wide at the widest point and still 1.5 inches long. The rig is out and it is out of the water resting on it's keel so most of the load is off the bulkhead. I think I will fill it and reinforce it with carbon tape, then paint to match.

Thanks for your comments.

Bill

.

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ok, but...

 

Is the boat carbon? If not, do not use it. Carbon is so much stiffer than glass that it will take all the load and unless you use enough carbon to take all the load, then it will break. An analogy is string and a rubber band tied in parallel and pulled, the string (carbon) takes all the load, the rubber band (fibreglass) nothing. Just use glass on glass, one of the few "cheaper and better" scenarios in boat repair.

How does the rest of the framing look, any cracks?

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Thanks, I have not been able to check everything thourghly yet, but I will. My overall look is that that is the only sign of stress. Good point on the carbon. My first thought was to reinforce it with carbon what you say makes sense.

Bill

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I got on the boat today, it looks like the crack has closed about 50%. It is now about 1/16 th wide at the widest point and still 1.5 inches long. The rig is out and it is out of the water resting on it's keel so most of the load is off the bulkhead. I think I will fill it and reinforce it with carbon tape, then paint to match.

Thanks for your comments.

Bill

.

It wouldn't occur to you that taking the rig out and cradling the hull has set all the loose and wobbly bits back in line?

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You should fill the interior with #8 rebar and pour 5000 lbs concrete in it. The only way to make sure.

 

OR you could post a photo or two so that you can have an intelligent advice and not a bunch of conjecture.

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