toad
Well-Known Member
Without lots more information and seeing the problem we are all taking guesses, this is the time to consult a surveyor.
the keel moved up and down in the shipyard
- Thread starter eranb2
- Start date
Twister_Ken
Well-Known Member
Jenny Sunlight 30 if you read the OP.
arth_tumbleweed
Member
[ QUOTE ]
According to our local boatyard all modern (lightly built) yachts do this. Maybe worthwhile getting a shipwright/surveyor to check that nothing unusual is happening.
[/ QUOTE ]
Seen it in a local yard where new boats have not only had the keel rise into the hull, but the pads from the cradle make the hull flex quite a bit. As far as I know none have sunk ofr beed damaged from it so you should be ok, but defo take advice from a surveyor and/or a boatbuilder
According to our local boatyard all modern (lightly built) yachts do this. Maybe worthwhile getting a shipwright/surveyor to check that nothing unusual is happening.
[/ QUOTE ]
Seen it in a local yard where new boats have not only had the keel rise into the hull, but the pads from the cradle make the hull flex quite a bit. As far as I know none have sunk ofr beed damaged from it so you should be ok, but defo take advice from a surveyor and/or a boatbuilder
eranb2
Well-Known Member
the boat model is " sun light 30"
jeanneau year 1987 .
jeanneau year 1987 .
thalassa
Well-Known Member
Re: is it ok to put the hull on the keel without any support?
[ QUOTE ]
The Hulls do flex when out, I always had to remember to open the heads door on my Dufour before lift out as once stood on the keel I couldn't get the door open again.
[/ QUOTE ]
My experience with the Dufour as well. When lifting out on the slipway, the hull would flex in by 5 cm or so if she was not sitting perfectly on the pads. Once, one pad cracked the inner shell round the battery box! If I remember well, the manual said "after a while, a crack will appear between the hull and the keel, this is normal" .
[ QUOTE ]
The Hulls do flex when out, I always had to remember to open the heads door on my Dufour before lift out as once stood on the keel I couldn't get the door open again.
[/ QUOTE ]
My experience with the Dufour as well. When lifting out on the slipway, the hull would flex in by 5 cm or so if she was not sitting perfectly on the pads. Once, one pad cracked the inner shell round the battery box! If I remember well, the manual said "after a while, a crack will appear between the hull and the keel, this is normal" .
brianhumber
Well-Known Member
Nobody can say via email it requires onsite inspection and assessment. As it is a production boat talk to the builders/designers as welland if you are not sure get surveyor advice.
ps All structures flex be they skyscrapers, VLCCs or yachts. Ships can flex several metres and my present yacht ( 1987) hull shape changes shape to her hull, deck and rig when lifted and again alters when sitting on her keel and rudders. She also moves when hit by a big sea.
Brian
ps All structures flex be they skyscrapers, VLCCs or yachts. Ships can flex several metres and my present yacht ( 1987) hull shape changes shape to her hull, deck and rig when lifted and again alters when sitting on her keel and rudders. She also moves when hit by a big sea.
Brian
Will
Well-Known Member
Re: is it ok to put the hull on the keel without any support?
My experience with the Dufour as well. When lifting out on the slipway, the hull would flex in by 5 cm or so if she was not sitting perfectly on the pads. Once, one pad cracked the inner shell round the battery box! If I remember well, the manual said "after a while, a crack will appear between the hull and the keel, this is normal" .
[/ QUOTE ]
It is normal practice to ensure that the weight of the boat is taken by the keel, and the pads are merely providing support to stop the thing falling over. However, the pads of either the cradle or boatmover should always be in the area of a bulkhead and therefore the hull should never flex - if it does, it will almost inevitably cause stress cracking and/or internal damage to floors/stringers and in your case your battery box.
Secondly, it is not at all uncommon for a keel to flex as the weight is lowered onto it. It isn't a good thing, but it isn't out of the norm either for particular boats. If it does cause damage, this is usually quite evident both visually and from the horrible splintering noises (these tend to sound worse than they actually are with GRP) but as others have said, it is worth checking the seating of the keelbolts.
My experience with the Dufour as well. When lifting out on the slipway, the hull would flex in by 5 cm or so if she was not sitting perfectly on the pads. Once, one pad cracked the inner shell round the battery box! If I remember well, the manual said "after a while, a crack will appear between the hull and the keel, this is normal" .
[/ QUOTE ]
It is normal practice to ensure that the weight of the boat is taken by the keel, and the pads are merely providing support to stop the thing falling over. However, the pads of either the cradle or boatmover should always be in the area of a bulkhead and therefore the hull should never flex - if it does, it will almost inevitably cause stress cracking and/or internal damage to floors/stringers and in your case your battery box.
Secondly, it is not at all uncommon for a keel to flex as the weight is lowered onto it. It isn't a good thing, but it isn't out of the norm either for particular boats. If it does cause damage, this is usually quite evident both visually and from the horrible splintering noises (these tend to sound worse than they actually are with GRP) but as others have said, it is worth checking the seating of the keelbolts.
wotayottie
Well-Known Member
[ QUOTE ]
This scares the poo out of me. Get an opinion from a surveyor with experience of this type of boat.
I am from the old school where keels should not move at all. Any flexing IMHO is a sign that the keel or more likely the keelson (such as it is) will fail.
[/ QUOTE ]
In practical terms this is nonsense. Ever sat in the window seat of a 747 and wathced the wings bend as the plane flies. Or stood on the top of the Empire State and felt it bend with the wind?
All keels move without exception - the question is whether this keel is designed to move as much as it is doing. If he is unsure then a good surveyor (there are a lot of engineering numpties out there) should be able to advise. Personally, unless there are signs of recent damage / repair I would take some comfort from its age - if its lasted so long .....
This scares the poo out of me. Get an opinion from a surveyor with experience of this type of boat.
I am from the old school where keels should not move at all. Any flexing IMHO is a sign that the keel or more likely the keelson (such as it is) will fail.
[/ QUOTE ]
In practical terms this is nonsense. Ever sat in the window seat of a 747 and wathced the wings bend as the plane flies. Or stood on the top of the Empire State and felt it bend with the wind?
All keels move without exception - the question is whether this keel is designed to move as much as it is doing. If he is unsure then a good surveyor (there are a lot of engineering numpties out there) should be able to advise. Personally, unless there are signs of recent damage / repair I would take some comfort from its age - if its lasted so long .....
fisherman
Well-Known Member
I agree: my boat is a 1976 Cygnus 32, a long keel commercial fishing boat laid up like a brick outhouse, but it changes shape when it dries out. It's 13 or so tons, somethings got to give. IMHO beware if you over strengthen one section it is possible this will over stress surrounding areas, as happened to a boat with over re-inforced bulwarks and rails, leaned against the quay a bit hard, topsides wouldn't give, so the hull did.
As you say, if aeroplane wings did not flex something would break. All a matter of original design.........IMHO
As you say, if aeroplane wings did not flex something would break. All a matter of original design.........IMHO
PuffTheMagicDragon
Well-Known Member
It is not just a question of flexing; within limits, that is acceptable.
It seems to be implied in the (not too clear) description of what happened, that the keel moved <u>relative to the hull</u> - which is not the same thing at all! I have seen a similar Jeanneau that 'tripped' over a reef. There was not much to be seen on the outside. However, subsequent inspection <u>inside</u> after the boat was lifted out, revealed structural damage to the floors at the <u>aft</u> end of the keel.
The OP also implied (or so I understood) that the keel bolt nuts were glassed over. This is not good practice as it prevents the nuts from being 'taken up'.
Of course, I have not seen this particular boat but I would not be surprised if, in the past, it has also 'tripped' and the glassing-over was added to stop the resulting seepage. I hope, for his sake, that I am wrong because if I am right, the only acceptable solution would be the removal of the keel, followed by making good and strengthening of the floor as necessary, and eventually rebedding the keel as from new.
It seems to be implied in the (not too clear) description of what happened, that the keel moved <u>relative to the hull</u> - which is not the same thing at all! I have seen a similar Jeanneau that 'tripped' over a reef. There was not much to be seen on the outside. However, subsequent inspection <u>inside</u> after the boat was lifted out, revealed structural damage to the floors at the <u>aft</u> end of the keel.
The OP also implied (or so I understood) that the keel bolt nuts were glassed over. This is not good practice as it prevents the nuts from being 'taken up'.
Of course, I have not seen this particular boat but I would not be surprised if, in the past, it has also 'tripped' and the glassing-over was added to stop the resulting seepage. I hope, for his sake, that I am wrong because if I am right, the only acceptable solution would be the removal of the keel, followed by making good and strengthening of the floor as necessary, and eventually rebedding the keel as from new.
