captainslarty
N/A
Is there any math on this subject to work out the suitablity of the rig to take the loads ?.
Are there any structural engineers / rigger on here ?
Are there any structural engineers / rigger on here ?
careening a yacht
- Thread starter captainslarty
- Start date
Phoenix of Hamble
Well-Known Member
Why the rig?.... surely its easier to just let her dry out rather than force her over with the rig?
sailorman
Well-Known Member
thats wot the rig is designed 4 ????????????????????????/
captainslarty
N/A
Hi Morgan..
Just interested, ya never know, I might want to do it one day..... seriously, its another option...
Joe.
Just interested, ya never know, I might want to do it one day..... seriously, its another option...
Joe.
captainslarty
N/A
But are the loads not spread over the whole rig whilst sailing ?.. what is the situation with running a single line from the top ?
Bajansailor
Well-Known Member
I am thinking that the factor of safety in your rig should allow you to pull the vessel over on to her beam ends - the same effect would happen if you were knocked down in a squall with too much sail up, and with a conservative rig, one wouldnt expect to automatically lose the rig in such a situation.
Here is a photo of a schooner being careened - the Careenage in Bridgetown here in Barbados was also a very popular location for careening schooners, and it was still happening in the 1960's here.
http://ngb.chebucto.org/Dist_Photo/blp-skiff.jpg
The schooners usually had the advantage of having internal removable ballast, which would all be taken out and stacked up on shore prior to being 'hauled down'.
Re careening your Seastream, I am thinking that if you hauled her over using the main mast, the centre of effort would be forward of the centre of buoyancy / floatation, and she would tend to 'slew round' because of the turning moment being applied.
Here is a photo of a schooner being careened - the Careenage in Bridgetown here in Barbados was also a very popular location for careening schooners, and it was still happening in the 1960's here.
http://ngb.chebucto.org/Dist_Photo/blp-skiff.jpg
The schooners usually had the advantage of having internal removable ballast, which would all be taken out and stacked up on shore prior to being 'hauled down'.
Re careening your Seastream, I am thinking that if you hauled her over using the main mast, the centre of effort would be forward of the centre of buoyancy / floatation, and she would tend to 'slew round' because of the turning moment being applied.
KenMcCulloch
Well-Known Member
[ QUOTE ]
But are the loads not spread over the whole rig whilst sailing ?.. what is the situation with running a single line from the top ?
[/ QUOTE ]
I'm only a sociologist /forums/images/graemlins/grin.gif but I do remember some basic mechanics. If you run a line from the top of your mast to an anchor somewhere abeam and heave down, the forces will resolve to a tension load in the uphill shroud and a compresssive load in the mast. There will however be some unusual stresses in the hull where the whole mass of the vessel acts through a small area rather than through the whole immersed section.
But are the loads not spread over the whole rig whilst sailing ?.. what is the situation with running a single line from the top ?
[/ QUOTE ]
I'm only a sociologist /forums/images/graemlins/grin.gif but I do remember some basic mechanics. If you run a line from the top of your mast to an anchor somewhere abeam and heave down, the forces will resolve to a tension load in the uphill shroud and a compresssive load in the mast. There will however be some unusual stresses in the hull where the whole mass of the vessel acts through a small area rather than through the whole immersed section.
sailorman
Well-Known Member
its called a Spinnaker when sailing /forums/images/graemlins/wink.gif
kandoma
Well-Known Member
Eric Hiscock is discussing careening a yacht in his book "Cruising under sail" and even has a picture of a large yacht heeled over. Either in "Cruising under sail" or "Voyaging under sail" he has also the basic formula to calculate the minimal size of the rigging on an ocean going yacht. Unfortunatly I do not have the books with me for another 4 weeks to give you the details. I'm sure, somebody is having access to the books and can help you.
Peter
Peter
BlueSkyNick
Well-Known Member
[ QUOTE ]
its called a Spinnaker when sailing /forums/images/graemlins/wink.gif
[/ QUOTE ]not entirely true, as a spinnaker is attached in 2 other places, not just the top of the mast, innit?
its called a Spinnaker when sailing /forums/images/graemlins/wink.gif
[/ QUOTE ]not entirely true, as a spinnaker is attached in 2 other places, not just the top of the mast, innit?
mikemonty
Well-Known Member
I think that the forces will go through the same points and transfer to the same areas of the hull whether you pull the boat over by the top of the mast or whether the sail is applying the force.
The forces must go via tension in the rigging to the chainplates and compressively through the mast base.
To heel the boat over to the same degree as when sailing, the forces must be the same as when sailing so no problems there.
In fact there will (theoretically) be no bending moment on the mast, which is a plus.
At the masthead, any bending moment applied by the shroud will be more or less offset by the opposing force on the careening "warp".
From another post - As far as the boat trying to slew round when careened - I can't see this happening, what is being suggested is the discovery of perpetual motion!
The boat would continually revolve around a vertical axis meeting at the masthead.
The forces must go via tension in the rigging to the chainplates and compressively through the mast base.
To heel the boat over to the same degree as when sailing, the forces must be the same as when sailing so no problems there.
In fact there will (theoretically) be no bending moment on the mast, which is a plus.
At the masthead, any bending moment applied by the shroud will be more or less offset by the opposing force on the careening "warp".
From another post - As far as the boat trying to slew round when careened - I can't see this happening, what is being suggested is the discovery of perpetual motion!
The boat would continually revolve around a vertical axis meeting at the masthead.
Poignard
Well-Known Member
Isn't there a danger of the lower cockpit coaming going under the water and the boat filling up in consequence?
mikemonty
Well-Known Member
Carreening is meant to be a controlled procedure, but even if you filled up your cockpit, shouldn't the companionway step be above the water level when heeled to that degree?
(Not that I would like to put it to the test!)
(Not that I would like to put it to the test!)
captainslarty
N/A
lol, yes, we would HAVE to careen to starboard due to the offset companionway (Due to the Mizzen)
Will HAVE to try it sometime..
Will HAVE to try it sometime..
Leighb
Well-Known Member
[ QUOTE ]
Isn't there a danger of the lower cockpit coaming going under the water and the boat filling up in consequence?
[/ QUOTE ]
I would think it depends on how far over you want to go?
It also depends on shape of hull and type of keel, a modern design would need to be nearly on its beam ends before the tip of the keel was clear of the water, not so for older types.
I use this technique in a minor way to scrub my One Design. I use the weight of the dinghy hanging off the end of the boom to haul her down on the mooring, perhaps about 30 degrees from upright, I can then easily reach all the hull and keel when leaning over the side with a long brush.
The topmast above the hounds does bend a bit, but then so it would if sailing hard, so I just assume that the rig can take the load. With a masthead rig you would not have that problem.
Isn't there a danger of the lower cockpit coaming going under the water and the boat filling up in consequence?
[/ QUOTE ]
I would think it depends on how far over you want to go?
It also depends on shape of hull and type of keel, a modern design would need to be nearly on its beam ends before the tip of the keel was clear of the water, not so for older types.
I use this technique in a minor way to scrub my One Design. I use the weight of the dinghy hanging off the end of the boom to haul her down on the mooring, perhaps about 30 degrees from upright, I can then easily reach all the hull and keel when leaning over the side with a long brush.
The topmast above the hounds does bend a bit, but then so it would if sailing hard, so I just assume that the rig can take the load. With a masthead rig you would not have that problem.
Lakesailor
Well-Known Member
On Windermere (and any other non-tidal water) if a yacht goes off it's mooring and ends up aground careening is often the only way to float them off rocks. Bilge-them-off they refer to it around here.
Success
Success
Poignard
Well-Known Member
Although my cockpit is self-draining it is far from being watertight. Being built of wood, water can seep in around the seat lockers and other places. Also she does not have much beam compared with modern boats. There is no bridge deck, just a flap hinged at the bottom, and two vertically hinged companionway doors. Probably not the most seaworthy arrangement but she hasn't sunk in 40 years and she has been to the Azores and back so I'll try not to worry too much.
Anyway, I'm not planning on trying careening! The only reason for careening is when there is insufficient tidal range to dry out against a wall or piles, [or if there is no boatyard to lift her out, or money to pay for it!].
Anyway, I'm not planning on trying careening! The only reason for careening is when there is insufficient tidal range to dry out against a wall or piles, [or if there is no boatyard to lift her out, or money to pay for it!].
mikemonty
Well-Known Member
My boats a Contessa 26 and I THINK the companionway is designed such that she could be knocked down flat and still have the opening above the (calm water) waterline.
Damn well hope so, or else whats the point of having to get in and out like a thunderbirds puppet into thunderbird 1!
If any one would like to disabuse me of this please do so.(again - I'm not intending to test the theory!)
Damn well hope so, or else whats the point of having to get in and out like a thunderbirds puppet into thunderbird 1!
If any one would like to disabuse me of this please do so.(again - I'm not intending to test the theory!)
