Daydream believer
Well-Known Member
Have you tried searching for a SBS road trailer. That will take a 26 ft fin keeler and mine took up to 5 tonnes
Where have all the cradles gone?
- Thread starter Jonny A
- Start date
Robert Wilson
Well-Known Member
This idea set me thinking (again).
Forgive the apparent thread drift, but is it better for a boat (e.g. GRP) to sit with all its weight on the keel, or part/wholly-supported by stands+pads in four/six positions on the hull?
I appreciate there are different hull-forms, keel types and overall weights of boat.
I ask because I'm faced with potential major overhaul of my existing part keel/part hull supporting old cradle or replacement with a new one.
TIA
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Quandary
Well-Known Member
Boats invariably sit on the keel, the legs and pads only serve to keep the hull upright. When the crane sets the boat down the pads should not be in contact with the hull, they are screwed into position before the slings are removed. Even then I have seen grp distorted by the pad and recall one large yacht of a popular make where the pads always had to be positioned relative to internal bulkheads.
I had a yard trolley for our Sigma 38 (mickey mouses ear shaped keel) the legs were long enough to come above the deck so that it could be used on the slipway with a tractor, though generally it was lifted by a travel hoist. The pads were vertical on the side of the legs and were moved over horizontally to hold it upright, the contact was at deck level. We wintered it one year with the mast up, though the trolley was always jacked solid with the weight off the tyres.
I had a yard trolley for our Sigma 38 (mickey mouses ear shaped keel) the legs were long enough to come above the deck so that it could be used on the slipway with a tractor, though generally it was lifted by a travel hoist. The pads were vertical on the side of the legs and were moved over horizontally to hold it upright, the contact was at deck level. We wintered it one year with the mast up, though the trolley was always jacked solid with the weight off the tyres.
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Daydream believer
Well-Known Member
I Know that my own boat, a hanse 311, will distort if not supported at the ends. If no additional supports from the pads the front bulkhead door can stick and the floor panel just aft of the keel will stick up 10-12mm.
a dehler 28( think that was the length.) was stored at our club on a trailer and no support under the stern. One could flex the aft end up and down several inches just by applying ones weight to the transom.
no idea how a Bavaria would perform without support
a dehler 28( think that was the length.) was stored at our club on a trailer and no support under the stern. One could flex the aft end up and down several inches just by applying ones weight to the transom.
no idea how a Bavaria would perform without support
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Quandary
Well-Known Member
Never been aware of that but all my boats with the exception of the Finngulf and Nimbus were overdesigned British built and far from state of the art. Surely if your hull bends under its own weight when sitting static on the keel it must flex like anything when you are crashing into a heavy sea?
Daydream believer
Well-Known Member
Slacken the rig. Stretch a line inside down centre of boat. Measure bilge to line at centre point. Tension rig inc backstay. Then, assuming you have modern AWB , tell us , after checking measurement, that your boat does not bend
i know of a 3/4 tonner where the designer was delighted that difference was only 1.5 inches
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Jonny A
Well-Known Member
Unfortunately I don't have anywhere to store a road trailer during the summer so I need something that comes apart into reasonable sized pieces.
Seajet
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No, lift keelers don't which is why I keep my boat on high trestles during winter so as to have the keel lowered and accessible for maintenance.
Some boats - the Listang and Jaguar 22 lift keeler spring to mind - can't support the weight of the hull on the keel or ballast bulb when dried out or ashore.
Racing keelboats like Flying Fifteens etc use full beam hull trestles - may be a direction to investigate depending on size of boat, maybe find out what larger lift keelers like Parkers and Southerlys use ?
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maby
Well-Known Member
Even "crashing into heavy sea", the weight of the boat is spread over a large area. The pads on the ends of the average cradle arm are a few square inches and the average cradle has six or eight arms - nowhere near enough contact area to carry even a small fraction of the weight of the boat.
Quandary
Well-Known Member
You are not disagreeing with me, (I think?) Did you read 23 as well as 25?
If the hull is very flexible, enough to bend downwards under just the hull weight as suggested above in post 24 (and I accept that rig forces can distort hulls, I once had a Sigma 33!) I have a vision of the much heavier fin keel wnking back and forth as it is bounced up and down and back and forward. I know it should not happen but the moment applied by a static tapered grp box extending 3 metres fore and aft is a lot less than a ton and a half of keel being bounced up and down in a heavy sea. I simply find it amazing that, taking account of the shape, strength and relative lightness of a normal yacht hull, that it would droop when supported by the keel, I have yet to meet a boat so weak that the hull will not support itself adequately, perhaps some J boats or such but they are not your average cruising yacht.
Seajet
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I have seen two Jaguar / Alacrity 22 ( definitely cruiser not racer ) lift keelers left ashore with keels retracted, the unsupported hulls sagged like pudding around the ballast bulbs.
Quandary
Well-Known Member
A friend started sailing many years ago with an Alacrity, in the club it was referred to as the 'Atrocity', it did seem kinda slow.
Never having had to put up with shallow water I tend to think of yachts as fin keeled, my knowledge and experience of lifting or even bilge keels is zero though an odd one does turn up here sometimes. I still maintain that a hull that can support a fin keel afloat should be able to support itself?
Seajet
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Fin or any keel type, I agree, it's always nice to think the bows won't fall off after a big wave or a winter ashore
Robert Wilson
Well-Known Member
Fin or any keel type, I agree, it's always nice to think the bows won't fall off after a big wave or a winter ashore
Fredrift warning!
Which reminds me of being told by a very experienced B747 pilot on seeing me nervously watching the wings and engine pods "flapping" at 30,000Ft+.
"The wings are the strongest part of a plane, don't worry, they won't fall off. In fact they build the wings, then put the fuselage on top.
The wings WILL NOT break."
Phew said I, that's reassuring. Thank you.
A minute later he turned to me and said:-
"The wings won't snap - but the fuselage might."...………………
So, Seajet, be careful what you tell yourself when pounding into a Chanel Easterly !!
Seajet
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Robert Wilson
Well-Known Member
Well, That's OK then. When its bow fell off and spilled 20,000 tonnes of crude, it was towed out of the environment, and no he doesn't mean another environment!!
:encouragement: