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#1
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bilge keeler - tidal wear & tear?
My 28ft bilge keeler bounces around a good deal when the tide has moved to
be settling or lifting the boat. Not only does it get damn noisy but it can get a bit frightening when wind & wave combine to cause it to pitch up on one keel. But thats not my main worry, I'm more curious to learn from folk who permanently moor in the shallows and effectively have their boat on the dry once or twice a day. Does this long term bouncing about cause any strutural damage? I'm thinking it cant be doing my radar dome any good either. I've just done an ad-hoc solo 2200mile voyage from southern New Zealand to north Queensland. Conditions went as bad as 55knot gales with 7m seas the boat handled it a damn site better than I did. cheers bruce |
#2
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root wrote:
My 28ft bilge keeler bounces around a good deal when the tide has moved to be settling or lifting the boat. Not only does it get damn noisy but it can get a bit frightening when wind & wave combine to cause it to pitch up on one keel. But thats not my main worry, I'm more curious to learn from folk who permanently moor in the shallows and effectively have their boat on the dry once or twice a day. Does this long term bouncing about cause any strutural damage? I'm thinking it cant be doing my radar dome any good either. I've just done an ad-hoc solo 2200mile voyage from southern New Zealand to north Queensland. Conditions went as bad as 55knot gales with 7m seas the boat handled it a damn site better than I did. cheers bruce Drying moorings with bilge keelers are best located over soft bottoms. The sand, whatever, squishes during transition of the tide, and all should be well. Once the keels touch down, only the weight of the hull minus it's bouyancy plus it's mass coupling delta-vee matters to the keel roots. Wet mud is an excellant cushion. I wouldn't worry about your rig. You can fix your pendulum mount. Rubber mounts? A drying mooring with waves will, likely at least 50% of the time, end up with the boat head to waves. Once unstuck, the boat rises perceptibly above the grooves in the mud, after rocking a bit from the grounded flat keel to front afloat / back afloat, bonk a pointy rudder, etc. Likely only a few inches. The noise is amplified by the absence of distractions and fear. Even a far off power boat will sound loud through the hull, remember? Over a lumpy bottom, structural damage might well occur. Even the mooring weight counts as a lump. Good reason for a chain mooring and a long painter with a kellet mid span to a stern anchor? Yuchy mud on everything. Got an engine driven wash pump? "...use it." - Un-named Commissar in "Dr. Chivago" On ROUGH days, we all took our chances. Most still float. Terry K |
#3
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"Terry Spragg" wrote in message ... root wrote: My 28ft bilge keeler bounces around a good deal when the tide has moved to be settling or lifting the boat. Not only does it get damn noisy but it can get a bit frightening when wind & wave combine to cause it to pitch up on one keel. But thats not my main worry, I'm more curious to learn from folk who permanently moor in the shallows and effectively have their boat on the dry once or twice a day. Does this long term bouncing about cause any strutural damage? I'm thinking it cant be doing my radar dome any good either. I've just done an ad-hoc solo 2200mile voyage from southern New Zealand to north Queensland. Conditions went as bad as 55knot gales with 7m seas the boat handled it a damn site better than I did. cheers bruce I had a Westerly 30 Bk on a thames estuary mud berth near tilbury for many years where there was a strong tidal flow reasonably rough water in gales and very heavy wash from large ships in close proximity. The boats on swinging mud berths rotate about the mooring root twice a day and point direction is influenced by tidal flow, wind and river current. After a boat has been on its mooring for a while the boats sit in a circle of very soft mud surrounded by harder mud that hasn't been affected by the boat. In severe or unusual conditions the boats are thrown against their moorings and outside the usual circle of soft mud. The rudder is then very vulnerable and I have lost one before in these conditions removable or lifting rudders can help. The replacement for the grp spade rudder I fabricated out of stainless steel rather like a model aeroplane wing and it lasted fine. |
#4
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The main danger is keel spread. Most prevalent in older boats such as the
60's Westerly's and when the boat is on the dry for extended periods. What you have to do is put cleats on the outside of the keels. Not realizing this my heretofor always dry Centaur developed leak problems where the keel joined the keel stub but only after being on the dry for three months. The inside of the early keel stubs was a long hollow trough like area. In later models transverse stiffeners were built in which served to stop this problem. On the dry you still want the outside cleats as it's supporting it's entire weight 24/7. In the tidal situation the problem is far reduced. In tidal water you want to pick a spot where the bottom, if possible, is fairly even and does not have large rocks littering the area underneath, rememberingthe anchor is the center of a circle while the diameter of same is described by the stern. In my current boat a Westerly Berwick we've applied all the lessons learned and so far no problem. M. "ChrisR" wrote in message ... "Terry Spragg" wrote in message ... root wrote: My 28ft bilge keeler bounces around a good deal when the tide has moved to be settling or lifting the boat. Not only does it get damn noisy but it can get a bit frightening when wind & wave combine to cause it to pitch up on one keel. But thats not my main worry, I'm more curious to learn from folk who permanently moor in the shallows and effectively have their boat on the dry once or twice a day. Does this long term bouncing about cause any strutural damage? I'm thinking it cant be doing my radar dome any good either. I've just done an ad-hoc solo 2200mile voyage from southern New Zealand to north Queensland. Conditions went as bad as 55knot gales with 7m seas the boat handled it a damn site better than I did. cheers bruce I had a Westerly 30 Bk on a thames estuary mud berth near tilbury for many years where there was a strong tidal flow reasonably rough water in gales and very heavy wash from large ships in close proximity. The boats on swinging mud berths rotate about the mooring root twice a day and point direction is influenced by tidal flow, wind and river current. After a boat has been on its mooring for a while the boats sit in a circle of very soft mud surrounded by harder mud that hasn't been affected by the boat. In severe or unusual conditions the boats are thrown against their moorings and outside the usual circle of soft mud. The rudder is then very vulnerable and I have lost one before in these conditions removable or lifting rudders can help. The replacement for the grp spade rudder I fabricated out of stainless steel rather like a model aeroplane wing and it lasted fine. |
#5
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"root" wrote in message
news My 28ft bilge keeler bounces around a good deal when the tide has moved to be settling or lifting the boat. Not only does it get damn noisy but it can get a bit frightening when wind & wave combine to cause it to pitch up on one keel. But thats not my main worry, I'm more curious to learn from folk who permanently moor in the shallows and effectively have their boat on the dry once or twice a day. Does this long term bouncing about cause any strutural damage? I'm thinking it cant be doing my radar dome any good either. We had problems with 2 bilge keelers (Westerly Centaur & Berwick) on a drying swing mooring, . In both cases, the keel stubs were damaged and had to be reinforced. The estuary mooring we had at that time dried so far on springs that by the time the boat floated, the tide was up to 2 or 3 kts and the boat was dragged sideways over ridges on the sand bottom when swinging. I doubt that any keels/hulls are designed for such repeated shock loads and it's not unknown for keels to break off completely. Graham. |
#6
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root wrote:
My snip cheers bruce you're using pan so you must have a clue, but you're not really logging in and posting as root are you? |
#7
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prodigal1 wrote:
root wrote: My snip cheers bruce you're using pan so you must have a clue, but you're not really logging in and posting as root are you? Nah, he's Aussie, root has a different meaning there. Probably just happy to root his wife/gf/sheep -- With Kind regards, Jelle Boomstra |
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