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Author
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Topic: Keel movement
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Tony
unregistered
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posted November 04, 2003 12:08 AM
I have a 1983 Sandpiper (hull # 935) that I purchased this summer. During my outings with the boat, I noticed that the keel tends to move around somewhat when the vessel is not in a forward motion. When I am sitting at anchor with the keel down and with waves hitting the boat, I can therefore hear the keel move around and thump against the bottom of the keel trunk.
Is this normal? Have any of you ever heard this sound onboard your boats?
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Celtic Kiss
unregistered
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posted November 04, 2003 01:03 AM
Tony: I am not overly familiar with the inner workings of the SandPiper BUT from what you described I think something is not quite right with the pivot bolt. Maybe the fibreglass is a bit worn thus allowing the bolt to wiggle a bit?? If I were you I'd inspect this area. Robert
Celtic Kiss #2120
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SuperPiper
Member
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posted November 04, 2003 05:39 AM
Tony:It may not be right; but, I think it is typical. The keel is suspended from a bronze lead-screw. When it is not loaded, the keel is free to rotate against the trunk. I know the sound you are talking about.
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whited
unregistered
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posted November 04, 2003 08:21 AM
When I had a 17' Siren, I would crank the keel up when it was at it's mooring at the club. Wonder if this would be a good practice when anchoring.On the other hand...that's a lot of cranking for a 'lunch stop'. 90 up and 90 back down again.
I once forgot to let my keel down and tried to sail away from my mooring. I was almost on the rocks before I clued in.
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Tony
unregistered
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posted November 04, 2003 10:13 AM
Thanks for the prompt replies everyone! This forum is very effective! I'll keep you posted on my findings as I will further investigate the problem next summer.
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elmet3
unregistered
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posted November 04, 2003 11:29 AM
It sounds like you have your answer, but I'll weigh in anyway. In my experience, this is normal. There MUST be clearance around the keel for it to go up and down. When there is no steady force on the keel, it is free to swing about a bit. I always hear a bit of this as I am raising or lowering the keel. I may hear it if the keel is down and I have no forward speed if I am rocked by a wave. I hear it most often when the keel is only part way down, especially around 60-65 turns. It is so consistent that if I loose count of the turns, I feel pretty comfortable just picking up the count again when I hear the thump-thump with every turn of the screw, and I know that it is about 60 turns down. If the keel is all the way down the forces tend to keep it tight against one side. Presumabely it thumps over to the other side when I tack, but I never hear it.
This is related to an issue that comes up here from time to time. How securely is the keel attached to the boat? Just one large screw! I am sure it is well designed and more than adequate, but, all of our boats are now quite old and things wear out, screws come loose, etc. I have not heard of a keel actually falling off, but just the same I think I will put a safety strap on the keel this winter, AND a turns counter. I ususally don't have the keel all the way down, and I REALLY would like to know at a glance where it is at.
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whited
unregistered
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posted November 04, 2003 06:55 PM
Did you notice the price of a new keel for your Sandpiper??
Or even a rebuilt? Big bucks!
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Celtic Kiss
unregistered
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posted November 05, 2003 01:55 AM
I found another discussion about swing keels that is quite interesting and a bit scary.
http://bbs.trailersailor.com/forums/tsbbcomp/trailersailor/index.cgi/read/295695 Robert
Celtic Kiss #2120
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SuperPiper
Member
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posted November 05, 2003 05:18 AM
Elmet3:I like the safety strap idea! It should not be too difficult to install. Could it also be a grounding strap and part of an anti-lightening system?
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Ken
Member
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posted November 06, 2003 09:57 AM
1. I have been listening to my keel when at anchor since 1988. The jack screw is strong and overbuilt. The keel is suspended vertically from the screw, and a certain amount of sideways motion inside the keel's trunk is inevitable. When sleeping at anchor, I often cranked it up 20-25 turns to silence it. My advice when leaving the boat unattended at a swing mooring is to leave the keel most of the way down. This will keep the hull from skating around the mooring tire without any keel form stability. 2. Do not be confused by swing keel horror stories. A swing keel is usually poorly designed due to inadequate STEEL hinge pins (underwater all summer) which cannot be inspected. Also, the keel hoist is usually only a length of "aircraft" cable cranked up by a trailer-type winch. 3. The Sandpiper keel system is well designed and thought out.....the jack screw is naval bronze, and the upper end is captured by the thrust bearing and double nuts with split cotter pins. The bottom of the screw is harder to inspect without dropping the keel under the trailer. Due to my trailer's construction, I have been unable to do that, but after 15 seasons I remain confident in this system's integrity. Just remember to crank up the jack screw and lubricate both it and the thrust bearing annually with waterproof winch grease.
http://www.sailnet.com/store/item.cfm?pid=16497 See previous discussion below:
http://www.vaxxine.com/clsailboats/ubb/Forum1/HTML/000321.html
http://www.vaxxine.com/clsailboats/ubb/Forum1/HTML/000324.html ------------------
"Never be afraid to try something new: Professionals built the Titanic
And amateurs built the Ark." [This message has been edited by Ken (edited November 06, 2003).]
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