Vibration

V

vegatern

.
Oct 2, 2005
465
I noticed today that I get a little, very faint, intermittent vibration while under sail. I've felt it before, but thought tonight I would ask for some advice because I can't tell where it is coming from. I feel it in the deck (well in my butt really) and it seems to coincide with coming to the top of a swell and picking up a bit more wind, not much wind, maybe 12 knots or a little bit more. My headsails are old and pretty much blown out and the leech flutters. Perhaps that is enough to transfer down the forestay or maybe the sheets? The rig is tuned tight, perhaps too tight. I used the instructions on the Selden website which suggests stretchering the cap stays to 5% of breaking strength. Could the wind against the stay transfer to the deck? I didn't feel any movement in the mast. What I don't know is if this could be an indication of a problem or not.

Craig Tern V1519
 
P

pjacobs55

.
Oct 30, 2019
1,459
Craig,
Maybe wander around the deck while it's humming and lay a hand on various lines and stays. A gentle pull on the offending line should change the pitch of the hum.
I had a buzzing sound, while moored, that turned out to be the Amsteel topping lift.

Peter
#1331 'Sin Tacha'
 
B

brockhaus77

.
Jul 24, 2002
149
In German we say "Das Kielschwein brummt" - meaning the keel pig (some mythological beast, I presume, that lives in your keel) is humming - being happy about making good speed through the water. :)
I've heard similar vibrations on VegaLyra when going at a good clip - but I admit to sometimes leaving the prop in neutral ("freewheeling") - can't say for sure whether it ONLY hums in that condition. Anyway, I've always taken it for a "GOOD" sign - nothing to worry about (unless it is really noticeable). Maybe foolishly so...

- Sebastian
 
S

SVFlyAway

.
Oct 31, 2019
303
It could be the rudder. I doubt if it is the prop turning as that us usually
heard more than felt. (On little centerboard boats it is sometimes the
centerboard, but that isn't the case here.)

If it is intermittent then it seems to me that it could be the jib. I used
to race a lot and a vibration, actually a hum, was often heard in heavier
winds (we were in bigger boats and drove them to the point of blowing out
our sails, which we did more than once). This can occur even when the sails
are trimmed well and all the sail telltails are flying right. It is more
noticeable on boats with a foil on the headstay, as one has with roller
furling (in racing we used a foil, but no roller furling, often the foil had
two slots and we could do an inside out sail swap). I also have noticed it
often in the tradewinds in cruising boats when driving hard (I guess that is
the only way I know how to sail).

Next time, play with the back stay adjuster, tighten it a bit to put more
tension on the head stay, or slacken it to relieve the tension . That is an
easy thing to test. Also try moving the cars a little. If the vibration
changes, then you know what it is. And if that is the problem, it won't
cause any damage.
 
T

tim_klynn

.
Feb 12, 2008
337
I would also guess the rudder or prop.
My prop shaft bushing had a bit of play in it, but I never had any noticeable vibration.
I would guess that if the rudder had enough vibration, you would feel it in the tiller.
-Tim
________________________________
From: n4lbl alan.schulman@...
To: AlbinVega@yahoogroups.com
Sent: Saturday, August 13, 2011 9:57 PM
Subject: Re: [AlbinVega] Vibration
Could the transmission have been in neutral and the propeller free-wheeling?

Alan
 
T

tim_klynn

.
Feb 12, 2008
337
If it is a higher pitched vibrations maybe it is just the rudder and keel.
Apparently, Santana 20's get a substantial hum going on the rudder if you fly the spinnaker in over 20 knots and start to plane.
I don't think I'll ever find out about this on purpose.
Here's an interesting youtube vid on some racing boats going by an underwater photographer:
They have a hum or whine while sailing by.
________________________________
From: n4lbl alan.schulman@...
To: AlbinVega@yahoogroups.com
Sent: Saturday, August 13, 2011 9:57 PM
Subject: Re: [AlbinVega] Vibration
Could the transmission have been in neutral and the propeller free-wheeling?

Alan
 
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