Cruisers Forum
 


Join CruisersForum Today

Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 06-07-2020, 09:33   #1
Registered User

Join Date: Aug 2017
Location: Rochester, NY
Boat: Beneteau 41.1
Posts: 155
Things That Go Bump in the Night

This is a strange one. When overnighting onboard our 41 foot sloop, thereís invariably a loudish ďthumpĒ sound that occurs once every night just around dawn. The first tine it happened I thought someone hit us but nobody for miles around. I canít tell for sure but it sounds like itís coming from above, maybe as if you plucked a shroud or gave the mast a wack.

Iíve inspected the rigging, expecting to discover the mast was standing thanks to a single cotter pin or something. Everything looks sound. The boatís only in its third season.

Itís a mystery. Whatís causing it? Why every day? Why only once a day? Why at that time?

The only thing that comes to mind is thermal expansion. Something warms up faster than something else, on deck or in the standing rigging, when the temperature starts going up toward daybreak.

Anybody else experience this? Any ideas what it could be?

Thanks!
__________________

__________________
USCG Master - 100 GRT, Near Coastal, Auxiliary Sail
Howler is offline   Reply With Quote
Old 06-07-2020, 09:38   #2
Registered User

Join Date: Jun 2019
Location: Rochester, NY
Boat: Chris Craft Catalina 381
Posts: 908
Re: Things That Go Bump in the Night

I always get a few little pops as things expand from heat when the sun hits the boat in the morning. More so after a cool night. And we get a few pops in the evening as things cool after a hot, sunny day. No leaks or other known issues, so I just call it normal for this boat.
__________________

rslifkin is online now   Reply With Quote
Old 06-07-2020, 10:03   #3
Registered User
 
wingssail's Avatar

Join Date: Jan 2010
Location: On Vessel WINGS, wherever there's an ocean, currently in Mexico
Boat: Serendipity 43
Posts: 1,969
Send a message via AIM to wingssail Send a message via Skype™ to wingssail
Re: Things That Go Bump in the Night

Quote:
Originally Posted by Howler View Post
This is a strange one. When overnighting onboard our 41 foot sloop, thereís invariably a loudish ďthumpĒ sound that occurs once every night just around dawn. The first tine it happened I thought someone hit us but nobody for miles around. I canít tell for sure but it sounds like itís coming from above, maybe as if you plucked a shroud or gave the mast a wack.

Iíve inspected the rigging, expecting to discover the mast was standing thanks to a single cotter pin or something. Everything looks sound. The boatís only in its third season.

Itís a mystery. Whatís causing it? Why every day? Why only once a day? Why at that time?

The only thing that comes to mind is thermal expansion. Something warms up faster than something else, on deck or in the standing rigging, when the temperature starts going up toward daybreak.

Anybody else experience this? Any ideas what it could be?

Thanks!
Yeah, I've got one of these thunks. Mine happens in late afternoon on hot days, from a specific spot on deck, but there is nothing there. So? A mystery.
__________________
Sailing is a sport, an athletic activity, not a sedentary one.
Fred Roswold-Fred & Judy, SV Wings, Mexico
https://wingssail.blogspot.com/
wingssail is offline   Reply With Quote
Old 06-07-2020, 17:03   #4
Registered User
 
chris mac's Avatar

Join Date: May 2015
Location: edmonton alberta
Boat: 1992 lagoon 42 tpi
Posts: 869
Re: Things That Go Bump in the Night

An odd longshot, but if there is a breaker on your solar panels there could be an audible click or thunk from it activating.
chris mac is online now   Reply With Quote
Old 06-07-2020, 17:50   #5
Registered User

Join Date: Aug 2017
Location: Rochester, NY
Boat: Beneteau 41.1
Posts: 155
Re: Things That Go Bump in the Night

Quote:
Originally Posted by chris mac View Post
An odd longshot, but if there is a breaker on your solar panels there could be an audible click or thunk from it activating.
Good thought but we don't have solar panels and it's a deeper sound than a breaker. Thank you though.
__________________
USCG Master - 100 GRT, Near Coastal, Auxiliary Sail
Howler is offline   Reply With Quote
Old 07-07-2020, 03:00   #6
Bailing as fast as I can.
 
GILow's Avatar

Join Date: Sep 2008
Location: Adelaide, South Australia
Boat: Swanson 42
Posts: 6,666
Things That Go Bump in the Night

I was troubled by an odd thump that I thought was something hitting the hull, and it turned out to be dolphins slapping the water to stun the fish. Probably not the cause in this instance, but a possibility?
__________________
Count-down has commenced.
GILow is offline   Reply With Quote
Old 07-07-2020, 03:16   #7
Registered User
 
Tortuga's Lie's Avatar

Join Date: Oct 2007
Location: Virginia
Boat: Tartan 4100
Posts: 471
Re: Things That Go Bump in the Night

You could loosen up on the shrouds just a touch and see if that makes a difference, could be that the rig is over tensioned.
Tortuga's Lie is offline   Reply With Quote
Old 07-07-2020, 03:31   #8
Registered User

Join Date: Aug 2017
Location: Rochester, NY
Boat: Beneteau 41.1
Posts: 155
Re: Things That Go Bump in the Night

Quote:
Originally Posted by Tortuga's Lie View Post
You could loosen up on the shrouds just a touch and see if that makes a difference, could be that the rig is over tensioned.
They are pretty tight. I'll try that. Thanks.
__________________
USCG Master - 100 GRT, Near Coastal, Auxiliary Sail
Howler is offline   Reply With Quote
Old 07-07-2020, 03:36   #9
Registered User

Join Date: Aug 2017
Location: Rochester, NY
Boat: Beneteau 41.1
Posts: 155
Smile Re: Things That Go Bump in the Night

Quote:
Originally Posted by GILow View Post
I was troubled by an odd thump that I thought was something hitting the hull, and it turned out to be dolphins slapping the water to stun the fish. Probably not the cause in this instance, but a possibility?
I wish that were the answer, but we haven't spotted any dolphins on Lake Ontario lately. And it's literally one thump, once a day. Not sure dolphins are that consistent!

Similar story... We do have huge salmon that get sidetracked into our marina during their trek up the river. The first time one jumped just outside the boat, it made a very loud sound.
__________________
USCG Master - 100 GRT, Near Coastal, Auxiliary Sail
Howler is offline   Reply With Quote
Old 07-07-2020, 05:13   #10
Registered User

Join Date: Jun 2020
Location: New England
Boat: Bristol 31.1
Posts: 43
Re: Things That Go Bump in the Night

Could the sound be the departure of a large bird that had been roosting in the rigging over night? They usually begin their daily routines at dawn.
gansett is offline   Reply With Quote
Old 07-07-2020, 08:58   #11
Registered User

Join Date: Apr 2012
Posts: 49
Re: Things That Go Bump in the Night

Are you on a mooring ball? Is there a tidal shift at about the time of the thump?
jim King is offline   Reply With Quote
Old 07-07-2020, 09:27   #12
Registered User
 
wingssail's Avatar

Join Date: Jan 2010
Location: On Vessel WINGS, wherever there's an ocean, currently in Mexico
Boat: Serendipity 43
Posts: 1,969
Send a message via AIM to wingssail Send a message via Skype™ to wingssail
Re: Things That Go Bump in the Night

Quote:
Originally Posted by Tortuga's Lie View Post
You could loosen up on the shrouds just a touch and see if that makes a difference, could be that the rig is over tensioned.
Well, that would support the theory that it is some sort of thermal issue, since possibly the shrouds (or mast), are contracting as they cool and that relieves some pressure somewhere in the boat, possibly the deck, and something shifts as the pressure releases (like a tectonic shift in the earth, resulting in an earth quake, so you're having mini earth quakes on your boat) but honestly, on my boat I'd put up with the creaks and groans rather than ease the tension on your shrouds. Assumedly they have been tensioned properly, and easing them would make them somewhat slacker than ideal. Not what I'd do.

BTW, on my boat the sound comes at the heat of the afternoon, when most things have expanded, not contracted.

edit: Just looked it up, aluminum contracts and expands twice as much as stainless steel. So maybe when your mast contracts as it cools it is relieving pressure on the rig, as implied by Tortuga's Lie, and, yeah, something in your beneteau shifts.
__________________
Sailing is a sport, an athletic activity, not a sedentary one.
Fred Roswold-Fred & Judy, SV Wings, Mexico
https://wingssail.blogspot.com/
wingssail is offline   Reply With Quote
Old 07-07-2020, 09:42   #13
Registered User

Join Date: Dec 2014
Location: Lewes, DE
Boat: Island Pscket 31
Posts: 43
Re: Things That Go Bump in the Night

I heard bumps in the night when the wind picked up and the boat swung on her anchor rode. The roller in the anchor holder would slap back and forth with tension on the rode. If the sound goes away we are dragging the anchor.
Sirago is offline   Reply With Quote
Old 07-07-2020, 09:46   #14
Are you serious?
 
sailorboy1's Avatar

Join Date: Jul 2007
Location: currently in Jacksonville Fl
Boat: Hunter 410
Posts: 16,578
Re: Things That Go Bump in the Night

Some boats are just haunted and the ghosts go into hiding each morning at dawn.
__________________
jobless, houseless, clueless, living on a boat and cruising around somewhere
sailorboy1 is offline   Reply With Quote
Old 07-07-2020, 10:27   #15
Registered User

Join Date: Nov 2013
Location: Homeport: Oswego, NY
Boat: 1993 Sabre 362 #113
Posts: 445
Re: Things That Go Bump in the Night

If it happens more in the beginning of the season than later in the season could be carp. They can get frisky and may be slapping the boat.
__________________

Dave Lochner is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Things that go bump in the night qwert Our Community 0 23-11-2018 18:06
Things that go Bump in the Night caradow Atlantic & the Caribbean 0 25-10-2015 08:16
Things that go bump in the night. simonpickard Liveaboard's Forum 26 01-08-2014 15:52
Things that Go Bump in the Night forsailbyowner Auxiliary Equipment & Dinghy 10 13-04-2010 18:36
Things That Go Bump in the Night Hud3 General Sailing Forum 8 22-10-2007 08:33

Advertise Here


All times are GMT -7. The time now is 14:54.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.