Howling Boats
Printed From: Yachts and Yachting Online
Category: Dinghy classes
Forum Name: Dinghy development
Forum Discription: The latest moves in the dinghy market
URL: http://www.yachtsandyachting.com/forum/forum_posts.asp?TID=2281
Printed Date: 17 Aug 25 at 6:48am
Software Version: Web Wiz Forums 9.665y - http://www.webwizforums.com
Topic: Howling Boats
Posted By: NickA
Subject: Howling Boats
Date Posted: 05 Oct 06 at 2:42pm
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My lovely new boat howls when it planes. When it really gets going a second pitch kicks in and it howls in harmony. An F18 cat I once knew was so loud you could hear it take off from the club house! I quite like it ... but it's probably going to be really annoying to everyone else, plus all that noise must be robbing energy. Anyone else had this "feature" and cured it? |
Replies:
Posted By: Black no sugar
Date Posted: 05 Oct 06 at 3:26pm
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Laser4000s sing in a variety of pitches depending on the wind and the crew. Having one of those screeching things appearing out of nowhere when you're in a Topper in a force 6 is an experience to remember! ------------- http://www.lancingsc.org.uk/index.html - Lancing SC 
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Posted By: furtive
Date Posted: 05 Oct 06 at 3:34pm
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On Laser 4000s, this is caused by having a big fat trailing edge on the daggerboard (and rudder). Class rules allow you to sand down the back 75mm of both foils to make the trailing edge finer. This stops the high speed humming, presumably saving a bit of lost energy, but does make your foils a bit more fragile - be careful of the trailing edge if you capsize and are standing on the board. Foils made in the same way (ie other Laser boats) probably have similar issues, and also probably have the same allowance in the class rules as they all originiated in the same place. More hi-tech foils are probably designed/made to avoid this problem in the first place! |
Posted By: Jamie600
Date Posted: 05 Oct 06 at 3:37pm
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The back edge of one or both of your foils is vibrating. Try sanding to a finer point if your class rules allow it, should make it go away |
Posted By: Guest
Date Posted: 05 Oct 06 at 4:23pm
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Boat that do that really annoy me. The way to fix it is to make sure your foil is free of imperfections and sharpen the trailing edge ... Somtimes an assymetric trailing edge is needed. Rick ------------- |
Posted By: 49erGBR735HSC
Date Posted: 05 Oct 06 at 4:33pm
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We had a similar problem with the 5000, fairing the foils appropriately helps but there could also be areas on the mast which are causing the humming noises. The 5000 has a hole at least a few centimetres diameter bored into the top of the mast, so in big winds it used to hum and whistle. We simply taped it up, also preventing the boat from inverting so quickly when we decided to go swimming... We do experience mild humming when sailing at speed but it is from the windage coming off the rig and it's easy to distinguish that sort of humming compared to humming caused by innadequate fairing. ------------- Dennis Watson 49er GBR735 http://www.helensburghsailingclub.co.uk/ - Helensburgh S.C http://www.noblemarine.co.uk/home.php3?affid=560 - Boat Insurance from Noble Marine |
Posted By: m_liddell
Date Posted: 05 Oct 06 at 7:34pm
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The 5000 humms lounder than any boat I've ever sailed, it's really really loud. I fixed the hum on a laser buy replacing the pathetic bolt on the stock with an big fat bolt tightened up so that it was effectivly a fixed blade. Sailed a buzz that hummed from the shrouds which was weird. Some windsurf rig/board combos humm too. My 14 is silent |
Posted By: les5269
Date Posted: 05 Oct 06 at 7:37pm
Your sailing the wrong 5000's then. My old one never hummed at all and my helms is just as quiet ------------- 49er 531 & 5000 5025 and a mirror(now gone to mirror heaven)! http://www.grafham.org/" rel="nofollow - Grafham water Sailing Club The greatest inland sailing in the country |
Posted By: Medway Maniac
Date Posted: 05 Oct 06 at 9:03pm
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Noise generation requires very little energy, but the vibration might have undesirable effects on the boundary layer and consequentially on skin friction drag. Instead of simply thinning the trailing edge, you might like to try the solution proposed by United Technologies Corp in US Patent 4786016: http://patimg1.uspto.gov/.piw?docid=US004786016&PageNum=6&IDKey=BF34FF360F6D&HomeUrl=http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2%2526Sect2=HITOFF%2526p=1%2526u=%25252Fnetahtml%25252FPTO%25252Fsearch-bool.html%2526r=1%2526f=G%2526l=50%2526co1=AND%2526d=PTXT%2526s1=4786016.PN.%2526OS=PN/4786016%2526RS=PN/4786016 - http://patimg1.uspto.gov/.piw?docid=US004786016&PageNum= 6&IDKey=BF34FF360F6D&HomeUrl=http://patft.uspto.gov/ netacgi/nph-Parser?Sect1=PTO2%2526Sect2=HITOFF%2526p=1%2526u =%25252Fnetahtml%25252FPTO%25252Fsearch-bool.html%2526r=1%25 26f=G%2526l=50%2526co1=AND%2526d=PTXT%2526s1=4786016.PN.%252 6OS=PN/4786016%2526RS=PN/4786016 Use of patented subject matter is free for individuals for personal use. |
Posted By: Merlinboy
Date Posted: 05 Oct 06 at 11:31pm
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My laser used to do it back in the ay! Oh how i miss her! I used to have a knact slot gasket on my phantom that cause a fountain when you planed it was annoying because when you are hanging off the transom for dear life it would land right in my face - blinding me not good!!! ------------- |
Posted By: BBSCFaithfull
Date Posted: 06 Oct 06 at 10:54am
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My 14 is silent. The only thing that makes noise is me saying "where did that F*****G feva come from lol...........
------------- Greatfully Sponsored By www.allgoodfun.com Int 14 GBR 1503!! |
Posted By: BBSCFaithfull
Date Posted: 06 Oct 06 at 10:59am
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Les, Does black mamba make any noise? ------------- Greatfully Sponsored By www.allgoodfun.com Int 14 GBR 1503!! |
Posted By: Matt Jackson
Date Posted: 06 Oct 06 at 2:15pm
Used to have a motorbike that whisled at 40mph+ and really annoyed me. When I investigated I found that somone had taped one of those really loud safety whistles from their lifejacket to the forks . I wonder if a boat would go quick enough to play the same trick?------------- Laser 203001, Harrier (H+) 36 |
Posted By: mike ellis
Date Posted: 06 Oct 06 at 2:23pm
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the boat may not have to go fast enough for the whistle , the wind might do it for you. my feva hums downwind and on a flat day you get a fountain off the rudder, dont know if it happens on wavy days though ------------- 600 732, will call it Sticks and Stones when i get round to it. Also International 14, 1318 |
