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18-07-2015, 14:28
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#16
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Moderator
Join Date: Nov 2011
Location: aboard, cruising in Australia
Boat: Sayer 46' Solent rig sloop
Posts: 28,432
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Re: Paddle wheel speed transducer is driving me nuts
JD1,
Remove paddlewheel when not in use; set it in a plastic container with vinegar. The vinegar dissolves any hard growth on it. Clean off the dead stuff. Paint with bottom paint using an acid brush or a q tip.
Your problem has a simple, inexpensive fix. :-D
Ann
__________________
Who scorns the calm has forgotten the storm.
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18-07-2015, 14:38
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#17
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Registered User
Join Date: Apr 2011
Location: NZ
Boat: S34 Bob Stewart - 1959 Patiki class. Re--built by me & good mate.
Posts: 1,109
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Re: Paddle wheel speed transducer is driving me nuts
Thanks for that tip ATC. I have been reluctant to clean with anything other than water for
fear of increasing friction in the bearing. One of mine regularly becomes harder to spin.
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18-07-2015, 15:48
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#18
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Registered User
Join Date: Jan 2010
Location: Narragansett Bay
Boat: Able 50
Posts: 3,139
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Re: Paddle wheel speed transducer is driving me nuts
1 hour in the vinegar is all it takes and maybe less if the coral is thin. Then clean with a toothbrush. You do need one of those blank plug thingies.
Simple !
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18-07-2015, 18:15
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#19
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Registered User
Join Date: Dec 2013
Location: Tasmania
Boat: Hanse 400e 12M
Posts: 17
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Re: Paddle wheel speed transducer is driving me nuts
As far as I know, most if not all navigation instrument suppliers use the AirMac tridata transducer. Not much choice there.
Secondly, SOG does not substitute for STW.
Response is slow for SOG, whereas trimmers are looking for quick response for their adjustments.
The difference between SOG and STW readings gives the crew measure of current affects.
STW is also needed for wind readings, as pointed out by another forum member.
The only way to avoid annoying misreads is to keep the instrument clean by removing it when in the pen or on the mooring
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18-07-2015, 19:07
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#20
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Registered User
Join Date: Aug 2003
Boat: Dragonfly 1000 trimaran
Posts: 7,145
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Re: Paddle wheel speed transducer is driving me nuts
Not to start a flame war, but as soon as I installed an ultrasonic bottom cleaner system (still to be decided if it was a good investment or not) my paddle wheel is ALWAYS operational !!!
It used to foul in about 3 days, now I can leave it for a couple of weeks and it still works right away.
Hmmmm....
__________________
The question is not, "Who will let me?"
The question is,"Who is going to stop me?"
Ayn Rand
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18-07-2015, 19:24
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#21
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Registered User
Join Date: Jan 2010
Location: Narragansett Bay
Boat: Able 50
Posts: 3,139
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Re: Paddle wheel speed transducer is driving me nuts
Just be thankful that you don't have an ultrasonic anchoring system or things hereabouts could get really ugly.
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18-07-2015, 20:42
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#22
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Registered User
Join Date: Aug 2003
Boat: Dragonfly 1000 trimaran
Posts: 7,145
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Re: Paddle wheel speed transducer is driving me nuts
__________________
The question is not, "Who will let me?"
The question is,"Who is going to stop me?"
Ayn Rand
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18-07-2015, 21:04
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#23
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Registered User
Join Date: Feb 2013
Location: Kingston Ont Canada
Boat: Looking for my next boat!
Posts: 3,101
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Re: Paddle wheel speed transducer is driving me nuts
Quote:
Originally Posted by 44'cruisingcat
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I have a dead one too. So annoying. My instrument says 0 knots all the time. I use gps speed, but its not the same...you don't get that instant response to gusts and sail adjustments. Can't calculate current. Yes, I can estimate the speed pretty accurately by eye, but the speed instrument is nice too...if the little paddle wheel would just work.
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18-07-2015, 23:57
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#24
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Registered User
Join Date: Sep 2006
Posts: 9,398
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Re: Paddle wheel speed transducer is driving me nuts
Quote:
Originally Posted by aitch
As far as I know, most if not all navigation instrument suppliers use the AirMac tridata transducer.
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Most maybe, but certainly not all.
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19-07-2015, 01:40
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#25
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Registered User
Join Date: Jun 2007
Location: Western Caribbean
Boat: 48' Alu Cat
Posts: 218
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Re: Paddle wheel speed transducer is driving me nuts
I brushed Lanolin grease on my wheel about a month ago in tropical water, still spinning!
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19-07-2015, 02:48
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#26
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Registered User
Join Date: Jul 2012
Location: Pensacola, FL
Boat: Island Packet 35
Posts: 75
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Re: Paddle wheel speed transducer is driving me nuts
I replaced my ~1990 ST550 paddlewheel transducer with a new ST850 yesterday. The old paddle was still working but the temperature had gone bad. Airmar has done a great job of keeping the in hull port the same. The great news is the new one is narrower and has a screw in valve that you slide in and secure first. Then you slide the blanking plug or paddlewheel into that valve. Its awesome, no more huge flowing hole when I go from Paddlewheel to blanking plug.. just a trickle by comparison. The instructions did tell you to rough up the transducer and coat the end with water based anti-fouling transducer paint before using.
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19-07-2015, 04:45
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#27
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Registered User
Join Date: Jul 2015
Location: Netherlands
Boat: Piewiet 1050
Posts: 1
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Re: Paddle wheel speed transducer is driving me nuts
I do recognize your problem in tidal waters. On my search I found the Airmar without an paddle wheel CS4500 for Raymarine. It is more expensive, but it seems to be available.
Once it was part of the Raymarine catalogue.
It is an proven and old technique with an accuracy of 0.1 knots.
I did not buy it because my paddlewheel is working fine (for the moment)
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19-07-2015, 10:24
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#28
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Registered User
Join Date: Aug 2003
Boat: Dragonfly 1000 trimaran
Posts: 7,145
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Re: Paddle wheel speed transducer is driving me nuts
jhstacy,
Is the ST850 a more or less direct replacement for the ST550 or does it require new display or other black box?
I have ST50 gauges and as previously posted, no problem with paddlewheel getting stuck, but the temp gauge died many years ago.
__________________
The question is not, "Who will let me?"
The question is,"Who is going to stop me?"
Ayn Rand
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19-07-2015, 10:59
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#29
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Registered User
Join Date: Aug 2006
Location: Skagit City, WA
Posts: 25,477
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Re: Paddle wheel speed transducer is driving me nuts
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard
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19-07-2015, 16:41
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#30
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Registered User
Join Date: Dec 2014
Posts: 687
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Re: Paddle wheel speed transducer is driving me nuts
I have seen a possible solution on a GRP motor yacht under construction. A thick walled standard PVC tube was glassed into the hull so that the tube was vertical and the inside top of the PVC tube was well above the waterline. The tube was about 100 mm (about 4 inches) diameter from memory. The impeller was attached to the base of a second tube that slid down inside the first one so that the impeller was exposed to flowing water. The internal tube actually screwed into the base but I am not sure if that was necessary. However, the top of the internal tube screwed onto the larger tube presumably to stop the ingress of water when heeled. When not motoring the internal tube with impeller was replaced with a blank tube with a closed bottom end that would have had wax or grease impregnated with some nasty antifouling gloop. I am sure there would be many variations on the concept, but it allows for the impeller (and I guess sounder transducers) to be kept in pristine condition. Have not used same thing on my own boat nor seen this on a boat in the water, but as I had a VDO screw paddle damaged once during water blasting I wish I had removed the fitting.
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