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Catalina/Capri 25/250 Sailor's Forums

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Knot Meter Dummy/Balanking Plug

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Altman554
Deckhand

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USA
8 Posts

Initially Posted - 11/12/2017 : 14:23:52

I have a 1987 Catalina 25, and it has a Standard Horizon Knot Meter (either a SL1 or SL10). I do not have a dummy/blanking Plug and can�t find the information to order a new one. Was hoping someone here might know where to get one. Respectfully,

Steve

Steve

bigelowp
Master Marine Consultant

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USA
1736 Posts

Response Posted - 11/13/2017 : 05:00:57

Steve, welcome to the forum. I would contact Standard Horizon directly for any parts or information. Years a go I stopped using the original knot meter and now utilize GPS for speed, just a thought.

Peter Bigelow
C-25 TR/FK #2092 Limerick
Rowayton, Ct
Port Captain: Rowayton/Norwalk/Darien CT

dasreboot
Admiral

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803 Posts

Response Posted - 11/13/2017 : 07:33:47

darn i had one. i think i offered it on swap meet. dont know what i did with it. I'm cleaning up the basement this weekend. If I come upon it, Ill reply

Todd Lewis
Eowyn 87 TR/WK C25 #5656
ARWEN 84 TR/SK C25 #4031
www.mainsailsailingschool.com

Altman554
Deckhand

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USA
8 Posts

Response Posted - 11/13/2017 : 08:26:05

Peter,
Am relatively new to sailing, and believe that a knot meter will give me better feedback on sail trim than a GPS. But will try it in the spring!

Steve

Steve

Altman554
Deckhand

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USA
8 Posts

Response Posted - 11/13/2017 : 08:27:32

Todd,

Thanks! Hoping it is still in your basement. Trying to find parts for old equipment has been painful. Respectfully,

Steve

Steve

Steve Milby
Past Commodore

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USA
5851 Posts

Response Posted - 11/13/2017 : 09:16:58

quote:
Originally posted by Altman554

Am relatively new to sailing, and believe that a knot meter will give me better feedback on sail trim than a GPS.

"GPS satellites broadcast their signals in space with a certain accuracy, but what you receive depends on additional factors, including satellite geometry, signal blockage, atmospheric conditions, and receiver design features/quality.

For example, GPS-enabled smartphones are typically accurate to within a 4.9 m (16 ft.) radius under open sky (VIEW SOURCE AT ION.ORG). However, their accuracy worsens near buildings, bridges, and trees." https://www.gps.gov/systems/gps/performance/accuracy/

That 16 ft radius leaves room for error in calculating speed. Moreover, my observation, after using both a mechanical knotmeter and gps, is that there appears to be enough of a delay in the ability of a gps to sense and report changes in speed that they aren't nearly as helpful as a mechanical knotmeter in judging the effects of changes in sail trim. The latter device provides almost immediate feedback that tells you if your sail trim change affected the boat's speed through the water.

Steve Milby J/24 "Captiva Wind"
previously C&C 35, Cal 25, C25 TR/FK, C22
Past Commodore

HerdOfTurtles
1st Mate

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USA
68 Posts

Response Posted - 11/13/2017 : 11:32:43

I think I would like to have a knotmeter, but I'm concerned about the maintenance ie: how long does it take before grass growth renders it uselessly inaccurate? I'm also not sure it would be of much use once the seastate gets rough, say over 2 ft.

We have one on the boat I race on and it has never been close to accurate, presumably because he doesn't have it cleaned periodically.

I have the thru-hull on my boat and it is plugged.

1978 Standard Rig
Fin Keel
L-Dinette

Stinkpotter
Master Marine Consultant

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Djibouti
9013 Posts

Response Posted - 11/13/2017 : 11:53:14

The two tools can have one significant difference if you sail in areas of tidal or river currents. The knotmeter shows your speed through the water, and the GPS shows your speed over the bottom. Currents will affect the latter. So setting aside accuracy issues, in tidal areas, the knotmeter will give you more reliable feedback on sail trim--particularly if you're comparing speeds before and after tacks that change your angle of bearing relative to the current. That said, I pretty much gave up on my knotmeter--too often it was stalled by slime or whatever kind of growth.

EDIT: I'm guessing you don't have that much tidal current in central Iowa...

Dave Bristle
Association "Port Captain" for Mystic/Stonington CT
PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired),
Now on Eastern 27 $+!nkp*+ Sarge

Edited by - Stinkpotter on 11/13/2017 12:05:50

Steve Milby
Past Commodore

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USA
5851 Posts

Response Posted - 11/13/2017 : 13:08:18

The paddlewheel on a knotmeter is easily fouled by dirt or algae. To keep it spinning freely you have to clean it frequently. You remove it with the boat in the water, shove the plug in, clean the paddlewheel with a small paintbrush or toothbrush, remove the plug and re-install the paddlewheel. It's a 2-3 minute job. I have a tremor and don't do it, but my sure-handed friends do and it doesn't seem to be difficult.

Last year I did replace a hose on a thru hull fitting that didn't have a valve to shut off the water, and noticed that the water doesn't come through in a high pressure stream. It just sort of burbled up through the pipe, and I had plenty of time to pull off the old hose and stick on the new one. I only took in about a quart of water in the process.

Steve Milby J/24 "Captiva Wind"
previously C&C 35, Cal 25, C25 TR/FK, C22
Past Commodore

OLarryR
Master Marine Consultant

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USA
3367 Posts

Response Posted - 11/14/2017 : 05:06:58

Depending on your water environment and number of sunny days, you may/may not get thru a season without cleaning the knotmeter. Chances are you will have to clean it at least once, mid-season, inorder for it to read decently. While you can use a GPS for determining speed, I like the use of a knotmeter for indicating the speed relative to the water current, etc versus GPS that measures speed relative to land or point to point speed.

Removing, unscrewing the knotmeter to clean it off, as said earlier, is not such a big deal and the water that does come in is at low pressure. If you can remove it and screw in the dummy plug efficiently, the amount of water is perhaps a gallon or less that enters the boat. But I must admit that it is a bit unsettling unscrewing the knotmeter, seeing light come thru the hole along with water gshing in and you do not feel better until that dummy plug is snugged in.

One thing I learned the hard way - If you have the boat out for a ressure wash, recommend do not hit the knotmeter with the pressure washer or at least do so with less pressure or distance away from the knotmeter. The pressure washer will certainly clean off the slime from the paddle wheel but after several seasons of doing this, one year, the pressure washer ripped out the paddle wheel and part of the housing. Luckily for me, it was only the lower part of the housing and the upper part was still intact and watertight. I have a new paddlewheel/housing that I purchased directly from SR Mariner (maker of my knotmeter) but I have not yet installed it...going on 1 - 2 years....mainly due to procrastinating over the unsettling feeling unscrewing the knotmeter....even though it is not all that bad...but then having to do it again after a few months.

Larry
'89 Robin's Nest#5820, Potomac River/Quantico, Va
http://catalina25.homestead.com/olarryr.html

GaryB
Master Marine Consultant

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USA
4275 Posts

Response Posted - 11/17/2017 : 18:34:02

You could always just keep the plug in and put the paddle wheel assembly in when're going sailing or maybe even better, only when you're going to race. Never needs cleaning and will probably last a lot longer.

Also won't have to worry about the yard guy blowing it to pieces with the pressure washer.

Association Member

GaryB
Andiamo
'89 SR/WK #5862
Kemah,TX

Edited by - GaryB on 11/17/2017 18:35:22

Voyager
Master Marine Consultant

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USA
5231 Posts

Response Posted - 11/17/2017 : 20:22:30

You could always get one of those orange foam conical hole fillers that you can use when the hull gets holed by an errant rock.
Fore spar makes them and you can see it here

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain � Milford, CT

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The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.