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Round Knot Meter

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Mark Maxwell
Captain

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USA
329 Posts

Initially Posted - 10/04/2018 : 07:19:01

I�m looking for a round knot meter to replace the one on my 1978 C25. Analog or digital.

Thanks

Mark-
'Impulse...�
1978 C25 #533 SR/DIN/FIN ~_/)~
Bakersfield, CA.

OLarryR
Master Marine Consultant

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USA
3367 Posts

Response Posted - 10/04/2018 : 09:35:31

Not sure what knotmeter you have but many Catalina 25s came with a SR Mariner analog knotmeter. The hole size is fairly large, believe it is a just over 4" in diameter. Signet marine sells a knotmeter that believe requires a 4.5" hole.

The SR Mariner knotmeter was fairly expensive when it was available for purchase. If you have an SR Mariner knotmeter, you also have another option and that is to get it fixed by SR Instruments. They are located in New York. They do not sell marine instrumenst any longer but they still support the old knotmeters and depthfinders. Many years ago, I called them up and they indicated if I sent them the old meter and transducer, they would assess what needed to be replaced. I forget wehat it cost me but they furnished a new transducer and reconditioned the meter basically replacing the internals and a new display face. They did a great job - It was like new when received and installed operating fine. Benefit was that I was able to utilize the original thru hull housing as the new transducer is exactly the same as the old transducer. If you decide to go with another mfr's knotmeter, besides the hole size in the companionway bulkhead, the biggest issue is that you would need a new thru hull housing as it is unlikely that another mfr would have a transducer that would fit your old transducer housing.

Rcmd indicate what mfr knotmeter and model you have so if someone has an old one that works and they want to part with it, they can respond.

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

Mark Maxwell
Captain

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USA
329 Posts

Response Posted - 10/04/2018 : 15:41:03

Good advise Larry, Thanks

I have installed an early EMS U25K. The hole in the cabin wall is 4 1/8�. There is a place I can send it off to have rebuilt but it�s not cheap. I�m hoping to find a used one that some has left from an upgrade. I like the simplicity of this knot meter...itself powered, analog but trying to decide if I want to invest in the old or replace with newer....I have a Garmin GPS chart plotter/fish finder but I like to have actual paddle wheel info as well.

Everything Larry said is true, it�s nice to have the same through hull fitting, mount hole etc...

Mark-
'Impulse...�
1978 C25 #533 SR/DIN/FIN ~_/)~
Bakersfield, CA.

OLarryR
Master Marine Consultant

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USA
3367 Posts

Response Posted - 10/05/2018 : 03:38:07

I also like the analog knotmeters but they are expensive to buy or fix as you indicated. So, it puts the owner in a quandary as to what to do next. Some decide to utilize a handheld GPS or buy that one that West Marine sells, it is sort of a hockey puck (GPS) that you can mount/attach to the companionway bulkhead. But then you get into the debate or decision as to what you want to read - GPS (Speed over actual distance traveled) or by a knotmeter utilizing a transducer measuring speed over the water traveling past the hull/transducer.

Cost is definitely a factor but so is the labor and stress if replacing existing unit with a different mfr's knotmeter that then requires a new thru hull housing. My preference would be to repair or replace w/same mfr model. Second choice, go with a GPS handheld or mounted unit. Last choice go with another mfr's knotmeter either used or new but this option likely to more costly and/or more labor intensive than other options.

There is a fourth option - forgeddaboutit altogether. The thing is that oftentimes during the season, a knotmeter transducer may become clogged with algae, etc and then remains that way until you have time to unclog it which may be at end of the season. My transducer periodically becomes clogged and since I keep my boat in the water year-round and oftentimes do not like removing the transducer when boat is in the water, allowing 1-2 gallons of water in while sticking the dummy transducer plug in, and then cleaning the transducer, I wind up going without knotmeter readings until I go for an annual pressure wash. I do not race and just for day sailing, not having use of the knotmeter is not a big issue. I can always use my handheld GPS if I am curious as to speed but mostly just guess at my speed - Then again, I sail in a river and so relative speed is easier to gage from checking progress against trees and buildings on the sides of the river.

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

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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.