I have a fine old '75 Catalina 27, and the knotmeter has never worked. I have read all the horror stories about cleaning the paddlewheel, units that work every other day, etc., etc., so I don't want to get into trying to fix it. I have a Humminbird Fish Finder that serves as my depthsounder. Does anyone know if it can also tell me speed? I can't figure it out, and no manual came with the boat. Is there a simple knotmeter I can buy that uses a transducer that can be expoxied into the bilge area INSIDE the hull? Many thanks.
Replacing Knotmeter on Catalina 27
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Knotmeter
There is no knotmeter I know of that works without direct contact with the water. Have you actually pulled your existing KM sender and looked at it? It could be a very simple thing to fix, in fact likly easier than installing a new transducer with combined depth and speed. There are units on the market that do speed and depth but they need transducers that touch the water... sorry... unless someone can prove me wrong. David
There is no knotmeter I know of that works without direct contact with the water. Have you actually pulled your existing KM sender and looked at it? It could be a very simple thing to fix, in fact likly easier than installing a new transducer with combined depth and speed. There are units on the market that do speed and depth but they need transducers that touch the water... sorry... unless someone can prove me wrong. David
GPS
I too did not want to put a hole in the bottom of the boat for a paddlewheel/transducer
, so I bought a handheld GPS. It is WAAS enabled and therefore very accurate. It updates fast enough to see your speed increase and decrease going up and down waves. Additionally you get all the other features such average speeds, distance to the waypoints eta;s compass, etc... Depending on which model you buy, you wil not pay a lot more than for a knotmeter. I fabricated a plate to mount mine on the wheel pedestal, so that I can change the functions without having to move. Denis
I too did not want to put a hole in the bottom of the boat for a paddlewheel/transducer
, so I bought a handheld GPS. It is WAAS enabled and therefore very accurate. It updates fast enough to see your speed increase and decrease going up and down waves. Additionally you get all the other features such average speeds, distance to the waypoints eta;s compass, etc... Depending on which model you buy, you wil not pay a lot more than for a knotmeter. I fabricated a plate to mount mine on the wheel pedestal, so that I can change the functions without having to move. DenisI'm with Dennis ...
Get a hand held GPS. The added benefit of a GPS is it gives you a sum log function to keep track of total miles traveled. (A real necessity if you are plotting a DR course.) In addition, I bought a Knotstick. You trail a calibrated disc in the water and read the knots on a spring-loaded scale that attaches to the rear tafrail. I cross checked it with the GPS and the Knotstick was on the money. I have it as back up if the GPS fails.
Get a hand held GPS. The added benefit of a GPS is it gives you a sum log function to keep track of total miles traveled. (A real necessity if you are plotting a DR course.) In addition, I bought a Knotstick. You trail a calibrated disc in the water and read the knots on a spring-loaded scale that attaches to the rear tafrail. I cross checked it with the GPS and the Knotstick was on the money. I have it as back up if the GPS fails.
I'm with Denis ...
Get a hand held GPS. The added benefit of a GPS is it gives you a sum log function to keep track of total miles traveled. (A real necessity if you are plotting a DR course.) In addition, I bought a Knotstick. You trail a calibrated disc in the water and read the knots on a spring-loaded scale that attaches to the rear tafrail. I cross checked it with the GPS and the Knotstick was on the money. I have it as back up if the GPS fails.
Get a hand held GPS. The added benefit of a GPS is it gives you a sum log function to keep track of total miles traveled. (A real necessity if you are plotting a DR course.) In addition, I bought a Knotstick. You trail a calibrated disc in the water and read the knots on a spring-loaded scale that attaches to the rear tafrail. I cross checked it with the GPS and the Knotstick was on the money. I have it as back up if the GPS fails.
Except
that a GPS does not provide speed through the water, only speed over the ground (SOG) which can be radically different if you sail in areas with significant current. I have both and have seen differences of 3+ kts. As mentioned, DR requires speed X time to get distance covered. GPS distance is easy but will put you in a bind if your GPS fails... David
that a GPS does not provide speed through the water, only speed over the ground (SOG) which can be radically different if you sail in areas with significant current. I have both and have seen differences of 3+ kts. As mentioned, DR requires speed X time to get distance covered. GPS distance is easy but will put you in a bind if your GPS fails... David
Barry, if you know that you are bucking a 2 knot
current or being pushed on your way by it, you can make route decisions based on current.Speed thru water vs SOG lets you know what is going on. That being said I am with Dennis. I am going to pull out my inop knotmeter at next haul and not replace.
current or being pushed on your way by it, you can make route decisions based on current.Speed thru water vs SOG lets you know what is going on. That being said I am with Dennis. I am going to pull out my inop knotmeter at next haul and not replace.
Ever wonder...
why its blowing hard and water is flying but you aren't getting closer to your destination at the rate one would expect given all the fury? A comparasion of KM speed vs GPS speed will tell when you you are bucking a current. Eg. this summer I was in 25 kts of wind actual, single reef, 110% genny, green water over the bow regularily, speed thru the water was 5+ kts, SOG was less than 2 kts. Took me over three hrs to round a point that took me 1 hr the day before... I have both a GPS & KM but would always want a KM at least. Plus I think a KM is a more accurate indicator of trim changes on boat speed. IMHO David
why its blowing hard and water is flying but you aren't getting closer to your destination at the rate one would expect given all the fury? A comparasion of KM speed vs GPS speed will tell when you you are bucking a current. Eg. this summer I was in 25 kts of wind actual, single reef, 110% genny, green water over the bow regularily, speed thru the water was 5+ kts, SOG was less than 2 kts. Took me over three hrs to round a point that took me 1 hr the day before... I have both a GPS & KM but would always want a KM at least. Plus I think a KM is a more accurate indicator of trim changes on boat speed. IMHO David
tow unit
they used to make units to tow behind the boat (not a triangle board with knots in a string). also, i guess you could fashion a bracket off the back of the boat that would allow a standard transducer to be mounted. it may be that the turbulence would be problematic.
they used to make units to tow behind the boat (not a triangle board with knots in a string). also, i guess you could fashion a bracket off the back of the boat that would allow a standard transducer to be mounted. it may be that the turbulence would be problematic.
Some Hummingbird fishfinders will accept an option
paddlewheel that goes on transom and will give you speed. Many new fishfinders also have that capability. Paddlewheel driven "speedometers" are available for ski boats (expensive, for accuracy) and small fishing boats for trolling use because stock speed gauges for runabout have pitot tube pickup for high speed and don't work at very low speeds. Overton's has the optional paddlewheel fo $70, can you tell what model your fishfinder is? It's usually not that tough to pull them and clean, I know the thought of an open hole isn't appealing.
paddlewheel that goes on transom and will give you speed. Many new fishfinders also have that capability. Paddlewheel driven "speedometers" are available for ski boats (expensive, for accuracy) and small fishing boats for trolling use because stock speed gauges for runabout have pitot tube pickup for high speed and don't work at very low speeds. Overton's has the optional paddlewheel fo $70, can you tell what model your fishfinder is? It's usually not that tough to pull them and clean, I know the thought of an open hole isn't appealing.
This Works . . .
I too have a fine older '71 Catalina 27 and forget the paddle wheel as long as it isn't leaking. There is a transducer available that you can mount above the hull and under the forepeak. It sits in gel in a PVC cylinder and shoots thru the hull. The other end is a display you can mount anywhere. And you can angle the transducer, within a few degrees, any way you want. Nick "JuliaBell" C-27, #86
I too have a fine older '71 Catalina 27 and forget the paddle wheel as long as it isn't leaking. There is a transducer available that you can mount above the hull and under the forepeak. It sits in gel in a PVC cylinder and shoots thru the hull. The other end is a display you can mount anywhere. And you can angle the transducer, within a few degrees, any way you want. Nick "JuliaBell" C-27, #86
Darn Paddle Wheels!
The thru-hull that once housed the KM transducer on our B321 now is home for a backup depth system. A second GPS is more reliable. Currents are important, but you will probably have a feel for the strength and direction by observation and position. SOG is useful in so many many ways. s/v Parrot Tales, B321
The thru-hull that once housed the KM transducer on our B321 now is home for a backup depth system. A second GPS is more reliable. Currents are important, but you will probably have a feel for the strength and direction by observation and position. SOG is useful in so many many ways. s/v Parrot Tales, B321
Fish Finder
I have to say I prefer my solution. Purchased a Humminbird Matrix 65 for $315 at a West Marine sale. Like most Humminbird fish finders it not only finds fish, show bottom toppograhpy, it also has (or accepts) GPS. The Matrix 65 (replaced in the current line by the 67) Has GPS shows speed, provides track, monitors depth, and battery condition providing alarms for each. In addition to the above mentioned features the unit has a chart plotter that is updateable using a Navtronics memory card and can accept a weather sense module that will give you barametric pressure both current and a twelve hour history. Best of all the unit is Water Prof Jis7. The GPS unit will also connect to your DSC ready VHF.
I have to say I prefer my solution. Purchased a Humminbird Matrix 65 for $315 at a West Marine sale. Like most Humminbird fish finders it not only finds fish, show bottom toppograhpy, it also has (or accepts) GPS. The Matrix 65 (replaced in the current line by the 67) Has GPS shows speed, provides track, monitors depth, and battery condition providing alarms for each. In addition to the above mentioned features the unit has a chart plotter that is updateable using a Navtronics memory card and can accept a weather sense module that will give you barametric pressure both current and a twelve hour history. Best of all the unit is Water Prof Jis7. The GPS unit will also connect to your DSC ready VHF.
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