Chartplotter

[Frenchy]

On my boat, which has an old Signet paddlewheel and display, the paddlewheel sensor is secured with a large plastic
nut and then has to be pulled out with a large pair of hose clamp pliers. It is really impossible to pull out it by hand.
I would say it takes a good 4 or 5 minutes to pull it out. Forcing the plug in would take another couple of minutes.
The risk of sinking is just too high. - Jean

[BernieA]

I have a Garmin 4208 chart plotter on my CD28 Pinafore. It works well and is mounted on a swing away door so it sits in the hatchway when in use. I also have OpenCPN on two android tablets and two android phones. I also have it installed on my laptop and desktop. It is free on the google play store for android devices, and at opencpn.org for windows, IOS and other platforms. There is also a paid version on the google play store, but is is the exact same version as the free one. The caveat regarding OpenCPN for android is that it hasn't been updated and can't use the various plugins available from the web site. I do like the program and find hat it works very well, taking advantage of the GPS capabilities built into devices. Since my laptop does not have GPS capability, I bought a USB unit for about $15 that plugs into the laptop.
Along the way, I've compared the accuracy of all the devices to the Garmin, as well as fixes based on bearings. I haven't found any glitches so far, but I keep checking just to be sure. The Salish Sea, where I sail, has a lot of strong tidal currents and fluky winds, so I like to avoid trouble.

Bernie
CD28 Pinafore
Sequim Bay, WA

[wikakaru]

On my boat, which has an old Signet paddlewheel and display, the paddlewheel sensor is secured with a large plastic
nut and then has to be pulled out with a large pair of hose clamp pliers. It is really impossible to pull out it by hand.
I would say it takes a good 4 or 5 minutes to pull it out. Forcing the plug in would take another couple of minutes.
The risk of sinking is just too high. - Jean

Mine is held in place with a clevis pin that runs through holes in both the through-hull fitting and the transducer. (You can see the end of the clevis pin in the photo I posted earlier, stored in my spare impeller to prevent loss of the pin.) It is quite easy to pull the pin, and if the transducer itself is reluctant to come out, giving it a slight twist with a pair of vice grips is always enough to loosen it so it can be pulled out by hand. I have found that greasing the transducer's O-rings before re-installing helps keep it slippery enough to remove by hand the next time. I use Vasoline, but lanolin or a marine grease might work better. You might try applying some grease next time you are hauled so you don't have to worry about sinking the boat, and see if that helps you remove the transducer when the boat is back in the water. Also, the more often you remove it, the easier it is; if you made it a monthly task you might be able to do it quickly and easily.

Smooth sailing,

Jim

[karonoko]

Thanks for your thoughts on keeping my paddlewheel speed. How about keeping my depth vs removing it and using the Raymarine depth transducer that comes with the Element?

[wikakaru]

Thanks for your thoughts on keeping my paddlewheel speed. How about keeping my depth vs removing it and using the Raymarine depth transducer that comes with the Element?

I'd say it depends on whether you are interested in accessing depth information in any way other than in real-time in the cockpit. As far as I can tell, the Moor unit is stand-alone and is not capable of sending depth data on an NMEA interface. I don't see it in the Raymarine specs, but I assume that depth data for that unit would be available on the NMEA 2000 interface from the plotter. So if you want digital depth information to send to a mobile device app like Navionics that keeps a history of depths recorded on your boat's track so you can create your own charts, or if you want to add an NMEA2000 multi-function display down below at the nav station or where you can see it from your berth at night, you couldn't do that with the Moor.

If you are happy with the no-frills Moor depth unit and don't need the bells and whistles of digital depth data, go ahead and keep it. Also, if you keep the Moor, you don't have a single point of failure. If you lost the chart plotter for some reason, you'd also lose your depth information.

If you don't mind having extra holes in the hull, you could do both. On one of my boats I had both a standard depth sending unit and a fish finder. For some reason every depth sounder I have ever had decided to go wonky now and then, usually at the most inopportune moments like when negotiating a shallow silted-in part of the Intracoastal Waterway. It was really nice to have two independent units. They rarely both went wonky at the same time. Ideally the transducers will operate at different frequencies from one another. Low-frequency transducers operate better in deep water, and high-frequency units are better in shallow water.

It's nice to have choices!

Smooth sailing,

Jim

[Carl Thunberg]

Sorry, it's just WAY too much stress to pull the paddle wheel unit out in the water. I'll do without the information before I do that. Yes, I am a coward. I have no qualms admitting that. I can look around me and tell when I'm in a current. I'm okay with GPS speed over ground. That marginal lack of data won't affect my decisions on the water. Data is only useful if it affects your decisions.

[wikakaru]

Sorry, it's just WAY too much stress to pull the paddle wheel unit out in the water. I'll do without the information before I do that. Yes, I am a coward. I have no qualms admitting that. I can look around me and tell when I'm in a current. I'm okay with GPS speed over ground. That marginal lack of data won't affect my decisions on the water. Data is only useful if it affects your decisions.

I know what you mean. It's always a bit scary pulling that plug and having all the water rush in. But after reading this post (http://www.capedory.org/board/viewtopic ... 6&p=216383) by David on Ethan Gray who replaced his prop shaft with the boat in the water, pulling the knot meter paddle sounds like a piece of cake.

Smooth sailing,

Jim

[Tom Keevil]

It will take a lot of water to sink your boat, and the amount that enters when you pull your paddle wheel is pretty minor. We store stuff in our bilge, so I use a towel to soak up the water that spurts out, but it is really no big deal. The first time you do it is pretty tense, but then it is no sweat.

[jfischgrund]

Sorry, it's just WAY too much stress to pull the paddle wheel unit out in the water. I'll do without the information before I do that. Yes, I am a coward. I have no qualms admitting that. I can look around me and tell when I'm in a current. I'm okay with GPS speed over ground. That marginal lack of data won't affect my decisions on the water. Data is only useful if it affects your decisions.

Sign me up as a fellow coward. If I pull it out while on the hard to give it a good cleaning, what kind of anti-fouling paint would be best to keep it from getting fouled again? Maybe something like the MDR transducer paint?

[wikakaru]

If I pull it out while on the hard to give it a good cleaning, what kind of anti-fouling paint would be best to keep it from getting fouled again? Maybe something like the MDR transducer paint?

This is from Airmar's installation guide:

Anti-fouling Paint
Surfaces exposed to salt water must be coated with anti-fouling paint. Use water-based antifouling paint only. Never use ketone-based paint, since ketones can attack many plastics possibly damaging the transducer.

It is easier to apply paint before installation, but allow sufficient drying time. Reapply paint every 6 months or at the beginning of each boating season. Paint the following surfaces (Figure 4):
• Outside wall of the insert below the lower O-ring
• Exposed end of the insert
• Exterior flange of the housing
• Bore of the housing up 30mm (1-1/4")
• Blanking plug below the lower O-ring including the exposed end

My transducer feels like some kind of Teflon-impregnated plastic, which is another reason I prefer to pull the plug and clean it while it's in the water--I don't think paint sticks very well to it.

Smooth sailing,

--Jim

[jfischgrund]

Thanks. Great post and very informative replies. Looks like a spring pre-launch project. Thanks again!

[bottomscraper]

The web site linked below says that a 1 inch hole in the hull 1 foot below the surface floods at a rate of 19.4 gallons a minute.

The speed transducer on Mahalo is mounted so that it faces sideways on the keel about 3ft below the water line. (Maybe not the best place for it but that's how it was installed when we purchased the boat.) The hole when the transducer is removed is about 1.25". According to the chart I would estimate roughly 45+ gallons a minute. Access is not particularly easy reaching through a panel opening deep into the bilge, working fast isn't really possible. Call me chicken, for me the little bit of extra information of questionable accuracy isn't worth the risk, especially if I had to do it every couple of weeks! Ultimately speed over ground (GPS) is significantly more useful information than speed through the water.

I can tell you that I would definitely not bother installing an impeller style speed transducer in a boat that did not have one.

I have used water based bottom paint on the transducer and it has not been very effective.

http://www.whsyc.org/Flooding/Flooding.html

[Jim Walsh]

I’ve removed speed transducers while in the water to clean them since the early seventies. Eel grass was prevalent in the harbor and the transducers seemed to attract it, much to my chagrin. Usually I could just loosen it and draw it partially out before getting it back in place. The water pressure would clear the obstruction. For those times when that was insufficient I’d wait till the boat was back in the slip to pull the transducer, clean it, and return it to its place. Never had more than three of four gallons in the bilge.
With the advent of the flapper valves which dramatically decrease the inflow, just a dribble really, I am much more casual about the procedure. I keep the blanking plug, which is supplied with the Raymarine units tied to the throughhull ready for immediate insertion should there be an issue with the transducer.
As a side note the newer paddle wheels are much less prone to fouling that the vintage ones. And the MDR antifouling transducer paint is very effective.
We all have different needs, equipment, and standards, so we all have the luxury of doing what we are comfortable with.