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Old 13-01-2017, 09:41   #1
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Buying new instruments, speed paddle, GPS...

This year I'm looking to replace:

- My masthead wind speed/direction instrument (I have an old, non-networked Datamarine unit now)

- My speed-through-the-water paddlewheel that's never worked

- My inside and outside GPS chartplotters.

- And in a few years I'll want radar that I can overlay on my charts.

I imagine with that level of information the thing could be auto-generating polar plots for me, fun stuff like that... I've been a low tech sailor for some time, but geeking out on data sounds fun. Anyways, at the very least I'd like the display to be able to assemble this info and tell me the TRUE wind speed + direction.

I'd love to hear a sampling of people's opinions about what gear I should buy and why.
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Old 13-01-2017, 10:28   #2
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Re: Buying new instruments, speed paddle, GPS...

Chris,

We are in the midst of going through the same thing and I spent months going back and forth on the matter. While I prefer Furuno equipment for its robustness and repairability, we have finally settled for B&G instruments and replacement equipment based upon the cost/benefit trade-off given the time we are likely to continue owning our boat. There are several, if not many, threads on the various equipment one might choose that you can find suing the Search function (above) that might be worth taking a look at.

N'any case, good luck!
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Old 13-01-2017, 10:44   #3
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Re: Buying new instruments, speed paddle, GPS...

Personally I would forego a paddle wheel speed device and just use the GPS.
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Old 13-01-2017, 10:54   #4
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Re: Buying new instruments, speed paddle, GPS...

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Originally Posted by Cheechako View Post
Personally I would forego a paddle wheel speed device and just use the GPS.
Nah - they are two different numbers (Speed over ground, vs speed through water.) For evaluating performance, trim, sail configuration, etc, I imagine teasing out the fact that I'm in a half-knot southerly current could be quite illuminating... I said from the get go this was about nerding out.
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Old 13-01-2017, 11:00   #5
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Re: Buying new instruments, speed paddle, GPS...

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Nah - they are two different numbers (Speed over ground, vs speed through water.) For evaluating performance, trim, sail configuration, etc, I imagine teasing out the fact that I'm in a half-knot southerly current could be quite illuminating... I said from the get go this was about nerding out.
Well of course I know that. But realistically, how much has your frozen up paddle wheel been telling you lately? I guess if you are racing that's one thing. But cruising? It's all determinable by location and heading etc. If you have a current with or against you... speed over ground is what you need to know... In a seaway, your paddle speed will vary with each up the wave /down the wave occurrence anyway... but I guess if you do need toys... ya gotta have them!
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Old 13-01-2017, 12:26   #6
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Re: Buying new instruments, speed paddle, GPS...

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Originally Posted by Cheechako View Post
Well of course I know that. But realistically, how much has your frozen up paddle wheel been telling you lately? I guess if you are racing that's one thing. But cruising? It's all determinable by location and heading etc. If you have a current with or against you... speed over ground is what you need to know... In a seaway, your paddle speed will vary with each up the wave /down the wave occurrence anyway... but I guess if you do need toys... ya gotta have them!


Well for me its less about the "toys" more about the "data".

Lately I've been thinking that sailing big, heavy old boats has prevented me from learning some of sailing's finer points - I think giving my sailing a bit more scrutiny (=data) might help.
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Old 13-01-2017, 13:30   #7
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Re: Buying new instruments, speed paddle, GPS...

Be prepared to spend quite a bit of time getting all the instruments calibrated and regularly cleaning the paddle wheel. The data is very interesting though when you get there.
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Old 13-01-2017, 14:08   #8
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Re: Buying new instruments, speed paddle, GPS...

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Originally Posted by Cheechako View Post
Well of course I know that. But realistically, how much has your frozen up paddle wheel been telling you lately? I guess if you are racing that's one thing. But cruising? It's all determinable by location and heading etc. If you have a current with or against you... speed over ground is what you need to know... In a seaway, your paddle speed will vary with each up the wave /down the wave occurrence anyway... but I guess if you do need toys... ya gotta have them!
You can't determine water current speed and direction with just a GPS reading. If you don't know what the current is doing it is hard to make course changes to take advantage of it. The paddlewheel STW will vary, just like the GPS based SOG will vary as the boat jumps around. You can average either one, but the base readings will vary.
Having a good feel for what the current is doing can easily make a 50 mile a day difference on a passage. 1kt with you adds 24 miles and 1 kt against subjects 24 miles. Nice data to have and worth the effort to keep your paddle wheel clean.
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Old 13-01-2017, 15:18   #9
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Re: Buying new instruments, speed paddle, GPS...

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Personally I would forego a paddle wheel speed device and just use the GPS.
ridiculous... gps is speed over the bottom.... transducer is speed thru the water
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Old 13-01-2017, 15:36   #10
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Re: Buying new instruments, speed paddle, GPS...

I just replaced everything on my masthead and installed B&G instruments with 4G radar. The multi transducer comes with a plug so you can pull and replace the paddle wheel each time you go out. You would really get your geek on with this system. It also provides you with a fish finder, a fuel sensor, a pinger when you're late for lunch, etc. So beware because there's so much it can do, you just might spend more time playing with it, than sailing....
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Old 13-01-2017, 16:22   #11
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Re: Buying new instruments, speed paddle, GPS...

Quote:
Originally Posted by Paul L View Post
You can't determine water current speed and direction with just a GPS reading. If you don't know what the current is doing it is hard to make course changes to take advantage of it. The paddlewheel STW will vary, just like the GPS based SOG will vary as the boat jumps around. You can average either one, but the base readings will vary.
Having a good feel for what the current is doing can easily make a 50 mile a day difference on a passage. 1kt with you adds 24 miles and 1 kt against subjects 24 miles. Nice data to have and worth the effort to keep your paddle wheel clean.
One more vote for knowing STW, that can be very useful data in many situations!
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Old 13-01-2017, 16:42   #12
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Re: Buying new instruments, speed paddle, GPS...

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You can't determine water current speed and direction with just a GPS reading. If you don't know what the current is doing it is hard to make course changes to take advantage of it. The paddlewheel STW will vary, just like the GPS based SOG will vary as the boat jumps around. You can average either one, but the base readings will vary.
Having a good feel for what the current is doing can easily make a 50 mile a day difference on a passage. 1kt with you adds 24 miles and 1 kt against subjects 24 miles. Nice data to have and worth the effort to keep your paddle wheel clean.
While I'm not speaking so much against a knot log, I'm just saying you definitely don't need one. I certainly wouldn't cut a hole in my boat for one, although I have a few times in the past. Most often they are not working properly due to contamination. ...or you put a gallon+ of water in your boat to remove and clean it.
If you know your real SOG and progress toward your destination, you correct what you are doing. You know your boat, you know it does 8 knots at 2400 rpm.... if you are not going 8 knots over ground you know what's going on. Crossing the gulf stream from Biscayne to Bimini, your knot meter has no idea the heavy current is directly abeam... as the current flow is from the side. Your GPS does tell you your COG, you correct accordingly, sailing or motoring.
Knotmeter useful? at times, most often? I don't think so.
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Old 13-01-2017, 18:35   #13
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Re: Buying new instruments, speed paddle, GPS...

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While I'm not speaking so much against a knot log, I'm just saying you definitely don't need one. I certainly wouldn't cut a hole in my boat for one, although I have a few times in the past. Most often they are not working properly due to contamination. ...or you put a gallon+ of water in your boat to remove and clean it.
If you know your real SOG and progress toward your destination, you correct what you are doing. You know your boat, you know it does 8 knots at 2400 rpm.... if you are not going 8 knots over ground you know what's going on. Crossing the gulf stream from Biscayne to Bimini, your knot meter has no idea the heavy current is directly abeam... as the current flow is from the side. Your GPS does tell you your COG, you correct accordingly, sailing or motoring.
Knotmeter useful? at times, most often? I don't think so.
I see what you are saying, but, if my GPS dies when I am out of sight of land, I want my paddle wheel working. Imagine your GPS dies with 600 miles left to land. Your knot meter log will faithfully click off the miles under the keel. If nothing else, you can use it for dead reckoning to get in close to your destination.

Also, if I'm fishing, I would rather know my speed through the water than SOG. Ideal trolling speed it 6 or 7 knots for many fish. Chances of catching most tropical fish drop below 5 knots or so. Going 6 knots over ground with a favorable 1.5 knot current won't catch me many fish.

As far as data from the GPS for cruising, I find COG more useful than SOG, since I am more concerned with heading the right way than how fast.

At any rate, if you ever have a non working speed paddle wheel, I recommend changing it. My boat came with a broken paddle wheel. The previous owner had said he pulled it out and reinstalled it, but it still wasn't working. When I took possession of the boat, I pulled it out to bring it in to be tested (so I could know if it was a bad transducer or bad display unit).

When I pulled it out, I found it was cracked almost all the way through. I was glad to discover it was cracked the easy way, rather than having it turn into a hole in my boat in rough seas. So now I view any failed transducer as a warning to check the part.

I also don't think rpm is a good judge of speed through the water. Obviously if you are sailing it is not helpful at all. But even if motoring, sea state can make a huge difference.

For example, last week I motored around the end of grenada. I had a current with me but the wind and waves on the nose. I was motoring at 2500 rpms, which in flat water is good for 7 knots. I was going 3.5 knots over ground straight into the wind/waves. In unfavorable conditions in my boat, that isn't unreasonable. However, looking at my paddlewheel, my speed through the water was only 2 knots, since the waves were so
steep. It was hard to tell that I was going this slow without the paddle wheel.

Since I was going so slow, I put the sails up and bashed upwind instead. My boat sails much better in rough waves than she motors, so my speed through the water picked up to 5 knots, so I was actually going to windward faster than when I was motoring straight into it.

If I hadn't had the paddle wheel, I would have only seen the 3.5 knots sog from the gps and probably just suffered through instead of putting the sails up and going upwind faster while more comfortably.

So just some theoretical and real scenarios where I feel a paddle wheel is very useful information. In general I understand your point that you can get away with only sog, but I view a working paddle wheel as a high priority item.
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Old 13-01-2017, 19:03   #14
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Re: Buying new instruments, speed paddle, GPS...

Quote:
Originally Posted by Cheechako View Post
While I'm not speaking so much against a knot log, I'm just saying you definitely don't need one. I certainly wouldn't cut a hole in my boat for one, although I have a few times in the past. Most often they are not working properly due to contamination. ...or you put a gallon+ of water in your boat to remove and clean it.
If you know your real SOG and progress toward your destination, you correct what you are doing. You know your boat, you know it does 8 knots at 2400 rpm.... if you are not going 8 knots over ground you know what's going on. Crossing the gulf stream from Biscayne to Bimini, your knot meter has no idea the heavy current is directly abeam... as the current flow is from the side. Your GPS does tell you your COG, you correct accordingly, sailing or motoring.
Knotmeter useful? at times, most often? I don't think so.
Agreed, you definitely do not need one. Most times when I want to make a tactical decision about current my RPM is zero.
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Old 13-01-2017, 19:42   #15
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Re: Buying new instruments, speed paddle, GPS...

I'm a lover of the knotmeter/log. Really care about the speed of the boat through the water so I know if I'm sailing the boat to it's optimum. A GPS is fine for speed over the bottom but way too slow a response to measure sail trim. Also, if you are unfortunate to have a failure of your GPS, the knotmeter can still be used for DR navigation.
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