The big Speedometer

[Crikey]

Wouldn't that then be more accurate than a mechanical paddle wheel device?

Can you give me a manufacturers reference of some sort? It sounds like I would have to install more than one through hull device in order to achieve this...

[mastreb]

Wouldn't that then be more accurate than a mechanical paddle wheel device?

Can you give me a manufacturers reference of some sort? It sounds like I would have to install more than one through hull device in order to achieve this...

Yes, they are more accurate. Here's an example: http://www.blueheronmarine.com/servlet/Detail?no=6730

I appear to be a little obsolete in my information--I have found some high-end NMEA 2000 senders that are speed, temp, _and_ depth, with the speed being calculated as I describe by the sensor rather than in the head unit. They're a bit more than other sensors but might be worth it to reduce through-hull penetrations depending on what kind of trons you have.

This is the one I'd buy if I didn't already have depth: http://www.maretron.com/products/dst100.php

It's called a "triducer" because it has two transducers necessary for the speed calc and a third separate one for depth. Nice unit.

[Crikey]

Just the ticket Matt! I'm already sold on the Maretron wind sensor, and with this everything will hang nicely off the NMEA2000 bus.

Now if I can talk the Admiral out of those curtains for x-mas, things could be looking pretty good come next spring.
Anyone got any software ideas for displaying speed data as a running graph line? I run a pc computer on board, not a dedicated manufacturers box.

Ross

[mastreb]

Anyone got any software ideas for displaying speed data as a running graph line? I run a pc computer on board, not a dedicated manufacturers box.

I'm trying to visualize how this would work. If I was pulling ideas out of the ether, what I'd really want is a running "log" of "what I just did" as "tags" on the graph--so, for example, you'd see "reefed, heel 20%" tagged to the ramp line from 4.5 knots to 5.0 knots. Otherwise just having a graph that I can't relate to actions wouldn't be of much help to me.

So I think what I'd want to see is a speed graph that is "callout tagged" with other sensor data lines at the beginning and end of each speed transition.

The only thing I can imagine for attaching actions is to have a running vocal recording, perhaps imported from a smartphone, that would be time sync'd to the graph, so that at any point in the graph you could click to hear whatever you had said at the time. You'd call out your actions as you did them to then reference what you were doing that accomplished significant improvements on the graph.

This would not be difficult software to write or have written, any decent programmer could do it. If you had something simply text logging NMEA events, Microsoft Excel or Access could be used to trivially create the graph. The audio overlay is the only thing even remotely hard to accomplish.

But I don't know of anything existing that could do it.

[Crikey]

Yeah, I thought about the Excel spreadsheet thing too, but not sure at present that the nmea data from a speed sensor talks in the right language for an input there. The voice tag is interesting but probably overkill for my purposes. A running line graph history would simply show an increase, or decrease in water speed and serve the tuning aspect well enough. A spreadsheet could probably take a keyboard tag but I think too many variables are attached to a single adjustment.For instance: a mainsheet adjustment can jointly incorporate a traveller position as well as an outhaul retensioning. Take another boat heading relative to the wind and the intermix would be different. You'd go nuts afterwards trying to make sense of everything!
Simply trying to keep a graph line in its highest range, would be good enough.
Can you write nmea based excel macro's Matt?

Ross

[mastreb]

Can you write nmea based excel macro's Matt?

Sure--but what are you using to capture data? A USB-N2K adapter on a PC? If you can get me a datalogger dump of NMEA2K sentences, I'll work out an Excel macro for it.

I haven't yet found any software to directly datalog NMEA 2000 without first converting the sentences to NMEA 0183, which will loose all kinds of interesting data. There are three NMEA 2K-USB devices on the market, so perhaps just a USB capture application would be the right way to go.

Anyway, if you find a way to datalog it, working out the charting is simple.

[KevinB]

I'm an offshore racer and I don't see a Mac in my future, but the answer I've seen is;

The speed through the water as provided by a paddle wheel, etc is used to judge sail trim. If you make an adjustment, you need to know how much faster or slower the boat is moving through the water as compared to it's speed before you made an adjustment. (Raised the traveler, adjusted a sheet, etc.)

If you know the position of the next mark, then GPS VMG is the most valuable measurement for telling you how you're doing towards the next mark. It will catch you off guard when you tack and find yourself making much better or worse way towards the mark than you expected due to conditions. GPS speed and GPS Course over Ground are next, if you don't have the position of the next mark, and they're useful either way. The reason GPS is so much more useful is that it tells you what angle you're actually sailing and how quickly you're closing on the next mark regardless of any current or wave action which might be setting the boat off course.

So, the answer, in my mind is you need the paddle wheel to tell you how well you're pushing the boat through the water and the GPS for everything else.

A wind instrument is a damn good idea, principally because you can adjust your sails based on wind speed and angle and decide when to change headsails or hoist/douse a chute. But it's expensive and for a trailer sailor you're always going to have to worry about damaging it or it's wire when you lower the mast....

[mastreb]

Kevin, excellent points, and please do continue to check in Mac or no. I lack the experience to qualify your points but certainly which "speed" is best is dependent upon exactly what you're attempting to accomplish by knowing it.

As for the wind instrument, it's doubly complicated on the Mac because it cannot go atop the mast, which would be the obvious place, due to the mast rotation. I will say that in anything beyond light air, the stern position where I first mounted mine does not work. With the traveler to windward, spill from the sails kills the accuracy.

With the wind instrument below the masthead, there is some point of sail where the instrument will be affected by sails and therefore inaccurate. The question becomes "where do I not need accuracy?" and the answer is "when running." So, I'm moving mine to the bow pulpit on a 5' forward pole. This way my hope is that I'll have accurate true wind at all points of sail forward of a beam reach, which is where I need accuracy for pointing.

The mount I'm using to lower it works well and I'm not worried about damage as it's a solid state transducer-based device. I've already trailered it a number of times and there's no issue with that. There's no way a traditional anemometer would work unless you took it off completely when trailering.

We shall see, and I will post.

[KevinB]

Thank you mastreb,

I only posted because I'd been lurking here for years and I'd finally seen a post I was qualified to answer. If I owned a Mac, I would use if for fun. Poking into shallow spots with my family. It looks like a real sweet spot boat for inland lakes and the like. But there's really no reason to put a wind instrument on it. It's not going to point and it's never going to win a race, unless it's racing against other Macs........ (Which might be fun...)

I read this forum because you guys remind me of what yachting is supposed to be all about. Fun and f^^^^^ing around on boats.

--Kevin--

[mastreb]

But there's really no reason to put a wind instrument on it. It's not going to point and it's never going to win a race, unless it's racing against other Macs........ (Which might be fun...)

Kevin--firstly, your 100% right about the use of a Mac. It's on one hand a compromise boat, but on the other a capability boat--capability to sleep my family, capability to shallow water sail, capability to beat a storm, capability to beach. What's it's not is a racer (but then I drop my ETEC-60 and beat you to the restaurant by 45 minutes after you beat me racing).

One reason to have a wind instrument: The Admiral. Way easier for her to point by numbers, so to speak. Other reason is I'm a data guy and I want to know, not guess, how I'm pointing.

My first boat was a true racer, a Columbia Sabre 5.5 meter olympic race class. Hella fast under sail, we were literally never passed in San Diego bay by anything excepting the Stars & Stripes.

But I never learned to sail. Hoist, point, go. Simple. I didn't have to learn _anything_ about how to point that boat to make it go fast. I spilled air by heeling, I didn't even know what the word "reef" meant. Never rigged the vang, never put up a different foresail beyond the hank-on 110, rarely even winched in the jib. The thing pointed to 30 degrees, so both my SOG and VMG kicked ass. The keel was so heavy and the rudder so deep that I routinely sailed back into my slip without the motor even down--I could drop sail 100m from my slip and slide it in under pure momentum. I do miss it.

It was like driving an automatic Mercedes Benz AMG and thinking that my $120K makes me a good driver.

The Mac has really taught me how to sail, and while I've got a lot left to learn, I now know that I could really kick ass on a race boat. Now I know how to troubleshoot. I know why speed just dropped off. I know what it feels like to take the wrong tack and to make a bad pointing decision. I can feel the current underneath me and the wind above me.

It's like driving a Subaru WRT and doing your damnedest to keep up with that AMG, and having him look at you in his rear-view while you're drafting him and saying "sh~t, that guy might just catch me!"

[Crikey]

Thank you mastreb,

I only posted because I'd been lurking here for years and I'd finally seen a post I was qualified to answer. If I owned a Mac, I would use if for fun. Poking into shallow spots with my family. It looks like a real sweet spot boat for inland lakes and the like. But there's really no reason to put a wind instrument on it. It's not going to point and it's never going to win a race, unless it's racing against other Macs........ (Which might be fun...)

I read this forum because you guys remind me of what yachting is supposed to be all about. Fun and f^^^^^ing around on boats.

--Kevin--

Kevin, don't sell yourself short! We have many so-called 'lurkers' here without Mac's or boats and certainly, with your background, your point's of view are going to be appreciated by many.
As for racing - Mac to Mac, is of course the ideal. Maybe some day the famous blue hull vs white hull conjecture will be put to rest (it's blue!). Having said that, it's also about acknowledging the handicap (like horseracing), and putting the 'big boys' to task. Like I, and Matt said about an extra gizmo to us, as a training aid as well as an extension of our 'tinkering' genes, it's just another quest for the holy grail. We never find it, but the thrill of the journey is why we do it.

Regards .... Ross

[bscott]

Tel tails placed about 8' high on the upper windward shroud will give you a very good idea of the apparent wind-simple, cheap and ez to use

I haven't use a mast head windex for 30 years--too hard on the neck and the birds love them

Bob

[DaveB]

Sounds like you need a Iphone 4 with a Chart App.
Just came back from a 3 day cruise. The Chart App ($18) pin pointed me all the way on Natical charts with speed,route,Sat. land location,tides and much more.
All buoys were dead on except one with a 150 ft. diffrence. I compared the Iphone with my GPS. same results.
Just another backup plan.
You don't need sonar when you are pin pointed in depth of water.
Dave

So many posts dealing with sail trim, ballasting, methodology etcetera - etcetera - etcetera ..... all to squeeze that extra half knot or so (particularly while racing another synaptically challenged skipper!).
I would like to work towards the big digital cockpit readout to help out my old career burnt eyes (retired), and be able to tell at a glance what is helping, and what is not. Problem is there are three methods that I can see that produce this data - stern paddle wheel, gps and sonar transducer.
Should I have all three for some kind of joint switchable coverage? Or does one kind give a more immediate, and consistent picture of what's going on than the others?

Challenged

[mastreb]

You don't need sonar when you are pin pointed in depth of water.

Yeah, that how navy subs hit new volcanos. Sandbars shift, wrecks appear. I'll keep my sonar, thanks!

[Catigale]

I read this forum because you guys remind me of what yachting is supposed to be all about. Fun and f^^^^^ing around on boats.

Says it all. I love having both waterbago capability but hop into a dinghy for my sailing fix...usually a harpoon