Nav & Performance Data w/o Through Hull Transducers

The AC boats clearly had no in-water transducers. Moths, same. Olympic boats, same.

So clearly, one need not have thru-hull transducers to compete at the very highest levels.

So who has developed / seen / used a high performance sailing instrumentation system with no thru-hull transducers?

 

El Borracho

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They presumably figure their own speed swamps out current effects, they know the race course has no shoaling, and water temperature is unnecessary. Plus they can afford whatever software tweaks are necessary to compute the numbers they need from other data (GPS, inertial, compass). I have not used it, sorry. But is seems reasonable.

 
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CCruiser

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In my experience one design boats do not use instrumentation that would require thru-hulls.  The one designs I have sailed on had a compass and in some cases a masthead wind indicator. The compass was used to call lifts and headers.  You are sailing against other one design boats, so speed is relative speed not actual speed - are you faster or slower, are you higher or lower?  The rest is strategy and tactics. 

As the prior post pointed out you do not need depth. 

 

Christian

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In my experience one design boats do not use instrumentation that would require thru-hulls.  The one designs I have sailed on had a compass and in some cases a masthead wind indicator. The compass was used to call lifts and headers.  You are sailing against other one design boats, so speed is relative speed not actual speed - are you faster or slower, are you higher or lower?  The rest is strategy and tactics. 

As the prior post pointed out you do not need depth. 
That really depends on what OD.............................

 

Moonduster

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AC50s used GPS SOG for speed as paddle wheels aren't much good when the hull is 1m above the surface of the water. I cannot recall whether they were allowed to use ground-truth augmentation. OD classes use the instrumentation allowed by class rules. Where those rules allow full instrumentation, boats have thru-hull transducers for speed.

 

Christian

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In my experience one design boats do not use instrumentation that would require thru-hulls.  The one designs I have sailed on had a compass and in some cases a masthead wind indicator. The compass was used to call lifts and headers.  You are sailing against other one design boats, so speed is relative speed not actual speed - are you faster or slower, are you higher or lower?  The rest is strategy and tactics. 

As the prior post pointed out you do not need depth. 
Try that out racing e.g. Farr 40 in the Solent or the Chesapeake and you will walk that statement back as fast as you can 

 

rgeek

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Our market research showed:

  • The better the sailor the more fanatical they are about accurate boat speed and staying at target.
  • The differences between classes is down to the philosophy in the class, cost control and each SMOD builders attitude toward equipping the boat.

In terms of one design classes it brakes down like this:

  • Day boats, dinghies: compass only with variations on whether shift tracking is allowed
  • Moth and I14, Viper640, VX One, J24, 50/50 in the SB20 fleet (I'm sure there are others, these are the ones that came to mind): rely on GPS
  • Everyone else: speed from a paddle wheel

As Christian points out Solent and Chesapeake sailors class depth as a must have as they use it to find current relief. Not so much of an issue in Tampa or Dago. The trend in the travelling OD fleets in the US at the moment is towards using a speed only transducer sighting tack to tack differences when using a DST800 with offset paddle. Neither agree or disagree that's just what people are using.

 
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Perhaps I should attack this somewhat differently: the point of information (such as speed through water) is to be able to act in a better way than one could without such information. If actions are not improved, the information is not useful.

There are two common types of transducers: thru-hull for speed (STW), temp, depth, and masthead for wind speed and angle.

Windspeed is clearly pointless: you act based on being overpowered or underpowered, not based on wind speed.

Apparent wind is clearly pointless: its sail trim that matters, and the apparent wind you can achieve is a result of wind and wave, not a target undependent of wind and wave.

So there is certainly no reason for a masthead instrument.

Navigation is about SOG and COG, not STW. You need to take STW and mess around with currents to know what to do. If you just have SOG ad COG, you have the data you need.

So it seems, based on actionable information, there is no reason for a STW transducer, just as there is no reason for apparent wind speed and angle.

Right?

 
Our market research showed:

  • The better the sailor the more fanatical they are about accurate boat speed and staying at target.
  • The differences between classes is down to the philosophy in the class, cost control and each SMOD builders attitude toward equipping the boat.

In terms of one design classes it brakes down like this:

  • Day boats, dinghies: compass only with variations on whether shift tracking is allowed
  • Moth and I14, Viper640, VX One, J24, 50/50 in the SB20 fleet (I'm sure there are others, these are the ones that came to mind): rely on GPS
  • Everyone else: speed from a paddle wheel

As Christian points out Solent and Chesapeake sailors class depth as a must have as they use it to find current relief. Not so much of an issue in Tampa or Dago. The trend in the travelling OD fleets in the US at the moment is towards using a speed only transducer sighting tack to tack differences when using a DST800 with offset paddle. Neither agree or disagree that's just what people are using.
Yes, I see your point, especially in the Solent and Chesepeake, and perhaps SFO: current that is heavily influenced by depth.

And I do feel a bit weird about even thinking about skipping the speed/depth/temp.

But I'm challenging it, because its a new era, and our traditions of using magnetic compasses, paddle wheels, etc. developed when we could not simple immediately get the data we really wanted: VMG, for example.

Are we hanging onto these old fashioned, horribly imprecise with non-linear error transducers, simply because we "always did?"

 
If someone wants accurate boat speed, they don't use thru-hull transducers. If they do, they like to be fooled, because it is just not accurate. Precise, yes. Accurate, no. And the target speeds they are shooting for ignore all the important stuff that is actually going on, so if they do stay fixated on targets, they are mediocre, not good. You don't measure yourself against bogus data. You might consider it, but slavishly following it is really a novice approach, not an expert approach.

 

slug zitski

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If someone wants accurate boat speed, they don't use thru-hull transducers. If they do, they like to be fooled, because it is just not accurate. Precise, yes. Accurate, no. And the target speeds they are shooting for ignore all the important stuff that is actually going on, so if they do stay fixated on targets, they are mediocre, not good. You don't measure yourself against bogus data. You might consider it, but slavishly following it is really a novice approach, not an expert approach.
When you are sailing clear of other boats data is important ...this does not need  to be accurate data.  Only a reference.

without boat speed and angle it is very difficult to determine  your options.

 Particulary downwind when everyone is prone to  holding overspeed angles or when predicting sail choice at a mark rounding 

even flawed data is helpful. 

 
CarCrash -- clearly at this point you are just trying to troll the forum...  You're basically implying that most sailors are fools for using through-hull transducers.  I think the many, many sophisticated sailors who still have a through-hull (and spend $ maintaining/replacing them) are sufficient proof that they are valuable enough. 

As for your comments on apparent wind direction and speed being useless, I think they are laughable -- certainly for apparent wind sailors on multis and fast monos, apparent wind is everything.  For example, on a multi it helps to consider AWS to determine how close you are to being overpowered (e.g. I knew a cat that would religiously lift a hull at 32-33kt apparent upwind -- of course you didn't need instruments to know it was getting hairy, but it helped to tell how close you were, especially in gusty conditions).  And it also helps to have AWD downwind to ensure you're in the right groove (say 90deg), as it only takes 5-10 deg to really kill VMG.  For sure on a smaller boat you can estimate these things mostly by feel, but the bigger the boat, the more the instruments help visualize what's going on as the boats dampen a lot of the sensations.  And I'm not even going to go into how a good wind system helps when sailing at night...

 

rgeek

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If someone wants accurate boat speed, they don't use thru-hull transducers. If they do, they like to be fooled, because it is just not accurate. Precise, yes. Accurate, no. And the target speeds they are shooting for ignore all the important stuff that is actually going on, so if they do stay fixated on targets, they are mediocre, not good. You don't measure yourself against bogus data. You might consider it, but slavishly following it is really a novice approach, not an expert approach.
Quite a lot of different ways that people sail their boats but in general...

Unless you're trying to get an accurate True Wind how ultimately accurate or "true" the speedo is isn't actually all that relevant. The most important thing (for an instrument maker) is to get the speedo responding in a way that correlates with the sailors other senses.

Good sailors learn their speedo. They learn how it responded when the boat was performing well and they use it to identify new levels of performance internalising trim and feel when that happens.

Also the more calculation involved the more lag, the less useful the data is (for speed). No-one that we've come across uses VGM. There's a trend in more powered up assy classes designed to sail with heal to sail downwind on the heal angle indicator rather than TWA i.e. a more immediate response with minimal processing between the sensor and the sailor.

There's also a trend with new classes to leave the mast head unit out altogether.

But we have come across some front of the fleet guys who poo poo using a speedo. They tend to be class experts i.e. they have so much time in the boat they have internalised its feel. Discourage anyone else from using tools that might bring them up to the same level any faster isn't in their interest. The question for everyone else is, do you spend years in the class learning how it feels by luck, trail and error or do you use basic tool that will help you accelerate your learning and keep you on the same piece of water while you do?

The expert experts? The ones who hop from class to class? While they are boatspeed Nazi and use boatspeep to keep them selves as at the top of the performance curve they also keep their instruments simple, focusing on 1 or 2 basic and responsive numbers that keep them honest and then get their heads out of the boat.

 

slug zitski

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When you have the equipment,  you use it.

The stuff is expensive...if you  dont have it, and depending on your boat and schedule  .....you might be better off  skipping the instrument package and purchasing a new genoa  

the folks who most value number are new helmsman...they dont know the boat, the competition  and need  those numbers to help them figure out how to change gears. 

 

RImike

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Are you serious or trying to troll with those statements Carcrash? Thru-hulls play a huge role, especially with someone that understands what the data means.  For example, water temp when doing the Newport to Bermuda race will inform when your in the gulf stream. Differences of SOG vs SOW will tell you if your going with or against current. This is helpful when bouy racing and how you should be positioned with the current.  

About SOG and using only it, most stand alone chart plotters calculate CMG, and people consider it VMG and stand by the numbers like the 10 commandments. The flaw is that logic is the inability to account for water speed or direction under the hull. For boats on foils, this doesn't really matter however a displacement monohull bucking the tide sure does. 

The only time thru-hulls don't work is when they are out of the water, which happens quite often as they are not installed in the proper location and the boat is launching off waves. Move it aft or run dual speedos and the problem is corrected. 

Also windspeed does matter, especially with high end auto pilots which have gust mode which pinch up as the velocity increases and foot as it decreases. 

 
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El Borracho

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Carcrash asked in #1: "So who has developed / seen / used a high performance sailing instrumentation system with no thru-hull transducers?"

Interesting question. Didn't ask about opinions and folklore.

 
Sorry for the phrasing, you are all correct, way too troll-ish. Kinda trying to shock the system: all of us are prone to do what worked before, without as much questioning of "is this still the right thing to do?"

And Daddle nailed it: I have opinions, everyone else has opinions, but I'd like to hear about people who have actually done it, because clearly it has been done (foiling AC), and as foiling becomes more widespread, it will be the new normal.

I'm not exploring this for foiling (yet). But clearly, this is going to need to be solved.

 I'm exploring it now because I'd rather not cut new holes in the bottom and run wires, or add weight aloft and windage, when it seems that the actionable information is not STW, AWA, AWS, but VMG, COG, SOG, and dynamics such as heel, trim, and yaw (especially for autopilot steering).

I consider what I use to steer and trim: the shape of the sails, luffing, tell tales, sheet load, the sea state, disturbed air, hee/trim/yaw and first and second derivatives thereof, helm, and also stuff not measured by instruments: tactics, strategy, and  the competition. None of that comes from masthead or thru-hull transducers.

Boat speed is interesting, in a fuzzy way: hitting the polars is not the correct answer, but as mentioned it can help get oriented in a unfamiliar boat. Wind angle is interesting in a fuzzy way, in that its really in relation to sail trim, sea state, air disturbance, pre/post maneuver, and how the wind is shifting. The wind vane gives only the initial hint, but a useful hint.

Using water temp can detect currents, using a depth finder can help too, but again, these are the indirect and lagging indicators. What is a direct and predictive indicator is sea state, a very precise indicator that can be seen from a distance: tack before you get into negative flow, not after your instruments tell you what you should have already discerned. At sea, a change in VMG is a pretty darn good indicator, as is a change in COG.

So I've convinced myself that it should be possible, but convincing oneself on speculation is a lousy way to make progress. I'd rather hear some actual experience: that's science.

 

slug zitski

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Its up to you...

when I drive my eyes are fixed on compass and tell tales, sails.  

Wind angle gets an occasional glance  ...boat speed hardly ever .

the modern tactical compass is a beautiful tool 

 

RImike

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You answered your own question in the first post, boats on hydrofoils don't use thru-hulls. But they do use mast head units for wind speed/direction. Oracle had their unit on the mast, New Zealand had theirs on the bow sprit/mast. Electronics are good for data logging, especially during distance racing and you will be able to determiner who was fast and who was slow on the helm,  which helps the skipper make appropriate changes to be faster. 

You also still have to remember that VMG uses wind without it is really CMG though I believe Raymarine interchanges the two terms quite often but is that for another thread, you are focusing on the thru-hulls. I know some autopilot brands will automatically switch over to SOG if SOW is lost. This generally happens is really rough sea state or high speeds, that is why you will see boats with twin thru-hulls, one port the other starboard about 2/3's of the way aft from the bow and out, think in front of the rudders on the Class 40's. 

But alas, to answer your question on the foiling boats, specifically a maxi trimaran for reference on foils. Two GPS antennas are used, each positioned on the sterns of the armas (one on port the other on starboard). They then feed into a 3D hull sensor which calculates boat's position from GPS, and then reference each other to achieve heading. The 3D hull sensor not only measures roll, pitch and heal but also acceleration along the X,Y and Z axis. All this data of boat speed and heading drives a brain which also controls the attitude and altitude of a the foil system to properly "fly" the boat. Consider however that wires will still need to be run as well as sensors mounted on the deck. This is also how the ETNZ boat was setup which told the person flying the boat where it was and where it should be. 

 




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