carcrash

Nav & Performance Data w/o Through Hull Transducers

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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?

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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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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. 

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6 hours ago, CCruiser said:

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.............................

 

 

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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.

 

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22 hours ago, CCruiser said:

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 

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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?

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1 hour ago, rgeek said:

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?"

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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.

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2 hours ago, carcrash said:

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. 

 

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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...

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3 hours ago, carcrash said:

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.

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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. 

 

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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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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.

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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.

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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 

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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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Some of the stuff that has come up on Lioness's calibration page could make a through hull speed transducer obsolete. Mounting a high precision GPS on the bow and stern of a boat and then using some complicated filtering/averaging/magic one can come up with boat heading, which then can be used to calculate current speed and direction. This would remove my need for STW and Depth from a current perspective. However on the Cheapeake I would much rather have a depth display than a speed display simply to keep me from trying to get just a little further out of that current and sticking the boat in the mud. 

I have no need for AWS or AWA apart from a windex at the top of the mast, and I mostly use that for mark roundings and very light flukey conditions. 

Perhaps you could mount a flush, wireless depth sounder to the bottom of a foil? 

 

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1 hour ago, Mizzmo said:

Some of the stuff that has come up on Lioness's calibration page could make a through hull speed transducer obsolete. Mounting a high precision GPS on the bow and stern of a boat and then using some complicated filtering/averaging/magic one can come up with boat heading, which then can be used to calculate current speed and direction. This would remove my need for STW and Depth from a current perspective. However on the Cheapeake I would much rather have a depth display than a speed display simply to keep me from trying to get just a little further out of that current and sticking the boat in the mud. 

I have no need for AWS or AWA apart from a windex at the top of the mast, and I mostly use that for mark roundings and very light flukey conditions. 

Perhaps you could mount a flush, wireless depth sounder to the bottom of a foil? 

 

There is NO WAY to calculate BS (boat speed through the water) without a speedo - no matter how hard you try.  The derivative of this is that there is no way of calculating/seeing the set/push from current without a speedo

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AWA and TWA become more important when you are short-hand racing and you want your pilot to stay on a point of sail rather than a simple heading. TWA downwind sailing lets me fly my A2 in 15-18 knots single-handed, which I would not be able to do as easily without the AP keeping that deep angle.

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On 2/19/2018 at 12:15 AM, rgeek said:

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.

That - and stay off the sandy/muddy/hard bits

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7 hours ago, Christian said:

There is NO WAY to calculate BS (boat speed through the water) without a speedo - no matter how hard you try.  The derivative of this is that there is no way of calculating/seeing the set/push from current without a speedo

Didn’t say anything about Speed through the water. But as discussed in the referenced thread it may be possible to calculate current. In general if I know the current and SOG, I don’t really have a use for STW.

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7 hours ago, Christian said:

There is NO WAY to calculate BS (boat speed through the water) without a speedo - no matter how hard you try.  The derivative of this is that there is no way of calculating/seeing the set/push from current without a speedo

If one knows everything else with reasonable accuracy on two tacks then current is the residual (unaccounted for) vector. Maybe.

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1 hour ago, daddle said:

If one knows everything else with reasonable accuracy on two tacks then current is the residual (unaccounted for) vector. Maybe.

Nope.  You can make guesses but nothing more.  And that only works if you are going to windward with a fairly frequent tacks

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1 hour ago, Mizzmo said:

Didn’t say anything about Speed through the water. But as discussed in the referenced thread it may be possible to calculate current. In general if I know the current and SOG, I don’t really have a use for STW.

But - you don't know the current or your boatspeed sooooooo

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1 hour ago, Christian said:

Nope.  You can make guesses but nothing more.  And that only works if you are going to windward with a fairly frequent tacks

It would not be a guess. It would be calculated. If the boat has a course component that is not accounted for in classic calm water sailing - pehaps known from careful calibration - then that component must be current.

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If you are concerned about OD racing in the types of boats you mentioned, (Moths and Olympic Classes) then my comments addressed that question - they do not need thru hulls because they do not need the information that thru hulls provide (e.g. BS and Depth).  That is also true of the OD class boats I have owned and sailed on.  But there have always been two approaches to sailing such boats when you get in the 20'-30' range.  You have the big boat sailors (e.g. such as Christian on the the Farr 40) who are use to having the information, (AWA, TWA, BSP, SOG, COG, Depth etc), provided them by electronics and so used what they were use to when they move down to smaller OD classes; and those sailors who are moving up from dinghy classes, who are not and so do not use electronics, but rather have their head out of the boat, and understand that they are racing the other boats, not data.  As you note in one of you latter comments they race the boat, use a compass for lifts and headers, depend on tide tables and charts for tidal information on the course, and look to the other boats for speed and sail set/angle.  I have never raced Moths, (as you note as a planing boat they have little use for thru hulls) the fasted boat I have raced is a Melges 24 I owned for 7 years - none of the top guys in that class had thru hulls, none of them, and we are talking about some of the best sailors in the world.. They had compasses.  You would find the occasional guy moving down who loaded up with instruments, but they never did well, if ever, until they stopped depending on instruments and began racing the boat and the fleet.  As I said the OD's I have raced have not needed thru-hulls.

So it depends on what you are racing, and the type of racing you are doing - small boat (30' or under) OD fleet racing, or larger offshore or even inshore distance racing. (We had a 30' OD that had no thru hulls which we race inshore, in fleet.  Occasionally we raced it off shore, the longest being the Encinal Race - San Francisco Bay to Santa Barbara - we took a portable GPS and a handheld VHF to pick up weather forecast/conditions. 

So different boats, different types of sailing, no one correct answer.  However, I must say I enjoyed the small boat OD fleet racing, it was just more "in tune" with pure sailing, but that's a personal feeling.   

   

 

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11 hours ago, Christian said:

That - and stay off the sandy/muddy/hard bits

always a challenge

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In my experience (so yours might be different), depth is rarely useful. Rare, but sometimes very useful.

The entire Gulf Coast and East Coast up to, say, Long Island, its been sometimes essential. West Coast, Pacific, Caribbean, Europe (including Solent racing), not used.

As I mentioned before, in my experience, its MUCH better to read the current visually than guessing based on depth or temp or other indirect methods that providing lagging, rather than leading indication. Especially at sea, around islands when its too deep, and when tides a changin’. VMG is the important actionable data, again, in my experience. I dont care about the precise current, I decide based on if its faster or slower, and where else its better or worse.

Rarely consider when anchoring, as just observing the stripes on the rode when the anchor hits bottom is easier, less error prone, and the person on the bow can see it exactly when they need it.

The case where depth is really needed is when finding a way through shallows. Looking straight down is a very poor way to figure out which way to go. Forward looking sonar is a waste of time in practice, as you need to go slow you mght as well swim ahead of the boat with a leadline?

I think a drone will be the effective approach: survey well ahead of the boat to discover the appropriate course. Altitude hold while flying a zig zag pattern whils suspending a depth transducer, kinda like the sub chaser helicopters. Seems plausible, somebody has probably done this. Anyone hear of this approach yet?

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2 hours ago, carcrash said:

In my experience (so yours might be different), depth is rarely useful. Rare, but sometimes very useful.

The entire Gulf Coast and East Coast up to, say, Long Island, its been sometimes essential. West Coast, Pacific, Caribbean, Europe (including Solent racing), not used.

As I mentioned before, in my experience, its MUCH better to read the current visually than guessing based on depth or temp or other indirect methods that providing lagging, rather than leading indication. Especially at sea, around islands when its too deep, and when tides a changin’. VMG is the important actionable data, again, in my experience. I dont care about the precise current, I decide based on if its faster or slower, and where else its better or worse.

Rarely consider when anchoring, as just observing the stripes on the rode when the anchor hits bottom is easier, less error prone, and the person on the bow can see it exactly when they need it.

The case where depth is really needed is when finding a way through shallows. Looking straight down is a very poor way to figure out which way to go. Forward looking sonar is a waste of time in practice, as you need to go slow you mght as well swim ahead of the boat with a leadline?

I think a drone will be the effective approach: survey well ahead of the boat to discover the appropriate course. Altitude hold while flying a zig zag pattern whils suspending a depth transducer, kinda like the sub chaser helicopters. Seems plausible, somebody has probably done this. Anyone hear of this approach yet?

I am not lending you my boat.

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4 hours ago, carcrash said:

In my experience (so yours might be different), depth is rarely useful. Rare, but sometimes very useful.

The entire Gulf Coast and East Coast up to, say, Long Island, its been sometimes essential. West Coast, Pacific, Caribbean, Europe (including Solent racing), not used.

...

I think a drone will be the effective approach: survey well ahead of the boat to discover the appropriate course. Altitude hold while flying a zig zag pattern whils suspending a depth transducer, kinda like the sub chaser helicopters. Seems plausible, somebody has probably done this. Anyone hear of this approach yet?

CarCrash, I appreciate the fresh thinking, but you really are stretching reality...  Not needed in West Coast?  San Francisco Bay: multiple places to ground on shallows -- just happened to an F31 a few weeks ago around Angel Island (nothing bad), happens a lot in the Delta Ditch race, etc.   In the Pacific?  Try sailing in the Philippines without a depth sounder...  Same in Europe.  Also helps at night when you're in shoaling waters to avoid tricky wave situations.  And depth helps you properly adjust anchoring scope.  I could go on.

As for replacing the trusty depth sounder with a drone -- you're right visual nav between reefs would be helpful, but that's way complicating things.  There are other ways (stand on your boom or bow).

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Depends on your style of sailing, and what you are trying to do I guess.

A depth sounder is probably the first instrument you should have, though arguably an accurate chartplotter/GPS can to some extent tell you what your depth is supposed to be, it won't show the silting, and effects of wind on changing the actual water depth from the soundings taken sometime in the last millenium. 

Even is you are one design sailing, there are times/places  when you may not have a tuning partner, or you want to give the helm general directions to tack at XXX degrees/second and hold a heading of YYY TWA until speed builds to ZZZ and then climb up to target TWA and BSP based on accumulated testing. If you know the TWS and the AWS and the likely courses, you can make better sail selections, and have the correct one on deck at the mark. 

Some times the boat just feels wrong, and if you are not sure why, a quick scan at the calibrated instruments may show that you are slow for the wind angle, or that you have excessive leeway or more heel that expected, since the crew went on a diet. 

For those who don't sail multiple times a week, keeping the feel is hard, but having numbers that tell you when you are close is easier. If your boat is slow and heavy, then even more so. Knowing it's going to take 45 seconds to go from 2 - 5 kts at 8 Kts TWS keeps you from trying to pinch. 

 

your sailing will vary

 

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The way the electronics are packaged  speed and depth come together in one thru hull.

the compass is my most  important steering aid ...the units that mount on the back of the mast   Allow your eyes to do the most looking around.

i could sail with only a compass.

In general i find instruments distracting at night...to much light pollution.

less is best  

 

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On 2/19/2018 at 8:15 AM, rgeek said:

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.

Small OD, generally the course would be set in an area that is as consistent as possible.    Boats are generally close together and you (as a skipper/crew) are measuring your relative performance against the other boats.

The bigger the boat, the bigger the course, the more opportunity for having current variations.    I have sailed over multiple decades in Tampa Bay and there are very significant tides and currents that both, one: local knowledge and two: detection can take advantages of the pluses and minimize the negatives.

Racing cats and foiling vessels can get away with measuring their speed solely from GPS, as the effect of tide and current is less than %1 of the boat speed.   4-6ksbs on the other hand, can have a significant impact from tides.   I race on a S2 9.1 that uses a Pro Start for the boat speed.   When you start to see that you have 10-20% speed difference with the same trim on different tacks, you probably got a foul current on the slower board.     Having a functioning paddle wheel knot meter onboard would help show a foul current almost instantaneously by the differential between boat speed and speed over the bottom, as it would speed up the recognition of the condition, rather than the momentary questioning, 'Is the jib all the way in?'

Detecting current and direction becomes even more helpful in point to point sailing on the Bay, as you have more opportunity to steer a course to enhance a favorable current or to steer to a shallower part of the bay to dodge a foul current.   In lighter air, that becomes even more important.

- Stumbling

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5 hours ago, slug zitski said:

The way the electronics are packaged  speed and depth come together in one thru hull.

the compass is my most  important steering aid ...the units that mount on the back of the mast   Allow your eyes to do the most looking around.

i could sail with only a compass.

In general i find instruments distracting at night...to much light pollution.

less is best  

 

Sometimes yes - sometimes no - depends on the brand / setup

 

I guess you dont race - or win too many races - nor sail in areas with tricky bits to avoid.  Statements like the one you make and posting it like universal truth is beyond laughable

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26 minutes ago, Christian said:

Sometimes yes - sometimes no - depends on the brand / setup

 

I guess you dont race - or win too many races - nor sail in areas with tricky bits to avoid.  Statements like the one you make and posting it like universal truth is beyond laughable

Well...we can compare  sailing resumes !!! 

And i guarantee that you will come out looking like a little boy in short pants 

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2 hours ago, slug zitski said:

Well...we can compare  sailing resumes !!! 

And i guarantee that you will come out looking like a little boy in short pants 

Keep dreaming

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15 hours ago, stumblingthunder said:

Small OD, generally the course would be set in an area that is as consistent as possible.    Boats are generally close together and you (as a skipper/crew) are measuring your relative performance against the other boats.

The bigger the boat, the bigger the course, the more opportunity for having current variations.    I have sailed over multiple decades in Tampa Bay and there are very significant tides and currents that both, one: local knowledge and two: detection can take advantages of the pluses and minimize the negatives.

Racing cats and foiling vessels can get away with measuring their speed solely from GPS, as the effect of tide and current is less than %1 of the boat speed.   4-6ksbs on the other hand, can have a significant impact from tides.   I race on a S2 9.1 that uses a Pro Start for the boat speed.   When you start to see that you have 10-20% speed difference with the same trim on different tacks, you probably got a foul current on the slower board.     Having a functioning paddle wheel knot meter onboard would help show a foul current almost instantaneously by the differential between boat speed and speed over the bottom, as it would speed up the recognition of the condition, rather than the momentary questioning, 'Is the jib all the way in?'

Detecting current and direction becomes even more helpful in point to point sailing on the Bay, as you have more opportunity to steer a course to enhance a favorable current or to steer to a shallower part of the bay to dodge a foul current.   In lighter air, that becomes even more important.

- Stumbling

The problem with just lining up against the boats nearest to you is that you only get to make an incremental measure/improvement against those around you. And you don't know whether they're actually sailing well! Not good unless you can line up against the class hero and can hold onto them for a sustained period it's hard to make the performance gains/sustain the performance needed to hit the front.

Ed was really hot on us putting a comparison of SOG and STW into the d10 so there's a tide-depth page that has SOG/STW comparison together with boatspeed and depth. Or you can bring that info off to the phone APP and leave the boatspeed, heading and heal angle on the mast display.

I went back and reread some of the verbatums on the yes or no on the paddle wheel. How the boat is sailed in terms of crew configuration seems to have a lot to do with it.

The bigger the boat the more specialised the roles are, the higher the standard to which individual roles are performed, and the greater the demand not just for boatspeed but for 2 digit boat speed. Talent and weight distribution being equal a helm and trimmer out perform one person doing both. The question is to what degree compared to weight on the rail? And 20-30ft is right at that cross road.

A class like the Melges 24 where every one is hitting the straps bar the helm lends its self to the talents of dinghy sailors (J24 would be another example). What Slug is referring to is the tendency for a helm that's also trimming or that comes from a single handed background to put all their focus on boat speed and sail the compass for tactics. That'll only get you so far when the other boats are head-up shut up and drive. At some point it's worth swinging a pair of legs in to get the advantage of two people driving the boat. The 2-in-2 out rule in the j/70s, or the legs in Melges 20/SB20/Viper640 puts a different take on things too.

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7 hours ago, rgeek said:

The problem with just lining up against the boats nearest to you is that you only get to make an incremental measure/improvement against those around you. And you don't know whether they're actually sailing well! Not good unless you can line up against the class hero and can hold onto them for a sustained period it's hard to make the performance gains/sustain the performance needed to hit the front.

Ed was really hot on us putting a comparison of SOG and STW into the d10 so there's a tide-depth page that has SOG/STW comparison together with boatspeed and depth. Or you can bring that info off to the phone APP and leave the boatspeed, heading and heal angle on the mast display.

I went back and reread some of the verbatums on the yes or no on the paddle wheel. How the boat is sailed in terms of crew configuration seems to have a lot to do with it.

The bigger the boat the more specialised the roles are, the higher the standard to which individual roles are performed, and the greater the demand not just for boatspeed but for 2 digit boat speed. Talent and weight distribution being equal a helm and trimmer out perform one person doing both. The question is to what degree compared to weight on the rail? And 20-30ft is right at that cross road.

A class like the Melges 24 where every one is hitting the straps bar the helm lends its self to the talents of dinghy sailors (J24 would be another example). What Slug is referring to is the tendency for a helm that's also trimming or that comes from a single handed background to put all their focus on boat speed and sail the compass for tactics. That'll only get you so far when the other boats are head-up shut up and drive. At some point it's worth swinging a pair of legs in to get the advantage of two people driving the boat. The 2-in-2 out rule in the j/70s, or the legs in Melges 20/SB20/Viper640 puts a different take on things too.

I agree with you about the specialization on bigger boats.   It can get to the point that you have a dedicated navigator, watching the numbers and a tactician recognizing the numbers and calling out options on the course.   You then have to have really accurate, well calibrated, instruments to give good data for the specialists to have something useful to say.   Accuracy is something that is very hard to come by in sailing instruments and can futz up the operation of a lesser crew if it is inaccurate.  

The opposite is that there can be too much focusing on instruments, to the detriment of situational awareness.   It is all a balance.   Some folks can Jedi a helm, others can't do a thing without having readouts and dials to tell them what reality is.

- Stumbling

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Well calibrated being the tripper.

Will be interesting to see if we can get meaningful port/starboard splits courses out of the d10 with out a mast head.

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Not calibrating your instruments leaves them at best precise, qualitative indicators like making trees or bearing  on the competition. 

Akin to sailing against the same local fleet, you know your relative performance, not your absolute.

Installing, calibrating and using good instruments allows you to compare to absolute standards such as VPP Polars, where you can begin to understand your performance and the variables that affect it. As you record, analyze and find best/worst practices, for trim, tacking etc, you should develop better speed, acceleration and course keeping skills. The boat will metaphorically progress from single speed, to multiple speed to automatic transmission, as the crew and helm learn to switch modes with minimum prompting. 

That won’t totally compensate for a foul bottom, worn sails, an overloaded boat or distracted skipper, it will show plateaus, when you take out the available deficiencies and realize to get the last percent you need to make other changes. 

If you have a unique vessel, race with variable conditions and crew, having good target numbers is a start on recognizing tuning & steering problems. The first priority of good tactics is to have good speed. 

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