DIY Boat­ing

Which MFD?

Boating NZ - - Contents - BY NOR­MAN HOLTZHAUSEN

Marine elec­tron­ics have evolved spec­tac­u­larly in the past 70 years. It was the clever Ja­panese broth­ers, Kiy­otaka and Kiyokata Fu­runo, who in 1948 de­vel­oped a de­vice for de­tect­ing fish un­der­wa­ter. Their small elec­tron­ics firm, based in Na­gasaki, com­mer­cialised this rev­o­lu­tion­ary tech­nol­ogy. Ini­tial de­vices printed out the sonar trace on a strip of pa­per, be­fore small CRT tubes be­came prac­ti­cal and an on-screen dis­play be­came the stan­dard. The com­mer­cial avail­abil­ity of LCD dis­plays in the 1970s fi­nally al­lowed the cre­ation of slim dash­board-mount­able units that con­sumed rel­a­tively lit­tle power.

Sim­i­larly, it was the US mil­i­tary which de­vel­oped the fore­run­ner of the mod­ern GPS sys­tem. Once the net­work was opened up for civil­ian use in the 1980s, a wide range of de­vices were de­vel­oped to ac­cess the tech­nol­ogy and ac­cu­rately fix your po­si­tion on the globe.

Early units sim­ply pro­vided lat­i­tude and lon­gi­tude co­or­di­nates, which would then be man­u­ally plot­ted on pa­per charts. The marine elec­tron­ics in­dus­try ac­cepted the chal­lenge to de­velop the real-time plot­ting soft­ware, over­lay­ing these co-or­di­nates on gov­ern­ment or­di­nance charts to pro­duce the de­vice we now know as a chart­plot­ter.

And yet, un­til rel­a­tively re­cently, these two core boat­ing func­tions were usu­ally on sep­a­rate, ded­i­cated, de­vices. Other nav­i­ga­tion tech­nol­ogy such as radar and AIS (Au­to­matic

Iden­ti­fi­ca­tion Sys­tem, where the ves­sel ac­tively broad­casts its own po­si­tion to other ves­sels) each re­quired their own dis­play.

Added to this could be in­di­vid­ual dis­play units for en­gine mon­i­tor­ing, sound sys­tems and video mon­i­tor­ing. It is not un­usual for a com­mer­cial ves­sel (or even a larger recre­ational one) to have four or even more screens in­stalled at the helm.

But most boats do not have the lux­ury of this much space. Also, although the in­for­ma­tion shown on the dis­play may be quite dif­fer­ent in each case, the ba­sic tech­nol­ogy of the screen it­self is the same for all these func­tions.

It did not take long be­fore con­sumers be­gan to de­mand multi-func­tion dis­plays, which can be switched between the var­i­ous el­e­ments as re­quired. As screen res­o­lu­tion and sizes in­creased it also be­came pos­si­ble to split the screen in two, four or even six zones, each dis­play­ing a spe­cific type of in­for­ma­tion.

As the soft­ware im­proved it was also pos­si­ble to over­lay

...with a bet­ter un­der­stand­ing of the tech­nol­ogy you can weigh up the fea­tures you re­quire...

data, so it is now com­mon, for ex­am­ple, for chart­plot­ter, radar and AIS data to all over­lay on the same marine chart, of­ten with a con­toured 3D dis­play op­tion as well.

Sim­i­larly, new sonar tech­nol­ogy means that tra­di­tional down-fac­ing sonar can be com­ple­mented with side-scan­ning and for­ward-fac­ing beams, to give a full three-di­men­sional im­age of what lies be­neath the boat as well as all around.

So how does a boatie choose what to buy when faced with this plethora of op­tions? To add to the con­fu­sion, each man­u­fac­turer uses its own pro­pri­etary tech­nol­ogy, dis­plays the end re­sult in a dif­fer­ent way and calls it some­thing dif­fer­ent.

We’ve tried to es­tab­lish what the ter­mi­nol­ogy ac­tu­ally means, and ex­plore the con­sid­er­a­tions for those with more than one helm sta­tion. No ar­ti­cle can pro­duce a rec­om­men­da­tion for every ves­sel, but with a bet­ter un­der­stand­ing of the tech­nol­ogy you can weigh up the fea­tures you re­quire, the dash space you have avail­able, and the bud­get you have to work with.


MFD Multi-func­tion dis­play. This is the ac­tual screen you see. These range in size from 5-inch to 16-inch, and even larger for com­mer­cial mod­els. Smaller screen sizes are more likely to be sin­gle-use units (such as a fishfinder or chart­plot­ter, or both), while the larger mod­els will sup­port mul­ti­ple func­tions depend­ing on what in­puts are pro­vided.

Screen size This is al­ways mea­sured across the di­ag­o­nal, and most screens have a 4:3 ra­tio i.e. the screen is wider by about a third than its height. How­ever, some man­u­fac­tur­ers also pro­duce 5:3 ra­tio screens, which lend them­selves to being split ver­ti­cally into two sec­tions, such as chart­plot­ter and fishfinder.

Touch­screen Touch ca­pa­bil­ity is now stan­dard on al­most all ex­cept the very small­est mod­els, but for open run­abouts where the helm sta­tion can get wet you should con­sider a unit which pro­vides but­tons as well. Trying to op­er­ate a touch-sen­si­tive

screen is nigh-on im­pos­si­ble when your hands are wet and the boat is bounc­ing around.

NMEA-2000 De­vices ‘talk’ to each other over ei­ther a pro­pri­etary eth­er­net con­nec­tor, or the in­dus­try­s­tan­dard NMEA-2000. To share high-res­o­lu­tion im­ages like charts and sonar data between two screens you gen­er­ally re­quire an eth­er­net con­nec­tor, and so the MFDS gen­er­ally need to be of the same brand although not nec­es­sar­ily the same model.

What NMEA-2000 al­lows is the ex­change of nu­mer­i­cal data between dif­fer­ent types of de­vices, and al­lows, for ex­am­ple, the dis­play of en­gine and fuel data on the same screen as your chart­plot­ter.

SONAR The tech­nol­ogy used by fishfind­ers. Trans­mits a burst of high-fre­quency sound, then mea­sures the echo. Lower fre­quen­cies (50Hz is com­mon) have a greater range but are less good at iden­ti­fy­ing in­di­vid­ual fish. High fre­quen­cies (200Mhz) pro­duce bet­ter res­o­lu­tion but don’t reach as deep. Al­most all fishfind­ers avail­able to­day, apart from the bud­get mod­els, are at least dual-fre­quency, and many of them of­fer ad­di­tional op­tions.

Trans­ducer The part of the fishfinder that sits in the wa­ter, trans­mits the sound and de­tects the echo. Ar­guably the most im­por­tant part of a fishfinder and the dif­fer­ence between a qual­ity trans­ducer and a cheap one can be quite star­tling.

The best place­ment of the trans­ducer on the hull is a whole sub­ject in it­self. Note most man­u­fac­tur­ers of­fer sev­eral trans­ducer op­tions for each of their dis­plays, depend­ing on the in­tended ap­pli­ca­tion. Most stan­dard trans­duc­ers, re­gard­less of the brand name on the box, are made by Us-based com­pany Air­mar.

Trans­duc­ers are rated in terms of out­put power, and nat­u­rally a 2kw trans­ducer has more power, and so a greater depth range, than say a 1kw or even 500-watt model. For most in­shore recre­ational fish­ing the power out­put is not that im­por­tant, but game fish­er­men and com­mer­cial boats may re­quire the higher power.

CHIRP Com­pressed High-in­ten­sity Ra­di­ated Pulse. This is a sonar tech­nol­ogy first de­vel­oped by the mil­i­tary and now used in fishfind­ers from all ma­jor man­u­fac­tur­ers. In­stead of a burst of sin­gle-fre­quency sound, a CHIRP trans­ducer sends a sweep­ing range of fre­quen­cies.

This re­solves ob­jects bet­ter than the tra­di­tional sonar beam, and CHIRP is of­ten stated to be best for iden­ti­fy­ing fish. Again, all ex­cept the very cheap­est model fishfind­ers are likely to have CHIRP.

Sides­can­ning Sonar This is called var­i­ously Sides­can, Side­vi­sion or Sidevu, and es­sen­tially adds two smaller side-fac­ing trans­ducer el­e­ments to ei­ther side of the main el­e­ment in­side the trans­ducer block – which then be­comes elon­gated.

This lets you see what is ei­ther side of the boat, not just what is be­low. This can be a real ben­e­fit, es­pe­cially when hunt­ing for a par­tic­u­lar struc­ture or fea­ture since you do not need to go right over it to find it.

It did not take long be­fore con­sumers be­gan to de­mand multi-func­tion dis­plays, which can be switched between the var­i­ous el­e­ments as re­quired.

3D Sonar Known as To­talscan, Realvi­sion or Panop­tix, this fea­ture com­bines in­puts from the var­i­ous trans­ducer beams to dis­play the sea floor as a three-di­men­sional im­age.

This is one area where the dif­fer­ences between the brands is most ap­par­ent, and what looks ‘best’ can be a very per­sonal choice. When choos­ing a unit, find a re­tailer that sup­ports mul­ti­ple brands and com­pare them side-by-side to see which you pre­fer.

RADAR Ra­dio De­tec­tion and Rang­ing, this is an ‘ac­tive’ sys­tem for de­tect­ing ob­jects. Sim­i­lar to sonar in that the radar dome emits a pulse and then de­tects a re­turn echo, radar uses ra­dio waves rather than sound.

Tra­di­tional radar sys­tems re­quired large, ro­tat­ing an­ten­nae, which trans­mit strong elec­tro­mag­netic ra­di­a­tion that can be haz­ardous to hu­man health. The lat­est solid-state radar units from all the ma­jor brands have re­duced both the cost and ra­di­a­tion haz­ard of in­stalling a radar on a smaller recre­ational ves­sel, and most MFDS have the op­tion of adding a radar ca­pa­bil­ity.

Note: This tech­nol­ogy has made rapid gains in the past few years and will be ex­plored in more de­tail in next month’s is­sue.

AIS This is a ‘pas­sive’ ves­sel de­tec­tion sys­tem, which de­tects the AIS transpon­der that is manda­tory for all com­mer­cial ves­sels. AIS is an essen­tial piece of kit for off­shore, cruis­ing boat­ies who are con­cerned about com­mer­cial ship­ping, and in­te­grated units over­lay the other ves­sel’s de­tails onto the chart­plot­ter dis­play.

En­gine in­ter­face Most newer en­gines, both in­board and out­board, will have an op­tional dig­i­tal en­gine in­ter­face to out­put the en­gine data onto the NMEA-2000 net­work.

This en­ables your en­gine data to be fed into your MFD and ei­ther dis­played on a ded­i­cated sec­tion of the dis­play, or over­laid onto the chart of fishfinder. This is es­pe­cially help­ful for a se­condary helm, where a sin­gle MFD can re­place the need for ad­di­tional en­gine gauges.

Au­topi­lot When con­nected to a hy­draulic steer­ing sys­tem, an au­topi­lot en­ables you to set the boat’s course and lets the boat drive it­self. Fully-in­te­grated sys­tems even al­low you to plot a com­plex course to steer around ob­sta­cles such as is­lands.

Cam­eras Big­ger MFDS of­ten have one or more dig­i­tal video in­puts, al­low­ing the in­clu­sion of un­der­wa­ter cam­eras, en­gine-room cam­eras and even thermal and in­fra-red night vi­sion sys­tems.

BOT­TOM If you can’t land any fish with this kit, you’ll have to ac­cept the fault is yours alone...

LEFT You’d be for­given for as­sum­ing you’ll need a pi­lot’s qual­i­fi­ca­tion to drive this beauty.

BE­LOW Mod­ern units have an in­ter­face that con­nects the MFD to a NMEA-2000 net­work.LEFT The com­bi­na­tion of side and for­ward scan­ning – with 3D imag­ing, of­fers un­prece­dented de­tail and clar­ity.

ABOVE As with most mod­ern tech­nol­ogy, the more time you spend get­ting to know and un­der­stand your MFD, the more you’ll get out of it.

TOP LEFT Most mod­ern units of a rea­son­able size al­low the screen to be di­vided into dif­fer­ent func­tions.LEFT Or, if you have the bud­get, you can in­stall mul­ti­ple screens, each with a ded­i­cated func­tion.

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