Seven Ma­rine out­boards

Awe­some! A ter­ri­bly overused word, but af­ter putting a pair of Seven Ma­rine 627hp en­gines through their paces, it’s hard to think of an­other su­perla­tive to ad­e­quately de­scribe the world’s most pow­er­ful out­boards.

Boating NZ - - Contents - BY JOHN EICHELSHEIM

Power to Thrill. If you think V8 out­boards had reached the edge of the horse­power race, think again.

In the cur­rent horse­power race be­tween out­board en­gine man­u­fac­tur­ers, the US’ Seven Ma­rine leads the pack by a full length. Seven Ma­rine’s three su­per­charged V8 mod­els span a horse­power range of be­tween 527hp and 627hp, eclips­ing other high horse­power pro­duc­tion out­boards by at least 100hp.

Th­ese out­boards are built around highly-de­vel­oped, marinised ver­sions of Gen­eral Mo­tors’ fourth gen­er­a­tion (GEN-IV) 6.2-litre, small block V8, mounted hor­i­zon­tally, which in au­to­mo­tive guise pow­ers a range of GM vehicles, in­clud­ing the iconic Corvette. For New Zealand read­ers, ver­sions of this en­gine are prob­a­bly best known from Holden Spe­cial Vehicles’ (HSV) high-per­for­mance mod­els. Sadly, Holden Aus­tralia stopped man­u­fac­tur­ing cars in 2017.

In New Zealand, Power and Ma­rine Ltd is the dis­trib­u­tor and ser­vice agent for Seven Ma­rine. The com­pany also looks af­ter Honda out­boards.

The first two Seven Ma­rine en­gines in this coun­try, both halo 627hp mod­els, re­cently ar­rived in Auck­land where they were fit­ted to a cus­tomer’s 35-foot Ever­glades 350CC (cen­tre­con­sole) sport­fish­ing boat. They re­placed three 350hp V8 Yama­has on the boat’s tran­som.

Power and Ma­rine tech­ni­cians are cur­rently in­stalling an­other pair of Seven Ma­rine 627S out­boards to a sec­ond boat, also a large Amer­i­can sport­fisher.

Seven Ma­rine, head­quar­tered in Ger­man­town, Wis­con­sin, was founded in 2010 by Rick Davis and his sons Brian and Eric. Rick’s back­ground in­cluded 43 years of tech­nol­ogy and engi­neer­ing man­age­ment in the ma­rine mar­ket, in­clud­ing se­nior roles in en­gine de­vel­op­ment and ad­vanced engi­neer­ing for Mercury Ma­rine.

The 627S puts out an as­ton­ish­ing 813Nm of torque, trans­mit­ting this to the pro­pel­ler via a ZF trans­mis­sion fea­tur­ing pre­ci­sion-ground 90o spi­ral-bevel gears, in­board­style wet disc clutches, in­te­grated trolling func­tion­al­ity and smooth, pro­gres­sive shift­ing.

The gearcase is a twin-pin­ion de­sign that min­imises frontal area for less drag and di­vides torque across two drive gears for dura­bil­ity, high-speed cruise econ­omy and stonk­ing mid-range ac­cel­er­a­tion. Three gearcases are avail­able, in­clud­ing the high-per­for­mance GT gearcase and the high­thrust CR gearcase with contra-ro­tat­ing pro­pel­lers. The en­gines on the Ever­glades 350CC have stan­dard gearcases with counter-ro­tat­ing, five-bladed Mercury Max­imus 15 5/8inch by 26-inch pro­pel­lers.

Michael Roberts, the only per­son in New Zealand cur­rently qual­i­fied to op­er­ate the ves­sel, un­der­went com­pre­hen­sive train­ing with the Seven Ma­rine team sent to

It’s dif­fi­cult to ad­e­quately de­scribe the over­whelm­ing sen­sa­tion of power that re­sults from open­ing the throt­tles...

New Zealand to pro­vide in­stal­la­tion, engi­neer­ing and mar­ket­ing sup­port, as well as train­ing in en­gine op­er­a­tion and ser­vic­ing.

Bolt­ing the en­gines to the Ever­glades 350CC’S tran­som went ac­cord­ing to plan, said Honda Ma­rine’s Guy Oglesby, who looks af­ter tech­ni­cal sup­port.

“With the Seven Ma­rine team on hand to help out with tech­ni­cal ques­tions, we sim­ply fol­lowed the fac­tory’s in­stal­la­tion guide­lines.”

The Ever­glades hull and tran­som were eas­ily strong enough to han­dle the ex­tra horse­power and torque – a pair of Seven Ma­rine out­boards weighs con­sid­er­ably less than three Yamaha V8s – so no struc­tural changes were re­quired. The only mod­i­fi­ca­tions were to the tran­som where the orig­i­nal alu­minium back­ing plates for the en­gine brack­ets were re­placed with stronger stain­less-steel ver­sions.

How­ever, in­stal­la­tion wasn’t as sim­ple as just bolt­ing the en­gines on, hook­ing up the fuel lines and con­nect­ing ca­bles. Quite a bit of engi­neer­ing was re­quired. The en­gines are sup­plied with a sep­a­rate hy­draulic steer­ing pump and en­gine trim pumps. On the Ever­glades, the pumps are neatly in­stalled in a large stor­age locker un­der the cock­pit sole, the hy­draulic hoses ex­it­ing the tran­som through holes es­pe­cially cut for the pur­pose.

The en­gines are mounted on the Ever­glades’ tran­som at 32-inch cen­tres, as per Seven Ma­rine’s rec­om­men­da­tions, the cen­tres de­ter­mined by the hull type and its dead­rise at the tran­som. On the Ever­glades, this places them very close to­gether, but while they are just a few cen­time­tres apart in the straight-ahead po­si­tion and even closer when turn­ing, the cowls

never touch, even at full lock.

En­gine cowls are per­fectly colour-matched to the ves­sel’s hull. Seven Ma­rine cus­tomers can de­sign their own colour scheme from an ex­ten­sive on­line pal­ette, or the com­pany can match a paint sam­ple.

As part of a gen­eral over­haul prior to fit­ting the new en­gines, the Ever­glades was re­painted us­ing Awl­grip paint prod­ucts, a sam­ple of which was sent to Seven Ma­rine’s Wis­con­sin fa­cil­ity for match­ing. LED lights in­te­grated into the cowl­ings are cer­tainly eye-catch­ing. A re­mote con­trol al­lows you to cy­cle through a range of colours and flash­ing rou­tines.

We joined the boat for a test run on the Waitem­ata Har­bour, in com­pany with Honda Ma­rine tech­ni­cians who were gath­er­ing some bench­mark speed and fuel-flow data. We spent about three hours on the wa­ter putting the en­gines through their paces.

There is quite a long run down the Ta­maki River to the open sea, most of it at five knots. For­tu­nately, the ZF con­trols mod­u­late the amount of clutch slip, which al­lows the ves­sel to trickle along at five knots with the en­gines idling in gear. With­out slip it would be much faster.

My ini­tial im­pres­sions in­cluded smooth­ness and quiet run­ning, but even at idle – and es­pe­cially at start-up – there is a dis­tinc­tive V8 bur­ble. The cadence of the V8 ex­haust note be­came more ur­gent as the revs rose, but noise lev­els are nicely con­trolled. At higher speeds the whine of the su­per­charg­ers adds a dis­tinc­tive so­prano note to the throaty bark of the en­gines’ tubu­lar stain­less-steel ex­hausts.

It’s dif­fi­cult to ad­e­quately de­scribe the over­whelm­ing sen­sa­tion of power that re­sults from open­ing the throt­tles, but we quickly learned to heed Michael’s in­struc­tions to hold on tight!

Ac­cel­er­a­tion is awe-in­spir­ing, but it’s the ac­com­pa­ny­ing sound­track from two sets of dual ex­hausts, over­laid by the high-pitched whine of the su­per­charg­ers, that is truly out of this world! At full noise the en­gines sound like a su­per­sonic jet­liner tak­ing off.

At the same time, the out­boards never feel harsh, vi­bra­tion is non-ex­is­tent, and thanks to the su­per­charger, the power de­liv­ery is lin­ear – it’s like turn­ing on a tap.

ZF elec­tronic throt­tles pro­vide swift re­sponse, and the en­gines can be op­er­ated in­di­vid­u­ally or both to­gether us­ing two levers, or with en­gines synced us­ing one lever to con­trol both. The out­boards of­fer a wide trim range and Michael used most of it dur­ing our demon­stra­tion. At higher speeds, the en­gines need to be trimmed well out and small en­gine trim ad­just­ments make a big dif­fer­ence to speed and econ­omy. Trim tabs were also used.

For­tu­nately, out­board trim set­tings, along with a vast range of en­gine data, fuel-burn fig­ures, range and much more, are promi­nently dis­played on the TEC7 multi-func­tion touch­screen display – Michael says he is still learn­ing the menu. The de­fault display is con­fig­ured so that all the most im­por­tant data is easy to see, but users can cus­tomise the display. The en­gines are stopped and started from vir­tual but­tons on the screen.

With out­boards of this size, fuel econ­omy is prob­a­bly moot, but de­cent fig­ures are achiev­able. At 30 knots each en­gine was burn­ing 60 litres an hour, ris­ing to 220 litres per hour at 40 knots. The Ever­glades car­ries 1,500 litres of fuel and the tank was three-quar­ters full on demo day.

On one two-hour trip dur­ing the en­gines’ run-in pe­riod the boat trav­elled from Westhaven to Ma­ti­aitia, Wai­heke Is­land, on to Bon Ac­cord Har­bour, Kawau Is­land, down the coast to Mahu­rangi Har­bour and then back to Westhaven. To­tal fuel burn was 400 litres.

As ex­pected, per­for­mance was spec­tac­u­lar: this rig is quite ca­pa­ble of mak­ing fast, com­fort­able pas­sages in most con­di­tions. The Ever­glades is a big, heavy ves­sel, but we saw a top speed of 57 knots at the 5,500rpm red­line. The rev lim­iters cut in if the rev­o­lu­tions climb too high and the com­puter au­to­mat­i­cally shuts down the en­gine if it is ac­ci­den­tally trimmed up too far, as we dis­cov­ered while try­ing to eke out an ex­tra half-knot.

At a fast cruis­ing speed of 40 knots, the ride was com­fort­able and noise lev­els were rel­a­tively muted. In­deed, it was hard to credit how fast you were trav­el­ling. At 50 knot­splus, the rush of wind was the main in­di­ca­tor of speed, along with the tur­bine-like howl of the en­gines. And what a glo­ri­ous sound it is!

OP­PO­SITE Seven Ma­rine’s 627S is the most pow­er­ful model in the com­pany’s V8 out­board port­fo­lio. Th­ese two are the first in New Zealand.LEFT The Ever­glades 350CC rel­ished the ex­tra horse­power.

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