My bat­ter­ies are full

Not a phrase of­ten heard on a cruis­ing yacht, but it’s not un­known on ves­sels equipped with a hy­dro­gen­er­a­tor.

Boating NZ - - Contents - BY ROGER MILLS

In­stalling a Watt & Sea POD 600 Hy­dro­gen­er­a­tor.

Auck­land’s An­drew Berry has just in­stalled a Watt & Sea POD 600 Hy­dro­gen­er­a­tor on his 13.5m El­liot pi­lot­house yacht, Mar­i­ana. It’s the first of the units to be fit­ted in New Zealand.

Sup­plied by Kiwi Yacht­ing, the POD 600 is a new vari­ant of the Watt & Sea Hy­dro­gen­er­a­tors – mounted on the hull. More com­monly the units are tran­som-mounted on re­tractable brack­ets so that they can be lifted clear of the wa­ter when not in use.

The new ver­sion is widely-used by race boats – from the Vendee Globe to the Volvo Ocean Race – and the tech­nol­ogy has been tested in the most ex­treme con­di­tions.

I caught up with An­drew to ask what led him to choose the POD 600 for his power gen­er­a­tion re­quire­ments.


An­drew pur­chased Mar­i­ana in July 2017 with a view to cruis­ing through the Pa­cific, vis­it­ing is­lands in Tonga, Fiji, Van­u­atu and New Cale­do­nia.

Sail­ing dur­ing the 2017-18 sum­mer, he had plenty of time to con­sider what ad­di­tional gear he needed for com­fort­able and safe cruis­ing. The list in­cluded a wa­ter­maker, bow thruster, new B&G in­stru­ments and an au­topi­lot.

The re­frig­er­a­tion on the yacht is a com­pres­sor-driven freezer and fridge, with a 12-volt plate added to the fridge.

An­other im­por­tant con­sid­er­a­tion was the power gen­er­a­tion re­quired to run the yacht’s elec­tri­cal equip­ment, and to min­imise en­gine run­ning.

A pair of 100-watt flex­i­ble Juice so­lar pan­els are fit­ted to

Mar­i­ana’s bi­mini, but these can’t pro­vide for the boat’s re­quire­ments.

“This re­ally left us with two op­tions – ei­ther wind gen­er­a­tor or some form of hy­dro­gena­tor,” says An­drew. “We dis­counted the wind gen­er­a­tor early on – for two rea­sons.

“The yacht has a rel­a­tively nar­row tran­som as the beam isn’t car­ried all the way aft, so adding a stain­less-steel pole to the stern to carry the wind gen­er­a­tor didn’t make sense – and se­condly, the noise!

“We shifted our think­ing to the hy­dro­gen­er­a­tor op­tion and pretty quickly came to check out the Watt & Sea tech­nol­ogy. There’s a tran­som-mounted op­tion or the fixed, POD ver­sion.

“I didn’t like the tran­som-mounted ver­sion – partly be­cause of the rel­a­tively nar­row tran­som, but also the aes­thet­ics – I wanted to keep the ex­te­rior of the boat look­ing clean, as it was de­signed, rather than start bolt­ing on things willy-nilly.

“We dis­cov­ered the POD 600 op­tion on the web­site – I hadn’t

seen it in the flesh. I made some en­quiries and al­though the POD’S a rel­a­tively new op­tion, the me­chan­ics of it and the way it gen­er­ates power is ex­actly the same as in the tran­som-mounted legs. We cruise com­fort­ably at 6.5 knots plus, and at that speed I could gen­er­ate 250 watts or more. Per­fect!”

On pas­sage the POD will be run­ning the fridge, elec­tron­ics and au­topi­lot, and An­drew an­tic­i­pates that the only time he’ll need the en­gine is for the freezer.


The yacht was pulled out of the wa­ter at Half Moon Bay to have the new equip­ment in­stalled. Joe Richard­son and his team from The Boat­builders un­der­took all ex­te­rior work, with electrics done by Si­mon Jen­nings from Half Moon Bay Elec­tri­cal.

The in­stal­la­tion in­struc­tions rec­om­mend mount­ing the POD 600 slightly off the cen­tre­line, away from the keel, to en­sure a clean wa­ter flow and keep any mi­nor tur­bu­lence away from the rud­der.

Prac­ti­cal con­sid­er­a­tions, how­ever, dic­tated the unit be­ing in­stalled slightly fur­ther to port in a space that was clear of the en­gine, with good ac­cess.

Three 10mm di­am­e­ter holes were drilled for the two mount­ing bolts and the elec­tri­cal con­nec­tion. A back­ing plate and sealant was all that was re­quired to phys­i­cally mount the unit.

As the POD 600 is made of alu­minium care is re­quired with the type of an­tifoul­ing used.

On pas­sage the POD will be run­ning the fridge, elec­tron­ics and au­topi­lot...

“We scraped back the stan­dard an­tifoul­ing we had put on the boat around the unit and used non-cop­per an­tifoul­ing – ex­tend­ing it a rea­son­able dis­tance around the unit. The unit it­self has been cov­ered with Prop Speed,” says An­drew.

The three-core cable from the unit was run to a three-pole re­lay. The re­lay goes to the con­trol mo­d­ule, with the other side go­ing to the bat­tery pos­i­tive and neg­a­tive. The con­troller should be mounted ver­ti­cally so it can be cooled by air­flow.

The con­trol unit can also ac­cept so­lar power – in fact it op­er­ates as a full MPPT con­troller, though the con­verter pri­ori­tises the hy­dro sys­tem ahead of the so­lar. But on Mar­i­ana this op­tion is not used as the so­lar power goes through a Master­volt in­verter, which is a con­troller as well. The bat­tery house bank was in­creased to 660 amp-hours, us­ing AGM (Ab­sorbent Glass Mat) bat­ter­ies.


At the time of writ­ing only one test trip had been un­der­taken which was mainly to test out all the other new elec­tronic sys­tems on the yacht. As the bat­ter­ies were full (they’d been con­nected to shore power) the hy­dro­gen­er­a­tor was not re­quired.

Per­for­mance is de­tailed in the ac­com­pa­ny­ing speed out­put graph show­ing the power in watts pro­duced with dif­fer­ent-sized pro­pel­lers. Mar­i­ana is fit­ted with the 280mm prop, which will pro­duce 200 watts at 6.5 knots.

When the bat­ter­ies are fully charged the prop free­wheels and

makes a rum­bling sound – and that’s the sig­nal to turn it off, via the iso­la­tor switch on the in­stru­ment panel.

At 6 knots the es­ti­mated drag is 10kg, which for a cruis­ing boat is a small per­cent­age of the to­tal drag.

“If we were a rac­ing yacht we’d have con­sid­ered a tran­som­mounted unit. The Vendee Globe boats all had the re­tractable car­bon fi­bre rac­ing stern op­tion. Which can come up and down like an out­board,” says An­drew.


The man­u­fac­tur­ers rec­om­mend a main­te­nance pro­gramme for the POD600 at ev­ery two years or 10,000 miles. An­drew says this lines up with his ex­pected bian­nual haul-out for an­tifoul­ing, so it’s not a sig­nif­i­cant is­sue.

In the event of the unit tak­ing a knock, he car­ries a spare pro­pel­ler which can be re­placed un­der­wa­ter with scuba gear.


Kiwi Yacht­ing mar­ket­ing man­ager Tris­tan Camp­bell – the sup­plier of the POD 600 – sees a great fu­ture for hy­dro gen­er­a­tors.

“We’ve seen a growth in cruiser num­bers in New Zealand, with the big­ger boats look­ing to go off­shore for con­sid­er­able amounts of time. There’s also been an in­crease in longerdis­tance, short­handed races, like the Mel­bourne Osaka twohanded race and the Round The North Is­land race.

“Race yachts want to save weight by car­ry­ing less diesel. In the last Vendee Globe, al­most ev­ery Open 60 was equipped with a Watt & Sea be­cause the weight-to-power out­put equa­tion is so much higher,” says Tris­tan.

Kiwi Yacht­ing is al­ways on the look­out for clean, green, qual­ity prod­ucts that use re­new­able re­sources and Tris­tan says the Watt & Sea Hy­dro­gen­er­a­tors meet this ob­jec­tive.

“We hope to see more boat­builders rec­om­mend­ing it as a low fos­sil-fuel power gen­er­a­tion op­tion.” BNZ FOR FUR­THER IN­FOR­MA­TION ON THE POD 600: Watt and Sea hy­dro­gen­er­a­tors, www.wat­tand­ or Kiwi Yacht­ing Ltd,­wiy­acht­ BOATINGNZ. CO. NZ

ABOVE Mar­i­ana on the hard at Half Moon Bay.

ABOVE LEFTMar­i­ana’s POD 600 hy­dro­gen­er­a­tor is fit­ted with the 280mm pro­pel­ler.

TOP Un-box­ing the POD 600 sup­plied by Kiwi Yacht­ing. LEFT Pre­par­ing to in­stall the POD 600 at Half Moon Bay.

ABOVE An un­der­wa­ter view of the POD 600 in­stalled off-cen­tre on Mar­i­ana’s hull.

ABOVE LEFT The re­lay can be seen to the left of the cir­cuit break­ers.

ABOVE RIGHT The con­verter was mounted ver­ti­cally.

ABOVE Mar­i­ana’s tran­som is nar­row, so An­drew didn’t want to mount the POD there.

RIGHT The unit’s on-off switch is in the cen­tre of the in­stru­ment panel.

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