ZF JMS systems

JMS Joystick

Grampstr,

I have experience on this system on a few applications. What kind of questions are looking for, operating, or technical.

Thanks!

1. Yes- this systems relies heavily on the bow thruster and with an electric bow thruster, you will be out of juice really quick.

2. Don't know anything about sea keeping. But skyhook works out really well if you're waiting for a bridge or something like that it comes in handy.

However the ZF system doesn't work nearly as well as with any of the pods.

ZF JMS Joystick

I agree with CAPTJ, if your going to purchase the system, definitely go with the hydraulic bow thruster, especially if your going into a Cat hull.

The skyhook works great as well, but not as good as the pod systems, and like CaptJ said, great for bridges, or getting fenders and lines ready to moor up. It also works well for after your into your slip, you can engage it, and depending on prevailing conditions, can get off the boat to get your lines on the dock. Also, just be careful to pay attention to wind / current, etc.

I agree with all of the above except engaging skyhook in the slip. It is not precise enough for that and skyhook can and does do some wacky maneuvers, like deciding to scoot over 20'.

It is basically not a bad system but it cant be (theoretically and physically) as precise and powerfull as a pod drive DP system. As said before, it relies very much on the bowthruster and (if extistend) the sternthruster. On a typical 80 ft boat with 45 to 50 HP bow- and sternthrusters, you need a good sized hydraulic system, which is independend of the main engines RPM and has enough power on idle already.

On normal shaft and prop systems, as the rudders are mechanically paralleled, it is unable to produce real vectored thrust in various directions like a multi pod drive DP system. When waiting (with skyhook) in front of a bridge or a lock with a lot of current (i.e. tidal current, especially from behind or as in our case from the side) or turbulence in the water or stronger crosswinds, the systems gets a bit erratic and needs manual input or override. Postion holding on a river with constant flow is no problem at all.

I say again, it works but do not expect the performance of an dual or quad IPS pod drive DP setup (which does it without bowthruster and hydraulic system). Depending on the GPS and compass accuracy, a quad IPS DP will park your boat vitually on a dime, regardless of current and wind. Docking the 80 ft quad IPS with the Volvo Joystick even makes my grandson look like an old saltneck . Our retractable bowthruster is only used (extended and on stby) for docking with Med mooring in tight spots.

The only problem, we encountered on longer DP maneuvering (after 10 to 15 minutes) with the quad IPS in calm sea, is the smell of exhaust gases comming out of the water around the boat. In no wind situations it can do the DP maneuver on the two outer engines allone. When passing the breakwater, the inner engines are switched off anyhow (Did not have a storm jet).

Putting a boat on DP hold at the pier, jumping ashore to secure the line and leave the boat unattended, is bad seamanship. I hope, I have misunderstood that post.

A power catamaran with twin inboards is super easy to run and maneuver without even a bow thruster. I think you're going overboard here with any of these systems. That being said. With a properly sized bow thruster and 2 days of practice, you should be able to put a power cat just about anywhere you want it and in any condition (docking). I can without a thruster.

ZF seems to have the longest history with this system and would be my first choice. Twin disc would be a second one. and I'd rude out Xenta just because they lack the dealership/service network of the above mentioned companies.

Why not just install the Zues system and pods if you preference is Cummins for the engines? I would prefer Cats with the ZF system or twin disc system if I was going that route but Cummins are ok too. I'm not a big Volvo fan. They run good when they run and are reliable for a while. But if they develop an overheat issue or electronic issue, you can chase your tail over and over again trying to find the cause of it. And they've done some hokey things along the way, like plastic heat exchanger end caps on the D5's for the first year or two.... which they then went to bronze after that, but the owners with the plastic ones were left holding the bag and paying to change them after they leaked saltwater all over everything.

Well, you can look up the 43' Grand Banks trawler as it is outfitted with a Zues package. You can definately go with less fuel if you're going with a POD package because on a POD twin engine installation generally your fuel burn will be about 30% less if not 40% and make up the weight difference there and lower HP engines still netting the same cruise speed as before. The specs show that your boat holds 1000 gallons of fuel, with PODS you could easily go with 800 gallons of fuel capacity and have the same range. Or have the tanks split and have 2-200 (or even 100 gallon each) gallon tanks with a transfer pump and keep them empty unless you're going on a very long journey and 2-300 gallon main tanks. I would do that anyways because with twin 380hp diesels, unless you're constantly cruising and going through a lot of fuel you're going to start developing algae issues within 2 years. I know with the 310hp volvo's and 400 gallons, I could run at cruise easily 20 hours on 400 gallons capacity with a 20% reserve on the 44' Lagoon.

Also, the weight of the engines will be less because lower HP engines will equal the same speed as larger ones with conventional drives. What is the weight of the shafts/struts/propellors in a conventional installation that won't be there? So if you're going with 380hp conventional drives, you'd have the same performance with about 300hp engines and zues. For example. 2 equal Cabo 40' SF express'. The zues boat with 600hp cruises at 32knots with 80% load. The 800HP MAN boat with conventional drives cruises at 31.5 knots at 80% load.

Quite honestly if I wasn't going with pods, I'd skip the expense of the other system. Maybe add a bow thruster if you have to, but on a powercat the motors/propellors are spread so far apart they're a piece of cake to dock as long as you use the current to your advantage. If it makes you feel comfortable add a bow thruster......but the whole JMS package boats are clunky and maneuver in a clunky manner and I don't see the benefit compared over not having it. Plus they're going to have a lot of programming time on the boat, probably 20 hours to get it really right if they can get it right. A buddy of mine oversaw a Tiara with a factory installed ZF system and ZF spent weeks on the boat and never got it where it was right, if you went sideways with the joystick the whole boat would really lean over from the force and all kinds of wacky stuff.......

Also, if you do have any of the JMS systems in skyhook, you're going to hear bow thruster noise throughout the boat often as it keeps using the bow thruster to maintain position. I delivered 2 Lagoon 43/44'. One from Corpus Christi, TX to Ft. Lauderdale and another from WPB to Cancun, neither had a bow thruster and never once did I see the need for one. But individual results may vary. What is your boating experience and how are you at handling a boat that size?

I haven't really seen any seakeeping issues with pods, but have heard about it briefly in very very extensive seas. You do not feel the pods on the bow in skyhook mode and unless it's REALLY windy or a lot of current the system is pretty smooth at keeping place. Every maneuver in skyhook and with the pods is computer controlled so it doesn't really overstress anything, it's designed for that. As for the break-away when it runs aground, it's made for that and you just pickup the drive and replace the bolts. It sure beats hauling the boat out to replace shafts, props, struts and possibly a broken gear. Everything has it's place, but I believe pods would be a good fit for your boat. Especially if you're really considering the JMS system.....

As for the fuel tank recommendation, I would highly consider that regardless of what you do elsewhere. You always keep your fuel fresh, transfer the older fuel out of the auxilary tanks to the main tanks, then when you fuel, the transfer tank fuel is 100% fresh and you go through the old fuel first, you could also put a racor before the transfer pump and filter it while transfering it also.

There is an interesting article on this site about the Zeus pod drive for an Horizon power catamaran.

www.horizonpowercatamarans.com/news/pod-drives-fuel-efficient-high-performance-power-catamarans

From what I find on various sites and forums, the Zeus pod drives and multihulls work very well together. As I have no personel experience with powercats, only with sailing catamarans in the 58 to 62 ft size (Catana 58 and Lagoon 620), like Capt J said before, you do not need a bow thruster on a 48 ft and bigger cat. Neither with pod drives, nor with prop and shaft. Because of the larger distance between the props, your control authority with differential power is higher than ever needed. The Lagoon I sailed, had one thruster in the starboard hull. It was never needed, the boat turned on the dime just with differental power (two Volvo D3-150). And this boat had Gori, foldable props. A power cat with fixed high scew props and bigger engines will do even better.

If you're intent on keeping 500 gallons a side, I'd try to split them into 300 gallon main, 200 gallon transfer and use a transfer pump to transfer the 200 gallons to the 300 gallon tank. That way you can get out almost all 200 gallons and keep them dry/empty most of the time. 300 gallons of fuel for a 380hp diesel is enough for 2 full days at cruise or more most likely anyways, so personally I wouldn't even put fuel in the transfer tanks unless you were running the boat 1000 NM or got one heck of a deal on fuel. A dry tank doesn't grow algae.