Jet Thrusters - Thoughts

[Statistical]

Regarding the amps I think I was looking in service manual not install manual. The install manual does have amps for various thruster pumps.

https://irp.cdn-website.com/265d2296...n%20Manual.pdf

[skipperpete]

Call me old fashioned but I’m not really comfortable with having a seriously high powered pump pushing huge volumes of water through the inside of the boat. If one of those pipes fails , it’s gonna get real wet real quick in the bilges. The thought of having more big holes through the hull raises questions about extra drag, seems like a 4” hole would create a lot of turbulence. On the plus side, I wonder if the installation could be dual function and act as a mega bilge pump ( I’m thinking Orca induced flooding).
One of the hardest parts of installing a Yanmar engine is getting the new 75-100mm exhaust hose to sit nicely through the boat without it intruding into the storage and accommodation, I can’t imagine how difficult it will be to route those rigid thruster pipes and locate the fairly chunky pump in the average cruising yacht.

[spaman]

I have a 22 year old Oceanis 393 and installed a regular Vetus bow thruster 11 years ago. Had jet thrusters been around at the time and with some reasonable feedback, I would have gone for it. Having said that, there is another 393 on the same pontoon as I am on that has jet thrusters. He says they are great, but don't work as efficiently in a significant crosswind (mine would do better). The other big plus on the jets is that less moving parts under the waterline. Keeping the tunnel/prop/leg clean is a pain with the regular thruster. The annual maintenance is a fiddly job and will invariably include a new anode.
In 11 years I have only used the thruster in anger (ie to avoid damage/injury) a handful of times, but those times were enough to justify on their own. Otherwise it's a stress reliever to know it's there and can help out when needed.

[HopCar]

Vetus sold a similar system years ago but discontinued it.

[carmarche]

Our friends are having one installed on a 2020 40.1 Beneteau next week. Items just got dropped off at the marina and I put them onto their boat. I’m really looking forward to seeing how it performs.

[PineyWoodsPete]

Originally Posted by Statistical

Regarding the amps I think I was looking in service manual not install manual. The install manual does have amps for various thruster pumps.

https://irp.cdn-website.com/265d2296...n%20Manual.pdf

As a point of reference, my 33' 5.5 ton MV has 2.2kW SidePower-40 thrusters, with 105lbs thrust drawing 315A @ 12V. Thrust falls to 88lbs @ 10.5V, and operate happily with a 12V/100Ah AGM close to each - the bow batt. supplying windlass as well.

They are well-used docking and departing in our Monterey marina with the surge of the usual 5'+ swells refracting around the breakwater. My stern thruster AGM recently failed and replaced, but only after 9 years, as has the starter batt., and have a spare for the bow to be installed soon.

The equivalent 110lbs thrust 6 kW Jet Thruster draws a whopping 480A @ 24V, requiring two 12V 75 Ah batts.
Pete

[ohdrinkboy]

Originally Posted by carmarche

Our friends are having one installed on a 2020 40.1 Beneteau next week. Items just got dropped off at the marina and I put them onto their boat. I’m really looking forward to seeing how it performs.

Please post back with updates!

[bugbitten]

Well, this is one HUGE can o' worms I'm not sure my sciatica will let me sit long enough to close once I've opened it. I've actually installed the Jet Thruster system in my Beneateau 411. Did it myself. I'd put a conventional (Lewmar) thruster in the bow of my little S2 9.2A thirty footer (I solo sail mostly and generally terrify folks when I dock - I don't use the thruster often, but when I do, I REALLY need to!). I went with the Jet Thruster partly because I like trying new things (ask me about my DuoGen wind/water generator some time), and it was a bit easier to put those ~two inch ports in the bow than a full tunnel. I could mount the jets far enough forward that I had a lot of mechanical advantage, so you don't really need quite so much power. Plus I don't have as much of an issue with fouling as I did with the tunnel/prop of the Lewmar thruster in the S2. Another advantage is there's no cavitation issue, so the jets can even be above the waterline, with no loss of effectiveness (but probably some loss of popularity with your slip neighbors).

Added to that, I liked the idea of being able to put jets in the stern without having to add a second pump, or an extremely long fiberglass tunnel. Makes holding the boat against a fueling dock, for example, very easy for this old coot.

You normally install this system with a separate battery bank for the pump. JT supplied two Optima 12V units to run the 24V pump. I burned through three or four (eventually you just learn to avert your eyes) $800 control boxes before their salesmen/techs and I realized there was some issue with my charging system. The unit would work until I started the engine! Nothing else on the boat has an issue like that (it's a factory-installed Balmar system), so eventually I just installed a small 12V battery just to run the control box. I've had no fried boxes since. I have had issues with the power button that they've not yet responded to.

So, overall I like the system. I think they are improving it as time goes by (I can't stand the Deutsch connectors mine came with). It is a LOT of work running that hose. I put my pump in the huge cockpit compartment this boat has, along with the electronics and batteries, so the hose runs a LONG way to get to the bow. You could simplify it by skipping the aft thrusters, but I really do like having those. I've been toying with posting a web page devoted to this, but I'm not sure anyone would want to try it after all I went through! But hey, it's a GD boat, so what the heck!

I'll add a few pics that may give you an idea of some of the process.

Daredevil John

[bugbitten]

The first picture if of the first hole drilled, just aft of the chain locker. The second pic is of the Optimas placed, but not yet wired. JT has a system that allows you to charge the two batteries as separate 12 volters, but then have them in series to give the pump its 24V. We took that out and just put in a 24V 120V AC charger (after trying another set up that I won't go into). Then you see the pump with the Y fitting sending water fore and aft. There is an electric valve at either end that determines which one or two jets get the fire hose of water. There's a slight delay when you hit the joystick, of maybe a second, while the control box makes SURE the valve is open before it sends out that torrent of water. Next you see how close I put the bow jets to the waterline. The aft jet, in the last photo, is SS, as that was what was available with the oblique angle required. It is VERY close to the end of the boat and thus works quite well.

John

[bugbitten]

Two recommendations I'd make for anyone considering this system:
1. If space permits, go with the horizontal pump. I went with the vertical, since I couldn't see how to fit the horizontal in my situation. The problem is that the shut off valve is AFTER the vertical pump, so if you need to do something to the pump, the boat will need to be hauled. The valve is right after the thru hull on the horizontal version.
2. Use Sikaflex 291 LOT (long open time), rather than the fast-drying version JT sends. I foolishly/stubbornly installed the pump by myself, where you really should have a second person under the boat, screwing the thru hull into the pump while another person holds it in place. I had to adjust things a bit. Unbeknownst to be, the Sikaflex had already dried enough that it broke the seal, allowing a slow but serious leak. Probably more of an issue with the vertical pump, but the LOT version is much easier to work with generally, I think, so go with that.

John

[bugbitten]

I would also get a quote from JT about having the system professionally installed. I am generally dead set against putting in anything I can't DIY, BUT, after we burned up the third control box, with no fix in sight, I had a JT tech fly (from FL to VA) to look things over. I paid for two nights' lodging, air fare, food, and half of control box #4, and it only came to $1500. They, I think, just charged me costs, and nothing for the tech's time. His solution (changing the parallel/series charging switch to a 12V to 24V DC charger) seemed to work, until we started the engine! Luckily, the company in Holland had just sent me a FIFTH control box, which was a warrantied replacement for the first one, and we realized what the issue was before we hooked up that one. I could go on for days about this, but folks will tell you I could go on for days about most anything. It's quite the saga.

John

[bugbitten]

Another worm from the can: We took the boat on a 2200NM whirlwind tour of the Bahamas this spring. First among the crew of three (including me) was a retired doctor who'd been sailing pretty much all his life. He has an Island Packet 37, and he is a very serious sailor. I don't think his boat even has a fridge. He quickly became quite the Jet Thruster fan. He used it getting into marina slips (one time we had a major, last-second course correction when it became clear that it wasn't the "end one" slip they wanted us in, it was "N1!"), of course, and at fuel docks, but he also found it helpful keeping the boat lined up nicely when picking up a mooring or retrieving the anchor. Of course, that would apply to any system, but I think he found he used the stern thrusters more than expected. As mentioned earlier, I do think it's easier to have stern thrusters with this system.

John

[Schapera]

The engine would be running so batteries would be getting charged.

[ohdrinkboy]

Thanks for the update. It is an intriguing system.

[Statistical]

Originally Posted by bugbitten

Another worm from the can: We took the boat on a 2200NM whirlwind tour of the Bahamas this spring. First among the crew of three (including me) was a retired doctor who'd been sailing pretty much all his life. He has an Island Packet 37, and he is a very serious sailor. I don't think his boat even has a fridge. He quickly became quite the Jet Thruster fan. He used it getting into marina slips (one time we had a major, last-second course correction when it became clear that it wasn't the "end one" slip they wanted us in, it was "N1!"), of course, and at fuel docks, but he also found it helpful keeping the boat lined up nicely when picking up a mooring or retrieving the anchor. Of course, that would apply to any system, but I think he found he used the stern thrusters more than expected. As mentioned earlier, I do think it's easier to have stern thrusters with this system.

John

It is an interesting system. I think the big advantage is the ability to do both bow & stern with one system especially in space limited boats and without two huge tunnels cut into the hull.