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Old 02-01-2023, 09:47 AM   #81
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Originally Posted by Circumnavigator View Post
Forgive me if I repeat a comment above -- I haven't read them all.


Wind force varies with the square of the wind speed. If your thruster works OK in a 15 knot crosswind, a ten percent increase in thrust will make it work OK in a 15.7 knot wind. A 44% increase -- the $3500 option -- will get you up to 18 knots of cross wind.


To my way of thinking, 10% is nowhere near worth it and even the 40% increase is marginal.



If you have the slightest doubt about your cable size, you'll get much better results per dollar by doubling whatever cabling you have.


Jim

The wiring as far as I can tell is good
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Old 02-01-2023, 09:51 AM   #82
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The wiring as far as I can tell is good

What size wire and what's the one way distance battery to thruster? From the amperage quoted above, I assume it's 12VDC.


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Old 02-01-2023, 10:02 AM   #83
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What size wire and what's the one way distance battery to thruster? From the amperage quoted above, I assume it's 12VDC.


Jim
Not sure on the exact wiring size. I had to replace an 4/0 cable just the other day. I would say the next size bigger. But on the next warm day I will check it out. MAYBE the thing to do is replace the wiring. The boat is 20 years old.
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Old 02-01-2023, 11:57 AM   #84
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What kind of boat are we talking about here? We have a 39ft Mainship 350. Thruster is under powered for very strong winds for sure. With this model having lots of windage, small rudder placed too far forward, the thruster is pretty much mandatory to dock. You can't even turn into a slip down a small channel without using the thruster, turn radius is horrible. Trying to come along side any dock with just the slightest of breeses and using rudder alone will have you swinging the wheel enuff to measure it in rpm LOL! Requiring the use of thruster in the Mainship 350/390 and leaving the rudder amidship is the only way to dock these suckas. The point is, depending on the boat, years of skill do not determine your use of the thruster. Take a 30 or 36 Willard with big rudder, sailboat keel, and double ender and no thruster at all, you can put that baby in any slip or pull alongside any dock with ease.
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Old 02-01-2023, 04:08 PM   #85
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The tank runs most of the stern. There is about 12 to 14" storage compartments on ether side of the tank.
Check out SideShift thrusters. They mount above the waterline and the mount could be extended to mount above the fuel tank. It takes 4 bolt holes and 2 cable holes. Pretty simple DIY installation.
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Old 02-01-2023, 04:09 PM   #86
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The wiring as far as I can tell is good
Check the connectors, they may be corroded inside them. Also check every connection for voltage drop.
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Old 02-01-2023, 04:25 PM   #87
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Check out SideShift thrusters. They mount above the waterline and the mount could be extended to mount above the fuel tank. It takes 4 bolt holes and 2 cable holes. Pretty simple DIY installation.
We went though this in earlier post. It can not be done.

Yes, of course check the connections.

But how do you tell if the cable is good though and though. I had a boat with twin engines and one would not start. I combined them and it started. That told me that I had a bad connection or cable. Connections looked good, but I sliced the cable open and the inside was burned.
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Old 02-01-2023, 08:03 PM   #88
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Measure voltage at and across each connection and see if there is a voltage drop. If there is a drop then the connection is suspect.
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Old 02-01-2023, 08:33 PM   #89
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For a once yearly event, I’d hire someone in a dinghy / pusher boat to help you make the spin. chances are the yard has someone skilled at that.
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Old 02-01-2023, 10:20 PM   #90
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Go out on a calm day and practice maneuvering backwards. It's a fun and rewarding challenge.
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Old 02-02-2023, 05:34 AM   #91
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Measure voltage at and across each connection and see if there is a voltage drop. If there is a drop then the connection is suspect.
That I know ,but it also needs to be under load. If the boat is on the hard, it can not be done.

On the other hand, I would expect some amount of a voltage drop. It would be pulling about 325A. The question would be, how much is too much? Plus, given the wire is 21 years old I am thinking of replacing it anyways. The house bank and thruster are only 7 or 8 feet apart. Add some twist and turns its about 11 to a 12' run. With 4/0 cost for both wires are about $275.00
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Old 02-02-2023, 06:35 AM   #92
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Thruster is under powered for very strong winds for sure. With this model having lots of windage, small rudder placed too far forward, the thruster is pretty much mandatory to dock. You can't even turn into a slip down a small channel without using the thruster, turn radius is horrible. Trying to come along side any dock with just the slightest of breeses and using rudder alone will have you swinging the wheel enuff to measure it in rpm LOL! Requiring the use of thruster in the Mainship 350/390 and leaving the rudder amidship is the only way to dock these suckas.

Sounds odd. I'd have thought gears alone (without rudders or thruster) would work at least 90% of the time. Haven't noticed anyone else with a 350/390 making the same observation.

Your comment got my attention because we shopped hard on those back when the 350s were first introduced....

-Chris
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Old 02-02-2023, 07:39 AM   #93
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I've seen a few people with single engine 350/390s end up relying pretty heavily on the thruster. After seeing one out of the water, it's not surprising. You have the whole swim platform bustle in the water aft of the rudder (reduces sideways movement aft and reduces rudder effectiveness), and the rudders aren't exactly huge. The single engine 350/390 rudder is a little larger than mine from what I've seen (don't have exact measurements to compare), but with the important difference that those only have a single rudder, I have 2.

I'd expect the 350/390 with twins to handle much better in close quarters, but I haven't seen under one with twins to know how good the layout is.
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Old 02-02-2023, 10:46 AM   #94
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Ah. Maybe Duck's 350 is a single-screw.

OTOH, we had a single-screw 34, no thruster... no particular issues under normal weather conditions. Didn't use the rudder much for that, either.... mostly just back-and-forth plus prop walk.

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Old 02-02-2023, 03:26 PM   #95
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Ah. Maybe Duck's 350 is a single-screw.

OTOH, we had a single-screw 34, no thruster... no particular issues under normal weather conditions. Didn't use the rudder much for that, either.... mostly just back-and-forth plus prop walk.

-Chris
With our single screw MS34 the bow thruster is the best upgrade we did. Our slip is oriented N/S (also, tight fit) and with the constant FL east wind the thruster is great.

I can get in the slip without it but it may take 10 shifts and on a blustery day it can be problematic. The thruster made our lives incredibly easy and less stressful.

As a matter of fact, we just got back home after a nice 4 hour cruise
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