Underpowered Stern Thruster?

[dbsea]

I feel like the stern thruster on my C30CB is underpowered after nearly getting blown into the dock at Port Madison this past weekend. The stern thruster couldn't overcome the wind and keep the stern away from the dock and I almost hit it, but thankful for some dock friends and roaming fenders we avoided any crash / damage. Can the stern thruster motor be upgraded with the existing tunnel? The stern of the boat is heaviest and the wash of the thruster is blocked by trim tabs and the rudder.

 

[watson1987]

Do you have the upgraded 4 prop blade? I know some easier thrusters had 3 props, I'm not sure when they switched

Edit: Rather the 5 prop upgrade from the 4 prop version.

 

[dbsea]

Do you have the upgraded 4 prop blade? I know some easier thrusters had 3 props, I'm not sure when they switched

Edit: Rather the 5 prop upgrade from the 4 prop version.

not sure if that is an option for the sidepower thrusters. I know at some point they switched from Sidepower to Lewmar, mine has the Sidepower.

 

[dbsea]

looks like mine has the 5 blade already 🙂

 

[plewis]

The Thrusters on my 2013 29' run from the same battery, so if you run both simultaneously you lose some performance. I put them on different batteries and it helped. Put the boats voltmeter on the Thruster battery position and observe the difference in voltage between running one then run both thrusters. If the voltages are significantly different this could be remedyed by the wiring change amoung serveral other reasons like batteries or wiring connections. It isn't a miracle especially when it is windy but it does help.

 

[fishheadbarandgrill]

The stern thrusters are definitely under powered. But consider this. Learn to use your engine and rudder. You'll get much more side thrust by kicking your engine in and out of forward and keeping your rudder port or starboard. After a little practice, you'll find that you will rarely use your stern thruster.

 

[Morelords]

Dave, I feel your pain. In our maiden voyage in our R29 and my first time trying to pull into our slip, the stern thruster was overpowered by about a 15 mph wind, and I just about hit our new neighbor's boat. Luckily our friends and previous owners were with us and took over the helm to get the job done. I had another very difficult time trying to get off the dock at Sydney Spit where we were tied on the starboard side and had about a 15-20kt wind pushing us onto the dock from the port quarter, boat in back, boat in front. For that one, I kept on the thrusters for probably too long, and more or less pivoted off the starboard swim step and dinghy. In hind sight, we should have used a spring line and the thrust of the prop. and rudder to get the stern off, then back out (though I still haven't tried this). Since those experiences, I've really been practicing using the thrusters as minimal as possible, and that has helped a lot. I hope to have some discussions at the upcoming Roche Harbor Rendezvous about how to better handle the boat when docking and coming off the dock in windy conditions,with our limited power stern thruster. Can be very stressful in those situations! This is the one thing that has kept me from adding drop fins, as it appears the stern thruster would just blast into the fin, really rendering the thruster almost useless.

I like the suggestion about having the bow & stern thrusters run off different battery banks.

 

[watson1987]

The Thrusters on my 2013 29' run from the same battery, so if you run both simultaneously you lose some performance. I put them on different batteries and it helped. Put the boats voltmeter on the Thruster battery position and observe the difference in voltage between running one then run both thrusters. If the voltages are significantly different this could be remedyed by the wiring change amoung serveral other reasons like batteries or wiring connections. It isn't a miracle especially when it is windy but it does help.

Did you use the engine battery as the second or did you add an additional battery?

I would worry stressing the engine battery voltage might be harmful to the electronics on the engine. Using the house battery would work but at least on my boat, that's on the other side laz.

 

[jimv]

I also found the stern thruster on my 2011 R27 to be rather useless.
But I have to agree with Bob & Mike's advice to learn to pilot the vessel without needing the thrusters.
After we bought our R27 but before we took possession, my wife and I took a week long on the water course at Chapman School of Seamanship in Stuart FL. Great Experience.
We were trained on a single inboard that had bow thruster, but Capt. Al would slap your hand if you even looked at the truster control 😀
His philosophy, which I came to agree with, was that you should never rely on the thrusters being there for you. Blown fuse, shear pin, low Battery.... Many things that can go wrong.
I learned to use the engine and rudder to control rather than thrusters. I'll admit that they are nice to have to 'fine tune' the boats position, but I've always planned out my approach/departure without use of thrusters. Learning how to leverage slip lines is great as well, as suggested by Mike.
A good resource for some techniques is the book Stress Free Motorboating https://www.amazon.com/Stress-Free-Motorboating-Single-Short-Handed-Techniques-ebook/dp/B01NA91B5H/ You can sign up for a free account to get access to the videos which demonstrate many of the techniques.

~Jim

 

[dbsea]

thanks all for the tips. It did occur to me after the fact that I could have turned hard over to starboard and kicked it in fwd a little to pop the stern out, but that was after the fact . 🙂 I have my USCG 50 ton masters license, (just got it), but that doesn't teach you practical knowledge and I was coming from a twin screw outdrive boat of the same size before this one. I've had my CW30 for two seasons now, but still learning.

 

[aintmissb]

My 0.02 cents on this topic - these boats are heavy aft where the engine sits, and the stern thruster just can’t shift that much weight sideways. Rather than tax your brain in a stressful docking situation with 3 controls, engine plus two thrusters, I found it helpful to think of the stern as sitting still in the water, the bow thruster does a good job of rotating the bow around the centre of gravity near the stern. If you can back in, use the bow thruster to rotate the angle of the main prop, then reverse slowly in, adjusting angle as you go. In other words, forget the stern thruster.

 

[Mdennype]

I'll just add that on my 25, the rudder blocks the jet of the stern thruster when trying to move the stern to port. So, it's definitely the weakest direction and caught me off guard when trying to stay of the dock. My boat prop walks to port in reverse, so I can give that side a little help in reverse.

 

[iapota2021]

Would never expect to have the thrusters hold me off a dock in 15-20 knot wind.Huge amount of windage on these boats.