external stern thruster retro fit

[ozzie]

After a few tricky berthing situations, particularly now that my wife is unable to assist with ropes/fenders etc, I am thinking about fitting an external stern thruster. The boat is a Beneteau Monte Carlo 37HT. I know, twin stern drives, shouldnt need one, but it would give me an extra element of control (and confidence) should it be required. I am looking at the SidePower EX models in 12v, but am not sure on the thrust. I have read that the stern thruster should have less thrust than the bow to allow the boat to move parallel when both used together? So, advice please on size required and not a debate on helmsmanship!

 

[jrudge]

It is tricky to reply without mentioning helmanship if I am honest.

You have two massive stern thrusters - you just need to turn the wheel and engage the outer engine.

If you had a shaft drive I would absolutly day get one. Amazing things.

If you have outdrives you will save your self a lot of money with an hours instruction.

Please bear in mind I am not the anti stern thruster brigade.

 

[rubberduck]

I had this set up on an Absolute 41, Found that equal power caused stern to move slower than stern, so I would say you need more HP to stern.

 

[Bouba]

I agree with Rubberduck, there is nothing more disheartening than a beam wind overpowering your stern thruster as if it wasn’t there. To me the secret of boating is controlling your stern, anybody can aim the pointy end. If you think the stern thruster is too powerful (example on a calm day) then I do believe that you can get a variable control switch that will only give you the power you require. So my advice is to get the biggest one you can fit or afford. Upgrading my stern thruster is something I think about a lot.

 

[CaptainMike1970]

Hi We bought a Targa 34 some years ago that had been fitted with a stern truster by the previous owner.

It was an external module, it sat in a fibreglass box and had extended cowlings either side to deflect the thrust in front of the outdrives legs, otherwise the thrust just hits the outdrives!

I’d say that you need the most powerful unit possible as the stern of the boat is a heavy dead weight in the water and takes a lot of side thrust to get it moving.

It was a bit of a “nice to have” but we rarely used it, preferring to use the steer-before-gear power of the outdrives for berthing.

The one positive was that it had a dual remote control which allowed you to power both bow and stern thrusters from the pontoon! Very handy for holding the boat alongside when single handed or to pull the stern in a bit closer to allow stepping on/off when coming back from the pub!

 

[Andrew M]

I'm with everyone above, def go for greater power in the stern thruster, from memory I think we are 9hp Bow and 12hp Stern, they seem to work well together.

Been a long time since I've had outdrives so maybe it is worth speaking to an instructor and asking his opinion.

 

[MapisM]

I know, twin stern drives, shouldnt need one, but it would give me an extra element of control

Fwiw, I'm with jrudge ref. being a waste of money.
I've had more different sterndrives rather than shafts boats (albeit the latter for longer), and while in many cases I could have used a b/t if I had it, I never even thought that a stern thruster could have added any value.
Imho, an "extra element of control" is exactly what you do NOT want to have, in a sterndrives boat.
I mean, twin sterndrives are by far more difficult to maneuver, compared to twin shafts.
But that's because, on top of the inherent difficulty to make the boat spin around its center (hence the convenience of having a b/t), you must already deal with an additional control vs.shaft boats, i.e. the vectoring thrust.
Maneuvering with shafts as I said is generally easier, but you only have to deal with longitudinal thrust because rudders are useless at very low speed, so your only weapons, so to speak, are gear engagement/disengagement, plus thruster(s) if available.
With outdrives, you must deal also with the steering wheel in order to vector the thrust, if and when necessary.
And while this really gives you, as jrudge said, two stern thrusters at your fingertips, it can and does complicate the handling.
Bottom line, beware: an additional element of control could as well become an additional element of confusion, with no real benefit.

 

[sprocker]

Hi Ozzie,

One of the lads on B pontoon had a stern thruster fitted to his Fairline 38, maybe have a walk up and chat to him next time you're down? He went for a remote control system and it really is superb, transformed his boating as he single hands a lot.

My old brain can't recall the actual berth number at the moment, and he's just swapped to a Fairline 40 so I can't recall the boat name either, but I'll find out at the weekend and let you know.

 

[KINGFISHER 8]

In modern times I've had: one sterndrive, no thruster / one sterndrive, bowthruster / 2 sterndrives, no bowthruster, joystick / 2 outboards, bowthruster / and now, 1 shaftdrive, bowthruster, sternthruster …. and out of that lot what I've got now is by far the best! Bow & stern thrusters + throttle beat a joystick into a cocked hat! ….. :encouragement:

 

[ozzie]

Hi Sprocker, I know the boat (it was Krystal Klear) but he was on shafts.
The external thrusters are a lot more expensive than conventional, but there is not enough space between my engines to fit one. My thoughts are the larger the better, but I also have concerns about the thrust hitting the drives but the Sidepower EX series dont appear to have any cowls available. I am still in two minds as to whether to get one fitted....

 

[Switch]

I had one fitted on my old Sealine 42 which had O/D’s. I found it really useful especially for that last foot or two to the pontoon whilst in your berth. It was less powerful than the bow thruster but you get used to it. I don’t think you’d regret getting one.

 

[jimmy_the_builder]

Hi Sprocker, I know the boat (it was Krystal Klear) but he was on shafts.
The external thrusters are a lot more expensive than conventional, but there is not enough space between my engines to fit one. My thoughts are the larger the better, but I also have concerns about the thrust hitting the drives but the Sidepower EX series dont appear to have any cowls available. I am still in two minds as to whether to get one fitted....

How old are your outdrives? If they are more recent, what about trying the volvo outdrive joystick?

 

[ozzie]

I had one fitted on my old Sealine 42 which had O/D’s. I found it really useful especially for that last foot or two to the pontoon whilst in your berth. It was less powerful than the bow thruster but you get used to it. I don’t think you’d regret getting one.

Switch, was your stern thruster an external unit, and if so did it have deflector cowls? Would be interesting to know if the deflectors are really necessary

 

[Bouba]

It’s my understanding that thruster deflectors are for units that are mounted too high, therefore preventing air getting into the system

 

[Switch]

Switch, was your stern thruster an external unit, and if so did it have deflector cowls? Would be interesting to know if the deflectors are really necessary

It was an external unit with no deflector cowls. It sat between the outdrives. It was perfectly adequate for those small adjustments when berthing.

 

[Bouba]

Does anyone know if the deflection cowls rob the thruster of power?

 

[Mikehp0]

After a few tricky berthing situations, particularly now that my wife is unable to assist with ropes/fenders etc, I am thinking about fitting an external stern thruster. The boat is a Beneteau Monte Carlo 37HT. I know, twin stern drives, shouldnt need one, but it would give me an extra element of control (and confidence) should it be required. I am looking at the SidePower EX models in 12v, but am not sure on the thrust. I have read that the stern thruster should have less thrust than the bow to allow the boat to move parallel when both used together? So, advice please on size required and not a debate on helmsmanship!

I too had ‘tricky berthing situations’ with my Prestige 38s ‘Zen Dog’. Our two boats are very similar. Very light at the front, lots of windage and stern drives that don’t allow that positive ‘drive it like a tank’ engines only manoeuvring that the owners of shaft drive owners enjoy.

I only get to skipper my boat for 50 hours per year and that’s probably just 25 approaches into a berth. I probably bay park my car that many times in a week! I’ve had lots of instruction and it has certainly helped. In 20 of those 25 approaches, I deliberately use engines only but in the remaining 5 - the ones with the 15 knot forecast winds that are actually gusting 25 and keep swapping direction and strength - I am so pleased I paid the excellent Nick Nutt at All Boat Services in Plymouth about £6k to fit an external stern thruster with a remote control. I haven’t frightened anyone (least of all myself) since fitment. Solo trips out are now easy and being able to slide sideways off a berth or against a rafted up Yacht always puts a smile on my face (and confuses yachtsmen because the stern thruster is relatively silent).

Go for it - you won’t regret it...

 

[Momac]

I am looking at the SidePower EX models in 12v

Why not Sidepower SX - which is designed for sterndrive boats .
https://side-power.com/produkt/19104/sx80-stern-thruster-12v/

 

[rubberduck]

Why not Sidepower SX - which is designed for sterndrive boats .
https://side-power.com/produkt/19104/sx80-stern-thruster-12v/

Exactly what we had, never missed a beat.

 

[Mikehp0]

Mine is a Sidepower SX too. Mine has the ACT 20E wireless remote control - perfect for single handed berthing.