Stern thruster on Blue Angel

[BartW]

yes execuses, I realise that my text last night was not very clear,
this drawing might explain what I had in mind with that specially shaped rudder connection rod, and the possibility to slightly move the hydraulic ram; more forward,



drawing of the modified cross section will follow..

re Mapism PS, there is no space, no shelf and no acces ... to bring the ram to the outboard side ..

 

[benjenbav]

yes execuses, I realise that my text last night was not very clear,
this drawing might explain what I had in mind with that specially shaped rudder connection rod, and the possibility to slightly move the hydraulic ram; more forward,



drawing of the modified cross section will follow..

re Mapism PS, there is no space, no shelf and no acces ... to bring the ram to the outboard side ..

That looks like an unobtrusive modification. But that it will need some thought as to the loading at the point of the new angle in the push rod.

 

[MapisM]

this drawing might explain what I had in mind

Yes it does, thanks!
In hindsight, I understand that in your previous post when you said "move that ram 15cm to the right", you were referring to the side drawing, while I actually understood move it to port.

Moving it forward looks more feasible on paper, and I understand that my idea of a more "linear" modification by placing the ram outboard isn't feasible with no shelf and poor access.
When moving the ram fwd, you should still be careful to respect the geometries, but I can't think of any reason why this solution shouldn't work, in principle!

 

[BartW]

or make the tiller arms longer with a Stainless Steel extension (BLUE) ?

 

[Bouba]

or make the tiller arms longer with a Stainless Steel extension (BLUE) ?

If there is only one hydraulic ram activating both rudders (operating together with a tie rod)….can you turn the ram the other direction so it works the starboard rudder ?

 

[BartW]

here is a cross section with new position of stern thruster, and hydraulic ram

 

[BartW]

If there is only one hydraulic ram activating both rudders (operating together with a tie rod)….can you turn the ram the other direction so it works the starboard rudder ?

I could but the ram would be more or less in the same position / opbstruction for the thruster motor ..?

 

[MapisM]

or make the tiller arms longer with a Stainless Steel extension (BLUE) ?

Very good idea, because that would require no mods to the existing connecting rod!

 

[jfm]

All looks good to me. Both the U shaped tie bar and the tiller extension arms.

I suppose I would prefer to buy longer tillers, cast new, but extending the existing tillers seems ok too.

 

[vas]

+1 on extending the tillers (whichever way!)
Don't particularly like the U shaped tie rod as I'm not quite sure what the bearing on each tiller is and I'm afraid it will add an unaccounted for load to the bearings and they'll soon start loosing up and have some play.

 

[Richard.C]

Longer tillers will require a longer stroke from the ram to achieve the same rudder movement, it might be very small and of no concern though.

 

[Sticky Fingers]

Not if you don’t move the ram attachment point.

 

[Richard.C]

Not if you don’t move the ram attachment point.

Ah yes I just checked the sketch, I incorrectly assumed the ram was moving to make the space.

 

[vas]

...and tbh rudder movement in these boats does close to bugger all. Only useful for slight track correction at speed, when manoeuvring you use the engines, so we might as well had 5deg either side and be happy

 

[MapisM]

Ah yes I just checked the sketch, I incorrectly assumed the ram was moving to make the space.

It is going to move, but remaining attached along the centerline - in other words, no transversal movement.
And the longitudinal movement should be symmetrical to its current position - i.e., bringing its attachment point as much ahead of the stocks as it is now behind.
So, there shouldn't be any geometrical changes in the movements.
That's my understanding, anyway!

 

[Sticky Fingers]

It is going to move, but remaining attached along the centerline - in other words, no transversal movement.
And the longitudinal movement should be symmetrical to its current position - i.e., bringing its attachment point as much ahead of the stocks as it is now behind.
So, there shouldn't be any geometrical changes in the movements.
That's my understanding, anyway!

Yup that’s right assuming Bart’s sketches match what he’s proposed, ie the moment and lever arm dimensions remain the same

 

[BartW]

+1 on extending the tillers (whichever way!)
Don't particularly like the U shaped tie rod as I'm not quite sure what the bearing on each tiller is and I'm afraid it will add an unaccounted for load to the bearings and they'll soon start loosing up and have some play.

its a ball bearing between the rod and the tiller,
they have been replaced a few years ago, were totally warn after 25+ years..
now they are a nice and shiny see picture

so in the case of a U shaped rod,
this would allow for a unwanted vertical movement of the "long - straight" part of the rod,
so thats the reason why I dismissed that solution.

I' ve send the scetches and info to Andrea, the technical Yard manager, so far he has been very helpfull, lets see what he comes up with.


and yes I want to keep the original fixing point of the Ram to the tiller arm, so there is no changement of the stroke.

 

[Alicatt]

...and tbh rudder movement in these boats does close to bugger all. Only useful for slight track correction at speed, when manoeuvring you use the engines, so we might as well had 5deg either side and be happy

You would want enough movement to counter steer if having to run on one engine.

 

[vas]

You would want enough movement to counter steer if having to run on one engine.

very true! sometimes if I want to only go at 3.5kn (do some fishing-typically unsuccessfully I may add) then I have to switch off one engine and let a/p do it's thing, yes 5deg would end up going in big big circles...