Stern hanging rudders on 28

[Yannis]

I tried to find the thread where someone was looking for info on rudders installed externally on the stern of a 28, but was not successful, so here's a new thread about it:

I asked the person in my yard, involved in this modification, who told me the following:


- The modif was imperative because the new engines dictated such a rudder redesign (there was no space for the traditional design)

- They got the rudders from Italy, from a firm called Radicci, which is now closed (because the daughter of the owner passed and he had to stop working). However he kept the blueprints and the molds and he gives them out to sub contractors, so normally they could be found somewhere, although the delay is important, they had to wait 9 months.

- To his knowledge, there are no other suppliers of this type of rudders anywhere else. Also, they are pricey, they paid around 3,5K €

- The rudders are T shaped. For some reason they have to be so when they hang out from the stern.

- The boat performs very well, it turns as expected and the maneuverability in the port is also as expected.

- He hasn't tried to steer the boat on one engine to check if the boat turns. However, he adds that these rudders are much larger than stock so they perform better than stock rudders with two engines running.

- They had to reinforce the stern, by adding 1 cm of glass and 1,2 cm of ply.

If you need more info let me know, so I can torture him further.

[Joef]

Sounds like the rudder system on my old North Coast. When the rudders are that far back you can get the props
Back further and therefore lower shaft angle. I can tell you that on my boat it steered alike a big outboard… I could easily turn to port even when I had just the port engine in fwd. blackfins did this one the 29 and 32s. It works great - not sure why it’s not more common.

[Yannis]

Yes, he told me also that the shafts and propellers are positioned further back, but didn't mention anything about the angle.
I understood that this placement of shafts/props was dictated by the engine (bigger/longer engines?).

[Tony Meola]

Yannis

They must have had to modify the engine covers. Usually on the 28 going bigger resulted in the engine not fitting.

[Carl]

Yannis- Stern-mounted rudders were recently mentioned in JayJay's post, Prop Rake n Attitude. The T on the top of the rudders prevents them from ventilating/sucking air. Not needed when rudders are under the hull in the standard setup.

What did they install for power requiring such a modification?

[jayjays1]

Yup I am looking into these myself as the shaft angle can be reduced even further if props are as far back as possible but still allow for a decent sized wheel to be turned. Thats the theory anyway. Hope it works out. There is a company that makes them. I will try to dig it out.
JJ

[Tony Meola]

Yannis

If you lower the engines and design the strut properly you really don't need to move the rudders back. Spinning a bigger wheel means they put on larger engines than normal, dropped the engines closer to the hull, then extended the shaft so the angle lowers the prop.

That is not what Bob Lilco did when he lowered his engines. Strut size remained the same and in the same position. He pivoted the strut barrel to change the angle so it would all line up. That in theory should always allow you to spin the same size wheel or if you have the room to begin with go a little larger.

Plus, if you extend the shaft too far, you will need another strut in the middle of the shaft to prevent it from flexing.

Would love to know what size engines they dropped in that made them make those modifications.

[Yannis]

Tony,

I had that in mind, to ask about what motors they put in like Carl also asked, but I was too busy with my turbo stuff that I forgot it. Next time I go down Ill try to remember.

By the way, I have no intention myself to enter in any sort of such modifications, I have enough in my mind already!

Also, what you describe about lowering the motors to achieve a shallower angle, I doubt it is ever possible in the 28, there is simply no room for this. And that is probably why they had to move the rudders all the way aft to achieve that angle all the while even modifying the engine covers...
My Yanmars which are certainly not the most voluminous motors for their hp, just about fit in the engine room in my boat, leaving less than 2cm up until the cover and you cannot fit your arm under them to grab anything dropped in the bilge.
All what Bob and you describe can be done in the 31, not the 28.

[Yannis]

So, these guys put in 4LHA 240hp Yanmars!
Nothing more voluminous or as heavy as their choice of rudders suggests...
However, the guy said, because they had to install shafts of greater diameter and bigger wheels, the whole new configuration wouldn't fit, by a few centimeters.
Funny this very config fits my boat, albeit, to the millimeter. So much so, that the sacrificial anodes initially destined to fit on the wheel centers, do not fit anymore. They wouldn't clear the stock rudders...

[Tony Meola]

Yannis

I think they had no idea about what they were doing. My friend has the same configuration. The pain is he has to drop his rudders to remove a prop.

We put them on the shaft. Yours were on the end of the shaft. That is different.

[Yannis]

Tony,

When I bought my boat there were anodes BOTH on the shafts and on the wheel nuts.

I then removed the shafts for inspection, and upon re-installation, they mounted one shaft (port) a few mm aft from its previous position. Today, that port side only bears an anode on the shaft, not on the wheel center anymore. The starboard side still has anodes on the shaft and on the wheel nut.

I should note that the one remaining anode on the wheel of the starboard side doesn't seem to do anything; every year when I replace the anodes, all anodes are visibly sacrificed and replaced, that remaining wheel anode is always intact and is never replaced, so really I should probably remove that too.

I also have to drop the rudders to remove the wheels.

As for the other boat in question with the aft mounted rudders, my impression is that their choice was not due to the anodes not fitting. I don't even think that they had anodes on the wheel nuts.
As the guy explained to me, there was simply no room for the props to fit between the rudders and the barrel. Why? Because when they increased the shaft diameter, they had to also increase the space between the strut and the props respectively. Those extra few mm were the problem.

They thought to move the struts a few mm forward instead, but that would change the shaft angle, which they didn't want. Hence they mounted these stern rudders. I would most probably move the struts forward myself and while at it, reinforce the hull according to the instructions presented by Capt. Pat and others here. That would be an easy task, as the new engines were not fitted yet, they wouldn't have to re position the old engines as these were new engines so the new engine mounts could well be calculated from the beginning.

[Carl]

Going up shaft size increases the taper length. As you mentioned Yannis, the distance between back of hub and strut increases keeping around 1/2 the shaft diameter spacing. Additionally, a larger diameter wheel can be a bit longer at the hub. Add it all together, and that room between the shaft, prop and rudder disappears.

I agree that chances are good they may have been able to squeak out a bit more room from the engine compartment to move the engine forward. SawZ-alls are great for that kind of thing. Trim a little off the back of the strut, leaving the cutless protrude forward. Remove the small diameter nipple that houses the cotter pin opting for the old Chris Craft castellated nut where the cotter pin goes through the threads.

There is more than one way to skin a cat.

What's best? I guess what works.

Me??? I'd keep simple and stock as much as possible. Stock for the reason if a custom rudder assembly gets wrecked, can a replacement be found or is it a special order, long wait, and $$$.

Hindsight is 20/20.

[Yannis]

Carl, yes, all of the above!

In other words, when you're looking for just a few extra mm there has to be a way. Going the stern mounted rudder way seems a bit too far fetched.
But then again, all we are doing here is speculate, what if this - what if that...we should have been present while the decision was being made so as to be able to tell if they did right or wrong...

Anyway, what I had promised to do was to find the facts and present them. This is done.
The fact however that we feel the need to validate the rightfulness of their choices remains an inherent "Bertram owner characteristic" and we won't give it up, or will we? LOL!!

[Carl]

Yannis- Getting the information is appreciated even if I never need to know. It all gets processed into the memory bank of what was done and why.

It would be great to be able to do a side by side running comparison between the two build methods to see if there is a clear Best Way. Even if our way won, they may have reason other than what we see for doing what they did...Bigger wheel diameter options down the road. Not wanting to drop rudder to pull prop.

I guess that is the best way of me saying, I'm being a hindsight, back seat driver, answering questions nobody is asking based on limited information.

[Yannis]

Carl,

One drawback I can think, which mostly applies to us here, has to do with the way we moor.
Most of the times, boats moor stern-in, against concrete piers.
What keeps you at a certain safe distance from the pier is your anchor.
So, if your anchor drags, which is NOT uncommon, then you might hear a light bang (initially) and if you don't act immediately a louder bang a bit later...
Guess what item this bang noise will come from if your rudders are mounted on the stern!

[Tony Meola]

Yannis

Banging the rudders on a concrete pier cannot be a good thing. I hear what you and Carl are saying, but every 28 done here in the US with those engines kept the traditional set up.

So I sit hear still scratching my head, but it is what it is. We will never know if here in the US we just have not figured out that there is a better way and your yard found it.

[Yannis]

Tony, rudders that much exposed can never be a better thing in my book.
You're asking for trouble, especially when you consider the way we moor.

[Carl]

Add a swim platform to save the rudders. Problem solved...lol.

After having this conversation I am seeing more and more boats with rudders way out past the transom. Penn Yann did with their tunnel drive, Blackfin yachts, and I just noticed Rampage did the same. There has to be some merit to the design...or at least a perceived merit.

To me...a bigger waste is a stern thruster on twin screw boats. I thought the Bow thruster was cheating but I'm seeing more and more boats with these thrusters bolted to the transom. It might be new to me as it's boats I would not normally look at, but as I'm looking at rudder placement I'm seeing new horizons. For me part of boating is learning the skills to handle a boat.

[Yannis]

Im also seeing these stern thrusters too, Carl, lately.
They look like sea turtles up against the stern.
Although I agree that they are redundant as all boats that carry them are twin screw and rather bigger boats, indeed when I remember some disastrous situations in various island ports where there is simply no room to maneuver properly, paired with gale winds, add some anchor chains and ropes...they could save the day, or at least help avoid the worst.

Also, consider that the captain of these boats is seldom the owner, so the owner provides this to his captain and hopes to save on insurance claims...

[Carl]

I was going to offer reason why thrusters are not needed on...but its a boat for recreational purposes.
NON of it is essential, Its all toys...


good toys, but toys non the less.

All toys to get us out on the water and make us smile.

[Yannis]

Also, the thicker the wallet, the more toys you can enjoy!

[Carl]

I cannot argue there Yannis.

Flip side, sometimes the thinner the wallet the more you appreciate the toys you have.

[Tony Meola]

You haven't seen anything until you see my neighbor dock his 46 Sea Ray using his bow thrusters. We dock beam too on our lagoon. He gets broadside to the dock about 30 feet away from it then uses the thrusters to move the boat to the dock. I always thought they were for assistance, not to just move a boat broadside that far.

Plus, they sound like they are grinding up some bone or something else hard.