Hints and Tips

 

 

Emergency Rudder and Propulsion System

Sailbleu shows how he designed and made a clever back up system

 

From original post on the Jeanneau Owners Forum by Sailbleu - December 2019

                                                                                                                     

Another Sailbleu Hints and Tips Project

 

A lot has been said about rudder failure and/or engine failure, none of both are recommendable, to say the least.
Now and then an article pops-up on the board of boaters having to deal with one of these ordeals. I read them too and hope like most of you it never happens us.
But why not be prepared, in the past I often played with the idea of adding an emergency propulsion of some sort in case of engine breakdown, clogged diesel filter, you name it. I'm aware of the use of the dinghy and outboard for that purpose, even experimented with it just in case, but what if it's deflated for whatever reason?
Our scheduled Trans-Atlantic crossing (no dinghy on deck or davits) next year made me reflect and re-think on what's possible. I came up with a concept where my setup would allow a backup propulsion as well as an emergency rudder.
On the internet, YouTube, we can find some devices to tow behind the boat, permitting a rudimentary steering, some DIY’s constructed their own redundancy systems, most of them have a not so interesting aesthetic outcome, but they do work.
My intention was to design a configuration which is not dominantly present (keep the swim platform clear), can be assembled & disassembled in no time and stored when not in use, and of course is multi-functional.

The solution was a hook-up system in combo with an outboard mount that can be taken away and also can be used for multiple purposes:

1: Emergency propulsion

2: Emergency rudder

3: step for easy dinghy access and vice versa

4: cruising hydro generator

5: who knows?


Let me guide you through my approach, it might be a jump start for others or give you some ideas, at your discretion.
The first few pictures illustrate the tests of both systems, what follows is how I tackled it, how it came about; and supplementary comments.

 

 

Not a very clear image, but the rudder test was done on the leg between the islands of El Hierro (most south west canary island) and La Palma last summer. 2000 meters deep I took no chances of something breaking off and attached a safety line to the davits above. The sails were in and the engine speed was 5kts, the main rudder was in brake mode a neutral position, the Emergency rudder performed flawlessly and made 360 turns without hesitation.

 

The Emergency propulsion test was done on the island La Gomera (Canary Islands). Safety line obligatory, and you will notice there was quite some cavitation going on due to the outboard not going deep enough. A formality as I have 3 height positions on the outboard mount, here the middle was used, obviously the lower level is required. The throttle was halfway and check the next photo for the speed result.

 

Sailing from the quay to the anchorage in the bay on the west side of La Gomera, I made 2,6 kts, half throttle, and outboard not properly immersed, not bad for a 6 HP 4stroke outboard pushing an 8 ton boat don't you agree.

 

This is where it all started, I call this the adapter plate (right) and the back plate (left). The adapter plate will remain visible at all time, this will permanently stay on the transom and the required back plat will offer some strength as the transom fiberglass is fairly thin. I remember a YouTube presentation of boaters that had to construct an Emergency rudder (for real) as their main rudder was gone. Several times the captain had to re-fix, re-screw the supports of the Emergency rudder on the transom as the screws were pulled out by the forces on that Emergency rudder that in fact was a cupboard door. The back part of the boat is not very thick glassed so I figured some distribution of the forces was necessary.

 

I welded some nuts on the back of the back plate to tighten the adapter plate. Then our puppet show started. Getting that back plate to inside of the post rudder area is/was a challenge. Bear in mind it had to be sikaflexed to prevent water ingress, so doing this correct was essential not to get the quadrant and surrounding area all covered with that nasty stuff. Like a puppeteer the admiral had to lower the back plate by the two top ropes into an inaccessible space and at the same time I pulled the two ropes on the middle holes to the inside of the transom so I could get the adapter plate screwed to it .

Mark the holes

 

Holes drilled, ropes in and pushing them in further so the fishing could start.

 

 

It's a bite


 

To give an idea of that maze inside. Obviously the back plate was too big to pass the hole for the main rudder stock, it had to sikaflexed, tight up and hanging without making a mess. Then lowered up to point where it touched the bottom and then I had to pull it towards the inside of the transom. So a delicate synchronization job. Once I got one blot in we were home free.

 

 

That won’t go anywhere.

 

This is option number 3, see above on list of multiple purpose. I'll call it the dinghy step made of SS 316L sheet so it can stay on without oxidizing , the rest is made out of SS 304 that - as you know - stains after awhile.
The admiral always had some difficulties getting in or out the dinghy to and from the swim platform, this little SS accessory makes life easy for her. The arrows show where in a later stage I glued some anti slip patches on. Works great and the wife is happy, and when the wife is happy.....

 

 

 This photo tells the story.

 

 

Rewind (end of previous year), back home I improvised a setup to copy the transom's angle so both the step and the outboard mount adapter are levelled. Also and very important the height to the water surface from the adapter plate Not being on the boat when I started the project I had to rely on the measurements given ( emailed ) to me by some friendly board members with a similar boat as we have . Thank you again Erkan, Alex and Chuck. The given numbers were correct, very helpful and allowed me to finish the project.

 

As mentioned, knowing the exact angle of the transom with regards to the water surface (the sea) was extremely important so both adapter and dinghy step are perfectly levelled.
I made a carton template, tried it on the wooden setup and then took it apart as a model for the SS sheet.

 

Crucial angle!


 

Nice puzzle


 

The outboard-mount-adapter gradually getting together, the four pieces of threaded rod you see are actually short bolts welded to the inside of the adapter, each side of the adapter has a set of 4 . They're there to hold the slats in place. These slats slide in the adapter plate holders like a cupboard drawer.

 

 

 

 


I forgot to mention that on this side of the adapter, the visible side, I welded nuts on the inside to screw on the base of the engine mount itself.


 

It falls in place, note the red arrow, this an on welded stop to prevent the adapter (and dinghy step) to drop to the rub rail where it could cause damage after awhile.

 

Time for the Emergency rudder itself, where to start? A piece of marine plywood and a rudder stock, or is it a rudder trunk, not sure?

 

 

Some research have led me to believe this shape is the most efficient shape for a rudder. Other research pointed out that the surface of an Emergency rudder should be 2/3 of that of the main rudder. I can now say to disagree with the surface theory. After my tests I find 50% of the main rudder is more than enough to get the boat steered. My luck is that I can raise the Emergency rudder so less surface is exposed to the water pressure. I'm convinced the first (highest) position on the mount is adequate to keep the boat's manual heading.


 

No harm no foul. If it doesn't help it doesn't harm. What I trying to say it that some fibreglassing can only add to the strength of the rudder.


 

One side done, flip side to go.


 

Time to address the stock and bearing. I've cut some segments out to fit over the Emergency rudder and drilled four holes.


 

 

Once the fiberglass had cured I gave the rudder four coats of black dyed epoxy resin, seal it.


 

How to fix the rudder to the mount? The smaller plate with the 3 holes on the right hand side of the picture will be bolted to the mount. Seen next pics.


 

 

Try getting a hole this size without a proper sized drill or plasma cutter, cutting and grinding is an alternative.



The lock pin allows the stock to come apart from the rudder, easy for storage.


 

Important photo, the stock guide bearing is there for some additional support and to keep everything together. Unfortunately, the test showed this support was not up to the task. Therefor I had to reconfigure this bearing.

Btw the nut above is for the suspension between stock and outside top of the Emergency rudder. See photo down


 

Only this feeble black nut preventing the complete rudder to swing from left to right, that didn't work.


 

I took the bearing off and welded it on an SS plate the shape of the mount. I yet have to drill the correct holes when we get back to the boat in May as most of the parts remained on board.



To illustrate how the outboard mount (with Emergency rudder) is held in position. Cross SS wires with tensioners stop any movement.



I managed to attach the wires on eye bolts on the davits base plates.


                                                                
A view on the Emergency rudder stock >> and Emergency rudder itself
  

 

 

                                                                     

Hope you enjoy this contribution


Kind regards

 

Sailbleu

 

From original post on the Jeanneau Owners Forum by Sailbleu - December 2019