rudder mountings

I have enclosed some photos of my rudders housings.
Does anyone have any advice to if they have splayed and if so the best way to address this?

32 Comments

rick.jones's picture

Re: rudder mountings

HI Paul

As you'll see I've edited your posts by reducing the photo size and putting them both into one message. Also, please keep related posts in the same topic by using the "Reply" button rather than starting a new topic each time (which I've also done).

Regarding the subject of your query, I would agree that the brackets do look splayed. I'm not too familiar with the M (I used to own an X), so maybe another M owner can offer advice? However, it might be possible to apply enough pressure with a Mole wrench or similar, or a portable vice.

Can anyone else help?

Rick Jones (Treasurer) 1994 Mac 19 "White Lightning", Isle of Wight

Re: rudder mountings

Thanks for advice.
I agree with you the housings look splayed and lower edges could be pinched back to upper widths but would appreciate any other help from owners

Re: rudder mountings

Hi Paul,
In theory the housings should be parallel to the post, but the rudder blades need to be able to move/rotate freely. In order to take up the play between rudder blade and housing I (as well as many other 26m owners!) have used old cd's as a packing spacer!

Navigation is a series of plots. In fog the plot thickens...

Re: rudder mountings


If I'm interpreting the photos correctly the two rudder stocks seem to be bent approximately equal and opposite. The most likely cause is simply the considerable force caused by the leverage during sailing. I would expect them to be bent toward midships if this is the case (I think this is what the photo's show). Depending on the grade of stainless used they should bend back into shape fairly easily but I would then examine them very closely for any signs of tiny cracks. A marker pen and some petrol to wipe it off leaves the stain in the cracks and they show up nicely.

Dave Newton Sailbadthesinner

Re: rudder mountings

Thanks Dave and Nick
.
I will adjust the housings to be parallel and use CDs to ensure a more secure fit. Hopefully if they have bent a little , re bending them a little should not cause a problem.
Thanks again

Re: rudder mountings

While on the subject of rudder mountings, I have noticed that the pivot bolts for the rudders on my 26X have worn very badly . Photo attached.

It appears that the solid shank part of the bolt is too short, and the action of lifting and dropping the rudders has worn the threads away quite badly. The bolts are 2.25" long with the shank only 1" long, and I guess these aren't the original bolts.

Can anyone suggest the spec for the correct rudder pivot bolts please, as obviously I'd like to replace them with the correct sizes?

Re: rudder mountings

These bolts look a little tired but the damage looks minor. The area where the stock bears on the bolt has flattened the thread but this is the section of thread that isn't required. Standard bolts often have more thread than needed.
If you used longer bolts so the stock bears on the shank both sides you would likely need to pack out with washers beneath the nyloc nut and have an excessive length of bolt protruding. If the rudder is a good fit (with CD packers as needed) between the stock plates then the load from the rudder should bear directly on the stock without too much load through the bolt. The resulting load on the bolt is axial (holding the stock together), not bearing shear (as witnessed by the damage to these bolts).
You could make custom bolts exactly the desired length or place sleeves over the bolts but I personally wouldn't worry.

Dave Newton Sailbadthesinner

Re: rudder mountings

Thanks for the reply Dave, and the suggestion of using CDs to pack out the rudders is a great idea (so thanks to Nick for that too)! After several unsuccessful attempts to burn blank DVDs, I have rather a lot of spare and useless DVDs I can use...

rick.jones's picture

Re: rudder mountings

Can anyone suggest the spec for the correct rudder pivot bolts please, as obviously I'd like to replace them with the correct sizes?

Slightly off topic but since you asked ...

The standard bolts used by MacGregor are UNC thread, mostly 1/4", 5/16" & 3/8". Spanner sizes are 7/16", 1/2", & 9/16" respectively. Readily-available threads in the UK are metric, the nearest equivalents being M6, M8 & M10, requiring 10, 13, & 15 mm spanners. M8 is almost exactly 5/16", but M6 is a bit thinner than 1/4", and M10 a bit thicker than 3/8".

If you want to buy UNC thread bolts & nuts, the best place is eBay. Just search for "UNC stainless" and there's lots of small traders selling all sizes in various quantities. Just make sure to get marine-grade stainless (A4 or 316).

Rick Jones (Treasurer) 1994 Mac 19 "White Lightning", Isle of Wight

Re: rudder mountings

In the past I have had excellent service from CCS Fasteners of West Lothian Tel: 01506 834344, email: enquiries@ccsfasteners.co.uk.
They have supplied marine grade s/s UNF nuts, bolts, washers and spring washers to the specific sizes and lengths I required. I prefer UNF as opposed to the original UNC because the TPI is inherently stronger and more secure.

Navigation is a series of plots. In fog the plot thickens...

rick.jones's picture

Re: rudder mountings

Hi Nick

I take your point on UNF, but in contrast I believe that the coarser threads of UNC are less prone to damage, less likely to seize, and of course quicker to assemble and disassemble as fewer turns are required!

Nexus 4, Lollipop 5.0

Rick Jones (Treasurer) 1994 Mac 19 "White Lightning", Isle of Wight

Re: rudder mountings

Hi Nick,
I had a similar kind of problem on my 26D although it has only one rudder and an exterior rudder stock. There was enormous pressure on the rudder and stock when sailing close hauled or in a following sea and this caused the damage. I solved the problem by reinforcing the stock, making a new longer rudder slightly angled forwards under the transom and creating a new rudder downhaul system to make sure the rudder went down well and stayed down as there is more pressure on the rudder if it is angled back away from your transom. I can now heel in a good wind close hauled and steer with a little finger, the rudder is balanced with the axis in the middle instead of forward.
Happy sailing,
Martin

rick.jones's picture

Re: rudder mountings

Good point Martin. I concur that it's very important to ensure the rudders are fully locked down. Even the slightest amount of aftwards "trail" massively increases the load on the brackets.

Nexus 4, Lollipop 5.0

Rick Jones (Treasurer) 1994 Mac 19 "White Lightning", Isle of Wight

mike.floutier's picture

As I'm just getting into

As I'm just getting into close quarters manouveuring :) I've had a close look at my rudder & o/b alignment.

The upshot is that my starboard rudder is aligned with the o/b BUT, in this position, my port rudder is well out of alignment.

Problem is that I can't see how to adjust the rudders.

Any ideas?

MacGregor 26M 2009 - Sky's the Limit -  Suzuki DF50

mike.floutier's picture

Ok, well, apparently, there

Ok, well, apparently, there is some form of adjustment on the X, but not on the M.

In theory no adjustment is needed because the correct geometry is built in at manufacture.

However you could say the same about car steering and suspension geometry BUT, as we all know, there is plenty of adjustment built into them.

I have come across a few suggestions for adjustment Mods but they seemed to involve such things as welding and hydraulic steering which I found a little off-putting.

My conclusion is that the easiest approach will be to add some extra holes at the ends of the long link rod that connects the extreme forward ends of the rudder actuator bars.

Looking at the geometry I'm estimating that I'll need to reduce the link rod length by at least an inch to get my rudders in sync. I'll have to re-assess things and possibly add more holes; not to mention possibly needing to adjust the o/b BUT the result should hopefully be the Mac equivalent of F1 DRS flap activation; so look out astern!

MacGregor 26M 2009 - Sky's the Limit -  Suzuki DF50

 

The rudders on high performance yachts are not absolutely parallel. The hydrodynamic flow near the transom is inward and upward (to fill in the hole left in the water behind the boat). The rudders are aligned with the neutral water flow so have a small amount of 'toe out'.

But at the speeds of a Mac this would be miniscule and anyway would be symmetrical. If yours aren't parallel I can only assume something is bent or has been modified.

Dave Newton Sailbadthesinner

mike.floutier's picture

Thanks Dave, that's

Thanks Dave, that's interesting.

Mine actually has toe-in anyway.

Will let you know how my simple adjustable track rod mod goes.

MacGregor 26M 2009 - Sky's the Limit -  Suzuki DF50

mike.floutier's picture

Haha, two things, Dave when

Haha, two things, Dave when you said toe-out I just twigged that, of course, the "toe" of the rudder is the leading edge. Doh, picture me looking over the transom thinking that the trailing edge is the toe.

So my rudders are set up with toe-out.

However, as you say, this toe-out effect shouldn't really apply to our typical speeds, eg 5 knots.

Also, the area I've been struggling with is slow speed manouvuering, eg docking against wind and tide, so hopefully it will help to have the rudders lined up.

MacGregor 26M 2009 - Sky's the Limit -  Suzuki DF50

 

Mike,

Part lifting the centre board does help maneuvering. The rudders turn the boat about a centre of rotation that is somewhere in the keel area. Moving that area aft and up has two effects. The centre of rotation moves aft giving a tighter turning circle and even though the keel area doesn't reduce much it moves up and so has less resistance to water passing around it. This gives less resistance to the boat yawing so the it turns with less effort. But if you go too far the keel loses it's effect as a pivot and the boat tends to simply crab sideways and not rotate as much.

I've found about half centre board seems to work nicely and has the added advantage that if I did ground it, it is more likely to lift and avoid damage.

Aggh! the above applies to an X not an M, please disregard!

Dave.

Dave Newton Sailbadthesinner

mike.floutier's picture

Thanks Dave, yes it's an M, I

Thanks Dave, yes it's an M, I can't even remember if I had my DB down at the time. It was my first try at a pontoon and I was concerned about the depth of water. Will try it again with full DB and straight rudders and see how I do:)

MacGregor 26M 2009 - Sky's the Limit -  Suzuki DF50

Hi Mike.  I have an M.  I don

Hi Mike. I have an M. I don't think the exact parallel alignment is an issue worth bothering with since there is quite a bit of play anyway. The main problem is have is that the rudders on the m turn further in one direction than the other. I think this is so with all of them and is due to the fixing bolts pushing against the ports side stern floatation charmber. I have thought to adjust or lengthen the tube but haven't managed to work it out without mucking something else up. The best idea I have would be to enlarge the hole and put a great big rubber sleeve on it. I've heard of people doing something similar to reduce the scratching sound and also to reduce water ingress along the metal tube.

When sailing or at speed there is no problem only when making a tight turn in a marina or river.

Roly

mike.floutier's picture

Yes Roly I know what you mean

Yes Roly I know what you mean about the turning circle, like you I'd like to fix it.

And I agree about not needed to get the rudder alignment exact; my problem is that it's about 10 degrees out so I'm definitely going to correct it, especially since it's so simple to do.

I guess then, having hacked the steering gear around a bit I'll feel more confident to tackle the turning circle issue.

Will keep you posted.

MacGregor 26M 2009 - Sky's the Limit -  Suzuki DF50

mike.floutier's picture

Here is a pic of the very

Here is a pic of the very simple mod to adjust the rudder alignment on an M.

See gallery comment for details

I still haven't figured out how to post pics to comments without needing to add to a gallery - sorry Rick:)

MacGregor 26M 2009 - Sky's the Limit -  Suzuki DF50

mike.floutier's picture

Here's a pic of the OBM link

Here's a pic of the OBM link bar with new hole drilled. Quite a job to drill the SS.

Rudders and outboard are now all aligned.

I also squeezed the metal plates that hold the rudders as these had been bent apart. Did this with a bench vice; good fun on the water from my dinghy:) Also tightened the rudder bolts which were quite loose. btw one problem relating to these plates getting bent apart is that the rudder adjusting nuts no longer have a stop to bang up against; messing up any adjustment setting.

While round the back I also noticed that neither rudder was pointing straight down so I adjusted this as well.

At this stage I realised that the bracket holding the port rudder adjusting bolt was loose.

Anyway all fixed now. One benefit of working on the rudders from a bobbing dinghy is that working in the confines of the aft berth seems a lot easier.

MacGregor 26M 2009 - Sky's the Limit -  Suzuki DF50

Now that I have ASHANTI on

Now that I have ASHANTI on the trailer for the winter I decided to take a closer look at the rudders and as the attached photo shows there is a lot of play due to the "Flareing" of the stock as discussed earlier in this thread.

I am going to try to straighten the stock using a portable vice as suggested.

It occurred to me that the stock could perhaps be strengthened by welding a piece of stainless steel angle or U section to the stock once it was straightened. To do this it would be necessary to remove the stock from the boat and it looks like it can be removed by undoing the 4 bolts of the bottom pivot bracket.

My question is, does anyone know how those bolts are fixed ? Do they go right through the hull with nut on the inside or is there a threaded plate glassed into the hull ? Or what ??

John

ASHANTI 2008M

david.claassen's picture

John, 

John,

My rudder brackets were replaced as part of the work done this summer. I am fairly certain that the bolts go all the way through.

David

David Claassen

"Logan's Run"

2006 26M

mike.floutier's picture

As far as I recall the

As far as I recall the "stocks" incorporate a "fuse" aspect in their design; i.e. They bend rather than the rudders fracturing.

I have checked them regularly and tightened/straightened them on the water or off as necessary.

On one occasion I noticed that a nut had worked lose; looks like it's worth replacing the nuts from time to time.

A good way to avoid some of the bending, is to avoid excessive weather and lee helm by balancing the sail/dagger-board plan carefully.

MacGregor 26M 2009 - Sky's the Limit -  Suzuki DF50

Hi David and Mike,

Hi David and Mike,

I did wonder if the splaying was, as you say Mike, a safety feature - I think I'm going to straighten them and maybe use the CD washers as suggested and see how that goes next season.

When I feel like a delve in the "back end" I'll endeavour to see if the bolts go all the way through.

Thanks

John

ASHANTI 2008M

Yes John there is some

Yes John there is some flaring of the rudder stock

I think it's inevitable to some extent but the agent (there was one when I bought mine ) told me that it was due to the tendency for the rudder to be sucked in when motoring fast with them down. The manual says always pull them up if motoring above 6 knots....and I guess that means through the water!

I used a g clamp and bent it in more than straight so they ping out straight. Use CD packing as required. Need to remove the rudder from stock to do this of course.

Ps...if there is enough force to bend the stop k there could be cracks in your rudder ...check and repair inb.

Roly

rick.jones's picture

Hi Tim

Hi Tim

Thanks for the heads-up on the drawings. They were supposed to be in the "26M drawings" page in the reference section of the Knowledge Base, but when I looked there was only one on the page. I think that page was originally a forum post, but then I archived it and due to the finer details of the site configuration, the long list of PDF files got reduced to one!

I've sorted out the configuration issue, and the reference page now has all the drawings on it again.

Rick Jones (Treasurer) 1994 Mac 19 "White Lightning", Isle of Wight