rudder mountings

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paul.coombs
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?

paul.coombs
26m rudder housings

Any comets on my rudder housing. Does anyone think they are splayed and if so what's the best way to correct? ?

rick.jones
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

paul.coombs
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

nick.beeton
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...

dave.newton
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

paul.coombs
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

john.richards
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?

dave.newton
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

john.richards
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
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

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