Modifying rudder, now I'm concerned about weight

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svscott
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Modifying rudder, now I'm concerned about weight

Post by svscott » Sat Nov 11, 2017 7:31 pm

I'm in the middle of modifying my rudder by extending the leading edge 3", extending the length 6" and I'm building it out to have the proper NACA 0012 shape. My new rudder is way heavier and now I'm worried that the stern hardware and rudder castle won't hold up. I'm also not sure how hard it's going to be to pivot the rudder up out of the water in between trips. I keep 3 Hour Tour in the marina for our boating season and I always keep the rudder picked up so it doesn't get scummy.

I talked to the guys at the auto body supply store and they suggested using Fibral fiberglass filler to build out the shape. I cut a groove into the rudder and glued 1/8" aluminum in to extend the profile and then made a jig to form the filler.

I'm down to final fairing and sanding then wrapping with fiberglass cloth or carbon fiber and a bunch of coats of resin.

The new rudder took just over 2 gallons of filler to build and now the blade weighs 33 pounds - the stock rudder is 11 pounds. I do like the idea of extra weight below the waterline but I'm concerned about the rudder castle and the stern brackets holding up to the added weight.

The rudder pivot holes where the castle fits into the stern bracket pins are getting worn out too so I need to find a way to press in bushings or get new mounting plates welded up.

Any help, suggestions or advice are appreciated.

I posted some pictures on the macgregor 26 facebook group and can post some pics after I get my photobucket account figured out.

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sailboatmike
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Re: Modifying rudder, now I'm concerned about weight

Post by sailboatmike » Sun Nov 12, 2017 4:08 pm

I have been musing on this post all night after reading it yesterday.

It seems that maybe auto shop people may not be the best people to talk boat related things too as they may not have any concept of how a sail boat works and the loading on parts.

While redesigning my rudders I have studied the rudders on other boats that seem to work well and have come up with my concept from them.

I think your on the ball with the added length, seems my original X rudders are around 8 inches too short, just adding those 8 inches on will increase the area around 25%. Most equivalent sized boats seem to have around 48 inches of rudder in the water, on my X the total rudder blade length is only 48 inches.

NACA 12 profiling will assist by decreasing the tendency to stall as the rudder angle increases, the profiling was very poor on the originals for some strange reason, as they were cast from epoxy I wonder why they couldnt of made the mould NACA 12 in the first place, it just seems a bit lazy and no more work once the moulds were made.

While I know my boat is never going to a be as nimble as some boats, her Queen Mary turning circle and lack of any form of rudder authority below about 3 knots without the motor for assistance in just a killer in tighter spaces

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Herschel
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Re: Modifying rudder, now I'm concerned about weight

Post by Herschel » Sun Nov 12, 2017 8:36 pm

sailbaotmike wrote:
While I know my boat is never going to a be as nimble as some boats, her Queen Mary turning circle and lack of any form of rudder authority below about 3 knots without the motor for assistance in just a killer in tighter spaces
I am curious. I have a '98 X with the original rudders. Yet, I have not noticed a problem. They seem to be very responsive at low speeds. Are these the rudders that you are complaining about?
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Re: Modifying rudder, now I'm concerned about weight

Post by NiceAft » Sun Nov 12, 2017 8:52 pm

svscott,

When I first read your post, and saw your concerns, I couldn’t help but think back several years to posting by MadMike.

He was thinking about doing a Pacific crossing to Hawaii. How this relates to your post is that he was concerned about his rudders. He felt that the factory rudder hardware needed replacement. He felt that the strong currents would overpower them.

Your rudders have been extended. I believe, the leverage of longer and heavier rudders, could, and under rough conditions, would, overpower the factory hardware. Whatever the assumed advantage, is it worth the potential problems. That’s what I feel. If you can upgrade to much hardier brackets. You should do it, at least that’s my opinion.

If the new rudders are too difficult to lift, you may have to devise a pulley system.

Ray

svscott
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Re: Modifying rudder, now I'm concerned about weight

Post by svscott » Sun Nov 12, 2017 8:56 pm

I based my design off of some write ups from our peers here on the forum and on the mac facebook groups... the body shop guys gave some advice on the fiberglass filler I used.

Reading up on the forums,they say that the 3" added to the leading edge will help with weather helm while reducing the amount of muscle required on the tiller. The added length should keep the rudder in the water a bit longer while heeled over. The NACA 12 profile is supposed to be the optimal shape for boats our size, with speeds between 3 and 6 knots.

I haven't sailed too many other boats aside from my 26d. I've taken out a couple Hobie Cats growing up and at a couple Caribbean resorts more recently. This summer, I spent a handful of hours on my friend's recently acquired C&C 29 Mark 2. He doesn't have much sailing experience so I was out playing on his boat and teaching him a bit about points of sail, sail trim, etc. and I was amazed at the slow speed maneuverability of his boat compared to mine.

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Re: Modifying rudder, now I'm concerned about weight

Post by svscott » Sun Nov 12, 2017 9:32 pm

NiceAft wrote:svscott,

When I first read your post, and saw your concerns, I couldn’t help but think back several years to posting by MadMike.

He was thinking about doing a Pacific crossing to Hawaii. How this relates to your post is that he was concerned about his rudders. He felt that the factory rudder hardware needed replacement. He felt that the strong currents would overpower them.

Your rudders have been extended. I believe, the leverage of longer and heavier rudders, could, and under rough conditions, would, overpower the factory hardware. Whatever the assumed advantage, is it worth the potential problems. That’s what I feel. If you can upgrade to much hardier brackets. You should do it, at least that’s my opinion.

If the new rudders are too difficult to lift, you may have to devise a pulley system.

Ray
I already reinforced the rudder castle with some stainless plates, where the rudder through-bolt attaches the rudder.
I'll also epoxy in a bushing for the through-bolt.

My main concern are whether the stern brackets and/or the welded on castle attachment plates will handle the weight and forces while sailing. I feel that there shouldn't be too many shocking/jolting forces at play so long as I don't run aground.

I'm thinking some sort of block/tackle or a gaff hook/strut post may be the ticket for lifting and holding the rudder up.

For about $500, Ruddercraft makes an almost identical rudder to what I'm building, but theirs is probably half the weight, due to it probably being hollow, if I had to guess.

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Re: Modifying rudder, now I'm concerned about weight

Post by svscott » Sun Nov 12, 2017 10:20 pm

First cut with the circular saw - about 2" deep all the way across the bottom and 32" up from the bottom:

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1/8" aluminum plate riveted together - It was cut from some leftover extrusions from a storefront project I recently installed:

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Aluminum fixture I made to help control the airfoil shape. The Fibral short strand filler I am using was easy to work with and gave results by dropping a big glop of material and pulling the fixture across the rudder to spread the filler material:

Image

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Re: Modifying rudder, now I'm concerned about weight

Post by svscott » Sun Nov 12, 2017 10:28 pm

I used a bead of 3M 5200 sealant to attach the embedded aluminum into the fiberglass:

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Spreading the Fibral filler with the aluminum fixture - After using multiple small batches while learning a bit about the material properties on the first side, I mixed up 1/2 gallon at a time for the second side and had it roughed out in only two batches.

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Rough sanding complete and test fitting to the boat before my really big tarp gets put over the boat for winter.

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Ixneigh
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Re: Modifying rudder, now I'm concerned about weight

Post by Ixneigh » Sun Nov 12, 2017 10:38 pm

Ummm. Yea. 2 gallons of auto body style putty is not actually that swift an idea. Even epoxy and some light weight additive in it would be a waste. I would recommend using foam to form the added shape, then glass over the foam and original rudder with say 4 layers of medium weight cloth.
The rudder hardware on all these boats are marginal at best. Oddly, Bluewater yachts was uncooperative when I asked about having thier supplier make me custom heavy duty brackets for my M model. I did assure them I had the skills to beef up the entire area the hardware in bolted to.
Any reinforcement you do to your metal rudder hardware can only help.
Ix

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Re: Modifying rudder, now I'm concerned about weight

Post by svscott » Sun Nov 12, 2017 10:43 pm

Here is a link to Rudder Craft's HDPE performance rudder that looks almost identical to mine - I don't know what theirs weighs but the notes say it's a direct bolt on unit with no modifications necessary. I think if I make sure my stern mounted brackets have acceptable blocking in the lazarette that I will be ok. I don't think that the welded spindles on the angle brackets will fail...

https://ruddercraft.com/index.php?route ... uct_id=113

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Re: Modifying rudder, now I'm concerned about weight

Post by svscott » Sun Nov 12, 2017 10:54 pm

Ixneigh wrote:Ummm. Yea. 2 gallons of auto body style putty is not actually that swift an idea. Even epoxy and some light weight additive in it would be a waste. I would recommend using foam to form the added shape, then glass over the foam and original rudder with say 4 layers of medium weight cloth.
The rudder hardware on all these boats are marginal at best. Oddly, Bluewater yachts was uncooperative when I asked about having thier supplier make me custom heavy duty brackets for my M model. I did assure them I had the skills to beef up the entire area the hardware in bolted to.
Any reinforcement you do to your metal rudder hardware can only help.
Ix
I had the same fears about an autobody products being used but the guys at the store swear it will be OK underwater and the product even says 100% waterproof and that it'll harden underwater. The filler is mainly just to fair out the shape and once I wrap with 2 layers of cloth and more resin, I feel totally confident that it will be absolutely solid and the rudder itself won't fail. It's just the surrounding bits that scare me.

Here is the fiberglass filler I used:
http://www.u-pol.com/us/en/product/upol ... ibral-lite

I AM NOT a boat builder or auto body guy but am an avid DIY enthusiast and am accustomed to successfully pulling off most projects I start, so I really hope I am not setting myself up for failure here but I have done considerable research before starting this. The only thing I overlooked (I think) is how much this thing would weigh once built.

svscott
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Re: Modifying rudder, now I'm concerned about weight

Post by svscott » Mon Nov 13, 2017 7:22 am

I just noticed the pictures I uploaded last night from photobucket don't appear to be working and it says I need to update my account for 3rd party image hosting.

What is the best way to post pictures?

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eodjedi
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Re: Modifying rudder, now I'm concerned about weight

Post by eodjedi » Mon Nov 13, 2017 7:31 am

Use imgur.com

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Sumner
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Re: Modifying rudder, now I'm concerned about weight

Post by Sumner » Mon Nov 13, 2017 10:25 am

I feel you will like the rudder modifications. Our S came with a ruddercraft rudder so don't have experience with the original but like it. I would just keep an eye on the hardware.

My rudder bracket at the bottom of the post, different than a D I believe, broke offshore of Florida coming back from the Bahamas. I had been hearing something clicking every so often but didn't know what it was. I'm sure now that it wasn't a sudden failure but one that had been working at failing for some time.

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One side broke off and the other bent up leaving the rudder useless but the bolt kept all of the pieces there.

Image

I welded it up at home on the outside and the inside.

Image

While repairing it I could see where it had broke before (not as much) and had been welded up as a repair. I'm not going to make a stronger bracket but will keep a closer eye on this one from now on. From the time we bought the boat to when it failed we had over 2,000 miles on it and I don't know how many miles with the previous owners. The failure was at the very end of a 1300 mile trip and I'll probably never have a single trip that long again with the Mac. Just keep an eye on the hardware and you will be fine,

Sumner

============================
1300 miles to the Bahamas and back -- 2015

The MacGregor 26-S

The Endeavour 37

Trips to Utah, Wyoming, Idaho, Canada, Florida

Mac-Venture Links

svscott
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Re: Modifying rudder, now I'm concerned about weight

Post by svscott » Mon Nov 13, 2017 12:39 pm

Sumner wrote:I feel you will like the rudder modifications. Our S came with a ruddercraft rudder so don't have experience with the original but like it. I would just keep an eye on the hardware.

My rudder bracket at the bottom of the post, different than a D I believe, broke offshore of Florida coming back from the Bahamas. I had been hearing something clicking every so often but didn't know what it was. I'm sure now that it wasn't a sudden failure but one that had been working at failing for some time.

Image

One side broke off and the other bent up leaving the rudder useless but the bolt kept all of the pieces there.

Image

I welded it up at home on the outside and the inside.

Image

While repairing it I could see where it had broke before (not as much) and had been welded up as a repair. I'm not going to make a stronger bracket but will keep a closer eye on this one from now on. From the time we bought the boat to when it failed we had over 2,000 miles on it and I don't know how many miles with the previous owners. The failure was at the very end of a 1300 mile trip and I'll probably never have a single trip that long again with the Mac. Just keep an eye on the hardware and you will be fine,

Sumner

============================
1300 miles to the Bahamas and back -- 2015

The MacGregor 26-S

The Endeavour 37

Trips to Utah, Wyoming, Idaho, Canada, Florida

Mac-Venture Links
Hey Summer, thanks for chiming in. So if I'm reading correctly, the bracket that actually holds the rudder broke, not the stern mounted brackets?

I just called rudder craft and it sounds like their rudder weighs about 25 pounds, so mine doesn't weigh much more than that.

This morning, I emailed the customer service for Fibral to get their feedback on my intended use of their fiberglass filler.

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