Making rudders

A forum for discussing boat or trailer repairs or modifications that you have made or are considering.

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Divecoz
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Re: Making rudders

Post by Divecoz » Mon Aug 06, 2018 12:38 pm

sailboatmike wrote:
Divecoz wrote: So what can you show us of these new designed rudders ( please no autocad drawings.. ) rudder design changes over a 15 year period go figure.. BTW Roger produced 20 different boats over the entire run.. thats a LOT OF CHANGES TOO :D :D :D
Yeah I can draw them in crayon for you, but I feel that still may be a little above you intellectual abilities :D :D :D :D :D :D
uncalled for personal attack.. AND my point was and you know it full well is... TALK is Cheap.. and autocad drawings mean almost nothing...

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Highlander
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Re: Making rudders

Post by Highlander » Mon Aug 06, 2018 3:42 pm

Holly Molly Mike !
The guy is only askin a query, never ever under estimate the strength & equation of a "Powerfart" that,s where some of my best mods came :wink: , boat bows used to sweep back / then straight I , now they sweep forward \ , so go figure where technology is taking us ?
As for crayon,s Please tell me u never talked too ur children or grandkids that way :o . My 6 yr old grandaughter speaks English, Cantonese & French she learned how to use a I-Pad when she was 3yrs old & is a whiz with it now , plays some Guitar & piano music , can hold a very intellectual conversation with me or any other adult for that matter ! , smart as a whip that one is :) but she still,s like to draw with crayons & her little sister joins in & when they ask grandpa too play & draw with them I gladly drop my laptop & proudly play & draw with them :)
So I guess I,ve proudly gone from diapers & crayons & back to Crayons :P So I guess Depends r next ! :D :D :D :D
So yes feel free to send me ur new rudder design on paper & crayons & I,ll see what I can figure out with a nice big "brainfart"

Just Sayin That,s All

Be Nice , Be Happy, So I think we should all sit down by a table with a sheet of paper each & crayons & the best drawing get,s to crack open the Scotch :wink:

J 8)

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sailboatmike
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Re: Making rudders

Post by sailboatmike » Mon Aug 06, 2018 4:14 pm

Highland,you know from my 1000 plus posts I don't get upset easily, in fact I would say I'm one of the most cordial people around, however I won't be belittled and run down by someone that has obviously has done little research into a subject.

I love learning and new ideas and rally against the status quo (although they were not a bad rock band back in the glam rock days :D ). However as we all know Roger got it all horribly wrong when it came to designing rudders on the power sailors.

I have been doing some reading into the new scalloped edge rudder shape they are now using on racing boats, these are taken from the shape of the fins on humpback whales (we can learn alot from nature) https://www.researchgate.net/figure/Pho ... 1_51130456

Makes interesting reading.

So basically when it comes down to it, if someone treats me with with respect, treat them the same way, attempt to belittle me with inane comments and I fire back.

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Divecoz
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Re: Making rudders

Post by Divecoz » Mon Aug 06, 2018 6:00 pm

Reading ISN'T building.. That was my point.. Drawing ISN'T Building.. Fiberglass is NOT an easy medium to work in.. Thats was my point.. But You didnt read my post .. I have worked in Fiberglass and sprayed Gel-coat. How Much Have You Done? Roger built very serviceable Boats in fact he designed developed built and sold close to 40,000 Fiberglas boats.. Drawing a scalloped edged Rudder is one thing Building one actually a matched pair.. that will withstand the stress loads required of it will be a major issuee! and Costly! I just helped with a One Off Dive Platform for a much larger sailboat that either the X or the M .. Nothing about it was easy and the fellow I assisted had ability far an beyond mine.. BTW NOT buying the needed materials in BULK ? Really adds to the price.. Roger built we can assume somewhere about 20,000 rudders and we have seen few if any failures under sailing conditions.. These boats dont justify RACING Quality Rudders.. So The Drawing is BY FAR the Easiest part of this project.

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Highlander
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Re: Making rudders

Post by Highlander » Mon Aug 06, 2018 7:16 pm

One of the reason,s that Roger stopped making the :mac19: was it was too costly & labour intensified to make the hard chines on the :mac19: Hull when he could make the :macx: Hull a lot cheaper & sell it for a lot more money ! :wink:

That concept & ideologically has been around for a few yrs now ! , if the thought train is so good why is it not being developed in the airspace & racing & sailboat design industry , I,ll read more about it when I have time could b due to cost of development & actual advantage percentage ?

J

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Divecoz
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Re: Making rudders

Post by Divecoz » Mon Aug 06, 2018 7:54 pm

Thank You Highlander.... my sentiments as well and I AM SO TIRED of arm chair engineers who think they can do.... at a professional level what they have NEVER DONE In REAL LIFE!!

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Jimmyt
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Re: Making rudders

Post by Jimmyt » Mon Aug 06, 2018 8:11 pm

Just for a point of interest, measured my 2013 26m starboard rudder about midway down the submerged section. Results show the foil looks pretty good till you get to the trailing edge... Comparison to symmetrical NACA 0012. In reality, it's pretty darn good, as the big error indications are where the foil is the thinnest and hardest to control (construction control - not steering)...

Image

There may be other factors at play than the lack of purity of the foil section. On my boat, the steering problems are due to the idiot holding the wheel. :?

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dlandersson
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Re: Making rudders

Post by dlandersson » Mon Aug 06, 2018 9:30 pm

This is nothing. You should see my Monday morning quarterbacking. :P
Divecoz wrote:Thank You Highlander.... my sentiments as well and I AM SO TIRED of arm chair engineers who think they can do.... at a professional level what they have NEVER DONE In REAL LIFE!!

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Divecoz
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Re: Making rudders

Post by Divecoz » Tue Aug 07, 2018 7:29 am

Thank you Jimmyt, that's some very interesting fact gathering and far different than what we were being expected to believe was true..
Jimmyt wrote:Just for a point of interest, measured my 2013 26m starboard rudder about midway down the submerged section. Results show the foil looks pretty good till you get to the trailing edge... Comparison to symmetrical NACA 0012. In reality, it's pretty darn good, as the big error indications are where the foil is the thinnest and hardest to control (construction control - not steering)...

Image

There may be other factors at play than the lack of purity of the foil section. On my boat, the steering problems are due to the idiot holding the wheel. :?

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Jimmyt
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Re: Making rudders

Post by Jimmyt » Tue Aug 07, 2018 8:49 am

Full disclosure: I am a retired design engineer (mechanical), with a fair amount of construction and fabrication experience. And, I’m sitting in an armchair. :) Anyway, just offering a datapoint for the discussion. After 33 years working for military clients, I no longer have any feelings...

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Tomfoolery
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Re: Making rudders

Post by Tomfoolery » Tue Aug 07, 2018 8:50 am

Jimmyt wrote:After 33 years working for military clients, I no longer have any feelings...
:D :D :D :D

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Jimmyt
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Re: Making rudders

Post by Jimmyt » Tue Aug 07, 2018 8:59 am

To be honest, it was a great honor to serve our military and their families. They deserve the best we can give them. It wasn’t ever easy, but it was always an honor.

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Divecoz
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Re: Making rudders

Post by Divecoz » Tue Aug 07, 2018 9:32 am

Jimmyt wrote:Full disclosure: I am a retired design engineer (mechanical), with a fair amount of construction and fabrication experience. And, I’m sitting in an armchair. :) Anyway, just offering a datapoint for the discussion. After 33 years working for military clients, I no longer have any feelings...
THUMBS UP!

Wayne nicol
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Re: Making rudders

Post by Wayne nicol » Wed Aug 08, 2018 10:50 pm

another option, is if the rudders are symmetrical, simply make a mold of the good one, and make a new rudder.- it will be identical. :)

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Re: Making rudders

Post by 1st Sail » Thu Aug 09, 2018 7:14 am

JImmyT,
Is the above chart thickness of the rudder fore to aft?

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