Nacra 5.0/5.7 Rudder Identification :: Catamaran Sailboats at TheBeachcats.com

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Nacra 5.0/5.7 Rudder Identification

leeboweffect

Rank: Mate

Registered: Apr 22, 2015

Last visit: May 21, 2023

Posts: 484
Posted: Sep 07, 2016 - 11:24 PM

My '83 Nacra 5.0 came with rudders shaped like:

A seller in ebay offers this rudder for the 5.0 and 5.7, but also offers this rudder for the 5.0 and 5.7:

Anyone know if in fact both rudders are for the 5.0/5.7 and what the difference is, other than the obvious overall shape?

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Hobie 16 (3 formerly)
MacGregor 25 (formerly)
Chrysler Dagger 14 (formerly)
NACRA 5.0 (currently)
High Point, NC
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Wolfman

Rank: Chief

Registered: Jun 24, 2009

Last visit: Jun 15, 2023

Posts: 1555
Posted: Sep 08, 2016 - 12:10 AM

Top are the early rudders. Wood and glass, bottom are later rudders and early 570s (before they changed to the inter rudder system) foam and glass. The bottom rudders are about half (maybe 2/3) the weight and tuck under the hulls more, easier to tune to balance the helm. I current have 2 pairs of the top ones and one pair of the bottom ones. I only ever use the bottom ones.

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Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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Wolfman

Rank: Chief

Registered: Jun 24, 2009

Last visit: Jun 15, 2023

Posts: 1555
Posted: Sep 08, 2016 - 12:16 AM

Oh and the bottom ones don't seem to split like the top ones do. Dan Berger sold me a set of the bottom ones and when they came in the mail I was like 'what the heck you sold me the wrong rudders'. We were both very confused until I put them on the castings and they fit perfectly.

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Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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leeboweffect

Rank: Mate

Registered: Apr 22, 2015

Last visit: May 21, 2023

Posts: 484
Posted: Sep 08, 2016 - 08:31 AM

Thanks Dave.

I have two sets and one odd (didn't get it as a set) of the top rudder. All of them need at least minor repair.

Does the bottom rudder have improved foil characteristics as in less drag etc.? They must be much rarer that the older top type. This is the only one I have ever seen although I'm only one year in to my first NACRA.

--
Hobie 16 (3 formerly)
MacGregor 25 (formerly)
Chrysler Dagger 14 (formerly)
NACRA 5.0 (currently)
High Point, NC
--
tominpa

Rank: Mate

Registered: Jul 29, 2015

Last visit: Apr 24, 2024

Posts: 578
Posted: Sep 08, 2016 - 03:56 PM

Many years ago I split one of the original rudders on my 5.7 that look like the top one, and the replacement looked like the newer bottom one. So, I seem to have a mis-match, but it has not affected the handling, but would like to get a second of the bottom type. You do need to have that trim bolt in the rudder casting to prevent the newer rudder style from striking the back of the hull. You can see both rudders here:

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Tom
NACRA 5.7 (1984 Sail 181)
Pennsylvania
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dmgbear55

Rank: Mate

Registered: Jun 22, 2015

Last visit: Jul 06, 2018

Posts: 258
Posted: Sep 08, 2016 - 05:41 PM

This newer rudder style would help some with weather helm and overall helm balance. By moving part of the blade area in front of the pivot point the lateral load is proportionately split, so at least the feeling of weather helm would be modestly reduced. Monohull rudders are often setup this way and I think it helps them deal with big shifts in the center of effort for their changing sail plans without getting big changes in the feel of the helm. This style of blade also makes good use of the adjustment screw you have to rake the rudder back, if that gets the best balance.

Depending how the new sails work out for my boat I may go looking for new rudders with this more forward blade setup.

dg

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dg
NACRA 5.2 #400
This End Up
Original owner since 1975
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leeboweffect

Rank: Mate

Registered: Apr 22, 2015

Last visit: May 21, 2023

Posts: 484
Posted: Sep 08, 2016 - 11:37 PM

Thanks tom and dg.

So thus far the group has confirmed that both rudders work for the 5.0/5.7.

dmgbear55This newer rudder style would help some with weather helm and overall helm balance.

I agree with you here dg. The newer rudder will help with balance. I used an aftermarket "racing rudder" with this feature on my MacGreagor 25. It handled like an entirely different boat compared to the stock rudder which I could easily overpower and stall in a blow upwind.

Still, I would like to know if the foil is improved on the newer (lower) rudder. Thus far with my boat, I have achieved satisfactory balance/helm with the older (top) rudder by playing around with rake so the newer design isn't worth consideration unless it reduces drag.

--
Hobie 16 (3 formerly)
MacGregor 25 (formerly)
Chrysler Dagger 14 (formerly)
NACRA 5.0 (currently)
High Point, NC
--
Edchris177

Rank: Chief

Registered: Nov 26, 2009

Last visit: Apr 10, 2024

Posts: 2524
Posted: Sep 09, 2016 - 09:15 AM

QuoteSo thus far the group has confirmed that both rudders work for the 5.0/5.7.

The big issue for the 5.0/5.7 is blade length, if they are the same length, they will work.
Length also leads into foil efficiency.
The blades cannot be thicker at the top, as they need to fit into the casting. They appear to also have the same chord length, (leading edge to trailing edge).
Chord vs span gives you the aspect ratio. (perhaps Wolfman can lay on on top of the other & see if they match?)
Given the same chord & span, there will be very little, if any difference in drag. You will gain more by fairing/polishing any dings, & making sure the blades are parallel.
If you are happy with the helm, save your money & put it towards new sails.

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Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
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leeboweffect

Rank: Mate

Registered: Apr 22, 2015

Last visit: May 21, 2023

Posts: 484
Posted: Sep 09, 2016 - 11:26 PM

tominpaSo, I seem to have a mis-match, but it has not affected the handling, but would like to get a second of the bottom type.

Here is a link to the newer style rudder offered on ebay if you care to have a matched set. Seems a bit pricey to me, but they don't carry these things at WalMart.

http://www.ebay.com/itm/Nacra-5-0-5-7-Catamaran-Rudder-Sailboat-/162045812273?hash=item25baaede31:g:ZxAAAOSwlfxXGO6w&vxp=mtr

--
Hobie 16 (3 formerly)
MacGregor 25 (formerly)
Chrysler Dagger 14 (formerly)
NACRA 5.0 (currently)
High Point, NC
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