I've got the NACRA 5.7 back on the water, and a couple things have changed in the helm. It is very neutral in most conditions. Letting go of the tiller, it goes in a straight line, which makes it nice for single handing and dealing with rudders and lines. Today the wind got up to where trapping out for a 250 lb guy would still produce some good loft and bury the lee hull. As the boat gained speed and pressure, the helm got extremely light and even tried to dive downwind.
I'm thinking I might add just a bit more rake to bias a safer windward helm. I tend to run a tight rig and don't have a lot of rake at this point. Any thoughts?
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Tom
NACRA 5.7 (1984 Sail 181)
Pennsylvania
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Fine-Tuning for moderate to high wind
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Posted: Aug 24, 2016 - 07:24 PM
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Posted: Aug 24, 2016 - 07:52 PM
So your rudders were coming out of the water as the bow buried? Yea anything to keep the bows up, trap from farther back, rake the mast more. If you flatten the sails you should have less power in the puffs trying to bury the bows and just get more speed so all the standard issue stuff to depower. Tighten downhaul / jib luff, loosen diamond wires (if you dont use prebend) etc. travel the main car out so you can keep the sheet tight and the sail flat. -
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Posted: Aug 24, 2016 - 08:35 PM
If I may... get yourself a copy of Catamaran Racing for the 90's... Chapter 6 really digs into the mast rake, rudder adjustment etc....... and a good book to have on the bedside table.
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John Schwartz
Ventura, CA
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Posted: Aug 25, 2016 - 07:35 AM
Do you have those little delrin screws in your rudder castings?
Some of the castings don't have them, & some of the screws are deteriorated to the point they are not visible. They get VERY brittle. Easy o drill them out, cleanup the threads & replace them.
I think I still have some threaded delrin rod. If you need them slightly longer thn the stock plugs, I can make them.
If your helm is neutral now, it doesn't take much to add a bit of weather helm.
http://www.thebeachcats.c…pictures?g2_itemId=80972
Edited by Edchris177 on Aug 25, 2016 - 07:39 AM.
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Hobie 18 Magnum
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Posted: Aug 25, 2016 - 09:43 AM
One side has a deteriorated Delrin screw and the other side does not. I have been unable to find a replacement, so thanks for your offer! The very light helm I experienced yesterday was on the side missing that spacer. Without the spacer, the rudders come further under the boat and increase the lee helm.
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Tom
NACRA 5.7 (1984 Sail 181)
Pennsylvania
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Posted: Aug 25, 2016 - 10:29 AM
light and straight helm is awesome when everything is going correctly
having a boat sail away due to many possible situations* is the worst feeling ....
some light weather helm is safer (as you mentioned)
*broken trap wire, slippery deck after using sunscreen, stupidity kicks in and you fall overboard, after righting the boat the jib fills with air and the boat takes off, etc
Edited by MN3 on Aug 25, 2016 - 10:34 AM. -
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Posted: Aug 25, 2016 - 11:09 AM
Here is the part you're looking for
http://www.murrays.com/56-4519.html
Edited by JohnES on Aug 25, 2016 - 11:09 AM.
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John Schwartz
Ventura, CA
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Posted: Aug 25, 2016 - 08:29 PM
That's it! And to think, only $9.00 each plus shipping. I'll have to add it to my next "must-have" order.
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Tom
NACRA 5.7 (1984 Sail 181)
Pennsylvania
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Posted: Aug 25, 2016 - 11:52 PM
I buy these (3/8"-16 X 1" UNC Hex Head Nylon Bolt), cut the head off and hack saw a screw driver slot in the end then cut them to length. Note that Murrays specifies 13 threads per inch, but standard UNC is 16 and that is what fits my castings.
http://www.ebay.com/itm/162036799258?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Right now I am using the actual bolt with the head left on cut to a 1/2" length screwed in from the inside. The rudder rests right on the bolt head which is about 1/4" thick.
My boat is an '83 Nacra 5.0 which seems to balance for me "just right" (slight weather helm) with this amount of rudder rake and about 5 degrees of mast rake (5th hole up on the shroud adjuster for me).
If you want more rudder rake (less weather helm), cut the head off and slot the end, then you have the magic Murrays $ 9 screw (nylon instead of Delrin, but they seem to work fine). You will likely need to use Blue Loctite with just the set screw as there is nothing for it to tighten up on to prevent movement.
If you want less rudder rake (more weather helm), add washers under the bolt head one at the time until it feels perfect.
Edited by leeboweffect on Aug 26, 2016 - 02:45 PM.
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Hobie 16 (3 formerly)
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NACRA 5.0 (currently)
High Point, NC
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Posted: Aug 26, 2016 - 12:15 AM
another option:
i don't have any of mine handy but if leeboweffect is correct on the diameter and threads then do a search for 'nylon socket set screw' of that size and see what you get.
i've bought and used those from grainger. not sure about the length but you can always cut them down if too long or order shorter ones.
https://www.grainger.com/…fZ1z0o3p9%3FperPage%3D48
nylon is soft so don't force them when screwing in or you'll mess up the screwdriver slot. ask me how i know.....
j
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Posted: Aug 26, 2016 - 01:37 PM
If you are getting overpowered and dumping mainsheet but with the jib still socked in tight, you will develop lee helm as the jib wants to pull the bows downwind. Crack off or travel out the jib and travel out the main and keep it sheeted hard. If the breeze really gets strong, furl or take down the jib.
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Posted: Aug 27, 2016 - 01:29 AM
That book Catamaran Racing for the 90's must be good:
https://www.amazon.com/Ca…Rick-White/dp/1880871009
They want a mere $483 for the very last copy. Unfortunately that amount of money for a book would for sure keep me up at night and armed keeping the rest of you away from this obviously critical racing information.
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dg
NACRA 5.2 #400
This End Up
Original owner since 1975
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Posted: Aug 27, 2016 - 02:12 AM
http://www.onlinemarinest…oduct=6437&idcategory=99
Here, it's $29.95
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Ron
Nacra F18
Reservoir Sailing Assn.
Brandon, Mississippi
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Posted: Aug 27, 2016 - 02:48 AM
Probably a very musty smelling thing left over from the first printing
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dg
NACRA 5.2 #400
This End Up
Original owner since 1975
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Posted: Aug 27, 2016 - 07:24 AM
I'll be glad to sell my copy for a mere $300
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Tim
Collierville (Memphis), TN
Supercat 15--sold :(
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Posted: Aug 27, 2016 - 10:13 AM
Thanks tnell. I already found the solution...just wait for the wind to die. I was out yesterday in light winds NNW and had gotten about 1-1/2 miles out and the wind just went away. Once again, without any forward momentum, my rudders would not steer the boat!
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Tom
NACRA 5.7 (1984 Sail 181)
Pennsylvania
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