So does anyone here know of any reason why my rudders could be shaking? Or why when i let go of my tiller the boat will fall off i though it suppose to turn up into IRONS? Im going to check the daggers to see if they have play in them from where they are connected to the boat! But i am not sure what else i can check?
Thanks
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Reynolds 21 Catamaran #38
Pennsylvania, PA.
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Drag?
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Posted: Aug 28, 2012 - 07:52 AM
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Posted: Aug 28, 2012 - 08:49 AM
Any damage to the rudders?
Too much toe in/out?
As to the falling off bit, has nothing to do with the rudders IMHO after all you said you let go, probably the sails (assuming Daggerboards are ok), perhaps the mast needs more rake or the headsail is simply a gigantic screacher? -
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Posted: Aug 28, 2012 - 09:09 AM
My guess is rudders raked too far forward is causing your lee helm, or like dennisMe said, rake the mast back some.
For the shaking, maybe shim between the rudders and casting.
It took me several attempts, adjusting both the rudder and mast rake, but I finally got a perfectly balanced helm. Makes sailing so much more enjoyable. -
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Posted: Aug 28, 2012 - 09:16 AM
Hmm not sure what you mean by Mast Rake?
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Reynolds 21 Catamaran #38
Pennsylvania, PA.
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Posted: Aug 28, 2012 - 09:32 AM
Mast rake is how far the mast 'leans back' as compared to straight up. Usually trimmed by lengthening the forestay turnbucle or whatever you have there and tightening the shrouds.
This brings the 'pressure point' of the combined sails backward, increasing the boats tendency to luff up.
Edited by dennisMe on Aug 28, 2012 - 09:34 AM. -
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Posted: Aug 28, 2012 - 09:36 AM
Ok but how would i know if what i have is right or wrong? Or if its right should the boat stear straight if you let go of tiller, is this one sign of a poor balanced boat , are all boats suppose to be balanced? i know my mast is all the way forward because this is where the last owner had it how tight is the Fore stay suppose to be?
thanks
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Reynolds 21 Catamaran #38
Pennsylvania, PA.
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Posted: Aug 28, 2012 - 10:04 AM
In my opinion, a balanced helm means you can steer the boat with two fingers, and when released will round up smoothly and reliably.
There are all kinds of calculations for Hobie mast rake that people have done, but the best thing to do is experiment. Trial and error will give you the best results. -
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Posted: Aug 28, 2012 - 11:25 AM
Mast rake is independent of forestay tightness, but it takes some adjustment to get everything set up just right.
On all cats that I know (fractional sloop rigged ) the real forstay tension is provided by the main sheet at sail time (the stays are only there to hold the boat together so you can sail it
)
I agree with Flaco, you need to experiment to get the boat sailing just the way you feel most comfortable with. I prefer for it to just track straight and not round up much, if at all. A mono will round up faster because of its shape and the effect of heel so don't expect the exact same kind of trim from a cat.
A vertical mast can generate slightly more power, that may be the reason the PO had it trimmed that way. Provided you have enough flotation in the bows to counter balance the (bow depressing) effect this could be fine (depends on boat and loading/crew). At any effect the boat should not fall off if you let go of the tiller, that plain sounds wrong!
Here's how to adjust it:
First set the forestay length to give you max mast rake, see how far you can go. then tighten the shrouds so much that the mast rotation still works properly (jiggle it by hand). If you can now no longer tighten them then ease off the forestay until you can.
Then go sailing, if you like what you feel, then stick with it, otherwise adjust and repeat. -
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Posted: Aug 28, 2012 - 12:08 PM
For the "shaking rudders" problem, is it like vibration or like wiggling? If your rudders are vibrating at higher speeds you could try sharpening up the trailing edge of the rudders to reduce tip vortex that causes cavitation.
If they are wiggling they must be loose in the castings.
To understand how your mast and rudders affect helm, weather or lee helm. There is an old but very good article here
What's All This About Weather Helm?
http://www.thebeachcats.c…s/15/about-weather-helm/
If you can digest that and apply it to your boat it will sail much better.
Lee helm is dangerous, especially on a 1,000 boat that you don't want to ever flip, so figure out the problem.
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Damon Linkous
1992 Hobie 18
Memphis, TN
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Posted: Aug 28, 2012 - 01:10 PM
that's a great article on lee/weather helm.
i restored a nacra 5.7 for a friend this spring which had horrible lee helm. by simply getting the tips of the rudders backward a few inches, it took care of the problem. that's where i would start if i were you.
j
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Posted: Aug 28, 2012 - 01:12 PM
Thanks guys, DamonLinkous , dennisMe , flaco
I have some fun work to do ! :)
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Reynolds 21 Catamaran #38
Pennsylvania, PA.
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